Why Are Solar Freakin Roadways So Freakin Popular?

May 31st, 2014 by Roy W. Spencer, Ph. D.

My blog traffic has been unexpectedly blowing up with visitors to my post, Solar Roadways Project: A Really Bad Idea.

The comments posted there suggest the Solar Roadways project remains very popular….it has now generated over $1.7 Million in Indiegogo.com crowd funding donations.

Now, I can only ask: Why the hell would any sane person take perfectly good solar collectors and try to embed them in roads and run over them repeatedly with heavy, dirty vehicles?

Do we take airplanes and drive them down roads? We could if we really wanted, I suppose.

I’m not the only one who sees the stupidity of the idea. Here’s a very critical post at ExtremeTech.com, and another at Jalopnik.com. And another at Equities.com.

The question that fascinates me is, why does this idea have such popular support? Here’s my theory.

We all have the experience of driving down, and walking on, roads. They are typically dirty, and hot. They represent sources of both eye pollution and real pollution.

The Solar Freakin’ Roadways project has cleverly suggested, why not replace those dirty awful road surfaces with nice, clean, hi-tech surfaces that do something useful (generate electricity)? Look how pretty it would be!:

I know I’ve wondered about all of that solar energy collected by the road, generating all that heat. But I also know that a solar heated surface does not mean you can generate much electricity. Solar domestic hot waters systems are over 90% efficient, but solar PV electricity generation is more like 15% efficient.

As discussed here, solar panels and roads that you drive on are two things that are very incompatible. There is no good reason to mix them. In fact there are many reasons to NOT mix them.

Nevertheless, the Department of Transportation awarded almost $1 million in Phase I and Phase II SBIR contracts to study the idea. Of course, we all know the government is careful about what it gives money away for, right? (I used to review SBIR proposals submitted to NASA. I wouldn’t have recommended this for funding.)

At the end of the SBIR Phase II, there is supposed to be a solar parking lot completed…which is big enough to park 4 cars on. Cars which would shade the parking lot from collecting solar energy. A parking lot which you can’t tilt toward the sun to collect more energy, as is usually done with solar panels. For close to $1 million.

Sorry, folks, but solar-based electricity is far from free. In fact, it’s very expensive, even under optimum collecting conditions. Even with subsidies and higher rates forced on consumers, less than 1 kWh of every 500 kWh generated in the U.S. comes from solar. You can have quite a bit more than that 0.2%…if you want to pay extra. After we went one week without power following the 2011 Alabama tornado outbreak, I looked into building my own system with cheap China-made collectors. I finally decided that it wasn’t worth several thousand dollars to collect enough energy to power only a refrigerator and a couple of light bulbs.

I encourage you to read the problems other people see with the idea, posted above. I agree we need to be investigating alternative sources of energy, but I can confidently predict this is an idea that is going nowhere. And as long as we keep spending money on stupid ideas, it takes that money away from funding more deserving ideas.

145 Responses to “Why Are Solar Freakin Roadways So Freakin Popular?”

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  1. Johan says:

    “Solar domestic hot waters systems are over 90% efficient” ? In my patch of the world (Western-Europe, latitude between 50 and 60 degrees) solar thermal at the very best can provide up to 60% of domestic hot water use.
    Really, dr. Spencer, the world does not end at your fence 🙂

    • Johan says:

      … should have added: where energy efficiency is determined by the solar fraction.

    • Johan, I didn’t say ” provide up to 90% of domestic hot water use”. I said 90% efficiency. Look up “energy efficiency”.

      • Johan says:

        I realized that, unfortunately after pressing enter (hence my 2nd post).
        I did not need to look up the definition of “energy efficiency”: (useful energy out) divided by (total energy in).
        But if I were to buy a Solar Domestic Hot Water system, I would still define its expected “useful energy output” to be my total “required” average annual domestic hot water heat demand (say 3600 kWh/year). Of course, a solar collector with a 90% energy efficiency would by definition be able to convert 4000 kWh/year of incoming solar energy into the required 3600 kWh/year DHW heat demand. But to say that the SDHW system has a 90% energy efficiency – although technically correct – would be very misleading, since (depending on many factors), it would only be able to deliver 30% to 75% of the “required” useful energy output. Which is probably why it is common practice to refer to “solar fraction” as “the efficiency” of a SDHW system.

        BTW, if you do decide to google “energy efficiency”, that turns out to be a very frustrating experience.

    • Wavelet says:

      Solar electricity generation doesn’t make sense everywhere, with current PV efficiency & prices (I think Germany is making a huge mistake with its current policy here; it’s quite possible that if that effort were delayed 4-5 years the systems would get much more cost-effective).

      However, in high-insolation areas, direct solar water heating make enormous sense. Here in Israel, 95% of dwellings have them, and such systems supply 3-4% of the entire energy needs of the country.

  2. Mike Bromley says:

    The thing that makes me wonder (to a chorus of boos) is how this whole system would be supported, both physically, and financially. It seems to me that one builds a road twice with this system. The supporting base would have to be very robust, like thick reinforced concrete, in order to steady the individual ’tiles’themselves rather massive, from jostling and shifting under constant pounding. This means that there is also the problem of hydraulic ramming if the system were deluged with water. If any road salt got down among the tiles (despite the idealistic dream of the road being self-clearing in winterthere still will be connecting roads that are salted, and that salt will make it to the ideal road), immediately you have the problem of corrosion of all the electrical connections needed to harvest the gobs of solar electricity and communicate all the fancy LED graphics from tile to tile. The system ain’t gonna be wireless, mama.

    1.7 million $ of crowdsourcing isn’t going to build much of a stretch of road. Sorry. The only way something like this is going to get under way is through massive subsidyand that’ll be just the tip of the iceberg. The tiles are necessarily going to have to be removable for maintenance or replacement, which means they WILL be clanking and klunking against each other. It sure is a cute idea. But cute is rarely practical or economical. Do re me fa so la-freakin te do.

    • Robin Pittwood says:

      And don’t forget beneath those tiles lie sewer, water, telecom, power, gas, services. You’re gonna have to install and maintain those too.

  3. David Roggendorff says:

    I haven’t read all your posts on this blog, but have a quick question. Realizing the cosine theta is alive and well, has anyone calculated the cost effectiveness in building solar panel roads in, say, Arizona where there is less traffic to damage the solar panels and to get virtually 100% exposure? I’m guessing that a square foot of I-10 would be occluded to the sun by vehicles much less than 1% of the time.

    Parking lots would be worse occlusion. Even NYC professionally parked car lots might get only 50% occlusion by parking bumper-to-bumper 4 deep and very close. Haven’t you waited 15 minutes for them to get your car out of the first spot by moving the last 3 to another slot to free your car?

    • of course, seldom traveled roadways in Arizona would be higher efficiency. But why would you put solar panels in a roadway in the first place? Even in Arizona, you should tilt the panels close to 30 degrees from horizontal.

      • Gunga Din says:

        Blowing sand in areas such as Arizona would also etch the surface of the collectors.

        And would a wild animal continue across a road if it’s first step lit up?

        • markx says:

          Tyres plus dust will etch the surface a fair bit quicker, IMHO.

        • Bill says:

          Wild animals will cross the road to get to the other side. In case you haven’t watched on recently, deer don’t like asphalt roadways all that much either.

    • Darren says:

      Given the VAST expanse of unused, desert land in Arizona, why would anyone go to the expense of building solar cells rugged enough to drive on? Cells that will get dirty from blowing dust, oil from the cars, rubber from the wheels, etc, etc, etc.

      Spending money on the most efficient solar cells possible and putting them on another small slice of the vast openness of Arizona makes a lot more sense.

      And the entire idea of a solar road is utterly absurd until every rooftop has a solar cell.

      • Mark says:

        NOT: “Given the VAST expanse of unused, desert land in Arizona”
        Just because vast areas of land are not currently used by humans should they be rendered parking lot status. A desert ecosystem is just as valid and in need of conservation as your northern treed ecosystems.
        Thank you but you’re not filling my Arizona with your ugly solar panels.

        • YippySkippy says:

          Please fill Arizona with solar panels! We might share our northern water with you if you play nice.

  4. Thanks for the sanity check, Dr. Spencer.
    The total amount of the donations for this project will be a proxy measure for the insanity of donors.
    Over $1.7 Million so far? How many different people?
    I think it is insane to know nothing about science in 2014.

    • Doug says:

      There’s a large gap between “knowing nothing about science” and “knowing little about solar panel efficiency”. While the question of maintenance is a biggie, the question of efficiency is more subtle. Yeah sure solar panels would be more efficient tilted towards the sun and in a place with more exposure, but that doesn’t mean they’d be totally useless lying flat and occasionally in the shade.
      If the price of the tech was to drop enough one day, and they actually could make them robust enough, it could work. To offset the reduced efficiency you have millions of square miles of space that isn’t an environmental concern, and you have the other proposed benefits with the LEDs etc.
      Keeping snow and ice at bay, though – that does sound ludicrous. 🙂

  5. p18n says:

    Dr. Spencer – I have given my post on the other thread some thought, and the only thing that I would change is to dial down my hubris – after reminding myself that it is healthy debate that moves these discussions forward. Also, after reading more of your web site I think that you do have some interesting and informed opinions on a variety of subjects.

    However, I would still like to live long enough to drive on solar roadways. Thank you for having an opinion and being brave enough to voice them and becoming a part of the discussion.

    • and I’d like to live long enough to see anti-gravity technology produce unlimited energy and a great new diet pill. 😉

      • TheOtherOne says:

        An argument is easier to ignore when that side lowers itself to sarcasm.
        It typically implies they see enough truth in the opposing side’s stance that they must resort to diversion tactics.

        Watch which articles you site as those, too, can undermine even the most educated position. Jalopnik’s article seems hardly creditable when it was written by someone whose own website looks like that of a shady car salesman.

  6. Groty says:

    I think it’s a function of prosperity. We effectively live in the golden age of humanity. Especially in America, but all over the world populations are increasing AND becoming more prosperous and better educated.

    Childhood disease that used to lead to early death can be prevented with vaccines that cost a trifling sum. In some cases mere pennies. We have an abundance of cheap food and cheap fuel. You know you’re living large and are dealing with first class problems when obesity among the poor is considered a greater problem than hunger and starvation.

    I may be dating myself here, but think about Maslow’s “hierarchy of needs”. We’ve mostly solved the basic problems of survival: food, water, shelter, security and basic education. With those needs met, people still need a purpose. So you get people who want to make their mark on the world by using the political process to chase uneconomic dreams. And THAT is what threatens our prosperity – indeed our society. Using politics rather than markets to allocate resources is the surest way to stifle growth and choke off the fantastically increasing prosperity we’ve achieved in the past 150 years.

    Highly educated, well fed, prosperous, environmental zealots who need a purpose in life want to believe they’ve saved the world by building roads out of solar panels.

  7. Robert says:

    I can see what your concerns regarding this matter are. This was the first thought that came to my mind as well, but then I though – hey, there’s a lot of roads with very little traffic, or roads where there’s only traffic during some time of the day. As I see it, these would be the roads where the system could be implemented first. Secondly, we don’t know how big a problem the dirt from the cars would be, unless we test it, right? And if this unit is manufactured in millions, if not even billions, one would assume the price would drop really low, don’t you agree on that? And if we have a huge surface covered with these solar panels, well then they don’t have to be 100 % effective, to still produce the electricity needed. So I still say – this needs to be tested, before we turn it down. I could easily concider covering my yard with these tiles, if it meant that I wouldn’t have to shovel snow in the winter 🙂

    • Massimo PORZIO says:

      It seems to me that you are one of those who push the argument of lowering prices for greater demand monocrystalline wafers, but that worked in conventional electronics only because along the passed years the microcircuits technologies have consistently reduced the size of the monocrystalline chips, not because the monocrystalline wafers have reduced their costs. Growing up a monocrystalline rod takes a very long time and the use of very expensive tools mounted over inertial platforms to avoid any minimal vibration to the rod and the underneath silicon melted bath.
      For example the famous Intel 8051 microcontroller designed in 1980 was made on a 12x12mm chip, now the very same processor with about 4 times the memory (say a Silicon Labs C8051F996) is made over a tiny 1.65×1.78mm chip, this is the real reason its price is about one tenth of the predecessor despite its more computational power.
      This dont apply for solar panel which need a great surface area (usually the whole wafer area) for convert photons in energy.
      A solar cell usually uses a whole monocrystalline slice.

      Have a nice day.


    • Frank K. says:

      Nothing is preventing you from spending your own money on this scheme technology. Please go ahead and purchase a bunch of these tiles, install and maintain them on your property, and tell us how it’s going in five years. Deal?

      My take is that this idea *could* be considered for pedestrian walkways or other easily maintainable spaces, but NEVER for roads. In New England where I live, here’s what they’d look like in one year…


  8. Gary says:

    Cover “my yard with theses tiles, if it meant that I wouldn’t have to shovel snow in the winter”?!?

    Um…if you get enough snow to need to shovel it, you will have enough snow to block nearly all of the sunlight, thereby making the panels worthless. You would eventually have an expensive, ice packed yard that would not work again until spring.

    Grow grass and don’t worry about shoveling it.

    P.S. Shoveling snow is excellent exercise.

    • Massimo PORZIO says:

      What (negatively) impressed me about the snow melting trough those tiles, is that the engineer seems not aware that instead of add to his “sandwich” the heating element, he could use the very same solar cell as an heater, since they behave just a groups of diodes placed in series.

      Not so smart indeed.

      Have a nice day.


  9. Sigmundb says:

    I have seen many good arguments for the idea beeing just not a competitive way to produce solar energy, using the available free,firm and flat road surface will not outweigh the cons.
    But what about the road properties, driving on a glass surface? Contaminate it and put water on it and it will be like driving on ice.
    In their FAQ they brag about high friction when they treat the surface but how long will treatments last on a road?
    Ask any road engineer what he thinks about it and will shake his head. Tell him about the million from the department of transportation and there is a good chance you see a grown man/woman cry, so many better uses for that money.

    • Jenn says:

      The problem with using solar panels to generate electricity in the U.S. Is that here, we use alternating current for most of our needs. Solar panels generate direct current electricity. Converting from DC to AC loses quite a lot of energy in the process. I don’t know if this is the inefficiency being discussed here. However, if not, solar panels are not the way to go in the Great Lakes region, where we get only 20% to 35% sun, on average! between November and March as a rule. As for roads being dirty? Yes. Just mix some snow with exhaust from gas-burning cars and diesel-burning trucks, some of shock aren’t in good repair.

  10. geran says:

    Dr. Roy, you wrote:

    “…why not replace those dirty awful road surfaces with nice, clean, hi-tech surfaces that do something useful (generate electricity)? Look how pretty it would be!”

    And, you hit the nail on the head. The eco-phonies only migrate to “how it looks”, or what it “promises”. They have no knowledge or understanding that the costs can not be justified, unless it is OPM (Other-Peoples-Money). They prefer glamour over engineering, time and time again.

    In their “minds”, they are “saving the planet”. They attempt to destroy all human progress, while claiming that we are “evolving”.

    • Massimo PORZIO says:

      For what it’s worth, I fully agree.

      Have a nice weekend.


    • Kashmir says:

      What do you mean by, “They attemt to destroy all human progress, while claimin that we are evolving.”? I’m not saying I don’t agree with you that this would not work. I just don’t see how these people are attempting to destroy all human progress.

      • Erny72 says:

        Hi Kashmir, What I believe Geran is suggesting is that by narrowing their interest away down to one (non) issue and then forcing their vision of utopia on everyone else, western closet ecomentalists who obsess over gullible warming are undermining the civilised lifestyle that two centuries of progress have bequeathed us. Reliable energy is demonised, personal mobility is demonised and both are either taxed or emburdened with costly carbon (dioxide) credit trading and as a direct consequence affordable energy, personal transport and industry all become unaffordable.

        I don’t suspect any of the committed ecomentalists are deliberately setting out to drag the world back into medieval lifestyles and the boom and bust manufacturers of solar panels who spring up overnight are only in it to make a quick buck before the fashionable fad (being seen to be fighting natural climate variation) inevitably passes, I don’t suspect any are aiming to destabilise the electricity grids of the developed world as part of some sinister conspiracy.
        It probably never occurs to any of them that foisting their agenda on the world risks the poor in developed and developing countries suffering from energy poverty (perhaps in the minds of the sort of people who come up with 10:10 ‘no pressure’ advertising, it’s worth culling a few paupers today so we can sleep well at night dreaming that we’ll save our children’s children from the worst affects of an extra degree in a century? We can’t put a price on that hypothetical pipe dream right?)

        More immediately though, as one poster mentioned already, all the financial and human capital being squandered pointlessly trying to fight gullible warming (or to cash in on the borrowed government grant money) is wasted capital that could have been better used to actually advance human progress rather than in hobbling and stagnating it.

        My children’s children will look back on this time and flights of folly such as solar roadways and wish to kick us all right up the arse for being so stupid and gullible.

  11. Marc Harlow says:

    I’m looking out my window here in northern New Mexico at 100,000’s of acres of sage brush that could be used for for solar collectives. I’m not sure what the combined surface area of our nations roadways is but between AZ, NM, and TX you could equal that surface area with highly efficient solar panels and generate a lot more energy for a much lower cost. Though it is nice that people are raising their awareness of the possibilities of solar power.

    • Marc Harlow says:

      Hey Roy what’s the deal with the “1.7 million dollars” comments? Go fishing in a different stream, there are bigger fish to fry. 1.7 million dollars is chump change and you know it.

    • Bart says:

      And, &%^$ the animal and plant life which inhabits those acres.

    • geran says:

      Marc Harlow, do you even have any clue. You are looking out over 100,000s acres of sage brush, from your window? Are you a comedian, a liar, or a comedienne?

      Please provide your altitude and location so we can check out your claims.

      Be there or be SQUARE.

  12. Bryan says:

    Why Are Solar Freakin Roadways So Freakin Popular?

    I just took a look at the other thread, and I have to admit I was amazed at the enthusiasm expressed for this idea.

    There is the appeal to emotion, the lure of “something for nothing” (free energy), fascination with technology, the desire to be part of something great and new.

    A lot of it comes down to wishful thinking and gullibility. A slick looking website with cool pictures and scientific sounding arguments is all it takes, apparently.

    • Bryan says:

      A reason I just thought of for some of the gullibility: I think we humans have too much willingness to believe people perceived to be in our “tribe”. The people pushing this idea are environmentally conscious and dedicated to the cause, so they must be good, honest, people. I don’t really understand all that scientific stuff, so I’ll trust them.

      • rah says:

        For many of us it used to be the older you got the less you “trust them”. For some reason that seems to be changing and I think it all comes back to the argument made above about how relatively easy the last couple generations have had it in the US. A country where we supply things to “the poor” that would be considered unobtainable luxuries to the impoverished in much of the rest of the world.

  13. Kit says:

    The funding success is another example of the LACK of critical thinking by otherwise intelligent people. As noted in an ealier comment, “it looks purty” wins out out over reality.

    • Frank K. says:

      No, no, no! Shhhhh. Don’t tell anyone. Let the left-wing progressives waste their money like this. In the end they have will less money to harass the hard working, sane people in our country…

  14. Massimo PORZIO says:

    Hi JohnKl,

    I apologize with Dr. Spencer and all the readers for this a little off topic post, but I reply here because the previous thread skyrocket over 400 posts!
    It remember me the nice times when Doug Cotton inflamed this arena 🙂

    About the solar panel stochastic energy production, the problem arises when the panels are connected to the grid and they pretend to supply energy to the grid itself.
    I know that, especially there in the US, many farmers use them for supply their farms. But in that case (AFAIK), they have some batteries and in last times they complement the energy system with some little windmills which are a little predictable (at least about their daily averaged energy production).
    The only problem with the localized stand alone solar energy production is the battery life.
    In fact, (always AFAIK), the best performing battery last up to 500-600 full charge cycles (for solar panel system, it equates to about a couple of years). I know that someone would argue that lithium polymers battery are rated up to 10000 charges, but there are two little details that are omitted for that statement, that is they perform that number of charges under controlled low currents (to avoid heating of the elements) and the charge cycles are function of the “deep of discharge”. The 10000 cycles are for very low “deep of discharge” (less than 10%), see here:


    Anyways, I’m not contrary to the stand alone solar panel, but the owner should be aware of the batteries changeover cycle.

    When the solar generator is attached to the power grid its all another story. Here in Italy anybody pays in the energy bill a 4% fee to allow those on-grid PV producers to gain some money from their little plants production. But since their very little production could never justify the cost of their PV plant, the government use those taxpayers money to give them three times the real value per kWh for their energy produced. I put producers between quotation marks because anyways, as already said, in this case they are just tolerated on the grid. Their energies are just dissipated along the grid connections.
    Just to say, its the same as per the domestic energy consumer: I dont really know if in LA where you live (by the way, very nice place, Id been there in 2002 for a vacation) is the same as here in Italy, but here a domestic user the more consumes the more pays the energy.
    What a strange thing I think, usually the more you buy the less you pay, do you asked yourself why?
    Its because a low power user is just like it was not on the grid, it just considered as an energy loss exactly as many other joule effect losses on the power grid.
    The same is valid for the little PV producers. By the way the Italian law I previously cited is applied only for the PV producers having peak systems rated above 3.5KWh.
    Until this little PV producers dont stress the power grid out of +/-15% the grid owner can do nothing, exactly as they didnt exist at all.

    About the PM10 issue:
    Unluckily Im not able to find any document in English but here is the Italian report commissioned by the city of Torino:

    (remove the two underscores I added to bypass the automatic moderation of the web site)

    The report is complex and it is about all the air measurement done by the city of Torino and some statistic about the city traffic.
    Anyways the graph on page 12 show you how the 1993 Euro 1 gasoline cars are many time less PM10 pollutant than the 2006 Euro 4 diesel cars (in Italian gasolio stands for diesel while benzina stands for gasoline).
    Now we are at Euro 6 but the improvements done are really negligible because, even if after Euro 5 the limit for the particulate has been set to maximum of 0.005g/km (anyways more than the Euro1 gasoline) . For gasoline cars it coincided with the introduction of an insane device on the exhausts which some times burns the particulate. Who owns one of those cars has to know that it happens when this burning process is running, that is the car speed is limited to no more than 70km/h!!!
    A friend of mine had that experience while he was surpassing other cars on the highway fast lane and he told me that it was not a good experience.
    If you believe this is not sufficiently crazy, well take a look to our European rules:

    (again remove the two underscores added around the slashes)

    Read the table under the chapter Emission standards for passenger cars, do you see the crazy thing?
    From Euro 5 also some gasoline cars are regulated about PM10 because now they introduced the gasoline direct injection engines!!!
    My current car is one of those gasoline direct injection engines Euro 4, it means that instead of having the stoichiometric ratio fixed by the air intake, it is fixed by the stupid microprocessor in the control box which drives the fuel pump (note that Im an electronic engineer, so I should be glad to see electronic device like the one I design applied here and there, but thats is a very stupid application IMHO).
    Well, I always had gasoline cars in my life, but this is the only one which make its exhausts so dirty. This kind of car is supposed to reduce the production of the other pollutants (CO2 is claimed to be reduced too), but now it is PM10 pollutant almost as the diesel cars!!!
    And they call this progress.
    Anyways I conclude saying that Im not a medical doctor, but I dont believe that PM10 at the current concentration shouldnt do so much to our health, look this last report:

    (remove the first three underscores)

    Also this one is in Italian, and only the abstract is in English but it says just a little of the results. Anyways looking at the graph on page 15 you can see how in the restaurant smoking areas the average concentration is about 4 times the 50ug/m^3 of the current open air regulation limit.
    Instead on page 13 you can see the indoor concentrations of PM in a ventilated room of 30m^3 produced from a single cigarette Its 10 times higher than the open air regulation limit!

    Anyways I don’t know what’s the situation of the air in LA today, when I visited downtown LA in 2002 the air was much better than in Milan.
    If you’ll visit Milan, I suggest you to take a breath on corso Buenos Aires, and feel the smell of a society which decided to move on diesel cars 🙁

    Have a great weekend.


    • Massimo PORZIO says:

      Ehm… One more time I reread my post and found a mistake, the one cigarette experiment demonstrates that the particulate is 100 times (10 as I wrote) the current open air limit.

      Sorry, is late at night here, and probably is much better I go to sleep.

      Again have a nice weekend


      • KuhnKat says:


        Here is what JunkScience thinks of PM10:

        “I suppose you would wonder why I bolded the Hazard Ratioswell because this is an observational study with mortality rates as the endpoint and here they are again, claiming that a less than 10% increase in rate of deaths is proof of causation.

        I need not point out that such a small association is always what these studies come up with, and it means nothing. ”


        • Massimo PORZIO says:

          Hi KunKat,
          Maybe I’ve been not clear, I fully agree with the conclusion of JunkScience. In fact I highlighted how it’s enough one single cigarette into a 30m^3 room to skyrocket the PM10 to 100 times the current open air limit.
          My point was: if PM10 was so dangerous we can’t discriminate cigarette as carcinogenic. Since we know that cigarettes are carcinogenic then we know that the open air PM10 is not so dangerous.

          But this doesn’t mean that we are born to breath particulates.

          My point is that since we are all organisms specialized in evolving and adapting by selection of the subjects who survive to the new established environmental conditions, some have to “pay the bill” (I think about the people who suffer from asthma, but also to the one like me who just feel bad sniffing the smell of the diesel exhausts).

          The answer should be: what is better between reduce a supposed pollutant such as CO2 and a reduce a well known pollutant (no matter how much dangerous) such as particulates?

          Have a nice Sunday.


          • Jenn says:


            The difference here is that while it may still be the social norm in Italy for some to smoke in a living room, I have never seen anyone park a car or a bus in someone’s living room, and leave it there to dispel exhaust fumes.

          • Massimo PORZIO says:

            Hi Jenn
            You miss the point.
            The point is that if PM10 was so carcinogenic to be dangerous at the current open air limit, then we didn’t discriminate smoking as the culprit of lug cancer.

            The kind of smoke produced by cigarette and diesel cars is very the same.

            Have a nice day.


          • Massimo PORZIO says:

            Sorry, I missed an “n”, it’s “lung” not “lug” of course.

    • Bart says:

      Massimo – thank you for your posts on this subject. Much good information.

  15. Pine Tree says:

    Why are solar freaking roadways so popular ?

    Did anyone consider for a minute that regardless of any scientific type studies or mind numbing mathematical data , Some of the people of this world would like to ease the strain on this over burdened planet in any way they can even if the costs of producing this energy appears ridiculously high or the benefits seem small.
    Perhaps they want to see change.
    Just saying (with out any scientific proof what so ever)

    • Bart says:

      Change can be good, and it can be bad. Changing from a world of plentiful energy and minor pollution, which is decreasing all the time as we devise more efficient methods to utilize the fuel and eliminate the byproducts (Jeez, if any of you could have seen LA in the 60’s and 70’s like I did growing up, you would have an inkling of just how far we have come), from fossil fuels…

      … to one of meager, intermittent energy with major pollution from toxic chemicals and heavy metals in the construction of these generation and storage devices on the enormous scale necessary to make even a small dent in our energy appetite, while creating intense heat sinks enough to make the worst urban heat island effect look moderate…

      This would not be good change.

    • Objectivist says:


      The problem with “easing the strain on this over burdened planet in any way they can even if the costs of producing this energy appears ridiculously high or the benefits seem small” is that it would be smarter to use the money spent for something more effective. We do not have an endless supply of money to address the myriad problems we face.

      Solar power is fine, and is particularly good when used for endpoint generation – roof space is generally wasted. Solar power is not good for industrial strength power generation. Since solar is not constant, there needs to be backup generation available. It would be bad if factories stopped running on cloudy days – or home heating for that matter. The other problem with solar is that to generate large amounts of power requires a lot of land – solar is a low density power source. Do we really want “hundreds of thousands of acres” covered with solar panels as another poster suggests above? (Amusingly, several large scale desert solar projects in CA are on hold for five years while the government evaluates their “environmental impact”).

      What is needed is plentiful, cheap, clean, high-density power. LFTR (Liquid Flouride Thorium Reactors) look to be the best and most practical approach until fusion becomes workable for power generation. Check out flibe-energy.com for more information.

  16. Mel says:

    As intimated by a number of bloggers; if you were to use these as roof panels, parking lot shade structures, or even as roadway shade structures (all of which could be more appropriately aligned to the sun), the possibility of even beginning a discussion whether the costs/benefit might be plausible or not could be entertained.

    Like with the global warming mantra crowd, don’t let the facts get in the way of the “warm fuzzy” agenda, seems to be in play here. There may be practical uses for the technology; (without regard to cost issues) but roadways would most assuredly be way down the list.

    At the top of the list would be safety type uses where conventional power sources might be very expensive.

    Just off the top of my head maybe channel markers or remote light houses- but based on my limited understanding of engineering probably would need the lumens from OLED’s versus what traditional LED’s emit.

    That it might be used as a gimmicky dance floor surface, while fun, hardly addresses the world’s energy needs.

  17. L leeman says:

    Thinking just a little about solar roadways…my thoughts wander to OHM’S LAW. It is one thing to generate electric power, another to move it to a useful place. Would we be talking about a DC system with huge copper bus bars embedded in the road or would we be talking about high voltage series connected DC roadways (ZAP!). The classic solution to power transmission is Alternating Current and high voltage. So maybe you would have to embed INVERTERS into every few hundred feet of roadway and have a high voltage AC roadway.


  18. David V says:

    If my Facebook timeline is anything to go by, Solar Freakin Roads has plenty more money to come. I’ve tried pointing out the flaws of the scheme to my otherwise intelligent Facebook ‘friends’, but they shout me down with the usual “we have to try anything to save the planet” guff.

    I’m afraid green religion is too entrenched in our society and we’ll see many more millions of pounds, dollars and Euros thrown into the bottomless Eco pit. Meanwhile, I have designed a proactive regulator for electrical heating systems which can save cut heating bills by around 20%. Can I get funding? Can I hell. We’re doomed.

    • Timothy Bull says:

      I know, people want technology to solve their problems and give them hope for the future.
      Real environmentalism isn’t all tech glamor It’s about cutting back and weighing the difference between what we want and what we need. Most pro supporters will argue fervently and with passion how solar paneled roadways will help save humanity while at the same time eat too much and buy too much junk let the water run while they brush their teeth boil more water than they need to make a cup of tea and so on.

  19. Paul Martin says:

    What I don’t understand why you guys that are so intelligent can’t speak with some respect, man you don’t. Like it, think it’ a bad idea fine. But how about listing the things you say are the problems give it to the them and see how they deal with it or address it. What’s your idea to theirs?

    • Joe Wooten says:

      Stupidity deserves absolutely NO respect. Only ridicule.

      • Kashmir says:

        While you may not like the idea (not saying I do) a little respect goes a long way. If you are disrepectful and bash people, others are not likely to put much effort into listening to any of your ideas, no matter how reasonable.

    • Kashmir says:

      I agree that the conversation should stay civil.

  20. gbaikie says:

    p18n says:
    “However, I would still like to live long enough to drive on solar roadways”

    Well why not be slightly reasonable and put the solar panel above the roadway. Why must drive over them with heavy vehicles?

    One combine a number of needs. One have these solar providing night time lightning. They could provide partial shade. And they could useful on the those roads when sun low on horizon so that to see the road, you looking into the sun.

    So they have to high above the road and/or partially covering walkway and parked cars. So the vehicle which taller are prevented form using the road.
    You have them able to tilt towards the sun- therefore need to be spaced apart.
    Probably biggest problem is vandalism. And therefore would also include surveillance. Second the components should low cost and thereby not offering an attractive target for criminals.
    Next, such panels will become dirty, so need a way to cheaply clean them. One think of solar panels as way to recycle water.
    Or the energy one harvests from solar energy will be only used by the road itself. So road collect water, purify water, and uses water to clean panels [and road] and provide night time lighting. And surplus power might provide power to parked electrical vehicles.

  21. russell says:

    1.7 mill is nothing. It’s worthwhile as a research project if nothing else and as long as it’s crowd sourced it doesn’t bother me even a little bit. Truth be told I’d rather see a few mil dollars spent on something like like than 2 billion on a basketball team or hundreds of millions on election year lies or futile military adventures. Even if this comes to nothing which I think most of us can agree will be the case, maybe we will learn something useful that some of us don’t already know and can move on to the next big idea.

    And for the record, my 2100 sq ft log house in extreme Northern Ca. is entirely powered and heated by a combination of solar and wind, (full disclosure, I have a diesel back-up generator though in the last two years I have put less than 20 hours on it and those were primarily for routine maint.) Not even wood burning stoves. It was expensive but has recently paid for itself. There is no good reason not to pursue “clean” , and I use the term guardedly, energy alternatives.

    • KuhnKat says:

      Fine, use a combination of Solar panels OVER the roadway and wind turbines along the route also. Except many of the routes will NOT be in areas where the wind turbines will produce much either.

      How much would it have cost you to lay down a transmission line to your cabin?!?! Probably MORE than the very expensive cost of your solar/wind/battery/generator installation. Try telling us what the cost per kwh for your system has been so far, oh, and don’t include any subsidies you may have gotten where WE paid for it for you!!!

      If 1.7 mil is nothing I am sure you would be happy to send that much to me as I would like to put a similar system on my mothers home in southern California where the solar WILL be reasonably effective. Who knows what we might learn that could be useful to others!!!

    • Bart says:

      I see people extrapolating their little cabin in the woods to the larger society all the time. Why do they think a major industrial plant can operate on such pittances of power? Do they ever bother to look up the numbers of just how much power we consume overall relative to their own little corner of the woods?

      • Aaron S says:

        When is it my turn to stay over? I feel I partially paid for your house through my tax dollars that subsidized the home’s energy system so I guess in fairness I should get one night stay. I get the concept, and also dream of Off the Grid living (I don’t have a car for a similar reason), but alternative energy is a luxery and I am curious that you say your home has paid for itself. Can you share the math please? Because I am curious about your set up. My guess is your weather is moderate so it would not be expensive to heat and cool anyways.

    • Kashmir says:

      Thank you. Since this is crowd funded, I also have no problem with these people researching a technology that could help humanity. Maybe they will have a breakthrough that could change how expensive solar energy is. Maybe they will change their minds about using it on roadways and go with something more logical. I would rather see money donated to a cause like this anyday than to see it donated to lobbyists or politicians.

  22. Henry Behring says:

    “There is not the slightest indication that nuclear energy will ever be obtainable. It would mean that the atom would have to be shattered at will.” – Albert Einstein (1932)

    “Everyone acquainted with the subject will recognize it as a conspicuous failure.” -Henry Morton, president of the Stevens Institute of Technology, on Edison’s light bulb (1880)

    “The horse is here to stay but the automobile is only a noveltya fad.” -The president of the Michigan Savings Bank advising Henry Ford’s lawyer not to invest in the Ford Motor Co. (1903)

    “Rail travel at high speed is not possible, because passengers, unable to breathe, would die of asphyxia.” – Dr. Dionysius Lardner, professor of Natural Philosophy and Astronomy (1823)

    “There is no reason for any individual to have a computer in his home.” -Ken Olson, president, chairman and founder of Digital Equipment Corporation (DEC), in a talk given to a 1977 World Future Society meeting in Boston.

    “The world potential market for copying machines is 5000 at most.” -IBM to the eventual founders of Xerox (1959)

    “A rocket will never be able to leave the Earth’s atmosphere.” – NY Times article. (1936)

    • Henry Behring says:

      “I agree we need to be investigating alternative sources of energy, but I can confidently predict this is an idea that is going nowhere.” – Roy W. Spencer, Ph. D. on Solar Powered Roadways (2014)

      • Chris says:

        Invest your money then.

        But don’t complain if that is the last you see of your money.

        It appears to me that it is your money they are risking, not their own.

  23. 1wyz-x-wyf says:

    I’ve read & read & gone from blog to blog and I am absolutely amazed at how thoughtless these comments are.
    Your opinions are “in the moment”.
    You might be coming from engineering backgrounds and scratching figures on envelopes, etc… but look at the big picture.
    To get started it creates jobs, jobs, and jobs!!!
    It creates lighter weight electric vehicles… plus safety by eventually using safer components.
    Recycling will run rampant in all facets of our lives!
    Engineers, inventors, all persons with vision will be creating a whole new world… a prosperous new world.
    The economy will receive the shot in the arm we’ve needed for years!
    This represents HOPE for our future!
    Instead of poo-pooing these people and their plan… just watch… and dream of your own piece of the pie!
    Every single person donating knows it’s a risk. They know they aren’t getting their money back. Perhaps they believe they are paying it forward.
    Why is your opinion any better, better or more meaningful than any of the other opinions? Some people are just willing to back it up than others.
    You are a product of what you think!
    Besides… what does it hurt if it fails?
    Does it benefit anyone for you to be right? Not really.

    • Massimo PORZIO says:


      “Does it benefit anyone for you to be right? Not really.”
      For the moment they already received $100,000 for Phase I and $750,000 for Phase II from DoT, that is from taxpayers.
      When the enterprise will fail all those taxpayers money are wasted.
      If DoT did a better analysis on the projects reliability, those money could be used for other better enterprises.
      A founding system works well until the founder side is operated by people sufficiently intelligent to determinate where and if put the money.

      Have a nice day.


      • Kashmir says:

        Those dollar amounts are measly compared to some of the stupid things our government spends money on.

        • Massimo PORZIO says:

          So, I suggest you to ask your government to give you $100,000 for idle every year, any US citizen should ask that, it’s so “measly compared to some of the stupid things our government spends money on”.


          Have a nice day.


    • Frank K. says:

      Please sell all of your own assets and invest in this technology. I mean every single cent you have. No one is stopping you. Then you can leave us productive citizens alone…

  24. Sren Visby, Aalborg, Denmark says:

    Ive installed solar panels on my roof. Over a year they produce more electricity than I use.
    In Denmark we can sell back power to the grit when the sun shines and buy when it doesnt. In the end of the year I pay for the difference. Works like putting money in the bank.

    So… There is a far way before solar panels should go in the road but

    • Sren Visby, Aalborg, Denmark says:

      … on roofs they are fine… 🙂

      • Chris says:

        Once people are paid wholesales rates for the electricity, and charged commercial rates for using the distribution system I expect things will be quite different.

        You can’t run a grid by paying people 44c /kWh for their electricity, but only charging them 33c /kWh for the power they use.

        The current system of solar subsidies is not sustainable.

    • Aaron S says:

      Like button pressed!

  25. Milton Hathaway says:

    Yep, I agree, it’s an odd one. The only thing I can think of is that a road looks cheap – it’s all underground, out of site. As opposed to even a very simple structure to hold solar panels at an angle – somehow we perceive even simple structures as being expensive, maybe? And that simple structure looks delicate, where a road looks robust. I’m almost tempted to call it an optical illusion. But probably ‘mental illusion’ would be a more appropriate description – the idea that you can take something expensive and delicate and recast it into the form of something robust and cheap, and magically the former assumes the desired characteristics of the latter.

    Even the skeptics seem way too optimistic in their criticisms. For example, the cost comparisons appear to compare materials + labor for an asphalt road to just the materials for a solar panel road.

    Hey, I got an idea! Instead of inflexible glass, make the solar cells out of a flexible material and wind it up on large rolls at the factory, then use a large ‘paving’ machine to lay the road down quickly at the job site with minimal labor cost. Wow, that’s really visionary, don’t you think? Crowd-funding, here I come!

  26. Jim says:

    PV’s embedded in a roadway?

    I have occasionally tried to think of ways to use the heat collected by a parking lot (e.g thermocouples) but using photovoltaic cells in the road? That is crazy for all the reasons cited by Dr. Spencer in his first post on the subject and more. (Driving over glass covered computer chips?)

    PVs mounted on posts over a parking lot (or road) would be much cheaper and more practical in every way, except for two considerations: (a) the higher profiles make them much more susceptible to wind damage, and (b) at current prices solar just cannot pay for itself without subsidies under any circumstances. (If it did companies would be putting it up themselves.)

  27. Andy Wessel says:

    There would be no problem raising the money to do this. The central banks could just print it up and loan it to the government, who would bankroll the whole thing, they wouldn’t even have to raise taxes. Then a couple years later a gallon of milk or a dozen eggs would cost 10 Million USD and those solar streets would be in flames in most urban areas. The social upheavals would likely terminate such a project before completion.

    The problem lies in creating the capital structure to do this on a wholesale basis and in a sustainable manner. As per the previous paragraph, credit expansion to bankroll the project would obfuscate the economic signals that would indicate if the project were viable in the first place. The jobs it would create would have no basis in economic permanence, they would exists at the whim of bureaucracy. A shift in the political winds would leave vast infrastructure and resource allocations wasted. If the market won’t do it, it shouldn’t be done.

  28. James F says:

    Another factor seems to have been completely overlooked. They’ve got a textured surface for traction.

    The road noise that will come from these textured sufaces if driven over at speed would be aweful. Road engineers have spent decades making roads quieter.

    Furthermore, their concept pictures show cycle lanes. The only cyclists who will rise on a textured surface out of choice are emuntain bikers. For normal bicycles, of the type you’d expect to find in the city as shown, a textured surface is incredibly uncomfortable and slippery to ride on.

    Also, most roadways have a camber so water drains off them. To create a camber using these, it would create a covex surface, so making the gaps between each tile larger and further increasing the road noise problem.

    • Kashmir says:

      It seems that motorcycles would have a very uncomfortable ride as well. That was my first thought when I saw the surface they were planning to use. I hadn’t thought of the noise.

  29. Onne says:

    Hi, I agree that solar roads are not a good idea on their own. And the presented plan has lots of issues to be solved and proven. But the whole affair is not as silly as you make it out to be.

    Perhaps a perspective where the solar power is more a side-effect, a means to an end, might make more sense? Basically a road tile, self-powering, some LED lights, perhaps some heating, (wireless) communication with neighbouring tiles, lasting at least 10 years. I can see that happening. Heck I would buy quite a few today!

    I’d guess the moment these need to be wired up, costs go way up, so does maintenance. The solar aspect is a very unlikely affair, even if all the unknowns come out favourable. But would wallmart this? At 100 times the cost of regular paving costs? Absolutely. Not for generating power, but for easing their customers into parking efficiently, customising the lot, commercials, … absolutely. If maintenance costs are extremely low.

    If that very same system would still have excess energy and without tradeoffs is able to transfer that into the grid. That is how solar roads could work. But that last bit is a very big if and highly unlikely. (More realistically, I’d guess wallmart would purchase some vehicle that can drive around charging these things, induction based or such, for days solar power is too weak to charge the tiles.)

  30. Massimo PORZIO says:

    What has impressed me it’s that they states that an university laboratory had checked the glass adherence while they don’t tell which university should have done the tests.

    If I was one of them, I surely put the tests on-line to shut down any argumentation against their tiles safety.
    Anyways they wrote “We sent samples of textured glass to a university civil engineering lab for traction testing. We started off being able to stop a car going 40 mph on a wet surface in the required distance. We designed a more and more aggressive surface pattern until we got a call form the lab one day: wed torn the boot off of the British Pendulum Testing apparatus! We backed off a little and ended up with a texture that can stop a vehicle going 80 mph in the required distance.”

    Uhmm… So they used the “British Pendulum Testing”?
    And do they “designed a more and more aggressive surface pattern”?

    Do they know that that measurement tool works right only with texture free surfaces?

    Take a look here:


    If you don’t want to read all the well done reliability analysis, the conclusions are:
    “This study demonstrated the effects of macrotexture on the British pendulum measurements. On closely-packed textured surfaces, the measurements were dependent on the surface contact area of the aggregates and aggregate gap width. However, for sparsely-packed textured surfaces or coarse-textured surfaces, the measurements showed significant variations which are attributed to edge impacts between the pendulum slider and coarse-textured surface features. The edge impact effects were associated mainly with textured surfaces which exhibited discontinuities. Simulation results showed that the sliding contact between the pavement surface and the rubber slider of the test device was not maintained as the latter bounced when it impacted on the edges of the textural features. The results demonstrated that the edge impacts between coarse-textured surface features and the pendulum slider would give rise to unreliable test measurements, and care must be exercised in interpretation of the test results.”

    I promised myself to stop posting about this argument, because I prefer to spend my time better that try to convince some ignorant which want remain ignorant.

    I’m very ignorant in climatology, but even if I don’t agree with some Dr.Spencer’s climate 101 (the isothermal GHG free atmosphere is an example), I never had insulted him for that. While now I read some posts at the end of the previous thread that clearly demonstrate that very ignorant and arrogant subjects have entered this blog. So let them swim in their oceanic ignorance.

    Have a nice day


    • Kashmir says:

      I have agreed with most of your posts. But, like I said before, when you start calling people ignorant and insulting what is essential their own opinion, you lose credibility.

      • Kashmir says:


      • Massimo PORZIO says:

        I don’t believe that in English “ignorant” means different than in Italian.
        Here in Italy “ignorant” means “one who doesn’t know”.
        In fact if you read till the end my post I admitted that I’m “ignorant” too in climate science, there is not any insulting intent in that, it’s just a simple constatation of the grade of knowledge one has in a certain field.
        The simple fact that they admitted that to improve adherence they just handled the texture, demonstrates that they “ignore” that a tire is more efficient without any texture on it (have you asked yourself why in racing on dry circuits the cars mount slicks?).
        The tire textures have been introduced to deal with aquaplaning when it rains, and for that the tires designer preferred a balance between efficiency on dry and wet grounds (reduced efficiency on dry grounds to give a little better efficiency on wet grounds).
        So introducing a texture on a road surface is a very demonstration of ignorance of how things work, because textures reduce the contact surface between the tires and the ground, reducing frictions thus adherence.
        They just deceived the british pendulum doing that.

        I apologize if you fell offended about that, but in my opinion it’s much better you learn something about what you are arguing before criticizing.

        Have a nice day.


        • Massimo PORZIO says:

          By the way,
          If you were referring to my “So let them swim in their oceanic ignorance” instead, go to the last posts of the previous thread and read about who I was referring too.
          Are you lazy, don’t want to search for who I was writing about? Do you want an example?
          Read this:


          He is so ignorant, that he don’t know that none, with a little degree in engineering like me, could be jealous of didn’t have that very bad idea.

          I always respected who have different point of view, but I’m not of that kind who stay quiet when someone call me “asshole”, sorry.

          He’s just one of those “happy oceanic ignorant” I was writing about.

          Have a nice day.


  31. Gary says:

    There are a number of issues as I see it.
    1. The panels they are using are small so they have room for the heating panels and LED. So power generation is lower then their claims. 2 solar panels generate DC power which cannot be transferred any distances with converting it to AC. Which lowers the amount of usable “extra” power.
    3. Where are they going to get the silicone and silver (and the other raw materials) to build enough solar panels to cover just the interstate highways?
    4. They are using a textured tempered glass. Two issues with that. 1. How slick will that be when wet. 2. How much sun light will make it through to the panels after they get scratches from all the dust and dirt and vehicles running on them.
    It is a feel good “freaking” idea.
    Take the 1.7 million and put it towards a cost effective way to produce hydrogen and you would have something we could really use in our lifetime.

  32. Gary Argabrite says:

    There are a number of issues as I see it.
    1. The panels they are using are small so they have room for the heating panels and LED. So power generation is lower then their claims. 2 solar panels generate DC power which cannot be transferred any distances with converting it to AC. Which lowers the amount of usable “extra” power.
    3. Where are they going to get the silicone and silver (and the other raw materials) to build enough solar panels to cover just the interstate highways?
    4. They are using a textured tempered glass. Two issues with that. 1. How slick will that be when wet. 2. How much sun light will make it through to the panels after they get scratches from all the dust and dirt and vehicles running on them.
    It is a feel good “freaking” idea.
    Take the 1.7 million and put it towards a cost effective way to produce hydrogen and you would have something we could really use in our lifetime.
    Unfortunately uneducated people like the shiny ideas instead of the dirty unglamorous ideas that would really make a difference.

  33. Walford S. says:

    I am neither an engineer nor an economist, but I do have a fundamental understanding of economics.

    Right now, solar power is, for the most part, economically infeasible. It has had some small measure of success in America’s desert Southwest, but only because of the high demand for daytime air conditioning, and HUGE government subsidies.

    So I have one simple question: If solar cells on the roof are not economically feasible, how is moving them to the ground going to make them economically sound?

    Answer: It’s not. This is a huge boondoggle which I suspect is meant to attract Solyndra-like government investment, then fold under its own weight and laugh all the way to the bank.

  34. nutso fasst says:

    Wouldn’t piezo-electric generation be more efficient?

  35. Kathy says:

    At one time, airplane inventors were told-they would never work… the same with cars. Computers would never catch on….etc etc. I could go on and on and on…. Too bad you have to be so negative. Of course big electric companies will invest tons on money to push out all the negatives or even buy out the progress ideas… just like the car companies did. There is more to life then pleasing investors.

    • John K says:

      Hi Kathy,

      The problem with this idea doesn’t reside in whether or not it will “work.” More than likely solar panels can be constructed and placed on the road. The question remains does it make any sense. Let me give you an example of what I meant. Decades ago when Nicola Tesla roamed the earth he dreamt up the idea of a step up generator that could send “free electricity” over the airways and allow people with everyday appliances to run them without having to plug them into a socket. He had the device built on some coastal town if I remember and and sure enough “free electricity” went out to the masses who could turn their lights on and run their appliances free of charge from their local utility. The DEVICE WORKED! The problem of course remained that the VAST MAJORITY OF THE ENERGY EMITTED over the airways went UNUSED. The energy dropped according to the inverse square law as the distance increased from the emitter and most of it went into empty space. It proved amazing WASTEFUL even though it worked. Simply making a device that work cannot be the only test.

      Have a great day!

    • Frank K. says:

      Actually, Kathy, the free market is very good at sorting out the good from the bad as far as new technology is concerned. You are free to invest in this technology, and if it catches on and is practical, then great! But, as a Mechanical Engineer, this is just an impractical boondoggle of the highest order, and I would never suggest anyone invest in it (much less putting ANY public money in it which is better spent on other things).

      (PS – if you don’t like corporations, stop using products and services from Apple, Microsoft, Facebook, Twitter, Starbucks, … corporations all).

    • Objectivist says:


      There are fundamental physical reasons this is not a good idea. It’s that simple.

      Solar cells have their place. If someone can figure out a way to manufacture them cheaply enough, they’ll be installed on every rooftop, and that would generate a lot of clean energy. That said, solar and wind alone aren’t sufficient for our total power needs. Even the most “green” experts admit that.

      Many of the experts most concerned about climate change are now calling for a new, massive nuclear buildout. That is also a CO2 free means of power generation.

  36. John K says:

    Hi Roy,

    It seems to me there exists another dimension to solar roadways that may not have been considered, bearing in mind I have not read all the posts. If enough time, expense and quality materials go into producing these solar road tiles it seems you have quite an attractive solar subsidy for thieves. Imagine hundreds of miles of open roadway covered by these expensive solar collectors all within arms reach merely by stooping down and either disconnecting them or tearing out enough roadway to retrieve a few in working condition. While a slab of asphalt road doesn’t excite many to remove and employ for personal use, expensive well constructed solar panels designed to withstand the elements probably would. It will be interesting to discover after some boutique stretch of solar road gets constructed how many tiles remain after the first year.

    Have a great day!

  37. Peter Norman says:

    Generating useful energy from roadways is probably bonkers. However, I strongly disagree with those who think solar heating in northern latitudes is ineffective. I have 6 panels of 30 evacuated tubes optimally place to pick up direct sunlight plus reflection of light/heat behind, at the sides and below. When the sun is shining they generate nearly 50Kw in June clear skies. Outside the winter months I have a pool at tropical temperatures, domestic hot water in abundance and under-floor heating. I could use my surplus energy to heat the road but who cares whether tarmac is hot or not!

    • Kashmir says:

      So many on this thread bash solar energy while there are stories, like yours, that show otherwise.

      • Massimo PORZIO says:

        Kashmir, you missed the point that he is talking about thermal solar and not photovoltaic.
        Thermal solar plants are much efficient, the problem is that you get the hot when it’s already hot outside.
        I have a friend of mine who decided to place those solar heater on the roof of his house here in North Italy.
        Now they can have a shower: him, his wife and his two children every night by summer, but not in winter (note that also Peter talked about summer in june and clear skies).
        Paradoxically, Peter is lucky because living in northern latitudes can better use that hot energy in summer.
        Here in Italy, during summer most people have cold shower and very few times need hot water.
        Returning to the friend of mine, not only he doesn’t have hot water during winter, but he had to install a couple of fans on the external exchanger to cool it, because in summer during the hot days if he and his family were not at home, the pressure inside the pipes of the solar thermal plant rises and could make explode the pipes themselves otherwise.
        So he is consuming some more electric power for dissipating the unwanted heat.
        Concluding: solar heating is more efficient than PV, but in many places you get the hot when you don’t need it and you miss the heat when you need instead.

        It’s not so simple.

        Have a nice day.


        • bernie says:

          “Here in Italy most people have cold showers in summer.”

          Not me, when I sweltered through Summer 1966 in Milan.
          Better to have a really hot shower and then just steam in the sunshine, until dry. Incidentally, the pollution was appalling then. The stink of oil-heating, in the following winter, was everywhere. I was told that the life expectancy of occupants of the city was two years less than in surrounding places, such as Lake Varese, in the foothills of the Alps.I moved there.

          The answer to Roy’s original question is obvious:

          “It is always a simple matter to drag the people along. All you have to tell them is that they are being attacked. It works the same in every country.”

          ReichsMarshalle Hermann Goering

          They have been attacked by Global Warming; it is what they have been told – and will continue to believe for a long time.

          • Massimo PORZIO says:

            Hi bernie,
            Of course, not all use to have cold showers. Even me, I never use completely cold water. I wrote that just to emphasize that while solar thermal panels are very efficient, they usually give you heating when you need very few, and miss the heating when you need it more.
            About the air in Milan 1966, I was too young to remember something, I was aged 1 in those days 🙂

            Have a nice day.


  38. Mike says:

    I see so many engineering and cost benefit issues I don’t know when to start. Without a lot more data and a full life-cycle analysis I can’t decide based on fact.
    Looks like another Solyndra to me.

    However, as a point of interest, look up Robert A. Heinleins “The roads Must Roll” stories. As far as I recall, he assumed a near 100% energy conversion rate and very cheap materials.
    I think he also went for overhead panels.

    So if we are funding stuff based on classical science fiction, I am putting up a proposal to melt down all guns on earth to create a cannon to fire a capsule to the moon, thus achieving world peace and interplanetary (sort of…) travel at one fell swoop.

    That should get the same credulous dreamers to buy in.

    Look for “Project Jules Verne” on kickstarter.

  39. KevinK says:

    Dr. Spencer, from the comments here and at the other post it is clear that there is a huge population of folks that have no concept of practically. Of course they have never designed anything, so they think its all simple.

    Of all the freaking places on the surface of the Earth putting solar cells on roadways has to be the stupidest, most ill informed “green” idea I’ve seen in a long time, perhaps ever. And I’ve been watching “solar energy” since I did a summer intern job in college back in 1978 (or 79) at a university lab doing solar cell research.

    Back then we where supposed to be all out of oil by now (as we were informed by our President). And all the nonsense has been resurrected like a zombie. Let’s go down the list;

    1) “Solar cell efficiency will just keep getting better”, nope, the Silicon PV cells that where launched on Skylab (yes Skylab) were about 35% efficient. For various technical reasons there is and always will be a practical upper limit of about 40%. And the very best you can ever do would be 100%, only about three times higher than today. You can throw money at this all day long (The government sure has for decades) and you cannot get above 100%, no way, no how, not now, not ever. Moore’s Law (computers double in speed every 18 months) was really just an observation about how many more transistors could be stuffed into the same integrated circuit area, It does not and never will apply to solar cells.

    2) “Costs will go down as volume goes up”, nope. While some manufacturing processes do result in lower costs as the learning curve matures, there are always practical limits. Once automation and mass production techniques are applied there is a lower limit to what it costs to produce anything. Back in the late 70’s solar cells where going to be cheap enough to use as roofing shingles (I heard from a leading researcher at a university). Funny, last time I was at Home Depot(tm) I didn’t see any solar cells in the roofing aisle. And the materials are already fairly inexpensive, its all the processes like growing pure silicon crystals that add the value.

    3) “Once we figure out how to store electricity all the demand and availability problems will be solved”. Yeah right, I just threw out a college textbook from the late 1970’s with a couple of nice chapters about how we would soon be able to “Store” electricity. I remember a few nice photos of exotic (at that time) carbon fiber flywheels made at Argonne Labs. The truth is that nature has already stored the energy for us in the chemical bonds between the atoms in hydrocarbon fuels. Coal fired power plants store months of energy in big piles just outside the plant doors, all they have to do is shovel it into the furnace when we need more power.

    I’m with you on this, this idea is about as useful as a screen door on a submarine.

    I suppose it could be even stupider, we could put them on airport runways. After all the planes spend very little time on the runway, just a quick landing (with extreme forces involved) and then taxi to the gate at 100 mph. And an airport is a secure location, so nobody could steal them. And we could change the runway numbers with the LED’s (Ok, that was extra sarcasm).

    Good Lord, pave our roads with the equivalent of fine bone china to get some electricity, it can’t get any stupider than this can it ?

    Cheers, Kevin

    • Kashmir says:

      I don’t agree that solar panels should be used on roads. I do, however, think that just because solar energy has not become much cheaper in the last 40 years, that does not mean that it never will.

  40. KevinK says:

    Just did some “back of the envelop” calculations;

    The US has about 1.93 billion acres of surface area.

    Roads (and transport, i.e. railroads, airports, ports) take up about 0.027 billion acres (27 million acres).

    So the amount of surface area available for this idea is about 1.3 percent max, probably more like 0.5 percent in reality.

    What fool would bother solving all the problems (durability, safety, cost) to apply this to less than 1 percent of our surface area ??

    Oh, never mind, I see that the government funded it, there’s your fool right there.


    • Kashmir says:

      It’s crowd funded. The amount the government is giving these people is so small that I don’t care. There are worse things the government is spending on that I do care about. I won’t go into them here.

  41. Streetcred says:

    Dr Spencer, you are mystified at the “support” for the solar roads? Most likely they are all of the fanboys who have parted with a bit of capital now trying to deflect the fact that they are easily scammed … anybody that buys into the global warming / climate change / wielding / whatever, are easily scammed. Stands to reason, how foolish do they otherwise look … at least now they can point to your blog and say well see, there are plenty of (silly) people that were also taken in by this scam.

  42. Winston says:

    From http://market-ticker.org/akcs-www?post=229039


    My Ghod, The Stupid…


    “Heres an idea crazy enough that it just might work: Pave the streets with solar-powered panels that have their own built-in heat and LED lights. Thats what Scott and Julie Brusaw hope to accomplish with their ongoing Solar Roadways project, which they just funded through a hugely popular crowdfunding campaign.

    The husband-and-wife team has spent the better part of the last decade developing solar-powered modular panels that could be installed in roadways and parking lots, and would be able to collect power from the sun. Those panels could also keep streets clear of snow and ice, while illuminating them with LEDs.”

    This sort of “crowdfunding” needs to lead to indictments.


    Let’s just look at the basics. The sun falling on a black road surface will convert nearly all of the energy that falls into heat. Why? Because the road is a “black body”, and highly efficient at converting the energy into heat energy for this reason. That is, very little of that energy is lost to something other than heating.

    A solar cell, on the other hand, is typically 15% efficient at turning the energy into electricity. A resistance heater is nearly 100% efficient (call it 95% with switching and wiring losses) at turning electricity into heat but less than 20% of the energy makes it to electricity in the first place.

    So the path of solar->electric->heat is one fifth as efficient at heating the road surface as just allowing the sun to heat the road directly.

    In other words, it won’t work. At all.

    “Rather than paving streets and driveways with asphalt, the Solar Roadways panels would theoretically be able to decrease our nations dependence on fossil fuels by generating massive amounts of clean energy.”


    Not only will it not work to heat the roads you have to store the energy if you want to use LED lights because nobody wants to light the road while the sun is shining — you want to do that at night, yes? Where is that going to happen and who’s going to buy the batteries? Never mind their replacement cycles; about three years worth if you get 1,000 cycles out of them, which might be a bit ambitious (but is not entirely ridiculous.)

    In short this is utter and complete crap.

    It won’t work from a technological perspective and from a cost-replacement perspective it’s entirely impractical and cost-prohibitive.

    The laws of thermodynamics forbid obtaining a “free lunch.”


  43. Slipstick says:

    This actually sounds interesting. While certainly not as efficient as other PV applications, it makes use of an otherwise passive surface. This would be especially appropriate for sunny sidewalks, bike paths, suburban streets, and parking lots, locations where the low speeds minimize wear as a factor. As to “duty cycle” concerns for parking lots, consider the actual occupancy of the average retail parking lot, mostly vacant for much of the day and the lanes only obscured for moments. I do, however, agree with the previous comment that building roofs would be the first choice.

  44. LOL says:

    Why the fuck would you put solar panels for the cars and heavy trucks to run over? Put that shit somewhere else. Yeah, oil companies are messed up but this is no way close to being a best solution. And as for funding, if you can get Obama to stop wasting our tax dollars supporting wars and conflicts oversea, than maybe this can actually work. Good luck with that shit.

  45. Randal says:

    I’ve seen this on both FB and G+ with many people saying it’s a great idea. I don’t think it to be great at all, mainly due to the already mentioned issues (dirt/oil/tire tracking/sand), but I think it’s horrible for a whole other reason.

    It would be rather slick in morning (can we all say dew), and during any rain (I live in FL so that is a huge consideration for me).

    The tile shape and ability to connect – yes brilliant – let’s replace the sidewalks… not super efficient, but more often maintained, and not covered with cars… (and I know the 30 degree angle thing, but it would not have been angled in the road either).

    Also, how much per unit – and what are the dimensions of each unit? What type of inverter would be required? And, how many units can be connected to a single inverter? – So, many questions without answers.

  46. Kevin Race says:

    I embrace Solar Roadways. Not because I feel it is the only possible option for us as a species to drastically reduce our carbon output. Not because it is the best idea currently available. Not because it makes better sense than anything else on the table, and not because it would be “cool”. I embrace Solar Roadways because, for the first time, I am seeing a multitude of people, 43,872 at the time of this writing to be exact, come together and put their own money and resources into an idea that, if implemented, could help us to keep the Earth habitable for future generations.

    The government is not going to stop corporations from buying, selling and burning fossil fuels. The corporations themselves that are in the business of producing fossil fuels are certainly not going to just up and stop doing business. It is the responsibility of common people to come together and make the changes happen through the private sector. In order to change how business is done WE must introduce a new way for business to transpire.

    Our society requires a certain amount of energy to maintain its current power needs. As time goes on those power needs will certainly increase. Just like oil companies and businesses that created internal combustion engines began the industrial revolution turned society from gas lamps and hand cranks into the thriving system of carbon burning power plants and transportation we know today, new businesses must emerge that introduce more efficient and economical ways to deliver the same level of energy we are already using and also be able to meet the growing demands of a larger and even more technologically advanced population.

    Solar Roadways is a business that is working towards doing just that, and with the power of crowdfunding it has been able to raise capital from people around the world who are desperately looking for a way to help turn the tide. Let’s face it. We as individuals can desire change all we want, but none of us have the power to simply wish away fossil fuels. We can all watch the latest episode of Cosmos “The World Set Free” (which EVERYONE should see, by the way) and just like I did, experience an overwhelming desire to go out there and make change happen.

    But we can’t just go and make change happen. We can’t call the president and convince him to switch things over to solar power. We can’t call the big oil companies and ask them to shut off the pumps. We also can’t ask every single person in the world who relies and depends upon the system that is in place in order to survive to simply stop using power and transportation. None of those things will ever work.

    BUT, if we realize that we DO have the power to change things by utilizing commerce and industry itself the same way the companies that began the industrial revolution did in the first place WE CAN make the necessary changes that we want to bring about, and much faster than waiting for government grants to be rationed out to those with the most promising ideas.

    I am so pleased to see Solar Roadways rapidly approaching the $2 million dollar mark, double its original goal. It is proof positive that if we can come up with a product that has the ability to change our future, even if it is a product that some call stupid or ridiculous, many people who want to change the world but can’t find any other means to do so are fully behind us.

    To those who proudly scoff at the idea of a highway system made up of LED solar panels I ask, what is YOUR great idea? What offering do YOU have that could change the future? If you do not have one, kindly come up with something you feel would be less ridiculous to share first before you expel your negative energy upon something positive. Solar Roadways may not end up being THE thing that solves all our problems, and perhaps it could prove to be nearly impossible to fully implement, but as long as there is a way for companies like them to invent, test and build creative concepts eventually the right product will come along. We needed direct current before we could have alternating current. The Wright brothers did not invent the first flying machine. They simply built the first one that worked because they were able to see why all the others failed. We need failure in order to progress. Don’t be so quick to judge people or ideas that fail or only appear as though they might. Embrace the desire to achieve.

    I embrace Solar Roadways, and I strongly feel that even if their idea doesn’t fully come to fruition, their research and hard work will become part of the system that does.

    • markx says:

      Hi Kevin,

      With all due respect, to me that approach is just weird and impractical.

      Sort of a “As long as it feels good, it must be right” concept.

      Although, I am a cynical type, and have always despised action for the sake of being seen to be doing something;

      “Do something! Do ANYTHING! But, do it NOW!”

  47. Dear Sir,
    your efficiency comparison is spurious.
    You are comparing a 90% storage efficiency for electrically heated water (thermodynamically much less for gas heated water) at a cost of (what are you paying per kW hour for your utility bills ?) vs 15% efficient (going up rapidly) capture of free solar power (1kW per square meter). No contest.

    • Massimo PORZIO says:

      Dear Dr.Webber,
      I’m not sure you get what Dr. Spencer meant.
      He was comparing solar panels water heaters (90% efficient) vs photovoltaic solar panels (15% efficient).
      I’m not sure what do you mean with “going up rapid”, if you refers to the PV efficiency, it’s a statement “half true”.
      Only multi-junction cells can exert efficiency more than 25%, but the availability of the semiconductor for that device is not enough for made much panels.
      For the moment the planck black body of silicon (which is the only material available for a massive PV production) limits the efficiency to about 25%.
      I see you are involved in nano technologies, and I know that someone suggested to design nano dipoles to catch the EM field of the sunlight that way, as there were antenna arrays. I don’t know how he could handle the multi antenna couplings for the high power capturing required, anyways I wish anybody involved in this research good luck.

      Have a nice day.


      • Hi Massimo, I am just saying that 0 pence per kWhr divided by 0.15, for solar power, is a lower cost than 17 pence per kWhr (what I pay) divided by 0.9.
        Also, I have recently been an advisor for the US Dept. of Energy in exactly these fields, and I can assure you that there are some excellent technologies ubder development, many of which, as you say, rely on nanotechnology. I can not say more.

        • Massimo PORZIO says:

          Dear Dr.Webber,
          what is wondering me is the supposition that the energy produced by the solar panel on the power grid can be really used.
          Since the production is discontinue and quickly changes depending not only by how much clouds are above but also by the percentage of humidity in the air, the power grid owner should have some alternative power generators to smooth the continuous high and low of the grid.
          AFAIK there is no way to do that, when Germans dealt with that issue about the slowly changing energy production of wind farms, concluded that they need a lake sized as their 4th national lake placed at an altitude of 3000 meters with the turbine placed at the sea level for buffering the grid.
          Note that they switched to the wind farms when they realized that solar power changes at ground are too quick to deal with.
          I would be optimistic like you, but I really skeptic about solar on the grid.

          Have a nice day.


  48. Europes first green train leaves the station thanks to Belgiums Solar Tunnel.
    These are not wooly-headed pie-in-the-sky people.

  49. David says:

    It is very easy to tear down an idea or talk smack about it. Is the first thought that came to mind after reading this thread. I don’t particularly believe this plan of solar road ways is very likely. However this is mostly due to implementation, sustainability and corrosion of the solar panels. However there are scientific arguments to be made. Just like the people who like the idea based on emotion I sense there are many here responding likewise.

    It frigging annoys me. sorry about that I really do not mean any offence and if you are against this idea because of the articles you read and based your opinion due to research on the matter you should not be offended. People like Roy W. Spencer, Ph. D, who have a better understanding of the subject matter should speak up. Me however having no background in either engineering or solar energy collection can only base my opinion on what experts say.

    I applaud the people that try to come up with ideas that could help. This idea might lead to something more constructive so I do hope this couple will continue their research, in fact I hope that people will join their efforts to prove or disprove their theories. So that further more realistic steps can be taken. People that just shout this is ridiculous don’t really add to the discussion of a; global warming ‘b; alternative energy resources.

    Thank you very much.

    • rog says:

      “It is very easy to tear down an idea or talk smack about it.”

      No, it isn’t.

      “A Lie goes half-way around the world, while Truth is pulling its boots on.”

  50. Dr. Strangelove says:

    Roy asked “Why the hell would any sane person take perfectly good solar collectors and try to embed them in roads and run over them repeatedly with heavy, dirty vehicles?”

    Because the inventors are fooling the ignorant and the ignorance of the Department of Transportation is astounding. This project made the winners of the Ig Nobel Prize look like amateurs. It deserves the highest award of the Annals of Improbably Research.

  51. Ansgar John says:

    Park cars UNDER solar panels. Utilizing parking lot space and keeping cars cooler. Makes sense Dr. Spencer?

  52. Some guy says:

    15 percent now is better than 0 percent. Also imagine what we thought of trains, cars, computers and every other form of advanced or advancing technology we had in the way you explain why not. Up front cost are always high, but trains were and are still very successful, although a large cost went into its infrastructure. Car design and production is not cheap but we still buy them and buy them again and the industry continues to grow. And computers have become the most profitable industry ever. Should of the Macintosh never been invented? What about the palm pilot? I think it is absurd to look at the cost and think hmm is it worth it? I put money on it that someone else is making a prototype of this now to see what they can do better. It appears it can be a very profitable industry for a long time. I am truly astonished how un-innovative we have become. It seems that this has more ducks in a row than a lot of other great ideas out there that we’re funded. If it was at its latter stage and the cost was where it would be at “mass production” I would use these for my driveway and side walk!

  53. K. Mueller says:

    If in doubt about the solar roadways project, please read the FAQ:
    They cover your concerns.

    Kind regards,
    K. Mueller

  54. Anna K says:

    Wow, people are pretty negative about something that is just a research project at this stage…

    The money is for research and further prototyping to see if it is feasible. Don’t say it’s not until the research has actually been done.

    Sure, there are lots of challenges, but I’m pretty sure that the designers have also thought of those challenges, folks.

  55. Bill McMurray says:

    Just what I’d expect to hear from an ‘ENGINEER’ after all you guys are never wrong, right!!!!!!!!!!!!!!!!!

  56. Ian McKay says:

    The general misunderstanding of thermodynamics, civil, mechanical and electrical engineering and economics doesn’t surprise or bother me. I know more about these things than the layperson but I am certainly no expert nor do I claim to be. What really bothers me is the hate filled rants of the ignorant stating that people like Dr. Spencer are stating that solar roads are a bad idea solely out of self interest. In what way does this help him? This project will undoubtedly fail and people will blame oil companies, right wing politics, venture capitalists, etc. I am a staunch socialist and I support well planned, well run government projects that serve citizens. Spend the money on better public transit, heat recovery systems, geothermal projects, and any number of more worthy projects.

    People who support solar roadways don’t understand that it is an idea that is flawed in virtually every aspect. Maybe they can ride their electric bicycles (good idea) to their homeopath appointments (don’t even get me started) rather than drive their magical cars on magical roads.

    If this project does get billions in government money before failing, I will not say “I told you so” with a smile on my face. I will not be smiling at all.

  57. D.Cole says:

    I posted this on the other page as well:

    Some calculations regarding heating roads in the winter.

    A “Sunpower” solar panel can produce a maximum 230W over a 13sqft area. If we assume the panel is at peak production for 4 hours every winter day (pretty optimistic given the sun angle, clouds, trees, parked cars, etc), then the panel will produce 920Wh (Watt-hours) over a 24 hour period. If we assume that the average winter temperature is -5 degrees Celsius (23 deg F) and that the panel must be kept at a temp of +1 degree C (34 F) to melt snow, ice etc, there is a 6 degree C temp difference.

    Convective heat transfer from a glass plate:

    Q = hc x A x dT

    Q = heat transfer in Watts
    dT = 6 degrees C
    hc = 50 W/(m^2K) (convective heat transfer coefficient for moving air)
    A = 1.21 m^2 (area per 230W solar panel. Equivalent of 13 sqft)

    Q = hc x A x dT
    Q = 50 x 1.21 x 6
    Q = 363 W

    So 363 Watts are required to keep the panel above freezing in -5 deg C air. Over 24 hours this becomes 8,712Wh.

    Energy produced per day: 920 Wh
    Energy consumed per day: 8,712 Wh

    To make this perfectly clear, the 13 square foot section uses almost ten times more energy than it produces in winter conditions. This does not take into consideration windy days or energy required to melt snow or ice, only to maintain the surface temperature in cold air.

    For those who say the energy can be imported from other areas, you can see that you will need a great deal. How far will this energy have to travel? Transmission losses in low-voltage lines can be significant.

    Other questions I can think of:

    1. How is energy stored at night? Batteries?

    2. Where do all the raw and processed materials come from to make the batteries, PV cells, and microchips? Is this any less harmful than extraction of petroleum products? How is this stuff disposed of?

    3. The losses to invert the DC to AC may also be significant.

    4. Cost? If you think concrete/asphalt is expensive, solar roadways would essentially pave the road with microchips, LEDs, load sensors, control circuitry, batteries, etc in addition to the still-required gravel or concrete base. How much $$ are rechargeable AAs at your corner store? What about microchips or LEDs?

    5. If optimized roof-mounted solar panels are only economical using government subsidies and require 100% back up grid power from hydro/nuclear/gas/coal, how will solar roads work?

    Solar roadies, please help me out here.

    D. Cole
    Mechanical Engineer

  58. spec homes says:

    I’m bookmarking your site, and I_m totally subscribing to your content!

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