France To Build 621 Miles Of Solar Roads

Yves here. Solar roads sound too “gee whiz” to work. But it would be terrific if they did. Readers?

By Michael McDonald an assistant professor of finance and a frequent consultant to companies regarding capital structure decisions and investments. Originally published at OilPrice

Roads have been mostly the same for a thousand years. Different types of vehicles traveled on them, and the surfaces might have been made with different materials, but the basic function of a road has been the same since the Romans built the world’s first highways. All that might be about to change.

Building on the Climate Accord reached in Paris last December, France’s minister of Ecology and Energy recently announced that it will pave 621 miles of road with solar panels over the next five years. The goal of the project is to provide enough energy to power homes for 5 million people – roughly 10 percent of the country’s population.

The project is called the Wattway and is going to be a collaboration between French road builder Colas and the National Institute of Solar Energy. The remarkable thing about the project is that the 1,000 km of road will be paved with solar panels embedded into the road itself. The panels are about a quarter of an inch thick and supposed to be able to withstand highway traffic without making roads more slippery.

There are a couple of other projects that are similar in concept including a 229 foot bike path in the Netherlands that is using a similar principle and a research-stage project in Idaho involving the research and development of solar panels for use in road applications in the future. Needless to say, neither of these projects is in any way comparable to paving more than 600 miles of road with panels. France’s effort is truly unparalleled.

There are a lot of skeptics of the French project, and just because it is an ambitious large scale effort does not mean France’s efforts will be successful. Yet in terms of taking a big risk with potential to change to way the world looks at one of the most basic transportation conduits, France’s effort is amazing. Colas says that 215 square feet of panels will be enough to power a single French home, with each kilometer of roadway supporting the energy needs of 5,000 houses.

The economics of the project will need to be markedly better than the Netherlands experiment before any of this effort makes sense in the future though. In the Netherlands, the 229 foot bike path cost $3.7 million to build and generated roughly $2,000 worth of electricity in its first year. At that rate of return, France’s project would be a complete fiasco. With that said, France is using entirely different technology, and it is impossible to project what the cost of the project might be. The Netherland’s bike path was around 1,000 square feet which means it cost roughly $3,700 per foot to install. The French project is a little more than 78.5 million square feet, so at the same cost per foot, the 620 miles of road would cost an unaffordable $290 billion. Obviously the economics for France will have to change drastically versus the Netherlands project for the project to ever get past the announcement stage.

There are a whole host of additional unanswered questions to be considered from what will happen when the solar panels get dirty or covered in snow to the issue of replacing panels that die over time and the expected useful life of the road. None of these questions have been answered yet, but the cost of the road is one of the first issues that will need to be settled. At this point trial portions of road are being laid out though, and financing plans for the project are being considered.

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    1. jgordon

      Well I do have some passing familiarity with science, and when I think about just how dumb the idea of solar roads are I want to cry. Everything that can/does make the economic of solar panels on a rooftop bad makes it 10x worse when you put them under extremely heavy motor vehicle traffic. Maintenance of glass and complicated electronics that has to survive under the load semi-trucks regularly rolling over it will be an absolute nightmare to begin with. Were talking about Startrek level technology here for the surface materials of these solar roads to combine all the properties of good roads with good solar panels. And it’s also supposed to be cheap.

      But the main problem with solar roads is that we could actually be doing real things to make the future survivable, yet people are being sucked into wasting limited resources on these snake oil fantasy hoaxes that do absolutely nothing for us. I am usually running the odds through my head about how likely it is that humanity will be going extinct in the next hundred years–and seeing things like solar roads being taken seriously by anyone means to me that it’s not looking good for us.

      1. Gaianne


        You have said it.

        The first time I saw a description of the French project, the promoters were quick to point out it was not “Freakin’ Solar Roadways”–a scam run out of Colorado. But the French project has all the same problems as FSR. Some Australians did a nice hour-long send up on Youtube of the absurdities of FSR that only touched the surface. From every aspect the numbers don’t work.

        The French project is really no different. What are these new miracle materials that can catch sunlight, stand up to road wear, ignore dust, snow, and ice–and all with no cost and no manufacture bottle-necks nor environmental costs? Scientists are just a few weeks from perfecting and rolling out . . . whatever it is!

        Here is the basic division: Those with experience with solar panels know that they are “uneconomic”–always!–but very useful for niche and low-power applications. If you were to reduce your own energy usage by 90% you could run your laptop, cell-phone and some LED desk lamps, and a few other small appliances very nicely with some solar panels and some on-site storage batteries.

        By the way, winter is tough, even at low latitudes.

        Those without experience believe religiously that solar panels will run business-as-usual and their ever-more-voracious all-electric home.

        Not happening. We will see the Second Coming of Jesus sooner.


  1. Kulantan

    I admittedly don’t know a lot of the science here but I can’t think of why roads would be better for solar generation than rooftops. The cynic in me wonders if it isn’t a ploy build some toll roads with less community opposition and then sell whatever power is generated to as an added bonus.

    1. Clive

      Don’t get me wrong, I’m a big fan of rooftop solar and encourage it most of the time.

      But I’m not unaware of its shortcomings. Here’s a few of the key points:

      1) Not all housing units can accommodate solar. The roof orientation may be completely unsuitable. There may be too much pitch (angle) in the roof. US housing stock is fairly modern, but Europe has a lot of much older housing where the roof many not be able to bear the weight of the panels or they can’t be secured effectively to the structure. And I’ve seen just where I live a few historic, beautiful buildings blighted by inappropriate panel installations — it is very easy to despoil the built environment through a few thoughtless and insensitive changes. And again, in Europe compared with the US, there’s a lot more multifamily buildings which make solar installations possible but they can’t satisfy the load density of the entire building. The road has already polluted the visual environment, so making it a co-site for clean (-ish) energy at least brings some good from the bad.

      2) Inefficiency due to the need to have one inverter unit per dwelling. If you can install panels in bulk, you can put in fewer, larger inverters. You can also feed into the grid at High Voltage (over 33kv typically) if you have a really big installation which you aggregate which is way more efficient than small pools of Low Voltage (less than 400v).

      3) Much easier maintainability. Most solar panel’s performance drops disproportionately if there’s a segment of the panel obscured (debris, leaf fall, dust, er… the output of birds) so they need cleaning now and again. This is one of the biggest snags with roof mounting panels. Even if you have a solar farm installation, it might be tricky to access and would need a new maintenance contract to do the cleaning*, but highways have maintenance crews covering them already so adding cleaning and general maintenance task to their schedule makes this a whole lot easier to manage.

      *My garden maintenance company’s boss told me he was asked to tender for the maintenance of a solar farm in my county, they turned it down because there was no water supply on site. The cleaning of a large installation of solar panels couldn’t be done economically without water, so they figured they’d have to tanker it in. The maintenance company figured they could factor in the cost, but they didn’t want the hassle — plus they guessed that some dumber schmuck would get the contract on a (low) price quote without realising this so didn’t bother providing a quote. Most inexperienced plant operators (solar attracts a lot of this sort) simply don’t realise the costs and problems that providing long-term maintenance can bring.

      1. rusti

        2) Inefficiency due to the need to have one inverter unit per dwelling. If you can install panels in bulk, you can put in fewer, larger inverters. You can also feed into the grid at High Voltage (over 33kv typically) if you have a really big installation which you aggregate which is way more efficient than small pools of Low Voltage (less than 400v).

        Aren’t you still relegated to sub-600V strings on the PV side? The data sheets I have for some panels that I know are used in utility-scale deployments list a max system voltage of 600V, and looking at central inverter specifications online I see max DC input voltages of 600V.

        I wonder how geographically distributed the central inverters would be along a long road and what sort of extra losses might be incurred by having longer cables to reach them compared to a PV farm.

        1. TKSolar

          Residential systems are limited to 600V DC. We are now installing commercial systems at 1000V DC. I have heard 2000V DC systems are on the horizon. These are the string voltages for panels joined in series. The AC voltage can be stepped up after the inverter to distribution voltage with transformers.

      2. Kulantan

        I hadn’t considered 2) and it makes sense that there would be some economies of scale. 3) on the other hand is less immediately convincing to me. The amount of rubber dust from tyres and plain old regular dust on vehicles would (I assume) mean that solar roads needed more regular cleaning than roof panels. I’m sceptical that the increased maintenance convenience would outweigh the increased maintenance burden.

        1. jgordon

          You are right. Solar panels are extremely sensitive to any sort light blockage, whether from dust or chemicals or even vehicles rolling over them. A road bed on a highway is one of the dirtiest and nastiest placed on the face of the face of the earth–and coincidentally that’s where people suddenly have a hankering to put solar panel. Why? God this is so depressing.

          1. beene

            Having owned a solar system for a couple of years now.

            Live on a main road where traffic is almost constant, the most trouble is caused by the street sweeper that runs once a year to clean up the sand put down in the winter. This is only minor blockage to panels which is taken care of by rain.

            Snow of an inch or more does eliminate production, I rake the snow off with a roof rake. Clouds can also cut production down to almost nothing.

            I had power optimizers put on each panel which means only one panel is effected by shade or something on a panel; with out these the whole string could loose ability to generate power.

            Since installing the system I have not paid a electric bill and have made a small income. It will take several years for me to recoup the cost of the system.

    2. hunkerdown

      That’s not excessively foily.

      For that matter, why not roadsides or elevated solar platforms instead of roads? Seems double-duty means treble-price anymore.

    3. rusti

      I have an extremely tough time believing that this makes anything resembling financial sense compared to rooftop deployment. Maybe some day it could make sense if polycrystalline silicon becomes so cheap and ubiquitous that we start running out of structures to put it on.

      Does this road not have signage? Trees? Light poles? Road debris? And if it is really out in the middle of nowhere, why not put the panels on the side so they can face south/southwest to match demand curves? Why distribute the power electronics over hundreds of miles making maintenance a pain? How much power is a dirty, not-south-facing panel going to provide during the winter?

      Even if they survive the mechanical stress of freeze/thaw cycles, snow plows, heavy vehicles and so forth they will still age and provide less power every year (usually with a steep drop the first few years). How often (and for how long) are you going to close sections of the road to change out panels?

  2. kl

    Solar roads are one of the dumbest things I’ve ever seen seriously discussed. There’s a couple of pretty humorous videos tearing apart the idea on common sense and basic estimates alone, but this is the last one I remembered enough keywords from to google: video.

    Every analysis of solar roadways I’ve read, put forth by someone who didn’t have kool-aid dribbling down their chin, has come to similar conclusions, solar roadways are terrible solar panels, terrible roadways, and terrible investments.

    We can’t even maintain our asphalt roads…

    1. tegnost

      There are a number of crispy critters who got zapped trying to steal copper out of light posts, so knock yourself out. We’re talking major voltage here…just saying….

  3. Cry Shop

    Guess it depends on how one defines solar power. Thermal or photo-voltaic (electric)?

    Solar thermal power roads (using solar heat sinks, or passive heat pipes, to provide ice-removal / snow melting potential, heat/hotwater for near-by homes, etc.) might be a practicable use.

    As to photo-voltaic The link below goes to one of the best comments, I’ve read about why building photo-voltaic solar panels into a road is plain dumb, and often part of a modern con-man game to get at (usually government) fools money. The comment is rather lengthy, but it has some solid calculations and references to back up it’s conclusion.

    1. Cry Shop

      Tested the link after the comment loaded. Apparently one has to scroll down and click on “comments”, then the page will auto-scroll to the correct comment. BTW, one of the funnier comments in it goes.

      “You could pave Rhode Island over with solar panels, power the nation, and rid yourself of the most corrupt state government all in one fell swoop.”

    2. Cry

      Apparently that Dutch bike path had trouble handling the stress of bikes and pedestrians, the protective layer de-laminated on over 1% of surface within 1 month and over 10% in 6 months. (and bike loading is usually less stressful than pedestrian loading). The most interesting point is how many of the blogs and even the main stream news sources glossed over the issues and trumpted the good news. It’s as if they want everyone to feel good about continuing their consumerist lifestyles because a solution is in the pipe.

  4. homeroid

    A stable road bed is expensive in it’s self. This idea will never fly. Small applications might be cool- drives and parking spots. Keep trying though i love the ideas.

  5. PlutoniumKun

    Like all the other commentators above, my immediate response to this is scepticism, especially because of the vagueness in all the sources I can find about both costs and real energy outputs over time (‘enough power for 5,000 homes per kilometre’ is pretty meaningless). I’m suspicious of any proposed power generator that doesn’t give total annualised estimates.

    But a few points potentially in its favour:

    1. Even if costly compared to regular panels, it may be that factoring in normal road resurfacing costs and land cost savings and that most roads are ‘wired’ anyway (lighting, services), it may make more financial sense.

    2. It is backed by a highly experienced road surfacing company, not some tech start-up, so I assume they know what they are doing when it comes to road repair and longevity. The company actually owns many toll roads, so its not like they are trying to sell this to unwary buyers – they seem to be putting their money (and know-how) where it counts.

    3. France is particularly suited to this sort of thing, especially the south. Major roads tend to be open and unshaded, there is plenty of sunshine, and the winters are mostly not too harsh on road surfaces.

    4. Solar is particularly valuable in France, as it is in hot summer days, when nuke stations struggle with coolant water while everyone has their aircon on, that electricity prices are at their highest.

  6. DakotabornKansan

    I recall viewing a solar roadways video some time ago.

    It was, as it turned out, a campaign production by a small Idaho small company named Solar Roadways owned by Scott and Julie Brusaw. They raised several million dollars worldwide for their project.

    Scott Brusaw, The Promise of Solar Roadways, TEDxSacramento:

    As one commenter noted, “TED – hosts of both the incredibly interesting and the profoundly retarded. “

    Actual engineers, according to Roy W. Spencer, point out, like Clive, that the “Solar Roadways Project: A Really Bad Idea.” Spencer writes, “I don’t see how anyone with an engineering background could have seriously entertained the idea.”

    In another post, Spencer asks, “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?”

    Joel Anderson @ at asks, “Why give money to the Brusaws for their business to develop an impractical idea with no shot of a return?”

    As P.T. Barnum once said, “Every crowd has a silver lining.”

      1. DakotabornKansan

        Yes, you rightly question the reference to Roy Spencer.

        Roy Spencer is on the board of directors of the George C. Marshall Institute, a right-wing conservative think tank on scientific issues and public policy. He listed as an expert for the Heartland Institute, a libertarian American public policy think tank. Dr. Spencer is also listed as an expert by the International Climate and Environmental Change Assessment Project (ICECAP), a global warming “skeptic” organization.

  7. TKSolar

    The engineering costs seem to me to be huge to design panels that could take the stress of vehicle traffic. A modern PV panel is made of tempered glass that can withstand a massive hailstorm or being jumped on like a trampoline without breaking. That being said, we avoid at all costs walking on the panels during installation due to microfracture degradation of the silicon cells themselves. Studies have shown serious degradation of entire arrays due to installers walking on the panels. Themal imagining scan shows hotspots at popular walkways and even individual footsteps. Walking on panels voids most manufacturer warranties these days knowing that I don’t see how you could design for many thousands of vehicles per day.

    1. nowhere

      Just quoting the article.

      The panels are made out of a thin polycrystalline silicon film and coated in a layer of resin to strengthen them and make them less slippery. Because the panels are so thin, they can adapt to small changes in the surface of pavement due to temperature shifts and are sealed tightly against the weather…

      No mention of glass.

  8. Felix47

    Could one of the experts here explain why it would be so hard to put lightweight overhead structures over the road with panels? I am thinking of the 15 Freeway out of Vegas. There is so much sun and the area the Freeway covers is really huge……it seems that developing a lightweight panel in a wind resistant structure you could just put over a Freeway might generate a lot of power.

    1. MyLessThanPrimeBeef

      There are things living in the desert that need that heat that will go into those solar panels.

      If we cover 0.4% of the US with solar panels to absorb the solar energy, that’s 0.4%of solar energy removed, extracted from the effected habitats.

      Do we know what impact that will have on little critters and plants?

      1. Gio Bruno

        Well, yes we do know. That’s why large scale solar installations get environmental review. The desert tortoise habitat (outside Las Vegas) has been deemed too important for some proposed installations.

        Many folks think the Great Basin is a great place for large-scale solar (Hey, it’s just desert, right.) While Nevada has super solar insolation, it also has a vibrant high plains biology/botany that is slowly being disturbed. There a plenty of opportunities for distributed solar installations in and near population centers. (That’s where the jobs are needed.) Placing large scale solar farms on real farms in Iowa seems like a good idea, too.

        As for the roadway solar concept, I don’t think the article gives enough detail to make an assessment. Although, I’m inclined to agree with most of the comments I’ve read.

        1. MyLessThanPrimeBeef

          If there is one thing we are sure of, it’s we won’t know the real impact until we have been there for a while.

          A consideration for large scale solar project is its impact on weather and wind patters due to differences in temperature. We can’t take all that solar energy out of something like the Sahara and not expect some unpredictable consequences.

          1. Gio Bruno

            Actually, the more immediate impact of large-scale solar projects is summer monsoon rains. Those concentrating panels also concentrate rainwater. New arroyo’s may form and generate unwanted sediment that flows to unanticipated locations.

        2. optimader

          I immediately scanned the webpage for the explanation of how & how often these Colas asphalt road surfaces with embedded panels will be recycled? Crickets.

  9. Mario Panziero

    I would love to read the feasibility studies and the ROI analysis the French government must have done to finance a dime of this project.

    1. Yassine

      The objective of the French ruling elites is to discredit renewable energies as an alternative while still being able to pretend it supports them. So financing ridiculous renewable energy projects with no feasibility and negative ROI is part of the plan, not a glitch in the system.

  10. Torsten

    How about installing photovoltaics in the road micro-aligned to the south, and then banning cars and trucks? France is choking from all of VW’s diesel.

  11. Nik

    If you follow the links, it does give the impression that they have some fancy new materials that can withstand traffic and function as a panel, but given that there is no discussion of cost or efficiency, I’m certain this is a case of government officials getting caught up in the enthusiasm of some overzealous researchers and the road building company (ka-ching!)

    The panels are to be placed on top of existing roads, which I imagine means that you still need to build and replace your existing stretches of asphalt. And what is the efficiency of these panels when they can’t be angled to catch the sun, or they get covered in the muck and dirt you wouldn’t find in a testing lab? This is a subsidy dumpster that will never, ever pay for itself with the energy it generates.

    It occurs to me that if they have really developed a competitive, ultra-thin solar panel that you can DRIVE on, they would be selling that tech as a proper panel as well.

  12. Paul Tioxon

    France has a legal mandate that all new commercial construction includes green rooftops. This means a choice of a combination of both solar PV panels and a landscaped roof to absorb rainfall runoff or just one. It is important to understand that 75% of the electricity in France comes from nukes. And while this does not have the problems of fossil fuels, it certainly does have its problems. Between the push by leftist politicians and environmentalists, the push to have more sustainable electricity is great. Changing the building codes of France for new commercial construction institutionalizes the commitment to solar in ways that are more familiar and practical. However, the extremely small initiative to try out 660 miles of road in the 8th ranked nation for roadways, over 1,000,000km, strikes me as a probing experiment. As usual, the customary questions about the practical nature of anything new in regards to solar is fueled with astounding skepticism. But this should be more welcomed than resisted with the questioning in the spirit of finding a real solution within the concept of the solar road, if there is one to be found, not just shooting it down with blind cynicism.

    The leviathan role the automobile has appropriated in terms of land use paved over in cities, around cities and connecting cities makes it an obvious target for liberation by the solar energy advocates. Without taking over anymore valuable real estate, internalizing electricity production into essentially wasted territory makes logical if not yet well engineered sense. It may never actually work out and the demonstration of 660 miles of roadway will be the empirical evidence of that. Or it may the beginning of a valuable learning curve.

    But considering how on one day, we are all hysterical about climate change, climate change deniers, Exxon and Koch bros knowing and then lying about the pending holocaust, you would think that a sign of the seriousness of policy change to move from fossil fuels to sustainable would be applauded. No matter how crazy the ideas seem at first concerning solar, throwing everything at the problem and risking failure to me is the best sign that there is a real shift in policy by governments and business. Any urban planning course will discuss the massive shift in building cities around the use of the automobile instead of its use as the natural habitat of most of humanity. The fact that approx 1/3 of the land use in and immediately around cities has been devoted to roadways for cars, driveways, garages, massive parking lots around shopping centers, office parks, schools, stadiums, etc should be enough knowledge to understand why anyone would target solar roads as a solution. It is simply too much real estate to ignore. And they are regularly ripped apart by use and resurfaced. This could be a way to make roads pay themselves if they can ever make this a workable situation.

    So while valid technical specifications that we know about now don’t lend themselves at all to this new proposal, I don’t believe that there is a challenge to roof top installations properly sited and so on. I think it is in addition to any of the many ideas as part of the massive effort to completely reconstruct our energy production. The engineering breakthrough and the materials breakthrough may not yet be here for this to work even for the roadways going through the flattest parts of the dry desert areas of the world. I am glad to see no idea is being spared in the attempts to free ourselves from the calamity of fossil fuels. It really is a signal moment that money is risked being totally wasted for something other than a new fighter jet or a really, really bigger bag of chips.

    1. Cry Shop

      The biggest problem is when this project flops, after the long wait to see why, it’s failure will be held up as a failure of solar energy, or rather more critically for government support for solar energy, and government support at this stage is still critical.

      The money spent to test the 70 meters of Dutch bike bath for 300kw capacity could have been used to build a power plant at one thousand times the capacity which would have been in production for 3+ years now. Most importantly, the only reason to build on roads is if there is no other space available, and that’s simply not the case. As some noted, “You could pave Rhode Island over with solar panels, power the US nation, and rid yourself of the most corrupt state government all in one fell swoop.” Even the Netherlands does not lack for suitable space. The problem with solar isn’t land costs. Mostly these projects are about legal corruption, the last thing we should want tainting a business which can ill afford the bad PR.

      1. Paul Tioxon

        Well that’s true, Solyndra is the Benghazi battle cry of republicans and oil lobbyists in the DC Beltway. But, to take a page out of Bernie supporters, if we just say something will never happen anyway, why bother at all? Nothing will ever get done. It is a given that there will always be organized political opposition, especially to a commercial challenge to the fossil fuel industry. It is important to bake in nay saying denouncing of solar as whole being a failure, when one instance of solar failure inevitably comes up.

        The right wing media loves to distort anything about solar, even the screaming headlines from an actual operating Concentrated Solar Power station, Ivanpah in California, making continuous 24/7 steam turbine electricity from stored molten salts is attacked as some kind of green fraud perpetrated due to the back up gas fueled steam generation for the turbines, in place due to contractual demands for constant base load current production.

        It’s not a secret that the government doesn’t want you to know, or even I don’t want you to know, but its portrayed as a government lie of the highest level of corruption, an impeachable offense against the US Constitution for picking winners and making losers, a tyranny of government interference sending us down the slippery slope on the road to serfdom. Whew, I’m exhausted just thinking about the critical denouncing. But ultimately, it’s irrelevant. Solar is going wild around the world, money is moving in massive investments that will continue because it just works out cheaper, cleaner, better for all concerned. Be prepared for solar failures, bankruptcies and the “I told you so” sniping from the Heartland Institutes(yes, that’s a real one along with CATO inter alia) of the world. Of course, they aren’t screaming for abandoning oil and coal due to all of the belly up mines and tight oil drillers, patience is in infinite supply for the fossil fuel industry.

        1. Adrienne Adams

          @Paul Tioxon,

          Your statement:

          “…an actual operating Concentrated Solar Power station, Ivanpah in California, making continuous 24/7 steam turbine electricity from stored molten salts…”

          Is incorrect. Ivnapah does not store any energy. Source: Ivanpah Generation Is On Track

          “Overnight, any CSP plant without storage (like Ivanpah) is ‘asleep.’ However, its turbines are kept revolving very slowly so they won’t cool all the way down and then be damaged by heat stress when the sun comes up and they start up again. In the morning, to warm up in the wakeup process, a small amount of natural gas is used at Ivanpah to gradually get the turbines warmed up as the sun comes up and takes over.

          “BrightSource designed Ivanpah as a direct steam CSP tower that simply boils water in the receiver, so instead of using its stored solar energy, it uses a small amount of gas for power block startup. Ivanpah, as the first of its kind at such scale, was not designed to include storage as well. Small steps.

          “(Of course, when a CSP plant includes storage, like the more recent 280 MW Solana project in Arizona or the 110 MW Crescent Dunes in Nevada — and like most CSP projects developed globally after 2011 — its own molten salt heat storage can be used to supply the fuel for the initial startup instead.)

          I agree that media often distorts the facts WRT solar power, but so do people who have a stake in the solar industry, as well as the misinformed public. There are real engineering and financial barriers to widespread use of solar energy technologies, and there realities must be faced head on—not swept aside in “rah rah solar” boosterism.

          I know what’s next… an accusation that I’m a shill for the Koch Bros or the fossil fuel industry… but no, I’m an ordinary citizen who’s studied the renewable industry at great length and have learned to see through much of the hype. The claims of the renewable industries are often inflated, unfeasible, or outright fanciful and this spreads distrust and cynicism.

          Replacing the fossil fuel system we rely upon now will be a massively difficult and expensive undertaking. Telling the public anything else is counterproductive, as the sooner we face the challenges and realities of a post-carbon civilization the better…

          1. craazyboy

            “molten salts” were developed as a more effective “working fluid” medium than water/steam. Technically, they are “storing” heat, but that is in the “steam cycle” between solar collector and turbine. It’s not long term heat storage – unless they happen to add another big storage system using it for long term heat storage. Tho I haven’t checked if anyone has determined if that’s feasible or if anyone is doing it.

            1. Adrienne Adams


              I was referring specifically to the claim that Ivanpah is producing electricity “24/7,” which it most certainly is not. CSP without storage is no more able to supply uninterrupted electricity as PV without some kind of storage.

              Crescent Dunes CSP is supposed to be able to store “up to” 10 hours’ power.

              Unfortunately in the US much of the data on actual performance of renewable power plants is considered proprietary, so we don’t really have any idea of the actual performance of specific facilities. Given how much these plants are being subsidized I think that’s a notable omission.

              1. craazyboy

                I agree with that. I was just trying to explain the tech reason for “molten salts”. There was a DOE program in the mid 2000s where they financed a demo plant – CSP w/ molten salts, but molten salts were just used to transfer heat from collector to probably a heat exchanger which then boiled water for the steam turbine. (can’t remember exact details) This only works during sunlight hours, of course.

                I see in your Cresent Dunes link, in this design they are heating a large storage tank of molten salts, and that can store 10 hrs of excess heat.

                I’d like to see data. We have some small ones in AZ and NV that were demos from the 80s. You can get data on those. But a plain old coal plant costs $1-2 billion nowadays so some comparative real data would be useful. We have too many people just pulling numbers outta their butts, then jabbering away in the press.

                Or, for that matter, what the magical material is you make PV roads from. Gotta be nano something or another. Or maybe it’s from Ringworld?

    2. tegnost

      Thanks paul, I’ll wait to put my cynic hat on for few more minutes this am and throw a couple of possibilities out. This first that came to mind is we don’t know (maybe it’s just me) whether the design requires cars to roll on the surface of the panels, a glance at oil based (not concrete) roadways indicates that the wear pattern is predictable, and over the entire roadbed (shoulder, 2 to 4+ lanes in each direction with median, another set of lanes, another shoulder) most of that space does not bear weight, so the weight bearing part can be made durable and the solar somewhere else in the easement. Another positive, (assuming asphault) is that road construction is heavy on petroleum content, so offsets carbon in the trade off, of the complaints re solar is it takes petroleum to make panels, so offset one for the other. Also, roadways are heat sinks, walk across a parking lot barefoot in the summer, damn! That’s hot! Add in Clive’s point that maintenence infrastructure exists in real time so no additional institution need be created and so that all said I can see it work in theory, and say dream big and go for it. Also municipal and up jobs because yes you would need the maintain and clean. Now, (put’s on cynic hat) in my younger days I knew an up and coming, and currently continuing to rise ivy league educated electric utility executive who felt that there needed to be laws prohibiting solar because how could his massive corp make money if they had to buy energy from their former customers? Get in the way of corps farming money from everyone and they”ll run you over…but this seems like metered power so they can get the blood funnel in there and then be (what they consider) happy.

  13. jnleareth

    I agree with most everyone who says that this will most certainly not pay for itself, and that the money could be better used elsewhere.

    However. I wonder if part of the value, the benefit of the sunk cost, would be that they – the builder and the National Institute – are faced with doing this for the first time and end up having to develop a whole lot of technologies and processes along the way that benefit in the long run. Someone here yesterday had linked to The Mythical Man-Month, which talked about the fact that the first system that gets designed has to be thrown away because the team is still figuring out how to build the system. You can’t effectively figure that out with a pilot program of a mile or two; prototypes always run great until they actually have users relying on them and then it’s a big question mark. The parallels to the Apollo program aren’t fair due to the scale, but one argument for all the sunk cost of sending someone to the moon was all the technology that got developed along the way. This could be a huge failure economically and still be a success in some ways in that the next major project will have learned from its failures.

    At least, that’s what I imagine some people are arguing from a policy perspective: the financial loss isn’t purely lost money; they end up buying a step a away from other sources of energy, as well as technical expertise in an area they see as a future major technology.

    To be clear, as a huge fan of John Michael Greer, I’m certainly in the camp of this being a giant waste of money chasing the latest fad to sustain the unsustainable lifestyle we’re all pretending will last forever. I just wanted to bring up a point I hadn’t seen yet.

    1. tegnost

      I see the attraction of end of the world scenarios but here we are on the crazy train. I know I will someday die so why do i continue to feed myself? After the end of the world no one will be left to care.

  14. Alex Hanin

    What do you expect from Ségolène Royal (minister of Ecology, Sustainable development and Energy), if not grand, wacky, populist (in the bad sense of the term), greenish ideas? The lady has always been a vote-catching fraud, and the fact that she chose to implement this project is quite worrying.

    As jnleareth wrote, this road will probably yield useful lessons, but that’s about it.

    1. nowhere

      Yes, much better to continue to allow all of those CO2 emitting, hydrocarbon sucking vehicles running at full blast.

    2. JE

      Success? The SolaRoad produced 3MWh in six months and had to be completely rebuilt once due to material failure. The road is 250 feet long and about 5 feet wide for a surface area of approximately 100 m^2. Assuming an insolation (sun energy) of 1kW/m^2 at 6 hours per day (108MWh possible in 180 days) the SolaRoad bike trail system is 2.8% efficient and cost $37k/m^2. For comparison, my rooftop array (in Minnesota, static alignment with no snow clearing) using the same math is roughly 12% efficient and cost $0.5k/m^2. I would not want my tax dollars devoted to this kind of “success”.

      I’m all for new tech, but any proposal to do this on a grand scale is a grand scam. 600 miles of roadway 20 feet wide is roughly 6Mm^2 and with current solar panels requiring around 800kWh/m^2 to manufacture the energy cost of making this much solar is in the neighborhood of 5000GWh. If we go by the SolaRoad experiment (6Mm^2 at 6 hrs per day and 1kW/m^2 and 2.7% efficiency) the 600 mile road will require roughly 13.5 years to recoup the energy spent just to manufacture the panels assuming they are as energy efficient to make as regular roof-top multi-crystalline panels. Which they are not likely to be. This also neglects installation and infrastructure costs. In short, this proposal has a snowball’s chance in hell of turning a positive energy return.

  15. Brooklin Bridge

    Skepticism is certainly understandable. If there is anything to it at all, other than the nuclear industry having a bit of good clean political fun, I suspect it’s the fact that cars already do keep roads clean (somewhat – perhaps clear is more accurate). Add in maintenance crews that are already necessary to clear snow and larger debris (as per Clive’s comment) and there may be some benefit that compensates for all the negatives, the bad orientation of the panels, durability, loss of efficiency by wear and tear, and so on.

    Something tells me this is too big a project to be simply an Obama horse for the purpose of slowing down the solar industry (too easy to backfire) and that even if it were, things are simply too far along in the technology for a Hillary horse (but I repeat myself) to work.

    It would be interesting to hear from someone with technical background to know if the numbers above (215 square feet to power a single house – without heat) is a standard or a very generous number for, say, rooftop with proper orientation and ample sunlight. If standard, then the skepticism seems a lot more warranted. One imagines that a lot of inefficiency is being traded off as being outweighed by the advantages for this project to make sense.

    Also, for what it’s worth, I think France has around 65 million inhabitants now, 50m in the 1970s, so 5 million is closer to 7 or 8 percent than 10. I know, I know, big deal, but the accuracy thing seems somehow important in this discussion. And in that vein, and with the caveat that I’m only familiar with driving in relatively small areas of France’s modern highways so this observation may not be a problem, France tends to bury long stretches of it’s highways by tall side slopes (no idea why or if this is prevalent in other parts of Europe) obscuring the road from the sun for considerable periods during the day. Note that 600 miles (1000 kilometers) would stretch from the Northern most boarder of France pretty much right down to the shore of the Mediterranean sea. So I assume wherever they plan to put this rather significant stretch would be free of such sunlight obstruction. If the plan is to use existing road, that in itself may be a challenge.

    1. Gio Bruno

      The 215 square feet of solar PV panel providing a single home with sufficient power may work in Europe, but not likely in a conventional US home. (Your fridge is the single largest continuous electrical demand in the home.)
      However, the topic is full of special conditions. See “Photovolataic system” at the Wikipedia.

      1. Brooklin Bridge

        Your fridge is the single largest continuous electrical demand in the home

        After heat, (if that were included as electric baseboard) I assume? Also, the washing machine draws more power all be it less frequently and for shorter duration than the fridge?

        Anyway, back to the point, if 215sf is already tight, then the numbers they suggest are likely off as well. Even with special technology, it is hard to imagine getting maximum efficiency with all the negatives in question. That doesn’t negate it outright however. Much can change and obviously we know next to nothing about the project.

  16. polecat

    Imagine, if you will, multitudes of low, misemployed serfs, in constant motion, cleaning and scrubbing the once luminous solar roadbed, always aware of the bots stationed accordingly, prodding the humans, cattle-like, to complete their tasks……only to have to repeat the assignment over, and over again, while other bots zoom by in their driverless conveyences…….

  17. cassandra

    It would surprise the heck out of me if any of the objections raised here would NOT have been addressed in the course of a basic preliminary feasibility study. After all, this mainly non-technical forum came up with these objections in a few hours, so one might expect (hope?) experts with some experience to have recognized and dealt with these issues. Of course there are many motivations and ways to corrupt competence (q.v. the F35), but my first inclination would be to have a look at white papers on the subject for an assessment before naively passing judgment. Unfortunately, the fluff on the Wattway site is of little help in this regard…except for the statement that the panels are laid upon existing roads and so require no new construction.

    1. JE

      It is difficult to get a man to understand something, when his salary depends on his not understanding it.

      -Upton Sinclair

    2. MyLessThanPrimeBeef

      Let us not stop ourselves from consuming less in the mean time.

      Debates about global warming rage on
      Heads becoming hot
      More carbon exhaled into the air
      As I sit calmly, reducing my consumption.

  18. Irrational

    I am as skeptical as the majority here, but tegnost’s comment gave me pause for thought. However, the Romans built roads 2000 years ago give or take a few hundred, so the opener in the article is wrong ;-)

  19. Skip Intro

    Most of the skeptical comments exhibit glib certainty, while seemingly focusing on relatively ancient technology, i.e. mono-crystalline silicon modules. These are the most costly and offer the highest efficiency, generally, but are fragile and require much support. They make sense for a rooftop or space station. There are many better options emerging from labs and factories, from organic photovoltaics, cheap polycrystalline silicon, perskovites, graphene, carbon nanotubes, liquid dyes, that are much cheaper to produce, albeit with lower efficiency.

    Also, the cost of all these projects must have the cost of the non-solar construction, i.e. an equivalent bike path, subtracted.

    It is a bit weird to see progressive, forward looking infrastructure spending mocked so stupidly, by armchair engineers second-guessing actual professionals.

  20. Brooklin Bridge

    A lot of France’s highways are in private hands (not sure about owned, but certainly managed) and quite expensive to drive on which has a tendency to reduce traffic volume. I wonder if this is an effort by those companies to extract more profit out them. If they can get the government to subsidize solar construction and then simply charge rent from the companies that are in charge of the solar project, they can rake in the profits so who gives a damn what the ratio of cost to performance is. The tax payer might, but all the corruption can be buried under huge fanfare regarding good energy stewardship and so on…

  21. Adrienne Adams

    Finding places to put PV panels is but one part of the task of deploying solar energy—and in may ways it is not even the most important.

    The really big problem with solar power (and with intermittent and non-dispatchable renewable energy as a whole) is how to integrate the power production into our existing grid. There’s a lot of hand-waving about the “Smart Grid” but the fact remains we have the grid we have, and will likely have for quite a while, given the lack of enthusiasm for upgrading critical infrastructure.

    For the consumers (including industry) the electric power grid has two jobs: one, provide uninterrupted, stable power 24/7/365; and two, do so at an affordable price. For the utilities, satisfying these two requirements is an extremely complex process. (The Eastern Interconnection has been described as “the world’s most complex machine.”)

    Our electric grid is a network of generators working synchronously to provide a precise 60 (or 50) cycle AC frequency. The backbone of this system are the spinning generators in thermal, nuclear, and hydropower plants. Solar and wind generators don’t provide the spinning frequency, so they cannot provide the basis of the electrical grid as we know it today. In a nutshell, non-dispatchable intermittent power sources are not plug-and-play replacements for synchronous generators: they currently can act only as fuel savers.

    The future electrical grid will need to rely much more upon DC power, be much more flexible in accepting & buffering unpredictable flows of energy, and will need to consist of both micro-level and continent-wide distribution systems. In short, the decarbonized grid will be an entirely new system.

    This is a big deal, and one that is usually ignored or glossed over by folks who claim that we can provide 100% of electrical power from non-fossil fuel sources in a short enough time frame to prevent catastrophic climate change. Add in the expectation that much of our transportation fleet can (must) be electrified, and we have a situation where the task of decarbonizing our power grid is a much, much bigger task than it is presented to the general public. Demonstration projects like these solar roadways may provide good PR for the solar industry and its supporters, but they do precious little to address the real problem of how to rebuild our existing electric grid to utilize non-carbon energy sources on a scale that really matters.

  22. RBHoughton

    If roads power the housing built alongside them, we have an extra reason to build more roads as population increases.

    There was a professor in (I think) Georgia who, a few years back, wanted to mix carbon fibres into the concrete used for roads as the slight compression of passing traffic induced an electrical charge in the fibres which, if sufficiently plentiful in the mix, provided a route to the roadside where the energy could be tapped.

    A century ago an American inventor sought to put a pump in the heels of shoes so wearers could generate power as they walked.

    The concept of taxing our everyday activities is attractive to me.

    1. Cry Shop

      Conservation of Energy: Adding those fibres to the roadway would increase the rolling resistance ever so slightly, such that any energy gained plus any losses to inefficiency in energy form conversion are off set by extra fuel consumption by the car, So Tax (a transfer of wealth plus increases in entropy) is about right.

  23. Cry Shop

    So far not a peep from COLAS in their news/press release section on this 1000 km long road, nor a reply to my email. My contacts in both EDF, Areva and Alstom have not heard anything. Makes me suspect the con-artist team running a scheme to sell solar roads in the Colorado might have floated a fake story via some of those internet based news release sites, made it specific for the English Press, hoping the French won’t dis-abuse the wider world any time soon. The Colorado clowns have been trying to convince some suckers investors to dump money into their hands, this might be part of the show. Hopefully this will all die away without doing the real solar industry much damage.

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