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Hard Road Ahead for Solar Freakin’ Roadways

The views expressed are those of the author and are not necessarily those of Scientific American.


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solar-road-panelsTake a solar panel. Surround it with light-emitting diodes attached to a microprocessor and, in northern climes at least, some kind of heater. Sheath all of that with the 100-year-old technology known as tempered glass. Voila: the basic building block of what has been dubbed by its creators, electrical engineer Scott Brusaw and his wife Julie, a solar roadway. It could one day make for a highway built of 0.4 –square-meter hexagonal panels, a hodge podge of green circuit boards surrounding 36-watts worth of blue solar panels, all covered in thick, bumpy glass for safety and traction.

The idea is to put unused roadway to good use (generating electricity) while also providing an electronic means for lane shifts, driver messages and other utilities. Bonus: solar roadways obviate the need for an electric grid by including a “Cable Corridor” right in the side of the roadway that eliminates the need for power lines running alongside it. And if outfitted with sensors as well the solar highway could transmit real time traffic data or other information of interest. The novel idea has been around for a few years now, bursting back into prominence this summer thanks to a new crowdfunding campaign to support further research and development that garnered $2.2 million before closing on June 20.

The solar roadway already exists, or at least an 11-meter-long solar parking lot outside the Brusaw backyard lab in Idaho made up of 108 of the prototype panels. That’s the equivalent of a 3.6 kilowatt solar array, capable of producing roughly 14 kilowatt-hours of electricity per day, or roughly half the electricity use of a typical U.S. home.

solar-roadway-parking-lotAs this prototype demonstrates, the Brusaws don’t have to start with roads—patios, parking lots or sidewalks, among other currently paved surfaces, might make for a more feasible starting point. But, in the long run, the vision is to take the continental U.S.’s roughly 75,000 square kilometers of road and turn it into a massive solar farm to replace the nation’s need for fossil fuel-fired power plants, thus solving climate change and energy security issues in one go. Even better, the solar roadways pair nicely with the need of electric cars for ubiquitous charging wherever the vehicles may go.

sandpoint-idaho-with-solar-roadThe Brusaw’s hometown of Sandpoint, Idaho and surrounding communities have already signed up to host future prototypes on sidewalks, parking lots, airport tarmacs, even train station passenger platforms. The goal of such testing is to prove that such panels can last for 20 years while supporting weights of more than 100,000 kilograms.

There are, however, a few challenges to overcome. What happens to the solar roads at night or on a cloudy day, when the PV is not generating electricity to power homes or cities? The Brusaws’ answer is to draw power from the grid, presumably from flexible generators, such as natural gas-burning combined cycle turbines or hydropower projects with the room to store water for a dark night (though Brusaw told me he expects wind turbines to fill this role back in 2009. He did not respond to repeated requests for an interview this time around.) As presently designed, the LEDs and heating elements are disconnected from the photovoltaics, meaning these elements require electricity from the grid 24/7. The heaters alone require more power than the available PV in the hexagon can supply.

solar-road-glassThen there’s the materials challenge posed by the novel use of glass. This glass must be tempered, self-cleaning, and capable of transmitting light to the PV below under trying conditions, among other characteristics—a type of glass that does not yet exist. And that’s just the glass. There’s the additional challenges posed by putting together photovoltaics, LEDs and other components, not unlike a smartphone but one that will be run over by trucks.

Finally, there’s the problem that these 50 United States barely maintain asphalt roads, crumbling highways and unafe overpasses and bridges as it is. U.S. roads are essentially run to failure (i.e. as poorly maintained as possible) so how will any city, state or federal government pay any amount more to put in a solar road rather than paving with asphalt? It’s not just that the panel is more expensive than pavement, it’s the additional expense of maintenance, replacing the inevitable defects and generally tending a technological jumble subjected to the brutal pounding of daily traffic and weather, among other stresses.

solar-road-LEDsOf course, that pounding can also be put to use via the piezoelectric effect. But that’s a whole ‘nother yellow brick roadway—and a technology that the Brusaws are also considering incorporating into their solar road panel.

Credit: All images courtesy of Solar Roadways

David Biello About the Author: David Biello is the associate editor for environment and energy at Scientific American. Follow on Twitter @dbiello.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. billbedford 9:28 am 07/10/2014

    I wonder if the EROEI of this idea is at all positive.

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  2. 2. David Biello in reply to David Biello 11:18 am 07/10/2014

    I looked into that a little bit (and ultimately decided not to include it b/c post was already kind of long and duration uncertain). The list of energy inputs is long, from refining the silicon for PV to melting the silicon (in natural gas-fired furnaces) for glass. Then, of course, it depends on where installed and what kind of insolation that place gets as well as how long the hexagons end up lasting. The latter are both uncertain at present.

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  3. 3. Lacota 2:31 pm 07/10/2014

    I think paths and driveways are the best application though you are likely better off putting up solar panels above the surface. Maybe you can turn them into shingles for homes. Perhaps it is just one of those ideas that sounds good but dies to the details.

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  4. 4. Kyotey 4:58 pm 07/10/2014

    Excellent summary David! I would add that another difficulty would be to provide a sound mounting surface for the panels that would not shift with roadway forces and would still work with existing storm water elevations and infra structure. In other words, it would require the removal of the existing impervious surface, base rock and lowering the subgrade, replacing the base rock and placing a new impervious surface with mounting hardware incorporated. A completely new road! These new roads under the panels would require all the same maintenance as they do now plus hardware repair.

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  5. 5. David Biello in reply to David Biello 5:06 pm 07/10/2014

    Very good point. Let’s call that pre-maintenance woes… ;)

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  6. 6. KiwiBuzz 7:06 pm 07/10/2014

    To me, this is about as credible as Black Light Power who claim to have found a new source of energy and whose website is full of technobabble.

    Apart from the fact that it is virtually technically impossible at any price, people should not forget that the world has not warmed for the last 17 years so we can be confident that man-made carbon dioxide does not cause dangerous global warming.

    As the world has huge amounts of fossil fuel resources and virtually unlimited nuclear power potential – although for strange reasons, people believe that nuclear power is dangerous in spite of the fact that proved to be the safest form of major power generation in the world – there is no need for a hugely expensive and allegedly low carbon source of electricity that, during the winter, will need more electricity for heating then it can generate.

    I am amazed that anybody gives its space.

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  7. 7. jrkipling 7:18 pm 07/10/2014

    KiwiBuzz,

    In this case the space was used to show this to be an absurd idea. Mr. Biello doesn’t support freakin’ roadways. SciAm online should be given credit for objectivity.

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  8. 8. jrkipling 7:21 pm 07/10/2014

    I liked the part about it being like smartphones run over by trucks. It would be exactly like that.

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  9. 9. darkspace 8:20 pm 07/10/2014

    Ive seen no one suggest the following; take each water reservoir in the nation and divide them into two sections, during the day part of the solar power pumps water to one side of the reservoir and away from the other, during the night the water is run back and hydroelectric power is generated, the water might be filtered at this time also.

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  10. 10. darkspace 8:40 pm 07/10/2014

    The current solution would be prohibitively expensive in most cases and electronics use some of the worst toxic chemicals and in large amounts, but the issue is how to find a simple inexpensive means, say a tarp materiel, of converting light energy to electric energy, then the roads, the tops of buildings and desert areas like salt flats can all cheaply harvest energy. why not attempt to genetically engineer a tree that generates electricity directly with linked roots that conduct? If we presume to predict the validity of a concept based on the current art then invention is brought to a standstill, its better to try what won’t work than fail to try what would, until you try you will never know one from the other, most of invention is recognizing the success in failure, many inventors were trying to do something else than what they ended up doing, if they had closed minds they would end up throwing away their best inventions. It takes no talent to ridicule from an arm chair, it does take talent to offer a useful practical suggestion.

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  11. 11. wjohnfaust 8:51 pm 07/10/2014

    It is bad enough that the automobile has given us suburbia, loss of community and a dying planet. Use some of those highways for mass transit; let the rest die along with the automobile.

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  12. 12. DEM7414 8:52 pm 07/10/2014

    This is about solving BIG problems. Not about solving every what if along the way. There is no perfect system. Is global warming real? Do our roads and power grid need a 21st century upgrade? look at the computer and cell phone technology over the past 10 years. No one can predict what will should or might work. Put enough money, power(influence), and determination and this may not work like it looks today in theory. But, could be much bigger and better. (99 ways not to create a light bulb)

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  13. 13. jtdwyer 10:42 pm 07/10/2014

    “… all covered in thick, bumpy glass for safety and traction.”
    Personally, I’d like to see a semi-trailer negotiate an incline in wet weather – then suddenly maneuver in response to an emergency condition…
    On second thought – I probably wouldn’t like seeing that!
    <%)

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  14. 14. Dr. Strangelove 3:31 am 07/11/2014

    Old news. This bad idea has been thoroughly discussed in other blogs. Read and learn.
    http://www.drroyspencer.com/2014/05/solar-roadways-project-a-really-bad-idea/

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  15. 15. jrkipling 12:20 pm 07/11/2014

    ‘Why don’t you knock it off with them negative waves?’ – Kelly’s Heroes, 1970.

    Not all of us read every other blog or website on the subject.

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  16. 16. SAULT18 6:46 pm 07/11/2014

    “Apart from the fact that it is virtually technically impossible at any price, people should not forget that the world has not warmed for the last 17 years so we can be confident that man-made carbon dioxide does not cause dangerous global warming.”

    First of all, what has this got to do with the article. Secondly, please spare us from long-debunked fossil fuel industry talking points. They are anti-scientific and have no place on SCIENTIFIC American.

    “As the world has huge amounts of fossil fuel resources…”

    Define “huge”. And how do you know what’s actually under the ground vs what reserves won’t eventually pan out? And please define the effects of relying on these resources into the indefinite future, including massive pollution, geopolitical nightmares and economic costs before making any premature assumptions that our fossil fueled future will be just fine.

    “…virtually unlimited nuclear power potential…”

    Sorry, we already tried nuclear power and it failed spectacularly in the 1970′s and 1980′s, requiring billions in bailouts and utility customer charges as we learned just how expensive properly-built nuclear reactors actually were. And you want to sink countless billions more into this debacle, even after the world was reminded how horribly wrong things can go after Fukushima? Gimme a break!

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  17. 17. SAULT18 6:51 pm 07/11/2014

    I agree, solar freakin’ roadways are a bad idea. Let’s cover the rooftop of every available building with solar pv first and shade every parking lot with it first before trying to turn road design on its head like this. Bad ideas with hardly any hope of success only serve to spin up the pro-pollution trolls around here.

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