Increase Text Size
Decrease Text Size
Email This Story
Share This Story
Reader Comments (26)
Image Gallery (2)
Add to Bookmarks
Printer Friendly Version
The concept of using road surfaces to generate clean solar power is moving beyond the idea stage. Roads absorb heat from the sun every day and are usually free of sightline obstructions that could otherwise block the transmission of light rays. And if the roads built for cars and driving are partly to blame for global warming, why not make them part of the solution too?
Brusaw believes his system, if implemented from coast-to-coast in place of the tarmac on existing highways, could produce enough energy to meet the entire world's electricity needs.
Idaho-based Solar Roadways is one of the trailblazers. Electrical engineer Scott Brusaw was inspired to start the company when he heard Caltech solar energy expert Nate Lewis suggest that covering just 1.7 percent of continental U.S. land surface with photovoltaic (PV) solar collectors could produce enough power to meet the nation's total energy demand.
Brusaw put two and two together when he realized that the interstate highway system already covers about that much of the nation's land surface, so he got to work designing a system that combines a durable and translucent glass road surface with PV solar collectors that could be wired directly into the electricity grid.
The heart of the solar roadway concept is the solar road panel. Each individual panel consists of three basic layers, the road surface layer, which is translucent and high-strength yet rough enough to provide traction. The surface layer is capable of handling today's heaviest loads under the worst of conditions and protect the electronics layer beneath it.
The three layers (top, middle, and bottom) of a solar road panel.
Next is the electronics layer, which contains a large array of cells, the bulk of which contain solar collecting cells with LEDs for "painting" the road surface. These cells also contain the "Super" or "Ultra" caps that store the sun's energy for later use. Batteries are not used in the solar roadway. Since each solar road panel manages its own electricity generation, storage, and distribution, they can heat themselves in northern climates to eliminate snow and ice accumulation.
The third layer is the base plate layer, which distributes power (collected from the electronics layer) and data signals (phone, TV, internet, etc.) "downline" to all homes and businesses connected to the solar roadway. The power and data signals are passed through each of the four sides of the base plate layer. The base plate layer is directly attached to vertical risers, pneumatic or hydraulic pistons that raise or lower different points of individual solar road panels. Riser bases are installed beneath the frost line to avoid the "heaving" phenomenon common in colder climates where the ground freezes and thaws. This provides a natural earth ground for the electronics layer of the Solar Road Panels. The risers are controlled (raised, lowered, or locked) by the solar road panel's microprocessor board. The microprocessor board communicates with each adjacent panel to ensure a seamless road surface.
Brusaw believes his system, if implemented from coast-to-coast in place of the tarmac on existing highways, could produce enough energy to meet the entire world's electricity needs. But skeptics wonder whether such an expensive high-tech road surface can stand up to the rigors of everyday use-from overloaded 18-wheelers putting extra stress on the highway to oil spills seeping into expensive electronic circuitry-without having to be replaced or repaired often. Brusaw acknowledges that his system still needs fine-tuning, but in the meantime is developing a working prototype along a 45-mile stretch of road between the Idaho cities of Coeur D'Alene and Sandpoint.
This week the company is meeting with professors from the University of Idaho's civil engineering faculty to discuss the development of the base plate (bottom layer). "U of I has been recognized by the U.S. Department of Transportation as one of the nation's top transportation research universities," says Brusaw.
For the top layer, Solar Roadways has approached the nations top materials research labs, "Penn State University's Materials Research Institute and the University of Dayton's Research Institute [are] working of figures for developing the top layer," he says.
After the cost estimates are in, "we'll be in position to approach our investors for funding. They seem far more interested in the time frame than the money required," says Brusaw. The company says that it has four interested investors at this time.
"It looks like 2008 is going to be our year. Everything seems to be falling into place at just the right time," says Brusaw.
Overseas, Europeans are also pioneering ways to use the sun's rays to work as they beat down on roadways. The British firm Astucia has developed a road stud that contains small solar panels and emits LED light to illuminate dark roadways. On the 120 U.K. roads where the new studs have been installed, night-time accidents are down 70 percent.
And the Dutch firm Ooms Avenhorn Holding BV has developed a way to siphon solar heat from asphalt road surfaces and use it to de-ice roads and help power nearby buildings. A latticework of pipes under the road surface allows water to heat up during warm weather. The water is then pumped deep under ground where it maintains its higher temperatures and can be retrieved months later to keep road surfaces ice-free during winter months. Apartment buildings, industrial parks and an air force base have benefited from the innovation, and the firm is working on exporting its system to other countries in the coming years.
Portions of this article were originally published in EarthTalk, a syndicated column published by "E - The Environmental Magazine" and were reprinted with permission.
I thought the application of LED solar studs to light the center line and edge of the road to be a great application. Here in Southern California with no snow, the studs could last years or decades.
As for roads made of solar panels, its got to be a joke.
The solar cells on my roof lose 1% of their production per week afer a cleaning. I wonder how fast they would drop if cars were driving on them.
If one cell in a string of cells is in shadow, the entire string stops working. Bypass diodes allow production to continue, but at reduced voltage. So any other string in parallel will also have to operate at reduced votage. With multiple shadows the array easily loses all power even if only a small fraction is in shadow. Trees, light poles, cars, power lines, all those shadows will kill output. I guess you could put a DC to DC converter on every cell......
OK, let's see, a solar array (of any kind) works best when it has a clear view of the sun, and even better if it is angled to be perpendicular to the sun (on average). How can anyone think that a road that is partially covered with vehicles (perhaps as much as 50% is some areas) is a good place to put a solar array? Not to mention servicing them (ok, let's stop traffic into Houston for a couple of days while we repair this connection), and installing them in the first place? (yes, mr president, we want to rip up the entire interstate system in the US to put in solar arrays). Good luck, you'll need it!
This could be taken a step further. There's the new technology for charging electronic devices from a distance. If this were put into the parking lots at rest areas, electric cars could be charging while people used the restroom or had lunch. With the new fast charge batteries that are coming out, the car batteries could be 50% charged in 10-15 minutes.
solar/LED studs are way cool
roads and parking lots & built-up flat roofs are ready for solar heating via liquid glycol and solar heat-driven electricity via thermocouple design.
Parking lots could also benefit all by having sunny areas of actual parking space covered with a net that can hold thin-film cells to provide power for LED lighting & electric car recharging while lowering reflective heat back to atmoshere and shading/cooling the cars parked in the lot.
I must agree that using current photovoltaic tech with road sufaces would be very problematic. But if we use those technologies and new ones as they develop on a large % of suitable surfaces, we'll be going in the right direction.
I am with Jim Berry on this one. Solar studs a great idea, but solar roads not so sure about. Maybe we should use up all the roof tops first before we hit the road but hey lets keep our minds open to all new technology and give the folks behind it a fair go.
Mike H. HYDROGENHEADS
Following upon what John Briggs offered, consider the impact upon power generation caused by road surface deterioration, oil/fluids leak, and tire residue. All that rubber lost from our tires goes to the road surface, the air, and water runoff. Now it will also impede solar gain.
PV is best installed closer to the load. Think BIG flat rooftops, as in public schools, big box retailers, malls, etc. The beauty is that, during PVs peak production months, the schools are underutilized, and much of the power can go directly to the grid.
The dilemma is that roof penetrations and/or system weight (ballast for non-penetrating systems), are show-stoppers. In wintry climes, building managers are not willing to risk compromising roof integrity in order to save a penny or two per kWhr. PV laminates adhered to EPDM are the solution (less weight, with minimal penetrations). As with residential roofs, timing these projects to coincide with re-roofing shrinks the market significantly.
And again, most are reluctant "to be the first"; everyone want to be next...
I have one word for you, "syncrete". This was a synthetic concrete used on an interstate in Utah. It was supposed to be more durable but turned out to be less durable. It crumbled shortly after installation. Then pieces of it came free, where kicked into the air by passing cars, and then broke windshields. Ultimately, it all had to be removed.
It is great to be optimistic about technology, but I think decades of testing are in order for anything that will change the road surface.
Thanks
John C. Briggs
Before those of you who are enthusiastic about this start calling for federal subsidies, tell us how much of YOUR OWN MONEY you're ready to put into this.... Conservation first. LEDs, CFLs, etc, etc, etc...
(cont.) I suspect the arrays can also be "strung" in such a way that shading on one panel doesn't take out the electrical production of an entire stretch of roadway (which would kill this idea instantly). Thin-film modules already do this at the module level: shading on one corner of the module reduces electrical output but doesn't stop it dead the way it can with crystalline solar modules.
BUT...I'm at a loss to see how these arrays will continue to function as oil and road grime build up on the "rough surface" glass. Or how such a technology can be rolled out on a timely basis. This reminds me a bit of building integrated PV (BIPV): worth doing on NEW roads perhaps (since you have to stop traffic and tear up the ground ANYWAY, there's less incremental cost for the arrays) but too expensive to retrofit into existing roadways. I certainly hope these obstacles can be overcome.
I think it is a great idea and we should go for it.
And why not recharge our electic cars when driving on the road. "There's the new technology for charging electronic devices from a distance."Let's open the door to new technoligies and take better care of our planet.
Boss, this is a great IDEA !!
In India, we are always short of power as we have less than 50 % generation as compared to the demand. And we do not have power at all in the rural areas. Many of our trunk roads like the Jodhpur Jaisalmer highway and many others are only 10 % busy. But we have plenty of Sun.
Maybe we can try this technology here and validate it !
Anyways, how can I join this initiative ?
Presently, I am at Dubai +971501574969 Jitendra
This may or may not be practical in all situations. How many square miles of suburban side streets, with minimal traffic do we have in this country? Slso close the homes that need the energy. PV technology in streets is not the total answer, but probably would work well in many situations.
We need to develop alternative energy sources in the very near term future. There seems to be no leadership in the USA, except the profit motive in our capitalistic society. I believe that the $$$ are going to be there,
Nobody has mentioned "Our Driveways" I bet most driveways are larger surface area than our roofs. Very little traffic , the system would not have to withstand large trucks. Partial shading problem would have to be controlled.
About that 1.7%...
There are 34 million acres of miltary bases...
There are 120 million acres of highway right-of-way
There are 124 million acres of urban and suburban sprawl
There are 10 million acres of fallow, subsidized farm land.
Depending on your efficiency assumptions...it would take between 34 million to 120 million acres of land to produce 100% of the US energy budget with and installed cost greater then 2 trillion dollars.
Hey, SDI costs 1 trillion.
Previous Article
