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A solar roadway is a road surface that generates electricity by solar power photovoltaics. One current proposal is for 12 ft x 12 ft (3.658 m x 3.658 m) panels including solar panels and LED signage, that can be driven on. The concept involves replacing highways, roads, parking lots, driveways, and sidewalks with such a system.
The United States Department of Transportation awarded the company Solar Roadways Incorporated a $100,000 research contract in 2009. This Small Business Innovation Research (SBIR) contract enabled Solar Roadways to prototype solar road panels. The concept has been used for lighting as well.
After successful completion of the Phase I SBIR contract, Solar Roadways Inc. announced that the Federal Highway Administration awarded it a follow-up $750,000 Phase II SBIR contract to take it to the next step: a solar parking lot. Constructed out of multiple 12' x 12' panels, this smart parking lot will also warm itself in cold weather to melt away snow and ice. A layer of embedded LEDs will be used to create traffic warnings or crosswalks, and excess electricity could be used to charge electric vehicles or routed into the power grid. The electrical components will be embedded between layers of extremely durable, textured glass.
A solar roadway is a series of structurally engineered solar panels that are driven upon. The idea is to replace current petroleum-based asphalt roads, parking lots, and driveways with solar road panels that collect energy to be used by homes and businesses, and ultimately to be able to store excess energy in or alongside the solar roadways. Thus renewable energy replaces the need for the current fossil fuels used for the generation of electricity, which cuts greenhouse gases and helps in sustainable development.
Parking lots, driveways, and eventually highways are all targets for the panels. If the entire United States Interstate Highway system were surfaced with Solar Roadways panels, it would produce more than three times the amount of electricity currently used nationwide.
Existing prototype panels consist of three layers.
- Road surface layer - translucent and high-strength, it is rough enough to provide sufficient traction, yet still passes sunlight through to the solar collector cells embedded within, along with LEDs and a heating element. This layer needs to be capable of handling today's heaviest loads under the worst of conditions and to be weatherproof, to protect the electronics layer beneath it.
- Electronics layer - Contains a microprocessor board with support circuitry for sensing loads on the surface and controlling a heating element with a view to reducing or eliminating snow and ice removal as well as school and business closings due to inclement weather. The microprocessor controls lighting, communications, monitoring, etc. With a communications device every 12 feet, a solar roadway can be an intelligent highway system.
- Base plate layer - While the electronics layer collects energy from the sun, it is the base plate layer that distributes that power as well as data signals (phone, TV, internet, etc.) down the line to all homes and businesses connected to the solar roadway. It needs to be weatherproof to protect the electronics layer above it.
Advantages and disadvantages
Renewability and life-span
The main advantage of the solar roadway concept is that it utilizes a renewable source of energy to produce electricity. It has the potential to reduce dependence on conventional sources of energy such as coal, petroleum and other fossil fuels. Also, the life span of the solar panels is around 20 years, much greater than normal asphalt roads, which only last 7–12 years.
Military and rescue assistance
In the event of an environmental disaster or military emergency, solar roadways would provide power when it is needed most. As solar power is renewable, it obviously requires no external connection to an artificial power source.
Roadways already in place
Another advantage of solar roadways is that they do not require the development of unused and potentially environmentally sensitive lands. This is currently a very controversial issue with large photovoltaic installations in the Southwestern US and other places. But since the roads are already there, this is not an issue. Also, unlike large photovoltaic installations, new transmission corridors – perhaps across environmentally sensitive land – would not be required to bring power to consumers in urban areas. Transmission lines could simply be run along already established roadways.
With induction plating embedded inside these roads, electric cars can be recharged while in motion on top of these roads. This would reduce the costs and the time-inconvenience of waiting at a charging station.
In spite of these advantages, initially, the start up and maintenance costs of building such roadways and parking lots may be high, although advances in this technology should cause the costs to fall. Road surfaces also accumulate rubber, salt, etc., which block sunlight. Salt might be easy to wash off, but not rubber. Furthermore, constructing a translucent road surface that is both safe for high-speed motor vehicle traffic and able to withstand years of traffic from cars as well as heavy trucks poses challenges.
- "YERT Conversation 19.1: Solar Roadways". Youtube. January 13, 2008. Retrieved 2009-11-19.
- "2009 DOT SBIR Phase I Recommendations, FY09.1". Volpe.dot.gov (U.S. Department of Transportation: Small Business Innovation Research (SBIR) Program). 2009. Retrieved 2012-04-15.
- Shoemaker-Galloway, Jace (September 8, 2009). "DOT Awards $100K for Super-Smart Solar Roadways Prototype". Energyboom.com. Retrieved 2012-04-15.
- "Introduction". Solar Roadways. 2010-04-16. Retrieved 2012-04-15.
- Brusaw, Scott. "Recycled Materials". Complex Cortex Designs. Retrieved 13 April 2011.