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Solar Roadways Proposed for Power Grid

Credits: ©2009 Solar Roadways

The Solar Roadways will collect solar energy to power businesses and homes via structurally-engineered solar panels that are driven upon, to be placed in parking lots and roadways in lieu of petroleum-based asphalt surfaces. The Solar Road Panels will contain embedded LEDs which "paint" the road lines from beneath to provide safer nighttime driving, as well as to give up to the minute instructions (via the road) to drivers (i.e. "detour ahead"). The road will be able to sense wildlife on the road and can warn drivers to "slow down". There will also be embedded heating elements in the surface to prevent snow and ice buildup, providing for safer winter driving. This feature-packed system will become an intelligent highway that will double as a secure, intelligent, decentralized, self-healing power grid which will enable a gradual weaning from fossil fuels. Replacing asphalt roads and parking lots with Solar Roadway panels could be a major step toward halting climate change. Fully electric vehicles will be able to recharge along the roadway and in parking lots, finally making electric cars practical for long trips. It is estimated that is will take roughly five billion (a stimulus package in itself) 12' by 12' Solar Road Panels to cover the asphalt surfaces in the U.S. alone, allowing us to produce three times more power than we've ever used as a nation - almost enough to power the entire world.


Solar Roadway Traffic Example

In Orange County, California during peak highway use, the upper six lanes are "bumper to bumper" traffic. Even with this congestion, the road surface is still exposed to sunlight. ©2009 Google Earth

The Solar Roadway™ is a series of structurally-engineered solar panels that are driven upon. The idea is to replace all current petroleum-based asphalt roads, parking lots, and driveways with Solar Road Panels™ that collect and store solar energy to be used by our homes and businesses. This renewable energy replaces the need for the current fossil fuels used for the generation of electricity. This, in turn, cuts greenhouse gases literally in half.

The Sagle, Idaho-based Solar Roadways has been awarded a U.S. Department of Transportation contract that will enable it to prototype the first solar road panel.

The heart of the Solar Roadway™ is the Solar Road Panel™. Each individual panel consists of three basic layers:

Road Surface Layer - translucent and high-strength, it is rough enough to provide great traction, yet still passes sunlight through to the solar collector cells. It is capable of handling today's heaviest loads under the worst of conditions. Weatherproof, it protects the electronics layer beneath it.

Electronics Layer - Contains a large array of cells, the bulk of which will 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. 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. No more snow/ice removal and no more school/business closings due to inclement weather. The on-board microprocessor controls lighting, communications, monitoring, etc. With a communications device every 12 feet, the Solar Roadway™ is an intelligent highway system.

Base Plate Layer - While the electronics layer collects and stores the energy from the sun, it is the base plate layer that 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. Weatherproof, it protects the electronics layer above it.

When multiple Solar Road Panels™ are interconnected, the intelligent Solar Roadway™ is formed. These panels replace current driveways, parking lots, and all road systems, be they interstate highways, state routes, downtown streets, residential streets, or even plain dirt or gravel country roads. Panels can also be used in amusement parks, raceways, bike paths, parking garage rooftops, remote military locations, etc. Any home or business connected to the Solar Roadway™ (via a Solar Road Panel™ driveway or parking lot) receives the power and data signals that the Solar Roadway™ provides.

The proposed Solar Roadway™ would become an intelligent, self-healing, decentralized (secure) power grid. A large-scale system such as in North America would allow the east coast to power the west coast during the first three hours of the day when the west coast is still dark. Conversely, the west coast would power the east coast during the last three hours of the day when the east coast was dark. A world-wide system could potentially see the "lit" half of the world always powering the "dark" half of the world.

The Numbers
In the contiguous 48 states, there are over 25,000 square miles of impervious surfaces (roads, parking lots, driveways, sidewalks, etc.), not including actual buildings and structures. Continuing development adds another quarter of a million acres each year. If these impervious surfaces were replaced with Solar Road Panels™, how much electricity could be produced?

Using conservative assumptions:

• We use solar cells that have a mere 15% efficiency (there is technology available that actually doubles this number)

• We average only 4 hours of peak daylight hours per day (4 x 365 = 1460 hours per year)

A popular manufacturer of solar panels offers a 200 Watt model rated at 15% efficiency. Its surface area is 15.16 square feet. If we covered the entire 25,000 square miles of impervious surfaces with solar collection panels, we'd get:
((25,000 mi²) x (5280 ft / mi)²) / (200W/15.16 ft²) =

((25,000 mi²) x (27,878,400 ft² / mi²)) / (200W/15.16 ft²) =

(696960000000 ft²) / (200W/15.16 ft²) = 9194722955145.118733509234828496 Watts ≈ 9.19 Billion Kilowatts

If we average only 4 hours of peak daylight hours (1460 hours per year), this gives us: 9.19 Billion Kilowatts x 1460 hours = 13424295514511873.350923482849604 Kilowatt-hours (or) ≈ 13,424 Billion Kilowatt-hours of electricity.

Now, keep in mind that this is a conservative estimate.

According to the Energy Information Administration, the United States (all 50) used just over 4,372 Billion Kilowatt-hours of electricity in 2003, while the entire world (including the U.S.) used approximately 14,768 Billion Kilowatt-hours of electricity total. It is easy to see that the Solar Roadways™ could produce over three times the electricity that we currently use in the United States. Slightly increasing the conservatively low 15% efficiency would allow the U.S. (the “lower 48”) to produce the entire world’s electricity needs.

About 40% of U.S. carbon dioxide emissions stem from the burning of fossil fuels for the purpose of electricity generation. Coal accounts for 93% of the emissions from the electric utility industry.

This is where some of the numbers become "fuzzy": as best we can tell, it is estimated that approximately half (different agencies provide different estimates, but the average is about 50%) of the greenhouse gases that are causing global warming come from the burning of fossil fuels (primarily coal) to generate electricity. The Solar Roadway™ could, therefore, eliminate half of the greenhouse gases currently being produced. Summary: the Solar Roadway™ can cut the causes of global warming in half!

What is all this going to cost?
The average cost of asphalt roads in 2006 was roughly $16 per square foot. The cost does not include maintenance (pot hole repair, repainting lines, etc.) or snow/ice removal. The average lane width is 12 feet, so a 4 lane highway would be 12' (width per lane) x 4 (lanes) x 5280' (one mile) = 253440 square feet. Multiply this by $16 per square foot and your one-mile stretch of asphalt highway will cost $4,055,040.00 and will last an average of seven years.

We plan to design the Solar Roadways™ to last at least 21 years (three times that of asphalt roads), at which time the panels would need to be refurbished. Adding no additional cost to the current asphalt system, this will allow us to invest about $48 ($16 x 3) per square foot. This means that if each individual panel can be made for no more than $6912.00, then the Solar Roadway™ can be built for the same cost as current asphalt roads. However, asphalt roads don't give you anything back.

Based on 15% efficiency, each Solar Road Panel™ can produce an average of 7.6kWh per day. Our hypothetical 4-lane, one-mile stretch of road would require 1760 Solar Road Panels™. That means that, each day, this stretch of Solar Roadway™ would produce at least 13,376 kWh of electricity. That's 4,882,240 kWh per year - enough to take 500 homes completely "off grid". You don't get that out of asphalt!

In addition, the Solar Roadway™ replaces our current aging power grid. The Solar Roadways™ carry power – not from a centralized point like a power station, but from the power-producing grid itself – along with data signals (cable TV, telephone, high-speed internet, etc.) to every home and business connected to the grid via their driveways and parking lots. In essence, the Solar Roadways™ becomes a conduit for all power and data signals.

For an accurate cost comparison between current systems and the Solar Roadways™ system, you’d have to combine the costs of asphalt roads, power plants, and power and data delivery systems (power poles and relay stations) to be compatible with the Solar Roadway™ system, which provides all three.

2003: the US used just over 4,372 Billion kilo-Watt hours of electricity. This would require 14,574 300MW power stations (coal-fired, nuclear, etc.). For the sake of argument, let’s assume coal-fired power stations, which cost roughly $1B each for a 300MW plant.

Asphalt roads: 25,000 square miles in the “lower 48” states = 696960000000 square feet. At $16/square foot, this is a cost of $11,151,360,000,000 and the cost of asphalt is rising rapidly with the cost of petroleum. This does not include maintenance (pot hole repair, repainting of lines, snow/ice removal, etc.)

4.84 billion (12’ by 12’) Solar Road Panels™ would be required to replace the current asphalt road system, parking lots, and driveways in the 48 contiguous states. This is enough to provide three times more electricity than the United States used in 2003 and almost enough to supply the entire world.

If the Solar Road Panels™last 21 years before needing to be refurbished (not replaced), then we can triple the amount of money spent on asphalt roads, which have to be replaced every seven years.

Adding the cost of the power plants and tripling the cost of the asphalt roads, we get a total cost of $48,059,670,000,000. Divide this amount by the 4.84 billion Solar Road Panels™ required to replace the asphalt, and we get a target cost of $9923.16 per panel. This number is considerably higher if you pad in the costs of utility poles and relay stations that will no longer be needed with the Solar Roadways™ system.

In addition, there is no way to calculate additional savings such as the reduction in costs of vehicle and health insurance (due to lighted night roads, wildlife avoidance systems, snow/ice removal, etc.). Accidents and the loss of life (both human and wildlife) will be drastically reduced upon the Solar Roadways™.

Then there is the whole environmental issue: elimination of the fossil fuel plants will take away about half of the CO2 emissions that are known to be contributing to the climate crisis. Providing a means to recharge all-electric cars anywhere along the roadside will open the door for the elimination of the internal combustion engines, which account for most of the other half of the CO2 emissions. With internal combustion engines now obsolete, our dependency on oil - foreign or domestic - will finally be over with.

Conclusion: for roughly the same cost of the current systems (asphalt roads and fossil fuel burning electricity generation plants), the Solar Roadways™ can be implemented. No more Global Warming. No more power outages (roaming or otherwise). Safer driving conditions. Far less pollution. A new secure highway infrastructure that pays for itself. A decentralized, self-healing, secure power grid. No more dependency on foreign oil.


Solar Roadways