How much electricity can we really produce?
Engineers love numbers. They (the numbers, that is) generally bore people to death, but at times they are necessary for understanding. One of the biggest questions that has been asked is simply, "Can we really generate enough pollution-free electricity to power our businesses and homes?" The calculations below are presented to answer this very important question.
First, the “givens”:
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 we produce?
Let us make these very 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 or 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, in other words, 13,424 Billion Kilowatt-hours of electricity.
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. US Emissions Inventory 2004
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™ will, therefore, eliminate half of the greenhouse gases currently being produced.