Factoid about solar energy
Last evening, one of those strange questions came up that I'll spend an inordinate amount of time researching, just out of curiosity. The question was this:
If we tried to provide all the electricity the United States needs using only photovoltaic solar cells (where sunlight is converted directly into electricity), how much area would it cover?
I'm going to throw out some numbers, but bear with me.
This DOE spreadsheet says the 2005 electrical generating capacity of the entire United States was 1,067,000 megawatts; I got that by summing up the "Nameplate Capacity" column.
This DOE page shows a photovoltaic project in Arizona that uses 100,000 square feet of photovoltaic panels to produce 1 megawatt of electricity.
To meet the entire electrical capacity of the country, then, we'd need 106,700,900,000 square feet of panels, which is 3,827 square miles; that's about 7.7 times the area of Knox County, or 5 times the area of the Great Smoky Mountains National Park.
I bet if we covered the roof of every building in the country with those panels, we'd have way more capacity than we needed. Of course, photovoltaic cells are expensive and require some exotic materials. According to this, the cost of those panels in Arizona was $2.86 per square foot. That'd be over $300 billion.
We need to find solutions that eliminate carbon dioxide emissions wherever possible; solar can't completely solve the problem, but a large-scale rollout of the technology would certainly help matters.