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Only so much bare roof area, but to say there is plenty left still would be an understatement.
by gascan 8y ago
Only so much bare roof area, but to say there is plenty left still would be an understatement.
- ben_w 8y agoUSA Interstate network has a total length of 77,556 km. A 1m wide strip of PV along the dividing barrier in the middle is, eyeballing the solar irradiance graphs, something like 77.5e6 m^2 * 1500 kWh/m^2/y = 116.250 TWh/y compared to USA annual use of about 25 TWh/y for all power not just electricity. Even accounting for PV efficiency, that’s basically enough from just one possible currently wasted location. Obviously every country is different — my country, the UK, much worse annual average light, and higher population density, but the point still applies. Almost every nation can do this without worrying about land use.
- philipkglass 8y agoI agree that most countries are not critically limited by land when it comes to solar power, but there are a couple of problems with your figures. The US consumes nearly 29000 TWh of primary energy per year, of which about 3700 TWh ends up as usable electricity: https://flowcharts.llnl.gov/content/assets/images/charts/Energy/Energy_2017_United-States.png https://flowcharts.llnl.gov/content/assets/images/charts/Ene... (1 "quad", quadrillion BTU, is 293 TWh.) The other is that you're estimating the energy of the sunlight that falls on 77.5e6 m^2 rather than the achievable electrical generation. The most efficient terrestrial solar panels are just a little above 20%.
- gascan 8y agoRooftops are also conveniently close to the demand.