“Two terawatts of photovoltaic would require installing 100 square meters of 15-percent-efficient solar cells every second, second after second, for the next 25 years. (That’s about 1,200 square miles of solar cells a year, times 25 equals 30,000 square miles of photovoltaic cells.) Two terawatts of solar thermal? If it’s 30 percent efficient all told, we’ll need 50 square meters of highly reflective mirrors every second. (Some 600 square miles a year, times 25.) Two terawatts of biofuels? Something like 4 Olympic swimming pools of genetically engineered algae, installed every second. (About 61,000 square miles a year, times 25.) Two terawatts of wind? That’s a 300-foot-diameter wind turbine every 5 minutes. (Install 105,000 turbines a year in good wind locations, times 25.) Two terawatts of geothermal? Build three 100-megawatt steam turbines every day—1,095 a year, times 25. Three terawatts of new nuclear? That’s a 3-reactor, 3-gigawatt plant every week—52 a year, times 25.” Add it up, and when you’re done, you’ve got an area about the size of America—“Call it Renewistan,” says Griffith—covered with stuff dedicated to generating humanity’s energy."
From the Whole Earth Catalog by stewart brand.