Newsweek

We Can’t Get There From Here
Newsweek

The world used 14 trillion watts (14 terawatts) of power in 2006. Assuming minimal population growth (to 9 billion people), slow economic growth (1.6 percent a year, practically recession level) and—this is key—unprecedented energy efficiency (improvements of 500 percent relative to current U.S. levels, worldwide), it will use 28 terawatts in 2050. (In a business-as-usual scenario, we would need 45 terawatts.) Simple physics shows that in order to keep CO2 to 450 ppm, 26.5 of those terawatts must be zero-carbon.

That’s a lot of solar, wind, hydro, biofuels and nuclear, especially since renewables kicked in a measly 0.2 terawatts in 2006 and nuclear provided 0.9 terawatts. Are you a fan of nuclear? To get 10 terawatts, less than half of what we’ll need in 2050, Lewis calculates, we’d have to build 10,000 reactors, or one every other day starting now. Do you like wind? If you use every single breeze that blows on land, you’ll get 10 or 15 terawatts. Since it’s impossible to capture all the wind, a more realistic number is 3 terawatts, or 1 million state-of-the art turbines, and even that requires storing the energy—something we don’t know how to do—for when the wind doesn’t blow. Solar? To get 10 terawatts by 2050, Lewis calculates, we’d need to cover 1 million roofs with panels every day from now until then. “It would take an army,” he says.