A March 14 Newsweek article by Sharon Begley explains why we can’t get to renewable energy-CO2 nirvana from where we are today:
… 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. Obama promised green jobs, but still.
Here’s more from the article:
If Mr. Obama is only counting wind power and solar power as renewables, then his promise is clearly doable. But the unfortunate truth is that even if he matches Mr. Bush’s effort by doubling wind and solar output by 2012, the contribution of those two sources to America’s overall energy needs will still be almost inconsequential.
Here’s why. The latest data from the U.S. Energy Information Administration show that total solar and wind output for 2008 will likely be about 45,493,000 megawatt-hours. That sounds significant until you consider this number: 4,118,198,000 megawatt-hours. That’s the total amount of electricity generated during the rolling 12-month period that ended last November. Solar and wind, in other words, produce about 1.1% of America’s total electricity consumption.
Of course, you might respond that renewables need to start somewhere. True enough — and to be clear, I’m not opposed to renewables. I have solar panels on the roof of my house here in Texas that generate 3,200 watts. And those panels (which were heavily subsidized by Austin Energy, the city-owned utility) provide about one-third of the electricity my family of five consumes. Better still, solar panel producers like First Solar Inc. are lowering the cost of solar cells. On the day of Mr. Obama’s speech, the company announced that it is now producing solar cells for $0.98 per watt, thereby breaking the important $1-per-watt price barrier.
And yet, while price reductions are important, the wind is intermittent, and so are sunny days. That means they cannot provide the baseload power, i.e., the amount of electricity required to meet minimum demand, that Americans want.
That issue aside, the scale problem persists. For the sake of convenience, let’s convert the energy produced by U.S. wind and solar installations into oil equivalents.
The conversion of electricity into oil terms is straightforward: one barrel of oil contains the energy equivalent of 1.64 megawatt-hours of electricity. Thus, 45,493,000 megawatt-hours divided by 1.64 megawatt-hours per barrel of oil equals 27.7 million barrels of oil equivalent from solar and wind for all of 2008.
Now divide that 27.7 million barrels by 365 days and you find that solar and wind sources are providing the equivalent of 76,000 barrels of oil per day. America’s total primary energy use is about 47.4 million barrels of oil equivalent per day.
Of that 47.4 million barrels of oil equivalent, oil itself has the biggest share — we consume about 19 million barrels per day. Natural gas is the second-biggest contributor, supplying the equivalent of 11.9 million barrels of oil, while coal provides the equivalent of 11.5 million barrels of oil per day. The balance comes from nuclear power (about 3.8 million barrels per day), and hydropower (about 1.1 million barrels), with smaller contributions coming from wind, solar, geothermal, wood waste, and other sources.
Here’s another way to consider the 76,000 barrels of oil equivalent per day that come from solar and wind: It’s approximately equal to the raw energy output of one average-sized coal mine.
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