Archive for August 15th, 2012


Potential of Renewables is Greater Than U.S. Power Demand

Post from Jeffrey Winters:

Jeffrey Winters

The biggest story in the U.S. power industry is the speed at which natural gas is replacing coal. Overshadowed but still critical is the rise of renewable energy: In the first half of 2012, non-hydroelectric renewable electricity accounted for 6 percent of net generation on the U.S. electric grid. Data from the Energy Information Agency shows that as recently as 2010, that figure was just 4 percent, and the amount of renewable electricity on the grid has gone up by a factor of 2.5 since 2003.

But according to a report released in July by the National Renewable Energy Laboratory in Boulder, Colo., we’ve only scratched the surface of the renewable electricity potential in the U.S. Based on a state-by-state assessment of the amount of technically possible renewable energy that’s available, the U.S. could generate all its electricity demand by tapping less than 1 percent of its renewable potential.

The NREL study is not a proposal, but a theoretical maximum. The team of researchers looked at the entire U.S. landmass and only excluded places that were either physically or politically unsuitable to host a renewable power facility. For instance, the potential wind power for each state was calculated based on the number of square miles that had less than a 20-degree slope and was more than two miles away from such features as cities, airports, Federal wildlife refuges, and national parks.

If you max out the solar, wind, geothermal, biomass, and low-impact hydroelectricy using existing technology, the NREL study found, you could generate an astonishing 481,800 TWh per year. That compares to roughly 4,000 TWh per year of net generation in the U.S.

Although wind power is the largest renewable energy source today—and has grown by a factor of ten over the past decade—the NREL report found that solar power, both thermal and photovoltaic, has the most potential in the U.S. While wind could theoretically max out at around 50,000 TWh per year, concentrating solar power plants could generate more than twice that much and utility scale photovoltaics could make 280,600 TWh per year in a full build out. Even the relatively modest 800 TWh per year that’s the maximum allotted to rooftop-mounted PV is roughly the same as the current U.S. nuclear fleet.

To be sure, the NREL study didn’t account for such limiting factors as price. But as the U.S. electrical grid becomes increasingly decarbonized, the study may serve as a reminder that it’s possible, in theory at least, to bring down carbon emissions to zero.

The Editor

John G. Falcioni is Editor-in-Chief of Mechanical Engineering magazine, the flagship publication of the American Society of Mechanical Engineers.

August 2012

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