Thursday, February 18, 2010

The Challenge of Scale

This morning's Wall St. Journal featured a front-page article on small-scale nuclear power, highlighting how reactors a tenth the size of current commercial designs could significantly reduce the financial risks associated with these mega-projects. This is one example of the need to think in new ways about scale when addressing our energy challenges. In his talk at this year's TED conference in Long Beach, Bill Gates offered another surprising perspective on scale: "All the batteries we make now could store less than 10 minutes of all the energy [in the world]," he said. Framed between those two examples is the basic proposition that while solving our energy problems may require breaking them down into more manageable pieces, they must still add up to mind-numbingly stupendous sums.

According to figures from the Energy Information Agency of the Department of Energy, in 2008 the US consumed 99.3 quads of primary energy--oil, gas, coal, nuclear power, hydropower, biomass and other renewables--down from 101.6 quads the year before. A quad is one quadrillion times the quantity of energy required to raise the temperature of a pound of water by one degree Fahrenheit, where a quadrillion is 1 followed by 15 zeroes (US definition.) Can you picture that? I can't. If I convert that consumption to barrels of oil equivalent at the rate of 5.8 million BTUs each, we get a value of just over 17 billion barrels--a much more familiar unit, especially when we divide by 365 to get 47 million barrels per day. Millions are much closer to something we can grasp, and if we are familiar with energy data we know that's equivalent to a little more than half the amount of oil produced globally every day. It's still hard to picture, though, until you work out that if it were all put in one place in outer space, it would form a spherical blob roughly 800 ft. in diameter--over half as tall as the Empire State Building--and that's every day.

By comparison the daily output of a 3 MW wind turbine, converted to its energy-equivalent of oil (assuming it backs out natural gas from a gas turbine power plant) would form a ball about 7 ft. across. It would take 1,400,000 such balls to fill the big sphere. Of course we can't really compare the output of 1.4 million wind turbines to the total amount of energy we use each day, for many reasons, though it's a handy reminder of just how big the challenge is, and why building nuclear reactors in increments of 125 MW each might be a smart way to finesse this gap.

A 125 MW reactor, if it operated with the same reliability that large nuclear plants have achieved, would produce as much power every day as 125 of those 3 MW wind turbines. And while we doubtless couldn't build these reactors as fast as wind turbines, I'll bet we could add nuclear power capacity faster in these increments than with 1,200-1,500 MW reactors, because of the advantages of being able to manufacture more of each facility in a factory, rather than constructing them on-site. Even if that translated into total project timelines only half as long as for large-scale nuclear plants of the kind for which the administration just awarded federal loan guarantees, that could be worth a lot to the utilities and merchant generating companies building them. It would greatly reduce project risks of the kind that can ruin the economics of big investments--delays, cost over-runs, accidents--and that give companies' bankers and shareholder chills. These aren't the kind of risks the government is offering to defray, by the way.

Of course that doesn't make small nuclear an either/or proposition vs. large-scale nuclear, any more than wind and solar are an either/or proposition vs. oil & gas platforms or big gas-fired power plants that can operate efficiently 24/7. There's room--and need--in our national energy economy for all of these, as our energy diet shifts from a heavy reliance on fossil fuels to a lighter, more sustainable diet in the future. At the same time, it's clear that we can't fill the gap exclusively with small-scale energy sources, without a sizable contribution from sources at least as big as these small reactors. "Drill, baby, drill" only captured one aspect of this concern. More accurately, our energy policy must deliver "scale, baby, scale."

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