A bridge to the renewable energy future: renewables are coming fast. In the meantime, here's a largely overlooked but potent way to minimize fossil fuel use and the damage it causes.

• Author: Ayres, Robert U.

Historically, Americans have been strong on big ideas, but not always so strong on the devil in the detail. So, for example, public officials looking for alternatives to imported oil have widely embraced corn ethanol, even though a range of studies assessed by the Natural Resources Defense Council and others show that corn ethanol has a nearly zero net gain in energy output, while taking a heavy toll on human food-producing capacity. Or, many of those looking for "energy independence" still embrace the John McCain mantra to "drill, baby, drill," perhaps because the notion of increased domestic oil output comes across as a manly defiance of the Middle-Eastern chokehold on our gas pumps. More domestic oil might be an attractive concept, except that the numbers say it would add nothing to our energy supply in the next 10 years and would never come close to replacing imports. (The U.S. Department of Energy estimates that U.S. territories, including coastal waters, have 3 percent of the known remaining global oil reserves.) That latter fact has provided Al Gore and others an opening for their claim that renewables, in contrast to more oil drilling, could bring America to full energy independence in a decade. But that claim, too, betrays an embrace of broad concept that isn't completely realistic about numbers.

What can renewables in the United States really do in 10 years? The Gore vision has been facilitated by the observation that renewables are growing spectacularly fast, much faster than any fossil fuel. But of course, that's percentage-wise, not in gigawatts or barrels of oil-equivalent. The hard truth is that renewables have started from such a tiny base that even with exponential growth it will take a long time for them to take over a large share of the work now done by coal, oil, and natural gas. The picture is also skewed by the fact that at present, the lion's share of renewable energy is provided by hydroelectric power, which cannot significantly expand. Virtually all of the U.S. rivers that have significant hydro potential are already dammed. The percentages of U.S. energy provided by the other renewable sources, as of 2006, were as follows: biofuels 1.4, windpower 0.8, solar photovoltaic (PV) 0.4, and geothermal 0.1. Of these, only the three zero-something resources are carbon-free (biofuels may add to supply, but also add to emissions).

Of course, emissions-free renewables have continued to grow fast since then, and the expansion will likely continue. President Obama has called for a doubling of solar power in three years. But even assuming that could be kept up for the next decade, it would still bring solar power to only about 13 percent of U.S. energy supply. Moreover, achieving the clean-energy future is not just a matter of expanding clean-energy production; it also requires massive rebuilding of infrastructure--the electric power grid, recharging stations for electric cars, retooling of car manufacturing, the factories to build next-generation batteries and fuel cells, expansion of public transit systems, and so on. Not all of this will happen as fast as the growth in solar PV capacity has been. The production of tellurium, an essential component of the most advanced thin-film PV panels, could become a major bottleneck, for example. Tellurium is very scarce, much scarcer even than platinum, and any limitation in the supply could put a drag on expansion of PV capacity.

However you figure it, the U.S. economy will still be heavily dependent on coal and oil 10 years from now, and for many years after that. Yet, in the meantime, the internal combustion engine-powered auto industry is plagued with overcapacity, coal is ravaging the climate, and global oil production is likely to peak and begin its terminal decline even as demand for it is expanding hugely in China and worldwide. So as demand begins to dwarf supply, fossil-fuel prices will rise inexorably during a period when renewables will not yet have the capacity to take over. What will happen in the meantime?

Recapturing Lost Energy

One answer to that question can be seen in one of the dirtiest corners of the industrial past. A few years ago, behind the gates of a large, rust-belt factory in East Chicago, Indiana, the world's largest steel company, Mittal Steel (now Arcelor Mittal), began using a facility that captured waste heat from one of its fossil fuel-burning processes and converted that heat to emissions-free electricity. The facility, called Cokenergy, heated coal to extremely high temperatures to make industrial coke, a key input to the steel-making process. But instead of blowing the residual heat into the air, as is done in conventional coke-making, the Cokenergy facility intercepted the heat to run a steam turbine to generate power, which in turn was used to provide power to the big steel plant next door.

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Meanwhile, a few kilometers down the road, a rival company, U.S. Steel, was using a similar strategy to generate emissions-free power from waste blast-furnace gas. In 2005, between them, the two rust-belt rivals generated 190 megawatts of carbon-free energy from their waste--more than the entire U.S. production of solar photovoltaic electricity that year. That was just the waste from two fossil fuel-burning plants in one corner of one state. Those two steel plants were--and are--using a strategy that, if more widely exploited, could hugely increase U.S. clean-energy output without any increase in fossil fuel consumption. It's a strategy that one of its pioneers, electric power engineer Tom Casten, calls "energy recycling." It was Casten whose company developed the facilities that now turn waste to clean energy for both Mittal and U.S. Steel.

Environmentalists, guided by the principle that we live on a planet of finite size, have vigorously promoted recycling for the past three decades, and recycling materials--paper, metals, plastic, water, yard waste, engine oil, even municipal sewage--is now well established. Yet, curiously, recycling of energy, which is essential to the processing and use of all materials, has been largely overlooked. That may be in part because we all know that energy can't actually be "used up." But Tom Casten shrugs that off; his phrase gets your attention, and what he's really talking about is the harnessing of energy that in conventional industrial processes is not used but thrown out. A factory blows its waste streams of energy-rich, high-temperature heat or steam into the air or a river, or gets rid of its flare gas by flaming it into the sky. If you've driven along certain stretches of the New Jersey Turnpike or the Cancer Alley region of Louisiana at night, you've seen flare gas...