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Carbon capture and storage for coal-fired power plants (Rev #7, changes)

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Idea

This page is a discussion of carbon capture and storage (CCS) for coal-fired power plants.

Introductory articles

For a good introduction to CCS for coal-fired power plants, see:

Here are some particularly relevant bits:

Overall, coal-burning power plants provide nearly half (about 46 percent this year) of the electricity consumed in the United States. For the record: natural gas supplies another 23 percent, nuclear power about 20 percent, hydroelectric power about 7 percent, and everything else the remaining 4 or 5 percent. The small size of the “everything else” total is worth noting; even if it doubles or triples, the solutions we often hear the most about won’t come close to meeting total demand. In China, coal-fired plants supply an even larger share of much faster-growing total electric demand: at least 70 percent, with the Three Gorges Dam and similar hydroelectric projects providing about 20 percent, and (in order) natural gas, nuclear power, wind, and solar energy making up the small remainder. For the world as a whole, coal-fired plants provide about half the total electric supply. On average, every American uses the electricity produced by 7,500 pounds of coal each year.

So, Fallows argues, it’s hopeless to quit burning coal anytime soon — so we need to do it better.

What would progress on coal entail? The proposals are variations on two approaches: ways to capture carbon dioxide before it can escape into the air and ways to reduce the carbon dioxide that coal produces when burned. In “post-combustion” systems, the coal is burned normally, but then chemical or physical processes separate carbon dioxide from the plume of hot flue gas that comes out of the smokestack. Once “captured” as a relatively pure stream of carbon dioxide, this part of the exhaust is pressurized into liquid form and then sold or stored. Refitting an existing coal plant can be very costly. “It’s like trying to remodel your home into a mansion,” a coal-plant manager told me in Beijing. “It’s more expensive, and it’s never quite right.” Apart from research projects, only two relatively small coal-fired power plants now operate in America with post-combustion capture.

Designing a capture system into a plant from the start is cheaper than doing refits. But even then the “parasitic load” of energy required to treat, compress, and otherwise handle the separated stream of carbon dioxide can come to 30 percent or more of the total output of a coal-fired power plant—so even more coal must be burned (and mined and shipped) to produce the same supply of electricity. Without mandatory emission limits or carbon prices, burning coal more cleanly is inevitably more expensive than simply burning coal the old way. “When people like me look for funding for carbon capture, the financial community asks, ‘Why should we do that now?’” an executive of a major American electric utility told me. “If there were a price on carbon”—a tax on carbon-dioxide emissions—“you could plug in, say, a loss of $30 to $50 per ton, and build a business case.”

“Pre-combustion” systems are fundamentally more efficient. In them, the coal is treated chemically to produce a flammable gas with lower carbon content than untreated coal. This means less carbon dioxide going up the smokestack to be separated and stored.

Either way, pre- or post-, the final step in dealing with carbon is “sequestration”—doing something with the carbon dioxide that has been isolated at such cost and effort, so it doesn’t just escape into the air. Carbon dioxide has a surprisingly large number of small-scale commercial uses, starting with adding the sparkle to carbonated soft drinks. (This is not a big help on the climate front, since the carbon dioxide is “sequestered” only until you pop open the bottle’s top.) All larger-scale, longer-term proposals for storing carbon involve injecting it deep underground, into porous rock that will trap it indefinitely. In the right geological circumstances, the captured carbon dioxide can even be used for “enhanced oil recovery,” forcing oil out of the porous rock into which it is introduced and up into wells.

These efforts are in one way completely different from “advanced research and development” as we often conceive of it, and in another way very much the same. They are different in that the scientists and entrepreneurs involved do not seem to count on, or even hope for, the large breakthroughs we have come to assume in biological sciences and info-tech.

Instead of big breakthroughs, he argues that we need the incremental improvements that come when you’re actually doing something on a large scale. And that’s where China comes in:

In the search for “progress on coal,” like other forms of energy research and development, China is now the Google, the Intel, the General Motors and Ford of their heyday—the place where the doing occurs, and thus the learning by doing as well. “They are doing so much so fast that their learning curve is at an inflection that simply could not be matched in the United States,” David Mohler of Duke Energy told me.

“In America, it takes a decade to get a permit for a plant,” a U.S. government official who works in China said. “Here, they build the whole thing in 21 months. To me, it’s all about accelerating our way to the right technologies, which will be much slower without the Chinese.

“You can think of China as a huge laboratory for deploying technology,” the official added. “The energy demand is going like this”—his hand mimicked an airplane taking off—“and they need to build new capacity all the time. They can go from concept to deployment in half the time we can, sometimes a third. We have some advanced ideas. They have the capability to deploy it very quickly. That is where the partnership works.”

How it works:

Ten years ago, at the end of the Clinton administration, the Chinese and American governments signed a “Fossil Energy Protocol,” to coordinate research on better use of coal and oil. Political leaders have come and gone since then, but the cast of technicians, civil servants, and business officials on each side has been relatively stable and has gotten used to working together. After taking office as secretary of energy last year, Steven Chu—a celebrity in China because of his Chinese heritage and his Nobel Prize—gave a new push to these efforts, hiring additional staff members for the U.S.-China office and committing $75 million to a joint Clean Energy Research Center.

The efforts of two scientists we’ve already met, Julio Friedmann and Ming Sung, illustrate what Americans can and cannot do to shape what happens in China—and the mounting advantages on China’s side relative to America’s.

Friedmann, who is in his mid-40s, has become one of the world’s experts on sequestration: how and where carbon dioxide can safely be stored underground. He was trained in geology at MIT and the University of Southern California and initially went to work for ExxonMobil. But by the early 2000s he had become fascinated with the emerging science of underground carbon-dioxide storage. “At that point, it was clear that nearly all of the really cool work was being done in the national labs,” he told me. In 2004 he and his family moved from Maryland to California, where he joined Lawrence Livermore. He is now the head of the Carbon Management Program there and the technical leader of a government-university-business consortium that this summer won a Department of Energy competition to help develop carbon-sequestration projects in China. To give an idea of the consortium’s range, it includes three universities, three national laboratories, two scientific nongovernmental organizations, and six large corporations, among them General Electric, Duke Energy, and AEP.

What [[Julio Friedmann]] does:

On a typical trip to China, he will spend half his time in Beijing or Shanghai, meeting with government and corporate officials—and the other half in Xi’an or the Inner Mongolian wilderness, where many of the most promising storage locations are found. What he and his team have to offer, from the American part of the supply chain, is expertise on geological formations, on computer models for how the “plume” of liquefied carbon dioxide will settle into porous rock, and on other benefits of America’s decades of experience in petroleum geology. He can also put Chinese plant managers, scientists, and bureaucrats in touch with overseas counterparts they would otherwise never meet. “Projects like these are sort of like the school dance,” he told me. “You’re not getting married, but you’re figuring out how to interact. We need to start the process in a way that gives people the confidence to do it again, and again, and again. The confidence is the product.” The more often Chinese and foreign officials work together, the more easily they continue to work together. This might sound trivial, but I’ve become convinced that the steady expansion of these contacts will make a major difference in how an ever more powerful China deals with the rest of the world. What does Friedmann, or the United States, get from the process? “More tons sequestered, rather than emitted, in China,” he told me. But also something unavailable in America: a chance to see new technology in new plants and learn how it works. “In the U.S. today, there is not a single demonstration of capturing CO2 from a coal-fired plant at large scale,” he said. “The technologies have been a little too expensive to actually implement. That’s why we started looking at China.” They can afford to build, and Americans can hope to watch and learn.

What Ming Sung’s [[Clean Air Task Force]] does:

In the early 2000s the task force, originally a conventional anti-air-pollution group, embraced the necessity of cleaning up coal. In Beijing, Sung gave me a copy of its latest working paper, in both Chinese and English, called “Coal Without Carbon.”

The group has sponsored research on sequestration, on post-combustion capture, and on the “cleanest” of the emerging pre-combustion coal technologies—“underground coal gasification.” In this process, jets of air (or pure oxygen), sometimes with steam or various chemicals, are blasted into coal seams deep underground. They interact chemically with the coal to produce a gas that flows back up a pipe and can be burned. It leaves in the ground much of the carbon, sulfur, nitrogen, and other elements that create [[greenhouse gases]] and other pollutants when coal is burned.

“And this can be very cheap,” Sung told me. “You don’t have to mine the coal. You don’t have to send men underground or haul coal around or dispose of ash. All the dirty stuff stays buried.” Because of these and other savings, he said, coal used this way could match or beat the price of today’s standard dirty power plant.

But in advocating the whole range of “clean coal” technologies, Sung and his team have the same problem Julio Friedmann has with carbon sequestration: it’s not happening in the United States. There’s one significant exception: the [[Texas Clean Energy Project]], a plant being built outside Odessa, which will apply underground-gasification technology to capture 90 percent of its carbon, more than any other commercial plant in the world. It received a $450 million federal award, just over half from the Department of Energy’s Clean Coal Power Initiative? and the rest from the American Recovery and Reinvestment stimulus program (toward the $2.1 billion total capital cost). If it works as promised, this facility will be an advance over any coal-fired plant operating anywhere: it will gasify coal underground, eliminating the cost and damage of mining; it will sell urea (for fertilizer) and other chemical by-products of the underground gasification; and it will use the captured carbon dioxide for enhanced oil recovery in the nearby Permian Basin oil fields—all in addition to generating power.

(Correction: The decarbonization and other cleanup steps that make this plant distinctive are done above rather than underground. For full details, see texascleanenergyproject.com/about-tcep.)

Recent progress in China

From Nature, 469. In 2009, the government-owned Huaneng Group opened a carbon capture facility at an existing power station.

The system scrubs roughly 120,000 tonnes of CO2 a year from 3% of the facility’s flue gases, but what has caught everybody’s eye is the cost that Huaneng quotes: a mere US$30–35 per tonne of CO2, including the further expense of purifying the captured gas for use in the food and beverage industry.

That is far below the $100 or more typically estimated for first-generation projects to retrofit existing power plants for carbon capture and storage (CCS) in the United States and Europe, and it is within the range of past carbon prices in the European Union emissions trading system.

category: carbon, energy

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