Technology is winning the war on coal

With helpful new recycling methods, scientists might actually be able to clean up the world's dirtiest fuel

Topics: Scientific American, Coal, Climate Change, Global Warming, Fuel, Energy, Science, carbon, carbon capture and storage, , ,

Technology is winning the war on coal (Credit: acilo via iStockphoto)
This article was originally published by Scientific American.

Scientific AmericanMississippi may prove the first state in the U.S. to help coal fight global warming. A new facility rising from Kemper County’s loamy soil will take the dirtiest coal from a local mine, turn it to gas, strip out the climate change-causing carbon dioxide, and then burn the gaseous fuel—resulting in pollution rates comparable with a power plant that burns natural gas. If coal use can truly be made (atmospherically) clean, it could act as a powerful counter to global warming.

The enabling technology to achieve this goal is a still relatively unknown form of recycling called carbon capture and storage, or CCS. Think of it as a way to shorten the geologic eras it takes for natural systems to pull carbon dioxide back out of the atmosphere. Instead, CCS traps the CO2 emitted whenever a fossil fuel is burned and then makes that gas available for disposal, perhaps deep underground. Various proposals for CCS have circulated for decades and technology demonstrations have ranged from large chemical facilities attached to coal-fired power plants to simple filters to capture the CO2 directly from the air.

Yet, when it comes to using CCS to solve the climate change brought on by ever-increasing CO2 emissions from human fossil-fuel burning, the technology has been, at best, stalled. A variety of projects exist (or existed) but the technology has failed to take off, largely because it remains more expensive to capture CO2 than to dump such fossil carbon for free into the atmosphere, where the trillions of freshly freed molecules can freely trap the heat causing global warming.

Regulators now want to make CCS more alluring. New rules from the U.S. Environmental Protection Agency mandate that any new coal-fired power plant willrequire at least part of its CO2 pollution to be captured and stored. The levels in the proposal would allow 1,100 pounds of CO2 per megawatt-hour of electricity produced to be emitted, the amount of gas spewed by the average new power plant burning natural gas. (Of course, to truly combat climate change, even that pollution would have to be captured and stored.)

The question now relates to whether the technology is ready for wide deployment. “It is happening now,” argues Secretary of Energy Ernest Moniz, a point backed up by a Congressional Research Service report from October and the new Kemper power plant. In fact, that facility is the first large-scale effort to move CCS beyond the scale of demonstration projects. The 550-megawatt coal-gasification power plant, fitted with CCS, is scheduled for completion in 2014. “It’s a monster,” says Moniz, who recently toured the site.

Kemper will use lignite or brown coal—the most polluting form of the dirtiest offossil fuels as well as the cheapest—but only after it has been transformed into a gas. This gasification process also allows the facility to strip out CO2. The captured CO2 will then be pumped into a dedicated 100-kilometer-long pipeline at the end of which sits an oil field.

Carbon dioxide has long been used in the oil industry to help scour extra petroleum out of the ground in old fields. “Today we are producing with CO2 [enhanced oil recovery] 300,000 barrels per day of oil,” Moniz notes. “This is not so small,” and there is the potential for as much as three million barrels a day of oil to be produced using this technique, according to some estimates. “You ain’t going to find that much CO2 except at things like power plants or large industrial facilities.”

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So the Kemper power plant will have some additional products to sell thanks to its recycling mission. As Moniz says: “they have their long-term contracts in place for electricity, for sulfuric acid, for ammonia and for carbon dioxide.”

Costly addition
The big problem remains cost; CCS adds at least $.04 per kilowatt-hour of electricity produced at a power plant that uses coal. Kemper is forecast to finish at a total cost of slightly more than $4 billion, more than a billion dollars over budget, according to the utility building it, Southern Co. subsidiary Mississippi Power—and further delays could lead to further cost. “Obviously, over time, the cost will come down,” Moniz argues.

The key to bringing cost down is deployment. To that end, the U.S. Department of Energy (DoE) has funded eight CCS demonstration projects, including an already opened facility in Port Arthur, Texas, as well as made $8 billion available for loan guarantees for CCS projects. At the same time, the DoE’s Advanced Research Projects Agency for Energy, or ARPA-E, has invested $40 million in novel methods for capturing CO2 under its IMPACCT program: Innovative Materials and Processes for Advanced Carbon Capture Technologies.

Already, three of the technologies that show promise have been picked up by the DoE’s Office of Fossil Energy for further development to test the cost-effectiveness of using these methods to capture CO2 after the coal has been burned. Alliant Techsystems (ATK) plans to strain flue gas through a nozzle that would cool the CO2 to turn it solid, and then separate the gas out with a rapidly rotating chamber that creates a cyclone-like effect, which collects the solid CO2. GE Global Research uses a proprietary material that becomes solid on contact with CO2 and the Research Triangle Institute (RTI International) has a new solvent that doesn’t require as much steam heat to release CO2 and be ready to capture more. But alternative technologies for CO2 capture are still largely engineering brainstorms; they will take years, if not decades, to make their way from laboratory to commercial power plant.

Industrial scale
Carbon capture will be needed everywhere from cement and steel to oil refineriesthat currently produce excess global warming pollution. That implies gigatonnes of CO2 looking for storage, and it is unclear where exactly that might be. Two of the DoE’s current slate of demonstration projects aim to show that excess CO2 can be safely stored in a deep aquifer of salty water in Illinois. And previous projects, such as CCS at the Mountaineer Power Plant in West Virginia, proved that CO2 could be stored without incident in underground rock formations—but the project stopped for lack of funds. “What electric utility company, for example, would want to spend a large sum of money to install CCS—even with an improved lower-cost capture process—if there is no requirement or incentive to reduce CO2 emissions?” the October CRS report asked.

According to DoE estimates there is enough subterranean real estate with the right geology to store 3,911 billion metric tons of CO2, or roughly 100 years of current U.S. CO2 pollutio. But that assumes building a national infrastructure—comparable with the one for moving oil and gas—simply for the disposal of an unwanted by-product. To justify that expense, the price on CO2 pollution would have to be high—or the greenhouse gas would have to be outlawed.

And other issues surrounding the S in CCS remain to be figured out, including how to monitor CO2 underground, how to manage underground pressures to ensure no venting in the event of an earthquake or the like, and who, ultimately, owns and is responsible for that entombed CO2, among other potential snags. “We have to work through that but we will only work through that once we start having these big projects,” Moniz says.

In fact, the only way to bring the cost of CCS down is to make the technology commonplace. The October CRS report estimates that CCS prices could fall by 30 percent once 100,000 megawatts worth of power plants have installed and operated some version. In a sense, it’s the same chicken-and-egg problem encountered with many new energy technologies—CCS cannot become cheap and ubiquitous without aprice on CO2 and politicians are not willing to impose a price on CO2 until CCS is cheap and ubiquitous.

War on coal
Adding CCS to existing power plants may be the best technological hope for restraining global warming, particularly in countries like China, which have seenmassive growth in greenhouse gas pollution as the nation’s prodigious expansion of coal-based electricity continues. More than 40 percent of all global warming pollution worldwide comes from burning coal and there are more than 1,000 new coal-fired power plants in the planning or building stages around the world. Since the turn of the 21st century coal has been the fastest growing source of energy year after year. “Coal must change rapidly and dramatically for everyone’s sake,” Christiana Figueres, executive secretary of the U.N. Framework Convention on Climate Change, told a gathering of coal executives in Warsaw this past November. “If we continue to meet energy needs as we have in the past, we will overshoot the internationally agreed goal to limit warming to less than 2 degrees Celsius.”

Even if CCS makes coal cleaner from a climate perspective, the fossil fuel still carries a host of problems, including what to do with all the residual toxic coal ash as well as the dangers of mining. And using captured CO2 to free more fossil CO2 (in the form of oil) is not the quickest route to significant cuts in greenhouse gas pollution. But the importance of CCS to the future has not escaped the notice of policy makers. In November energy ministers from nations representing 76 percent of global warming pollution noted that CCS “is an indispensable element of any effective response to climate change.”

Even more recently, Moniz’s immediate predecessor as energy secretary, Nobel laureate Steven Chu, joined the board of a Canadian company—Inventys Thermal Technologies—that is looking to commercialize its reputedly low-cost CO2 capture method. “We’re going to go to low carbon,” Moniz says, noting that implementing Pres. Obama’s climate action plan will be a big part of his time in office. “But we think all the fuels—with enough investment—are going to have a place in that low-carbon world.” In other words, there is no war on coal, thanks to big hopes for CCS.

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