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Putting the ‘Clean’ in Coal Technology

American Association of Petroleum Geologists (AAPG)

Clean coal technology is one of those concepts that in theory work for everyone: environmentalists, the industry at large, coal producing states, American consumers.

It also is, however, an illusive and expensive concept, often argued about.

How clean is clean? How much clean can we afford? Does it even exist?

The devil really is in the details – in this case, in the coal. Literally.

Simply put, the dirtier the coal, the tougher it is to clean; the more it’s cleaned, the more expensive the energy derived from it becomes.

William Ambrose
William Ambrose

AAPG member William Ambrose, who presented a paper on clean coal technology at the recent AAPG Annual Convention and Exhibition, admits that “CCS” (the catchall phrase for “carbon capture and storage”) isn’t cheap and isn’t easy, but is worth it.

“Coal-gasification technology can achieve reductions in mercury, arsenic and sulfur up to 80 percent, as well as CO2 capture at levels of as much as 90 percent.”

More importantly, says Ambrose, who is a research scientist for the Bureau of Economic Geology at the University of Texas, Austin, as well as a past president of AAPG’s Energy Minerals Division, there’s so much coal available, we owe it to ourselves to use it.

“The United States has a superabundance of coal, with almost six quintillion BTU of energy-equivalent resources,” he said, “more than Eastern Europe and the former Soviet Union (FSU) combined.”

The Price Is Right?

Cleaning coal involves stripping of minerals and other impurities via high-temperature and high-pressure gasification with capture of CO2 and hydrogen. Minerals and impurities that are stripped from coal are oxides of nitrogen and sulfur (referred to as NOx and SOx), mercury, sulfur, arsenic, metals such as lead and cadmium, and ash.

Here’s the catch, though. It comes, as Ambrose admits, with an “appreciable price tag.”

The costs of capture, transport and storage of CO2 range, he estimates, from $25 to more than $50 per metric ton. This depends on a variety of factors, including:

  • Pre- versus post-combustion carbon capture.
  • New plant versus retrofitted plant.
  • Type of gasifier feedstock.
  • Distance of new plants from user electric load.

Operational costs, too, will increase the cost $15 per metric ton.

The net result is that the overall energy penalty of installing CO2-capture equipment could reduce plant efficiency by as much as 40 percent.

“And when one figures in the additional costs on new construction of new CO2 pipelines or pumping costs associated with CO2 sequestration in deep, brine-bearing formations, the cost of electricity could go up by 25 to 50 percent or more,” Ambrose said.

To put those cost increases in perspective, he added, while $50 per metric ton may not seem like a great amount, the state of Texas, for instance, accounted for 152 million metric tons (Mt) from coal-fired power plants in 2008. To capture and sequester all this CO2 would cost $7.6 billion per year.

So why bother?

Ambrose is clear.

“Harnessing these vast resources could help the U.S. to lessen its dependence on foreign energy sources.”

Clean, Right Now

And it’s not like it isn’t already being done effectively.

“Actually, clean coal processes have been under way in the United States for more than 40 years since the Environmental Protection Agency began operations in December 1970,” Ambrose said.

For example, from 1970 through 2003, particulate emissions from coal-fired power plants declined by 87 percent and SOx emissions fell by 35 percent, although electricity from coal increased by almost 180 percent.

Successful CCT operations are occurring in:

  • Cranfield, Miss.
  • Hastings, Texas.
  • Decatur, Ill.
  • The Barry Generating Plant near Mount Vernon, Ala.
  • The Weyburn Field in Saskatchewan, Canada.

“These CCS projects are already demonstrating the technical feasibility of carbon capture and sequestration,” Ambrose said.

And these projects, like the coal itself, are embedded in the lives of a number of states, including their politics.

“States such as Illinois, West Virginia and Wyoming, with significant coal resources, tend to lobby for coal regardless of local party constituencies,” Ambrose noted.

The feds, too, have a part to play, and here Ambrose talks of FutureGen, a $1 billion government challenge to the states to build a clean coal re-powering program and carbon dioxide (CO2) storage network.

“These included Illinois (which was awarded the prize), Texas, Kentucky, North Dakota, Ohio, West Virginia and Indiana,” he said.

And though the FutureGen initiative was associated with the George W. Bush administration,” Ambrose admits other administrations also have shown interest in clean coal – like the present one, which actually awarded the prize.

The Competition

Whether they should be so active, though, or how much, is open to some debate, for there are many who believe that natural gas, rather than coal, is where the nation’s focus should be. Ambrose understands the attraction.

“Natural gas continues to make inroads at the expense of coal as a source of electrical power generation, owing to low gas prices,” he said. “Moreover, natural gas is an extremely versatile fuel, used in residential, commercial, industrial and transport sectors of the economy.

“Another advantage that natural gas has over coal,” he added, “is that the latter is the most carbon-intensive of the fossil fuels.”

And that is, and always has been, coal’s Achilles’ heel. It’s dirtier than everything else out (or under) there.

Economically, though, the plus side for coal is that these traditional coal-fired power plants (referred to as pulverized coal or “PC” plants) in Texas, for example, are still economically competitive with gas, he noted.

“This is because the capital investment in most PC plants is paid off, and lignite plus Powder River Basin coal is still cheaper on a BTU basis,” he said.

Ultimately, though, Ambrose, who is chair of the EMD Coal Committee, knows there has to be a reconciliation of sorts among not only the future energy options of the country, but among those fighting on behalf of them.

Specifically, as for where CCT and CCS stand right now, Ambrose says, “CCT is struggling to move ahead in today’s harsh project-financing climate and in the context of current low gas prices.”

He added both he and BEG Director Scott Tinker understand the dynamic of energy policy, which includes, “ … what’s possible, the science and technology; what’s doable, the regulatory and legal concerns; and most importantly, what’s sensible, the economic and climate impact in time frame needed.”

When it comes to supply America’s future energy needs, the devil, it seems, is everywhere.

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