Carbon capture success in Wisconsin
Capturing the carbon dioxide that wafts up the smokestack after burning
coal (or any other fossil fuel) has been identified by everyone from
President Obama to the United Nations Intergovernmental Panel on Climate
Change as a critical technology to help keep the lights on while combating
climate change. And now there has been yet another successful demonstration
that the technology to capture that CO2 from flue gas might actually work:
chilled ammonia can capture more than 88 percent of the greenhouse gas
before it goes up the smokestack.
Alstom Power and We Energies have released preliminary data on their carbon
capture pilot project at Pleasant Prairie, Wisc. The pilot plant, set up to
siphon the CO2 from a small stream of the total flue gas using chilled
ammonia, not only captured most of the CO2, it captured it in a more than 99
percent pure form, according to Robert Hilton, vice president of power
technologies and government affairs at Alstom, which is important for any
future storage or industrial reuse. "We can [capture] 90 percent [of the
CO2] and do it consistently," he notes. "We've done over 90 percent at
times."
So far the project has run some 4,600 hours continuously without issue
and captured some 18,000 tons of CO2 over the last year.
Because this was just a demonstration project, Alstom didn’t do anything
with the CO2, which in the future would either be sold to
industrial users for carbonated beverages or
oil recovery or
pumped deep underground for permanent storage. Alstom just re-released
the CO2 right back up the smokestack with the other flue gas.
A similar demonstration project using Alstom's chilled ammonia at AEP's
Mountaineer power plant in West Virginia this fall aims to be the first
to put together the full package. "It really will be the first plant that
will take flue gas from a coal-burning power plant, clean it, remove the CO2,
compress it and inject it in a true sequestration at 8,300 feet deep,"
Hilton says. "It's the first time that will be done anywhere in the world."
Following that test and others, the company plans to have the chilled
ammonia technology available for sale by 2015.
Of course, employing such technology uses up much of the energy produced by
burning the coal in the first place. Although Alstom declined to give exact
figures, Hilton claimed the process used up less than 25 percent of the
electricity produced: "We expect chilled ammonia to be in the low 20s."
In other words, capturing that CO2 will cost between $50 and $90
per metric ton, though Hilton believes that scaling up the process and
refining it will reduce that cost to as little as $20 per metric ton of CO2.
That could make such carbon capture and storage a cheap alternative for
avoiding CO2 emissions under any regulatory scheme to fight
global warming, such as the
cap-and-trade proposal currently being debated in Congress.
The company is also developing amine scrubbers as well as pilot projects in
Europe of so-called
oxyfuel combustion—burning coal in pure oxygen to create flue gas of
nearly pure CO2.
The reason to pursue multiple technologies, Hilton says, is because they can
be added on to existing plants—either by replacing the boiler in the case of
oxyfuel or adding processes to the back-end in the case of amine and
ammonia. And that may be the key to halting the
CO2 emissions from power plants driving climate change. As
Hilton says: "You can't make any of the goals [for emission reductions]
anybody's proposed without doing the existing fleet."
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