Friday, February 22, 2008

Coal Gassification: Challenge & Opportunity

ScienceDaily has a good article on our most prevalent US energy source - coal. Coal gets a bad name in many circles, but is our most abundant and economical source of energy and supplies us with approximately half of our national energy needs. The US has the most abundant coal resources of any nation on the planet. Of course, coal gets its bad name from some of the issues that come from burning it - namely, some not so nice emmissions, some of which have been addressed with technological innovations such as scrubbers, while other types of issues still need some work. There are plans in the works to address quite a number of these by utilizing the concept of coal gassification and sequestering the carbon dioxide released from burning.

""Coal gasification offers one of the most versatile and clean ways to convert coal into electricity, hydrogen and other valuable energy products," said George Muntean, staff scientist at the Department of Energy's Pacific Northwest National Laboratory.

"Gasification provides significant economic and environmental benefits to conventional coal power plants," Muntean said. Rather than burning coal directly, gasification breaks down coal into its basic chemical constituents using high temperature and pressure. Because of this, carbon dioxide can be captured from a gas stream far more easily than from the smokestacks of a conventional coal plant.

"If we plan to use our domestic supply of coal to produce energy, and do so in a way that does not intensify atmospheric CO2 concentrations, gasification is critical," Muntean said. "It has the potential to enable carbon capture and sequestration technologies and play an important role in securing domestic sources of transportation fuels."

The biggest technical hurdle in introducing this technology is in the lifespan of the refractories that line the gassification chamber, which are expensive (a million plus $ a pop) and difficult to replace (3-6 weeks of plant downtime). With a 12-16 month lifespan, this simply isn't economically feasible, but some of the research work at PNNL might expand this period up to three years. Reducing the capital costs of refractories by nearly half could wind up making gassification not only economically feasible, but profitable.

In a related note, the first commercial plant utilzing carbon sequestration technology is being built near Sweetwater Texas by Tenaska, Inc - an Omaha firm. (news release here)Up to 90% of the CO2 will be captured and sold to oil firms, which will pump it into the Permian Basin oil fields, allowing additional domestic black gold to be extracted. Talk about a win-win solution!

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