For Carbon Capture, DOE Moves Oxycombustion Ahead of IGCC
As reported by my fellow blogger David Levitan a couple of weeks ago, the U.S. Department of Energy has announced that its futuristic zero-carbon-generation project will be based on oxycombustion, not on integrated-gasification, combined-cycle technology, as had been expected for more than a decade. With some reason, Levitan suspects the whole project may have turned into an ongoing boondoggle; certainly, FutureGen has come to seem rather like nuclear fusion--the technology that's always just a decade or two away but, like a mirage, never actually gets any closer.
Nevertheless, I'd like to offer another perspective: Possibly DOE's decision is sound and will open the way, at last, for FutureGen to actually be built and then lead, as hoped, to commercial prospects for zero-carbon coal-fired generation.
Several years ago, IEEE Spectrum magazine designated as one of its January winners the oxycombustion plant that Vattenfall, Sweden's national energy company, was building at Schwarze Pumpe, a site in eastern Germany. At that time, as we explained, IGCC still was generally considered the front runner in so-called clean coal technology. Yet the Florida plant that had pioneered the technology in the United States did not make a particularly prepossessing impression and for years had been generating the country's most expensive electricity by far. And now, two companies with substantial reputations in the power business, Vattenfall and Alstom, were betting on a different horse, dubbed oxyfuel or oxyfiring or oxycombustion.
In oxycombustion, coal is burned in an almost pure oxygen atmosphere, so that emissions contain virtually no NOx, which makes it easier to separate and store the carbon initially contained in the coal. IGCC involves gasifying coal, filtering out the carbon, and finally burning hydrogen to generate power. A big barrier to commercialization of oxyfuel is the initial separation of oxygen from air, which is expensive. But the technology is conceptually much simpler and arguably more elegant than IGCC.
Last November, Vattenfall announced that it was recovering virtually 100 percent of the carbon from the fuel burned at its small Schwarze Pumpe demonstration plant. Spectrum's account of the plant is somewhat dated, as the facility is being continually redesigned and rebuilt as part of Vattenfall's ongoing experiment. A fairly recent, nicely illustrated update about the oxyfuel plant is available.