Coal is a dirty business, one of the leading sources of carbon emissions in the United States. But coal is also a big business, generating 51 percent of the nation’s electricity. With that in mind, in June the Obama administration revived FutureGen, an advanced-technology coal-fired power plant axed by the previous administration in 2008. By burying 60 percent of its carbon dioxide emissions deep underground, the 275-megawatt FutureGen plant, to be built in Mattoon, Illinois, seeks to show that coal can be, if not exactly clean, then at least cleaner.
Once FutureGen is up and running—now scheduled to happen in 2014—the carbon dioxide gas it produces will be siphoned off, compressed into a near-liquid state, and piped at least a mile down into porous sandstone capped by a layer of impermeable shale. Engineers will essentially be trying to duplicate the geologic circumstances that trapped natural gas deposits underground for millions of years.
Energy Secretary Steven Chu has called FutureGen “a flagship facility” that will demonstrate how to capture and store carbon on a commercial scale; that technology would allow us to rein in greenhouse-gas emissions while still burning coal. The project could also help spur other proposals for sequestering human-generated carbon.
But FutureGen has drawn criticism from left and right. Some environmentalists say America should shift from coal-generated electricity entirely; others believe the goal of capturing 60 percent of emissions is too modest. Meanwhile, some fiscal conservatives disapprove of spending so much money (the Department of Energy has committed $1 billion) on an unproven technology for an established industry. Their nickname for the behind-schedule and over-budget project: NeverGen.
How to Stash the Carbon
1. CAPTURE IT AT THE SOURCE A coal-fired power plant in Spremberg, Germany, is using the same carbon capture and storage method planned for FutureGen. Engineers are having no trouble capturing the carbon dioxide, but efforts to store it in underground rock formations in eastern Germany have run into local opposition.
2. GRAB IT WITH ARTIFICIAL TREES To corral widely dispersed CO2 emissions from cars, “artificial trees”—towers filled with carbon-absorbing materials—could line roadways, pulling the gas from the air and compressing it into a storable form. Several companies, including Global Research Technologies in Tucson, are testing prototypes.
3. BURY IT UNDER THE SEA Some research groups have tried fertilizing the ocean with iron to encourage massive plankton blooms that suck carbon dioxide from the air. When the plankton dies and sinks to the seafloor, it should bury the carbon, but early results have not been impressive. Proposals to pump CO2 directly to the ocean bottom also seem unlikely to move forward, as the piped-in carbon could have nasty environmental consequences.
4. TURN IT INTO CHARCOAL Wood or other biomass heated slowly in a chamber without oxygen will transform into charcoal that does not decompose for thousands of years. In addition to locking away carbon, this “biochar” makes a good fertilizer. Carbonscape in New Zealand and a few other companies are now working on economical biochar-producing ovens.
5. TURN IT INTO ROCK Certain types of minerals naturally combine with carbon dioxide. In the right locations, CO2 injected into the ground at high pressure would react with those minerals to form stable carbonate rock. This approach is currently being tested in Oman and at other sites around the world.