We Energies Pleasant Prairie power plant tests new cleaning process

Daily Reporter (Milwaukee), Sep 25, 2007 by Sean Ryan

We Energies' Pleasant Prairie power plant is hosting the first real-world test of a new scrubber that could capture up to 90 percent of the carbon dioxide created by burning coal.

But, since it's only a test and there's no where to go with the gas, the carbon dioxide that's captured will be pumped back into the plant's chimney and up into the sky. For the new scrubbers, developed by Alstom, to reach their potential, people must either bury the gas somewhere or find something useful to do with it, said Ed Morris, senior engineer and environmental coordinator at the Pleasant Prairie plant.

"Nationally, there's a lot of activity going on ... to look at storage sites," he said. "One could envision an infrastructure where carbon dioxide could be shipped from the fossil plants where it could be beneficially used or put into storage."

Future storage sites could be saline reservoirs 5,000 feet underground or old coal mines, where the gas would basically end up where it started. Researchers also found that the gas liquefies a little bit when deposited in the chilly spots at the bottom of the ocean, so underwater storage is an option.

The U.S. Department of Energy estimated there's enough potential storage sites to handle the country's industrial carbon dioxide emissions for at least 250 years.

Transporting the gas

Storage is one thing; transporting the gas is another. Moving the carbon dioxide to storage sites could involve building a new system of pipelines similar to those used to transport natural gas. Pleasant Prairie would need hundreds of miles of pipeline to reach the closest reservoirs in northwest Wisconsin, Michigan or central Illinois, Morris said.

Groups are also looking for a way to use the gas instead of storing it. Utilities have already found uses for their plants' fly ash, which can be mixed into concrete, and gypsum, which is used in construction materials.

We Energies is looking into opportunities to combine carbon dioxide with the fly ash to make a useful product.

Another option is using the gas in greenhouses. The Department of Energy has a test project in Arizona where carbon dioxide is being used to grow algae that can be converted into ethanol or biodiesel, Morris said.

"If utilities or industries are able to remove the carbon dioxide, there may grow new industries to use that," he said.

Fine-tuning the process

But first thing's first. Concerns about storage or reuse won't spring up until the carbon dioxide scrubber technology is perfected. Perhaps even more important, it must become economically beneficial for utilities to install them.

The industry is developing the technology in anticipation of new federal regulations that would require utilities to control their carbon dioxide emissions or pay the price.

It's costing $10 million to install Alstom's test scrubber at Pleasant Prairie, and that will only treat 1 percent of the plant's emissions. The funding came from Alstom and 20 nationwide utilities working through the Electric Power Research Institute.

Alstom's tests at Pleasant Prairie will generate scrubber operation cost estimates, which can then be compared to the costs associated with any new government regulations. That would give utilities about three options -- install a scrubber, shut down the plant or, if government regulations allow for a money-based, carbon- credit trading program, buy the credits to release the gas from other companies.