Columbia’s Biogas Power Plant

On Thursday I took a trip to Columbia Water and Light’s biogas plant. They currently produces about 2.1MW of power  —  enough for about 1500 home or 1.5 percent of Columbia’s electricity needs. They expect to expand as more gas becomes available to about 2.5 percent.

I think it's important to realize that energy comes from somewhere like this. It's not magic, it's complicated engineering.

The group I was with did some haphazard exploring of our own because of some miscommunication with the guide we had lined up. First we looked at the outside of the facility that houses the turbines, then started driving around the bumpy hills of refuse covered in dirt. It was an interesting experience off-roading on mounds of trash with a Prius. Eventually a water safety scientist on the site named Adam found us and brought us back to the site supervisor, Cynthia Mitchell, who told us more about the bioreactor and the biogas power plant operations.

The system works because methane gas from the landfill, powers turbines, which create electricity. The turbines also have to create a suction that pulls more methane in from the landfill. In fact they have to balance the load so that it always has suction, because there’s a fine if any of that methane gets into neighboring property. The work that goes into creating a safe pit for the trash is amazing. There are several layers of lining and materials to stop toxics from escaping.

Traditionally, trash pits are kept dry, trying to decrease the smell and gases released. But when you’re trying to create methane for power, they actually add liquid to the cells. This causes decomposition to go faster, creating more methane, and room for more garbage. Columbia has 6 cells in their landfill, cell 4 produces the methane for the gas turbines.

Columbia’s $2.85 million biogas plant is the 1st in the state and the 13th in the country according to our guide, Bill Allen.

The methane flare burns off excess mathane not used by the power-producing turbines. Methane is a very potent greenhouse gas if not burned off.
At the top of the landfill you can see giant crows circling the trash before it's covered by a layer of dirt.

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