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November 21, 2012


The Vision: Harness Renewable Energy (Part 2)

I recently toured several energy generation facilities on the South Side of Chicago with the Southeast Environmental Task Force. Two sites in particular — Waste Management’s gas to electricity facility to Exelon’s Solar City facility – suggested the diversity and complexity of clean, renewable energy in Chicago.

Exelon Solar City in Chicago, Scott Olson/Getty Images

Exelon’s Solar City facility, built and operated by San Jose-based Sunpower, generates 10 mW on a 41-acre site. Peggy Salazar of the Southeast Environmental Task Force raised the question of whether large-scale solar farms are an effective use of land in Chicago, when the same number of panels could be installed on existing buildings. Sunpower’s site engineered explained to us that there are some advantages to a large solar farm. For example, the panels are on a tracking system that boosts their production by 25 percent.

Solar City, privately funded, should not preclude installations on homes and commercial buildings. Its capacity is small compared to the total electricity demand in Chicago, and but the facility leverages an asset – vacant land – that wasn’t suitable for other uses. Since its commissioning in 2010, the panels have sent 19,000 kWh to the grid.

At the Waste Management facility on 130th Street, I learned that WM’s landfill gas-to-energy facilities generate more electricity than the entire solar industry in the U.S. Landfill gas is the methane released from capped landfills; if it’s not captured to generate electricity, it must be burned off anyway. Landfill gas isn’t most people think of as renewable resource, but the facility harnesses a fuel source that would otherwise be released into the atmosphere and produced electricity with no emissions.

The system has been running since 1989, and WM expects the landfill will continue to release the methane that can fuel the system for six to 10 more years. It began with three turbines, which are similar to jet engines, and now its single turbine generates 3.2 kW per hour. With other resources such as natural gas low in price, the operator of WM’s system says it is no longer profitable to operate the turbines.

Although neither Solar City nor landfill gas-to-energy can be scaled to meet Chicago’s entire energy demand, they demonstrate the potential to diversify electricity generation here. Both sites leverage assets – vacant land and landfills – as new opportunities for renewable energy.

Rachel Belanger is a researcher in SOM’s City Design Practice and is located in Chicago.