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Many chemical process industries (CPI) operations generate gaseous byproducts that are impure and have low energy densities. Ener-Core Power Inc. (Irvine, Calif.; www.ener-core.com) has introduced a technology to extract valuable energy and heat from gases that would otherwise be wasted by flaring or venting.

“Annually, there are about 65,000 MW of ‘free-energy’ available in the U.S. alone, in the form of low-quality methane from landfills, oil-and-gas operations, ethanol plants, chemical production facilities, coal mines and others,” explains John Millard, Ener-Core’s director for Europe and the Middle East. “Ener-Core’s technology allows companies to capture the energy and reduce pollutants,” he says.

The technology depends on carefully controlling a thermal oxidation reaction such that the reaction remains stable, even with diluted and impure gases. The chemical chain reaction that is characteristic of combustion cannot ordinarily be maintained with such low-quality gases, Millard says. By slowing the reaction and lowering its temperature, the Ener-Core system can quickly oxidize methane without producing pollutants, such as CO, NOx and particulate matter.

In the Ener-Core system (diagram), the raw waste gas is first diluted with air and compressed to 6–7 bars. Then, the compressed gas is fed into a packed-bed reactor at temperatures of 900–1,000°C. All species, including volatile organic compounds (VOCs), are oxidized in the reactor and the heat generated by the reaction is used to power a turbine that can generate electric power.

The company has set up its first 250-kW power station at a landfill in the Netherlands and has pending agreements to install several more systems in the near future, including a larger 2×1.75-MW system at an ethanol-production facility in California.