From Methane to Masonry

Landfill gas helps power an Oklahoma fired clay brick factory.

Like Many manufacturers, Boral Bricks Inc., headquartered in Roswell, Ga., is continuously seeking ways to use alternative fuels to cut costs, protect the environment and uphold its role as a community partner. A landfill-gas-to-energy (LFGTE) project at its new brick manufacturing plant in Union City, Okla., was designed to help the company meet these goals.

Boral Bricks' Union City plant is located approximately two miles from a solid waste landfill and uses methane gas from the facility to fire its kiln. The gas is processed using a collection/refrigeration/compression system and transported through a two-mile pipeline at low pressure (approximately 10 pounds per square inch) directly to the plant site.

Boral Bricks partnered with Long Beach, Calif.-based SCS Engineers to assess the project's feasibility, and to oversee its design and construction. The Oklahoma Environmental Management Authority (OEMA), an organization that provides waste collection services to the surrounding communities, owns the landfill from which the gas is collected. Boral established a long-term agreement with OEMA under which the authority will receive royalties for the landfill gas used for the kiln. OEMA plans to use these revenues to broaden its service offerings and reduce costs to its customers.

Columbus, Ohio-based Harrop Industries, the company responsible for designing and manufacturing the kiln, worked closely with Boral and SCS to accommodate the unique requirements of a landfill gas-fired kiln. The kiln also uses natural gas, but per cubic foot, natural gas has a higher British thermal unit (Btu) content than landfill gas. Thus, some design modifications and additional systems were required. The kiln is designed to operate using up to 50 percent landfill gas. The landfill gas and natural gas use separate combustion trains on the kiln, so that the energy input of each fuel can be easily regulated.

To minimize start-up variables, the kiln was initially fired solely by natural gas. Landfill gas was introduced into the mix in November 2006. Today, landfill gas supplies more than 33 percent of the kiln's energy. An integrated metering system allows plant operators to maximize and stabilize the flow of landfill gas. Over time, with planned waste placement and collection systems, it will supply more than half of the kiln's fuel.

Boral considered the project a success on several fronts. First and foremost, a clean, sustainable, alternative energy source was harnessed, benefiting the environment while minimizing costs for OEMA and Boral. The project was completed on schedule and within budget with no injuries. So far, landfill gas projections and gas flow from the landfill have met targets.

Going forward, waste-sequencing plans implemented in partnership with OEMA will optimize gas use. Every 2 to 3 years, additional gas extraction wells will be installed by SCS and Boral based on OEMA's waste placement and sequencing plan. Meanwhile, SCS and Boral will continue to optimize Btu utilization in the kiln to allow greater usage of landfill gas.

Boral is currently commissioning a plant in Indiana adjacent to a larger landfill with LFG capability to meet nearly all of the kiln's thermal energy requirements. The gas will be utilized immediately following start up.

By Dana Wilson, vice president of supply chain and Terry Schimmel, vice president of engineering for Boral Bricks; Tom Barham, senior vice president of SCS Engineers