September 2015 Vol. 70 No. 9
Features
Landfill Gas Grows As Viable Energy Source
New Piping Materials, Procedures Enhance Viability
Converting landfill gas – a natural byproduct of the decomposition of organic solid waste – isn’t new, but it is becoming more widely recognized as a viable option for producing renewable energy from waste from the huge supply of garbage in the world’s landfills.
The U.S. Environmental Protection Agency (EPA) says harnessing landfill gas (LFG) energy can provide environmental and economic benefits to landfill operators, energy users and communities with projects that can reduce emissions of greenhouse gases that contribute to global climate changes, offset the use of non-renewable resources, help improve local air quality and reduce energy costs to users.
The EPA says early LFG energy projects came on the scene in the mid- to late-1970s and increased notably during the 1990s as a track record for efficiency, dependability and cost savings was demonstrated.
“The enactment of federal tax credits,” says the EPA, “and regulatory requirements for LFG collection and control for larger landfills also helped to spur the growth of LFG energy projects, as did other factors such as increased concerns about how methane emissions contribute to global climate change and market demands for renewable energy options.”
The EPA says that 636 LFG energy projects currently are operating in 48 states and one U.S. territory. Roughly three-quarters of these projects generate electricity, while one-quarter are for direct-use where the LFG is used for its thermal capacity. Examples of direct-use projects include piping LFG to a nearby business or industry for use in a boiler.
Methods of collection, treatment and transporting LFG are complex and vary, depending on how the product will be used.
Underground construction contractors may become involved in drilling vertical extraction wells and constructing underground
piping to transport the gas.
Emerging tech
New technologies and procedures have helped increase interest in developing LFG energy projects.
For example, a recent project in Nebraska to bring LFG from a landfill to a local gas distribution system near Omaha required a three-mile-long, 2-inch diameter pipeline from the landfill to the tie in point (another pipe) to the existing network.
“This project demonstrates the advances made in thermoplastic piping systems, and the cost savings operators can realize by choosing high-pressure plastic piping,” said Brandon Babe, business development engineer for specialty polyamides at Arkema Inc., manufacturer of the Rilsan thermoplastic polyamide 11 resin used in the pipe.
“It is the first time polyamide 11 pipe has been used on a LFG project.”
Georg Fischer Central Plastics LLC supplied piping and fittings, for the project; BioResource Development LLC (BRD) is the pipeline system owner and operator. BRD has proprietary technology for treatment of the landfill gas. USDI Engineering was the design engineer and construction observer.
Arkema and BRD estimate the use of the Rilsan PA11 pipe brought a CAPEX savings of $95,000 per mile totaling approximately $285,000 with significant additional savings from the minimum maintenance when compared to epoxy coated steel pipe.
“From historical data on previous installations,” Babe said, “Arkema estimates maintenance savings of $6,300 per mile year each year for PA11 pipe – an estimated $18,000 per year savings, compared to steel pipe.”
The piping transports methane produced by the State Street Landfill in Douglas County, NE, to Metropolitan Utilities District’s 12-inch, 125 psi gas main in Omaha that feeds the district’s liquefaction facility.
The route of the pipe was along grassy rights-of-way.
Project
The total three-mile-long system was constructed in just over four weeks during December 2014 and January 2015.
To avoid excavation, a subcontractor used vibratory plowing equipment to bury the pipe. The ground was frozen when the pipe was laid, but the wheel-mounted plow unit’s blade easily cut through the frost. Lengths of pipe were fused together in strings, attached to the plow blade with a pulling grip and pulled into place as the machine moved forward.
To avoid cutting roads, pipe was installed by horizontal directional drilling. Vacuum excavation equipment was used to pothole and uncover existing utilities when the route of the pipe crossed or was in close proximity to pipe and cable already in the ground and to dig small excavations when necessary.
Project specifications required the system be operated at pressures up to 200 psi, exceeding the tolerances of HDPE, leaving BRD the options of either PA11 or steel pipe, said Babe.
“Up-front economics for PA11 were far more attractive than steel,” he pointed out.
“The PA11 not only enabled us to meet the delivery pressure requirements of the local utility, it helped keep our overall capital costs down which, in turn, helped maintain the project’s viability,” said Greg Maclean, co-founder of BRD. “The quick installation was icing on the cake.”
Arkema’s Babe said Rilsan PA11offers higher pressure and temperature capabilities than HDPE due to its chemical structure and expands the range in which operators can use plastic pipe and take advantage of the associated cost savings.
“It was approved by the Pipeline and Hazardous Materials Safety Administration (PHMSA) for use in regulated gas pipelines in December 2008,” he continued. “PHMSA permits the use of PA11 pipe for up to 4-inch diameter and 200 psi, although the material can achieve 6-inch, 250 psi with a special waiver. In late May, notice was given of a proposed rulemaking (NPRM) and was just released by PHMSA to allow PA11 to go up to 250 psi for six-inch pipe.
“The material also can be used for oilfield applications, including oil and gas gathering and water flow lines at pressures exceeding 300 psi.”
BRD anticipates production of approximately 130,000 to 140,000 MMBTU per day of untreated gas from the State Street Landfill, said Maclean. The landfill received its last solid waste in 1989 and began collecting and flaring the landfill gas in 1995.
Arkema is a global chemical company and France’s leading producer of chemicals, providing specialty chemicals that provide customers with practical solutions to such challenges as climate change, access to drinking water, the future of energy, fossil fuel preservation and the need for lighter materials. Arkema has operations in nearly 50 countries, including research centers in North America, France and Asia.
BioResource Development LLC is a Nebraska-based limited liability corporation that develops, manages and operates the collection, treatment, production, storage and distribution of biofuels made from renewable gases produced in landfills, feedlots and other sources.
Georg Fischer Central Plastics manufactures a broad line of pipe fittings and transitions and offers a complete PA11 piping system under the Hyperplast trade name.
FOR MORE INFORMATION:
Georg Fischer Central Plastics LLC supplied piping and fittings, for the project;
BioResource Development,
(402) 682-3680, bioresourcedevelopment.com
Arkema, (610) 205 7000, arkema-americas.com
USDI Engineering, (618) 392.5502, usdi.us
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