What’s in Your Pipeline?

Municipalities learning there are dependable supplements to natural gas.

Across the country, cities and towns are becoming more involved with alternative energy and renewable energy projects that deliver methane gas from non-traditional sources. What these municipalities are discovering is biogas can serve as a supplement to natural gas in this country’s transmission and distribution systems, thus aiding in the ongoing quest to relive this country of a dependence on fossil fuels. For example, Pittsfield, Mass, recently completed the final design for an upgrade to its wastewater treatment facility.

Under its proposed combined heat and power (CHP) system, the digester gas—which is a by-product of the facility’s anaerobic sludge digestion process and typically burned off, or flared—will be sent through a fuel gas conditioning system. This process will remove contaminants from the digester gas and boost the pressure of the gas to the micro-turbines. The target contaminants of the fuel gas conditioning system include water vapor, hydrogen sulfide, and siloxanes, which are silicone-based compounds contained in many health and beauty care products.

The conditioned digester gas will then be used to fuel three 65-kW rated micro-turbines, which will generate heat and electricity to meet the plant’s base load demands. The waste heat in the exhaust of the CHP system will be utilized in a heat exchanger to produce hot water, which will heat the sludge in the primary digester and serve as building heat in the digester building.

The CHP project is expected to have a payback period ranging from five to eight years, prior to receiving ARRA funding. The aforementioned proposed upgrades are expected to reduce the flaring of the digester gas and consumption of diesel fuel, and decrease the plant’s electric bill by an estimated 30 percent (saving taxpayers over $200,000 a year).

Landfill Methane

Another popular alternative to traditional fossil fuels is landfill methane. Flaring methane to minimize its release into the environment is quickly falling out of practice, as many people have begun to realize captured methane gas can be used to generate electricity and heat. In fact, according to the Environmental Protection Agency, there is approximately 480 operational landfill gas to energy projects in the United States, as well as an additional 130 projects currently under construction or in development.

The EcoLine project at the University of New Hampshire (UNH) in Durham, N.H., is one such project. UNH’s recently launched EcoLine project gave the university the distinction of being the first in the country to depend on landfill gas for its primary fuel source. UNH purchases methane gas from the nearby Turnkey Recycling and Environmental Enterprise facility in Rochester, N.H., located roughly 12 miles away.

Three-hundred extraction wells, as well as a series of collection pipes, capture the methane-rich landfill gas, which is then cleaned of compounds such as siloxanes through methods such as compression refrigeration and heating, and activated charcoal. The now enriched and purified gas is odorized at the landfill site, and then sent from Turnkey to UNH.

There, the gas is used to power UNH’s $28 million combined heat and power facility, or cogeneration (COGEN) plant, which features a chilled water plant. The COGEN plant takes waste heat typically lost during the production of electricity and uses it to heat campus buildings, thus making more efficient use of the university’s energy resources. All told, the methane gas helps produce roughly 85 percent of the electricity and heat consumed on the university’s five million square-foot campus.

The Costs

The landfill gas project cost an estimated $49 million and has an anticipated payback of 10 years. Also, be utilizing carbon-neutral landfill gas as its primary fuel, the COGEN plant will ensure the plant has a dependable, cost-effective source of fuel for decades to come.

Gas utilities, both domestic and international, are considering one simple question: “What’s in your pipeline?” Alternative energy and renewable energy projects like the ones detailed above, exhibit a stronger commitment to reducing greenhouse gas emissions, and a future that revolves around alternative and renewable energies. It also shows that being environmentally friendly can result in being economically savvy as well.

Michael A. Nicoloro, P.E., is a registered professional engineer (Massachusetts and New Hampshire) and is currently Director of Energy Services for S E A Consultants Inc., which is headquartered in Cambridge, Mass. Nicoloro’s focus is in the renewable and natural gas arenas. He has over 31 years of diverse experience working in plant and process environments. He is the former Manager of Gas Supply and LNG/ SCADA Operations for Commonwealth Gas Company (now N-Star), and Managing Director for the City of Cambridge Water Department.

Joan Fontaine, P.E., is a principal engineer in S E A Consultants’ Energy Sector. She has over 20 years of engineering experience, 12 years of which have been focused in the energy sector performing mechanical and process design, and analysis for numerous utility projects, as well as managing an array of projects, including both design and design/build projects. Her project experience includes propane, natural gas, LNG, and alternative fuel applications. The majority of the balance of her professional experience has been with two General Electric facilities, in which she gained experience in environmental compliance and permitting. She has a B.S. in chemical engineering from the University of Lowell and an M.S. in environmental engineering from Rensselaer Polytechnic Institute.