Instead of maintaining the equipment and operation of flaring LFG away to nothing, there are a few different procedures that make it possible to harness the energy potential of landfill gas for profit – and these represent areas of investment and increased returns for municipalities and landfill owners. Not every procedure is the most suitable for every landfill, but each procedure does involve cleaning or conditioning the gas to some degree, depending on the final application and its required gas composition.

While there are many different applications for treated LFG, there are three primary methods for utilizing landfill gas: electric power generation, the development of medium-BTU industrial fuels, and injection of high-BTU gas into utility company pipelines.

At Morrow Renewables, we believe the LFG-to-pipeline production model is usually the best all-around solution for landfills managing a quarter million tons of waste or more each year, particularly those in areas where the difference between the cost of fuel to produce electricity and the price of that same unit of electricity (known as the “spark spread”) is considered low. A high BTU gas project may be more viable in these areas where a power plant would not.

Generally speaking, a high BTU gas project offers many distinct advantages over an on-site electric generation project. These include:

• Shorter development time, allowing for earlier payment of royalties. Morrow Renewables can build a facility within 9 months of a notice to proceed, compared to over 2 years for a power project.
• Delivering the gas into a nearby pipeline for distribution so that electric generation can be maximized off-site, utilizing a high efficiency combined cycle power plant.
• Lower noise levels and emissions than an electric generation plant, thereby creating greater community support.
• Less permit requirements due to negligible air emissions.
• Processed gas can be transported to higher priced REC markets in most cases, offering much better economics to the landfill owner.

LFG-to-Electricity
Initially, nearly all LFG facilities were designed to produce high-BTU pipeline quality gas for injection into natural gas supply and distribution lines. Soon, plants were also being built to produce medium-BTU gas for use as an industrial fuel, but it was not until the early 1980’s that LFG began to be used for the on-site generation of electricity.

While the LFG-to-electricity production model has become a popular solution for landfill waste-to-energy projects, it has proven to be a much less dynamic alternative for landfills with over a quarter million tons of waste each year, particularly those geographically situated in a way that limits direct-use energy partnerships, or landfills in an area where the purchase price of electricity is very low.

Contributing to the popularity of electricity generation as a renewables solution, there is relatively little processing, engineering or operations experience required to make collected LFG ready as fuel for powering the turbines that eventually produce electricity. While this usually means less up-front investment, it also means greater amounts of diesel and carbon emissions during operation. This is a less ecologically-sound solution, and often requires additional ongoing costs related to maintenance and equipment repair that are difficult to anticipate up front. Neither can this operating model easily or inexpensively tap into any other energy modalities, such as compressed natural gas (CNG) or industrial fuels.

Nevertheless, because it takes time for trash to decompose and produce gas, the electricity generation model often makes more sense for smaller landfills, since it requires less gas and less processing to run a power plant.

LFG-to-Medium BTU
The processing required to produce medium-BTU gas (industrial fuels) from LFG is relatively minimal. It may consist of as little as selling the gas in its raw form, up to the removal of moisture by either dehydration or mechanical means, on up to the removal of heavier trace hydrocarbons and contaminants. The final product usually finds a use as fuel for furnaces, boilers or other large burner-tip applications.

LFG-to-Pipeline (high BTU)
Raw landfill gas is 56% methane, 42% carbon dioxide, and 2% nitrogen and other constituents. Morrow Renewables first compresses this raw landfill gas, and a majority of the sulfur compounds are removed by scavenger. The carbon dioxide component is then reduced to below 1% and the resulting product is sold into the commercial pipeline providing a royalty revenue stream for the landfill operator.

The production of high-BTU pipeline quality gas from LFG requires extensive processing to remove all moisture, trace components, and carbon dioxide from the raw LFG. This results in virtually pure methane with a heating value of near 1000 BTU per standard cubic foot (BTU/scf).  This is roughly equivalent to the energy content of natural gas, which is 95% methane, and has a typical heating value of approximately 1020 BTU/scf due to the presence of other higher hydrocarbons. LFG product gas must meet strict quality standards before it may be injected into utility company pipelines for mixing with natural gas, and distributed and sold to gas customers.

Additionally, this high BTU product may be compressed to levels approximately 3,000 psi and is then referred to as CNG. This form of fuel is extremely economical, and some sanitation districts and landfill owners have found CNG-fueled vehicle fleets a significant source of cost-containment. CNG can also be used to power landfill plants themselves. Congress is currently considering legislation to offer tax credits to automobile manufacturers who produce vehicles capable of utilizing CNG.