Landfill Gas
There are currently 2,200 active municipal solid waste landfills across the US. It’s time to drill the dump.
When the organic portion of landfill waste decomposes under anaerobic (without oxygen) conditions, a gas is produced that is typically composed of 50% methane, 50% carbon dioxide and trace amounts of other non-methane organic compounds. If vented to the atmosphere, landfill gas poses a great risk to the atmosphere.
Where there are people there is waste.
Where there is waste there is energy.
Municipal solid waste landfills account for over one quarter of the total methane emissions in the US; making landfills the single largest human-related source of methane.
Landfill gas also can be a troublesome environmental problem. At a minimum, the Environmental Protection Agency (EPA) has ordered U.S. landfills to install gas collection systems to burn the gas in a flare system. A collection system consists of vertical wells drilled into the waste or horizontal pipes buried within the landfill. The gas normally would be directed to a flare for incineration of heavy organic compounds and methane. Methane has 22 times the potential to retain heat in the Earth’s ozone as compared to carbon dioxide. Prometheus has the technology to offer an attractive alternative by conversion of this flared gas to LNG.
Trash trucks that make multiple daily trips to the landfill and other heavy duty vehicle applications are outstanding customers for a portion of this LNG. This provides the greatest opportunity for Prometheus Energy—to supply a closed loop whereby the very trash that is trucked into the landfill also powers the trucks that haul it.
Landfill gas is a particularly attractive waste gas supply option because it is a low-cost feedstock source due to the minimal processing required. Methane develops from the anaerobic digestion of organic waste buried within the landfill. This gas generation can continue at stable rates for more than 40 years after closure of a landfill.
A pilot-scale system for conversion of LFG to LNG was successfully designed, manufactured and installed with Prometheus’ technology at a municipal landfill in Victoria, B.C. in November 2000 as a proof of concept project. The system achieved production of LNG to 96% purity methane and recovery of CO2. Technology upgrades by Prometheus have enhanced both the capabilities and performance of the current commercial LFG to LNG systems Prometheus now provides.
| Component | Landfill Gas |
|---|---|
| Methane (CH4), % | 35-55 |
| Ethane + Propane, % | 0 |
| Water Vapor, % | 1-10 |
| Carbon Dioxide, % | 25-45 |
| Nitrogen, other inerts, % | 0-20 |
| Condensable hydrocarbons (NMOCs) ppmv | 250-3,000 |
| Chlorine in organic compounds, micrograms per liter | 250-3,000 |
| Hydrogen sulfide, ppm | 5-600 |
| Higher heating value, (btu/ft3) | 350-550 |
| Gas Source Pressure, (psig) | 1-2 |
