The Center for Transportation Research at the Energy Systems Division, Argonne National Laboratory, has released a report entitled Well-to-Wheels Analysis of Landfill Gas-Based Pathways and Their Addition to the GREET Model, May 2010. The report will be of interest to all communities looking to take advantage of the renewable fuel generated from landfill, a common utility found near all big population centers, with its obvious benefits if utilized for the generation of biomethane as a vehicle fuel. The following Executive Summary is taken from the report:
Executive Summary
Today, approximately 300 million standard cubic ft/day (mmscfd) of natural gas and 1600 MW of electricity are produced from the decomposition of organic waste at 519 U.S. landfills (EPA 2010a). Since landfill gas (LFG) is a renewable resource, this energy is considered renewable. When used as a vehicle fuel, compressed natural gas (CNG) produced from LFG consumes up to 185,000 Btu of fossil fuel and generates from 1.5 to 18.4 kg of carbon dioxide-equivalent (CO2e) emissions per million Btu of fuel on a “well-to-wheel” (WTW) basis. This compares with approximately 1.1 million Btu and 78.2 kg of CO2e per million Btu for CNG from fossil natural gas and 1.2 million Btu and 97.5 kg of CO2e per million Btu for petroleum gasoline. Because of the additional energy required for liquefaction, LFG-based liquefied natural gas (LNG) requires more fossil fuel (222,000–227,000 Btu/million Btu WTW) and generates more GHG emissions (approximately 22 kg CO2e /MM Btu WTW) if grid electricity is used for the liquefaction process. However, if some of the LFG is used to generate electricity for gas cleanup and liquefaction (or compression, in the case of CNG), vehicle fuel produced from LFG can have no fossil fuel input and only minimal GHG emissions (1.5–7.7 kg CO2e /MM Btu) on a WTW basis. Thus, LFG-based natural gas can be one of the lowest GHG-emitting fuels for light- or heavy-duty vehicles.
This report discusses the size and scope of biomethane resources from landfills and the pathways by which those resources can be turned into and utilized as vehicle fuel. It includes characterizations of the LFG stream and the processes used to convert low-Btu LFG into high-Btu renewable natural gas (RNG); documents the conversion efficiencies and losses of those processes, the choice of processes modeled in GREET, and other assumptions used to construct GREET pathways; and presents GREET results by pathway stage. GREET estimates of well-to-pump (WTP), pump-to-wheel (PTW), and WTW energy, fossil fuel, and GHG emissions for each LFG-based pathway are then summarized and compared with similar estimates for fossil natural gas and petroleum pathways.
The report is available here.
Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) Model
The US Argonne National laboratory says that to fully evaluate energy and emission impacts of advanced vehicle technologies and new transportation fuels, the fuel cycle from wells to wheels and the vehicle cycle through material recovery and vehicle disposal need to be considered. Sponsored by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE), Argonne has developed a full life-cycle model called GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation). It allows researchers and analysts to evaluate various vehicle and fuel combinations on a full fuel-cycle/vehicle-cycle basis.
Print 
PDF 