Life cycle water consumption associated with transportation in light-duty vehicles may be an increasingly important factor when one considers the sustainability of energy resources, according to a report published in Energy and Environmental Science (Issue 3, 16), of a study by David Lampert, Hao Cai and Amgad Elgowainya, researchers at Argonne National Laboratory. Entitled Wells to wheels: water consumption for transportation fuels in the United States, the U.S. based report finds Compressed Natural Gas (CNG) well placed amongst all fuels.
The Abstract states: “The sustainability of energy resources such as transportation fuels is increasingly connected to the consumption of water resources. Vehicles powered by petroleum, electricity, natural gas, ethanol, biodiesel, and hydrogen fuel cells consume water resources indirectly through fuel production cycles, and it is important to understand the impacts of these technologies on water resources. … Many alternative fuels were found to consume larger quantities of water on a per km basis than traditional petroleum pathways, and it is therefore important to consider the implications of transportation and energy policy changes on water resources in the future.”
Included in the study’s intentions was the development of a comprehensive baseline LCA (life cycle analysis) of water resource consumption associated with transportation fuel production. It addresses an oversight in other LCAs which ignored the water embedded in many intermediate resources. A covering report by Green Car Congress (GCC) explains: “System boundaries for the life cycle water consumed in the production of the transportation fuels in the study included mining and recovery operations; agricultural production of biomass; agricultural chemicals manufacturing; biofuel conversion; crude oil and natural gas refining and processing, and transportation and distribution. Life cycle water consumption was computed for each fuel pathway using the 2014 version of GREET.net.”
GCC cites Lampert et al: “Moves towards alternative fuels appear to have a greater impact on water resources than fossil fuels. Energy and environmental policy should consider the implications of alternative vehicles on water resources when planning changes to the transportation and energy infrastructure.
Amongst the findings, GCC summarises, is a clear position for CNG: “In terms of water liters/100 km, compressed natural gas vehicles show the lowest burden on water consumption—the majority of the water is associated with electric compression of the fuel and not with the recovery process. Reforming natural gas to H2 for use in a FCEV more than doubles the water consumption intensity of transportation.”
Green Car Congress article: Argonne LCA study finds many alternative fuels consume more water than petroleum and natural gas fuels