A spatially-resolved inventory analysis of the water consumed by the coal-to-gas transition of Pennsylvania

Life cycle assessments (LCA) typically exclude spatial information in estimating the water consumption associated with a product, resulting in calls to improve regional detail to better reflect spatial variation. In response to these calls, we have compiled a spatially-resolved inventory of changes in water consumption associated with the coal-to-gas transition in Pennsylvania at the resolution of watersheds from 2009 to 2012. Results indicate that the total water consumption of the fuel extraction and power sectors in Pennsylvania increased by 7.6 million m(3) (2 Bgal) over four years. At the state and watershed scales, we compare total water consumption for the coal-to-gas transition to a case where only the water consumed across two life cycle stages of electricity generation is considered fuel extraction and use at the power plant to generate electricity. The results for the latter indicate that water consumption decreased by over 15.1 million m3 (4 Bgal). For both cases, watershed-level results showed water consumption generally increased in watersheds with growing shale gas activity or new natural gas capacity, while it decreased with diminishing coal-fired generation. Watershed-scale water consumption from 2009 to 2012 may be reversed from a net increase to decrease (and vice versa) when the total water consumption is compared to the water consumed specifically for life cycle stages of electricity generation, reinforcing the importance of further developing spatially-resolved inventories for LCA. Focusing on the water consumption associated with only electricity generation and its fuel use does not capture the full effects of fuel extracted for use in other sectors. We suggest that spatially-explicit inventories that include multiple life cycle stages should be a critical component in the development of more comprehensive, spatial LCA methodology. Spatial differentiation in inventories is necessary to adequately characterize watershed-level impacts that can be normalized over a functional unit. The approach can be used as a complementary assessment to LCA that can inform policy-makers and investors about where energy developments may pose additional risks to water supply and availability. (C) 2018 Elsevier Ltd. All rights reserved.