Can switching fuels save water? A life cycle quantification of freshwater consumption for Texas coal- and natural gas-fired electricity

Abstract

Thermal electricity generation is a major consumer of freshwater for cooling, fuel extraction and air emissions controls, but the life cycle water impacts of different fossil fuel cycles are not well understood. Much of the existing literature relies on decades-old estimates for water intensity, particularly regarding water consumed for fuel extraction. This work uses contemporary data from specific resource basins and power plants in Texas to evaluate water intensity at three major stages of coal and natural gas fuel cycles: fuel extraction, power plant cooling and power plant emissions controls. In particular, the water intensity of fuel extraction is quantified for Texas lignite, conventional natural gas and 11 unconventional natural gas basins in Texas, including major second-order impacts associated with multi-stage hydraulic fracturing. Despite the rise of this water-intensive natural gas extraction method, natural gas extraction appears to consume less freshwater than coal per unit of energy extracted in Texas because of the high water intensity of Texas lignite extraction. This work uses new resource basin and power plant level water intensity data to estimate the potential effects of coal to natural gas fuel switching in Texas' power sector, a shift under consideration due to potential environmental benefits and very low natural gas prices. Replacing Texas' coal-fired power plants with natural gas combined cycle plants (NGCCs) would reduce annual freshwater consumption in the state by an estimated 53 billion gallons per year, or 60% of Texas coal power's water footprint, largely due to the higher efficiency of NGCCs.

Electricity generation

“…Previous studies on the water impacts of new natural gas developments have tended to either quantify the total water consumed in the production stage (Nicot et al 2012;Murray 2013) in a particular geographic region or have examined total water consumption over the fuel life cycle through use in the electricity generation sector (Grubert et al 2012;Laurenzi et al 2013). For Texas, Nicot et al (2012) found that water withdrawals for shale gas development were less than 1% of the total withdrawals in the state, but that withdrawals could be a much higher percentage of local withdrawals (up to 10%) during periods with locally-intense new well developments.…”

“…For Texas, Nicot et al (2012) found that water withdrawals for shale gas development were less than 1% of the total withdrawals in the state, but that withdrawals could be a much higher percentage of local withdrawals (up to 10%) during periods with locally-intense new well developments. Life cycle assessments (Grubert et al 2012;Laurenzi et al 2013) have found that the water consumption per MWh of electricity generated at an efficient natural gas combined cycle power plant is ~50% less per MWh of electricity generated at a coal-fired power plant.…”

“…Compared to coal-fired power plants, natural gas EGUs on average consume less water (Grubert et al 2012) From a program cost-benefit perspective in air quality, changes in fine particulate matter (PM) are important. For example, reductions in regional PM concentrations were the largest driver of health-based cost savings in the Acid Rain Program (Chestnut et al 2005).…”

“…Ozone responses to changes in NO x emissions are highly non-linear (Sillman 1999) and can differ regionally (Nobel et al 2001;Mauzerall et al 2005) and even within a single urban area (Daum et al 2003;Xiao et al 2010 compares the application of a seasonal NO x emissions price to an emissions price that is only imposed on predicted high ozone days when marginal health impacts (Gryparis et al 2004, Mauzerall et al 2005) and regulatory concerns would be elevated. ERCOT is an interesting test-bed for examining the potential impacts of a NO x emissions market based on air quality forecasting since the state has a relatively self-sufficient electric grid and large in-state production of natural gas and coal, leading to a diverse portfolio of generation options that are representative of the nation as a whole (Grubert et al 2012). …”

Eletricidade para o bombeamento de água subterrânea: limitações e oportunidades para respostas adaptativas às mudanças climáticas

“…Os seres humanos vêm exercendo impactos crescentes sobre os sistemas da Terra, sobretudo nos recursos hídricos (Sivapalan et al, 2012). Uma das principais preocupações é com o futuro da disponibilidade e da qualidade dos recursos hídricos para o desenvolvimento energético (Hightower & Pierce, 2008, King et al, 2008, especialmente para a geração de energia elétrica (Grubert et al, 2012). Em contrapartida, as demandas energéticas para a extração, transporte, tratamento e recuperação de água tendem a continuar crescendo no futuro.…”