How much water is needed to produce one quart of oil-equivalent energy? 2
As illustrated on the right, the amount of the freshwater needed to produce an identical unit of energy from natural gas is less than for a variety of other energy sources, including hydroelectric power and ethanol. According to a recent study by the U.S. Department of Energy’s National Energy Tech- nology Laboratory, shale gas production uses about 10 times less water than is used for coal production, and 1,000 times less water than is used for fuel ethanol or biodiesel production. Even so, we continue to look for opportunities to reduce our water use. ExxonMobil seeks to continuously improve the development and implementation of water management strategies. Part of this effort involves improving our understanding of not only the quantity of our water consumption, but also when and where this consumption occurs. In 2015, ExxonMobil collaborated with ETH Zurich, one of the leading international universities for technology and the natural sciences, to co-author a peer-reviewed paper on improving the capability to assess water stress indices. The purpose of the paper was to explain the impacts of freshwater consumption in life cycle assessments (LCA) of comparative energy sources. In particular, the paper highlights the importance of regional and seasonal variations when considering water stress as part of an LCA. Based on our analysis using the latest version of the oil and gas industry global water tool, almost 40 percent of our major operating sites are located in areas identified with the potential for water stress or scarcity. Where appropriate, we conduct a detailed local analysis of specific water use-related risks and develop site-specific management strategies such as the deployment of water conservation technologies, the use of alternative freshwater sources, recycling of municipal and industrial wastewater and harvesting of rainwater. For example, conventional methods of dust suppression can require large amounts of freshwater to maintain safe working conditions. By applying a biodegradable dust-control product to the roads at our oil sands operations in Kearl, Canada, we were able to significantly reduce the amount of water required to manage road dust. In 2015 alone, the Kearl oil sands operations saved an estimated 36 million gallons of water. American Chemical Society water stress index paper
Freshwater intensity is the total amount of freshwater needed to produce an identical unit of energy for a variety of energy sources and transportation fuels.
Petroleum One quart of petroleum requires from one to two-and-a-half quarts of water. (Extraction itself requires less than a cup — most of the water goes toward cooling in the refinery.)
Natural gas One oil-equivalent quart of natural gas requires anywhere from a tablespoon to a cup of water. Unconventional or “fracked” natural gas is at the higher end of the range.
x 18
Electric power from coal One oil-equivalent quart of electric power from coal requires anywhere from 11 to 18 quarts of water for cooling. (Gas-fired turbines also require cooling water, but are a bit more efficient and require less water than coal-fired plants.)
Extracted coal One oil-equivalent quart of extracted coal requires less than two quarts of water.
x 1,176
x 5,040
Ethanol One oil-equivalent quart of ethanol requires from six quarts to as much as 1,176 quarts of water (depending on irrigation). This is typical of most biofuels.
Hydroelectric power One oil-equivalent quart of hydroelectric power requires from 15 quarts to as much as 5,040 quarts of water because of evaporation and subsurface seepage from reservoirs.
10 13 80 or or = 10 13 80 or or = 10 1 80 or o =
0 13 80 or or = or or
0 13 80 or or =
One quart of oil
Ten cyclists in a 10-hour race
A team of 13 horses working one hour
Heating up an 80-gallon water heater to shower temperature
2 Adapted from the freshwater intensity page at exxonmobil.com.
Environmental performance exxonmobil.com/citizenship
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