Water for Natural Gas
More than 80 percent of natural gas-fired generation in the United States comes from natural gas combined-cycle (NGCC) power plants. The rest are simple gas combustion turbines (9 percent) or simple steam turbines (9 percent).[1] An NGCC plant first uses a gas combustion turbine to generate electricity, then uses the waste heat to make steam to generate additional electricity in a steam turbine. Because gas combustion turbines require no cooling (having no steam tocondense), the overall combined cycle system requires much less water for cooling than traditional steam turbine technologies.
Content
How it Works: Water for Natural Gas
About one fifth of electricity in the United States comes from natural gas power plants. Water is
required first to extract natural gas from its underground source and then to transform the fuel’s
chemical energy into electricity.
Electricity Generation
More than 80 percent of natural gas-fired generation in the United States comes from natural gas
combined-cycle (NGCC) power plants. The rest are simple gas combustion turbines (9 percent)
or simple steam turbines (9 percent).[1] An NGCC plant first uses a gas combustion turbine to
generate electricity, then uses the waste heat to make steam to generate additional electricity in a
steam turbine. Because gas combustion turbines require no cooling (having no steam to
condense), the overall combined cycle system requires much less water for cooling than
traditional steam turbine technologies.
Because the amount of cooling necessary is much less per unit of electricity output in NGCC
plants than in coal or nuclear plants, dry cooling systems are more economical for NGCC plants
than for other thermoelectric options. A dry cooling unit in a NGCC plant can only be one third
the size of a dry cooling unit for a coal or nuclear plant with the same electricity
output.[2] About 8 percent of natural gas combined cycle plants in the United States use dry
cooling technology; 80 percent rely on recirculating systems. Fewer than seven percent use
once-through cooling.[3]
Table 1: Water requirements for cooling by type in gallons per megawatt-hour [4]
Fuel Extraction
Natural gas in the United States has traditionally been extracted from deep vertical wells that
require relatively small amounts of water for drilling but that produce more than 200 billion
gallons of water per year that surfaces with the gas on extraction.[5] This "produced water" is
often trapped in these underground formations alongside natural gas.[6] The main methods of
disposing of produced water involve pumping it back into oil- or gas-producing wells to bolster
production, or injecting it deep into other formations below usable groundwater resources.[7]
Hydrofracking Diagram. Graphic Source: ProPublica
In recent years, natural gas from shale gas deposits has become a major new source in the United
States. These new supplies are less readily accessible than conventional deposits, and extracting
the gas requires a process called hydraulic fracturing or “hydrofracking.” The process involves
drilling vertically down to where the gas is trapped and then turning to follow the deposit
horizontally. A mixture of water and chemicals sent through the drill hole at high pressures
creates fractures in the rock and allows the trapped natural gas to escape to the surface.
According to the EIA, shale gas made up about one-third of total U.S. natural gas production in
2012, and will grow to nearly half by 2040.[8]
Hydrofracking has become controversial because of concerns about groundwater being
contaminated with natural gas and the chemicals used in the process. A single hydrofracking
treatment can yield 15,000 gallons of chemical waste from the fracking fluids.[9] Due to the
failure of the industry to disclose the mix of chemicals used in the process and to its successful
lobbying to exempt the process from the Federal Clean Water and Safe Drinking Water Acts,
concerns have emerged about the ability of local wastewater facilities to properly treat the
produced water.[10],[11]Recognizing the potential health and environmental impacts on local
water sources, the EPA is studying water impacts of hydrofracking on gas shale production.[12]
Active Marcellus Shale gas well in West Virginia. Additional water storage pit is not captured in
the photo. Photo Source: WVSORO
In addition to concerns about water quality, water quantity is also an issue. A single
hydrofracked well can require several million gallons per treatment — dozens of times what is
used in conventional vertical drilling.[13],[14],[15] Withdrawing this amount of water over a
short period of time can strain local water sources.
Fuel Processing
After the gas is extracted, an additional 400 million gallons of water per day are consumed for
natural gas refining and pipeline operations.[16]
For more data on lifecycle water use, see Meldrum et al. 2013.
Sources
[1] Energy Information Administration (EIA). 2012. Annual electric utility data.Washington,
DC.
[2] Government Accountability Office (GAO). 2009. Energy-Water Nexus: Improvements to
Federal Water Use Data Would Increase Understanding of Trends in Power Plant Water Use.
Washington, DC.
[3] Union of Concerned Scientists. 2012. UCS EW3 Energy-Water Database
V.1.3.www.ucsusa.org/ew3database.
[4] J. Macknick, R. Newmark, G. Heath, and K.C. Hallet. 2012. Operational water consumption
and withdrawal factors for electricity generating technologies: a review of existing
literature. Environmental Research Letters. 7 doi:10.1088/1748-9326/7/4/045802.
[5] US Department of Energy (DOE). 2006. Energy Demands on Water Resources: Report to
Congress on the Interdependency of Energy and Water.Washington, DC.
[6] U.S. Department of Energy (DOE). 2009. Oil and Natural Gas Water Resources
Program. Washington, DC.
[7] DOE. 2006.
[8] Energy Information Administration (EIA) 2013. AEO2013 early release overview. Table 1:
Comparison of projections in the AEO2013 and AEO2012 reference cases, 20102040. Washington, DC.
[9] U.S. Geological Survey (USGS). 2009. Estimated Use of Water in the United States in
2005. Reston, VA.
[10] New York State Water Resources Institute. 2010. The Marcellus Shale and natural gas.
[11] A.J.Daniel, and M. Layne. 2008. Hydraulic Fracturing Considerations for Natural Gas
Wells of the Marcellus Shale. ALL Consulting.
[12] Environmental Protection Agency (EPA). 2010. Natural gas Extraction - Hydraulic
Fracturing.
[13] P. Applebome. 2010. Will New York Rebel Against Fracking? Green Blog NYTimes.com.
[14] Chesapeake Energy. 2013. Hydraulic Fracturing Facts. Oklahoma City, OK.
[15] U.S. Geological Survey (USGS). 2009. Water Resources and Natural Gas Production from
the Marcellus Shale. Reston, VA.
[16] DOE. 2006.
About one fifth of electricity in the United States comes from natural gas power plants. Water is
required first to extract natural gas from its underground source and then to transform the fuel’s
chemical energy into electricity.
Electricity Generation
More than 80 percent of natural gas-fired generation in the United States comes from natural gas
combined-cycle (NGCC) power plants. The rest are simple gas combustion turbines (9 percent)
or simple steam turbines (9 percent).[1] An NGCC plant first uses a gas combustion turbine to
generate electricity, then uses the waste heat to make steam to generate additional electricity in a
steam turbine. Because gas combustion turbines require no cooling (having no steam to
condense), the overall combined cycle system requires much less water for cooling than
traditional steam turbine technologies.
Because the amount of cooling necessary is much less per unit of electricity output in NGCC
plants than in coal or nuclear plants, dry cooling systems are more economical for NGCC plants
than for other thermoelectric options. A dry cooling unit in a NGCC plant can only be one third
the size of a dry cooling unit for a coal or nuclear plant with the same electricity
output.[2] About 8 percent of natural gas combined cycle plants in the United States use dry
cooling technology; 80 percent rely on recirculating systems. Fewer than seven percent use
once-through cooling.[3]
Table 1: Water requirements for cooling by type in gallons per megawatt-hour [4]
Fuel Extraction
Natural gas in the United States has traditionally been extracted from deep vertical wells that
require relatively small amounts of water for drilling but that produce more than 200 billion
gallons of water per year that surfaces with the gas on extraction.[5] This "produced water" is
often trapped in these underground formations alongside natural gas.[6] The main methods of
disposing of produced water involve pumping it back into oil- or gas-producing wells to bolster
production, or injecting it deep into other formations below usable groundwater resources.[7]
Hydrofracking Diagram. Graphic Source: ProPublica
In recent years, natural gas from shale gas deposits has become a major new source in the United
States. These new supplies are less readily accessible than conventional deposits, and extracting
the gas requires a process called hydraulic fracturing or “hydrofracking.” The process involves
drilling vertically down to where the gas is trapped and then turning to follow the deposit
horizontally. A mixture of water and chemicals sent through the drill hole at high pressures
creates fractures in the rock and allows the trapped natural gas to escape to the surface.
According to the EIA, shale gas made up about one-third of total U.S. natural gas production in
2012, and will grow to nearly half by 2040.[8]
Hydrofracking has become controversial because of concerns about groundwater being
contaminated with natural gas and the chemicals used in the process. A single hydrofracking
treatment can yield 15,000 gallons of chemical waste from the fracking fluids.[9] Due to the
failure of the industry to disclose the mix of chemicals used in the process and to its successful
lobbying to exempt the process from the Federal Clean Water and Safe Drinking Water Acts,
concerns have emerged about the ability of local wastewater facilities to properly treat the
produced water.[10],[11]Recognizing the potential health and environmental impacts on local
water sources, the EPA is studying water impacts of hydrofracking on gas shale production.[12]
Active Marcellus Shale gas well in West Virginia. Additional water storage pit is not captured in
the photo. Photo Source: WVSORO
In addition to concerns about water quality, water quantity is also an issue. A single
hydrofracked well can require several million gallons per treatment — dozens of times what is
used in conventional vertical drilling.[13],[14],[15] Withdrawing this amount of water over a
short period of time can strain local water sources.
Fuel Processing
After the gas is extracted, an additional 400 million gallons of water per day are consumed for
natural gas refining and pipeline operations.[16]
For more data on lifecycle water use, see Meldrum et al. 2013.
Sources
[1] Energy Information Administration (EIA). 2012. Annual electric utility data.Washington,
DC.
[2] Government Accountability Office (GAO). 2009. Energy-Water Nexus: Improvements to
Federal Water Use Data Would Increase Understanding of Trends in Power Plant Water Use.
Washington, DC.
[3] Union of Concerned Scientists. 2012. UCS EW3 Energy-Water Database
V.1.3.www.ucsusa.org/ew3database.
[4] J. Macknick, R. Newmark, G. Heath, and K.C. Hallet. 2012. Operational water consumption
and withdrawal factors for electricity generating technologies: a review of existing
literature. Environmental Research Letters. 7 doi:10.1088/1748-9326/7/4/045802.
[5] US Department of Energy (DOE). 2006. Energy Demands on Water Resources: Report to
Congress on the Interdependency of Energy and Water.Washington, DC.
[6] U.S. Department of Energy (DOE). 2009. Oil and Natural Gas Water Resources
Program. Washington, DC.
[7] DOE. 2006.
[8] Energy Information Administration (EIA) 2013. AEO2013 early release overview. Table 1:
Comparison of projections in the AEO2013 and AEO2012 reference cases, 20102040. Washington, DC.
[9] U.S. Geological Survey (USGS). 2009. Estimated Use of Water in the United States in
2005. Reston, VA.
[10] New York State Water Resources Institute. 2010. The Marcellus Shale and natural gas.
[11] A.J.Daniel, and M. Layne. 2008. Hydraulic Fracturing Considerations for Natural Gas
Wells of the Marcellus Shale. ALL Consulting.
[12] Environmental Protection Agency (EPA). 2010. Natural gas Extraction - Hydraulic
Fracturing.
[13] P. Applebome. 2010. Will New York Rebel Against Fracking? Green Blog NYTimes.com.
[14] Chesapeake Energy. 2013. Hydraulic Fracturing Facts. Oklahoma City, OK.
[15] U.S. Geological Survey (USGS). 2009. Water Resources and Natural Gas Production from
the Marcellus Shale. Reston, VA.
[16] DOE. 2006.
