Chapter 7 DECARBONIZATION AND THE ENERGY/WATER NEXUS: FOCUS ON RENEWABLES
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DECARBONIZATION AND THE ENERGY/WATER NEXUS: FOCUS ON RENEWABLES
JANET NEUMAN is Senior Counsel with Tonkon Torp LLP in Portland, Oregon. Ms. Neuman was formerly a Professor at Lewis& Clark Law School, where she also co-directed the Natural Resources Law Institute and served as Associate Dean of Faculty. Prior to her teaching career, she was the Director of the Oregon Department of State Lands, and in the distant past, she was a litigator in Minneapolis and Portland. Ms. Neuman is the author of Oregon Water Law: A Comprehensive Treatise on the Law of Water and Water Rights in Oregon. She holds a B.A., summa cum laude, from Drake University and a J.D. from Stanford Law School.
Introduction
"Decarbonization"-- reducing carbon emissions into the atmosphere--is a critical component of addressing climate change.1 The use of fossil fuels is the source of most such emissions, particularly carbon dioxide (CO2). Electricity generation constitutes the second largest share of greenhouse gas emissions in the United States, at 25%, because of the dependence of the energy sector on fossil fuels.2 Thus, reducing emissions from power production is central to achieving emission reduction targets.
Energy use and water use are closely intertwined. Producing energy by any fuel or method requires water--and conversely, developing, conveying, and using water all require energy. Energy policy is therefore also water policy, and vice versa. A change in policy direction that focuses narrowly on a single desired goal-- such as reducing the use of fossil fuels--can have unintended consequences for other resources. As energy policy shifts to an intense focus on slashing greenhouse gas emissions, it is crucial not to lose sight of the water impacts of the changing methods and technologies. In order for a decarbonized energy sector to be resilient and sustainable over the long term, rapid progress in emissions reduction must be contextualized within a full understanding and appreciation of the energy-water nexus.3
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The 2021 global climate talks (COP-26) take place in October and November in Glasgow, Scotland. In advance of this important Conference of the Parties, the International Energy Agency has been highlighting the need for an integrated approach to "ensure that decarbonisation plans are water smart"--in order "to avoid unintended consequences, to anticipate stress points, and to implement the policies, technologies and practices that lead to a more secure and sustainable energy future."
This paper explores the energy-water nexus with a focus on renewables. Preliminarily, the paper briefly considers terminology and definitions in order to narrow the remainder of the discussion. Next, the paper reviews the data on current water use in the energy sector and how a shift to more renewable sources will impact water use. Last, a few case studies are described, with attention to particular water issues raised by renewable energy projects.
Terminology: Narrowing the Discussion
Low-carbon vs. Renewable
Decarbonization has already been simply defined as eliminating or reducing the sources of carbon emissions. The definition of renewable energy is also fairly simple--"energy from a source that is naturally replenished."4 The two categories partly overlap, but they are not completely congruent.
Carbon dioxide and other greenhouse gases come from combustion of fossil fuels--coal, oil, and natural gas--which are formed in the earth's crust by geologic processes operating on decomposing organic material from plants and animals. Since these emissions are the primary cause of climate change, decarbonization targets focus on reducing the use of fossil fuels.
But not all low-carbon forms of power production are renewable. For instance, nuclear power plants do not produce CO2 emissions because they do not run on fossil fuels. Nuclear power plants produce power from nuclear fission of Uranium 235, a heavy metal found in rocks, soil, and water.5 Like coal, oil, and natural gas, uranium is a finite resource that is removed from the earth, so it is not a renewable source of power. However nuclear plants do not contribute to
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greenhouse gas emissions, so they may still be considered as part of a decarbonized energy future, though they raise many other environmental issues.6
More pertinent to this discussion is the fact that, in terms of water use, nuclear power plants are similar to other thermoelectric facilities powered by fossil fuels. Water is used in the resource extraction phase, similar to mining for fossil fuels, and both fossil fuel power plants and nuclear power plants generate electricity using heat and steam to drive turbine generators, thus they both require cooling water.7 To the extent that nuclear plants replace fossil fuel plants, there will be no meaningful water savings. However, nuclear power as a low-carbon form of energy generation does not present new or unique water issues and it will not be discussed further here.
Another technology touted to play a role in decarbonizing the energy sector is carbon capture, utilization, and storage (or sequestration). These projects are used in conjunction with fossil-fuel plants (or with emissions-generating facilities in the industrial sector) to lower their carbon impact by capturing CO2 emissions from these sources and storing or sequestering the carbon so it will not be released into the atmosphere, or re-using the CO2 in some other process or product.8 Storage sites include geologic formations such as deep saline reservoirs, unmineable coal seams, and depleted oil and gas reservoirs. Carbon capture can thus be a bridge technology, helping to reach decarbonization goals during the many decades it will take to make significant progress in phasing out the use of fossil fuels. However, carbon capture is not a renewable source of energy in and of itself.
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Old Renewables vs. New Renewables
The sun, the wind, flowing water--all of these are naturally-replenishing and thus constitute renewable sources of energy. Some of these resources have been used for hundreds or thousands of years. For example, wind pumps and windmills were used many centuries ago in China and the Middle East, and in Europe for nearly as long.9 The ancient Greeks used the mechanical power of flowing water to turn water wheels to grind grain and the ancient Egyptians used water screws to move irrigation water.10 Even hydroelectric generation dates back to the 1800s.11 And of course, wood has been burned to produce energy for millennia.
Some of the old ways fell out of favor, replaced by electricity generated on a larger scale by centralized power plants. Old-fashioned single windmills mostly disappeared in the United States, but now wind power is back in the form of high- tech turbines and gigantic wind farms as a "new" renewable power source. Burning biofuels (including wood) has also come a long way from individual fires or woodstoves to large, centralized power generation facilities powered by everything from wood waste to garbage to ethanol made from corn or other crops. Similarly, solar power has emerged as a "new" renewable.
On the other hand, hydroelectric power generation is an "old" renewable that never went away but grew and expanded, solidifying its position in the U.S. energy sector in the mid-20th century with projects all over the country, some of considerable size. In fact, hydropower currently represents the largest single category of water withdrawals in the energy sector--100 times more than all of the other energy-related withdrawals combined.12 Furthermore, although run-of-the- river hydropower projects are technically non-consumptive, evaporation from reservoirs used in conjunction with many hydroelectric power generation facilities ranks third in terms of overall consumption of water in the energy sector.13
The water impacts from hydropower projects are significant, but they are not new. Furthermore, it is unlikely that new on-channel hydro facilities will play a large role in future U.S. renewable energy development, because most of the best locations for such projects have already been developed, and because the non- emissions-related environmental impacts are considerable. However, reconfigured
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"greener" hydro generation, such as off-channel pumped storage projects, will be part of a renewable, low-carbon future.
That brings us to the following list of renewable technologies that are likely to form a significant part of U.S. energy policy going forward: solar, wind, pumped storage (or other "green hydropower"), geothermal power, biofuels, and carbon capture, utilization, and storage.14 Moving toward these renewables for power generation bends--but does not break--the connection between energy use and water use. While all of these technologies decrease the use of fossil fuels, that reduction does not necessarily translate to decreased water use.15
Water Use in Energy Production
Current Snapshot of the Energy-Water Nexus
The energy sector as currently configured accounts for approximately 40% of the water withdrawals in the United States--excluding non-consumptive hydropower withdrawals--and 10% of total US water consumption.16 The resource extraction phase primarily uses groundwater, while the power generation phase primarily uses surface water.17
As of 2020, about 60% percent of electricity in the United States was still produced by fossil fuels, mostly in...
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