Figure 1. Energy/Water Nexus Amy Hardberger, Matthew E. Mantell, Michael Webber, Carey W. King, Karl Fennessey
[ This Senate hearing covers a lot of ground. I found the most interesting testimony to be the intersection of water and energy, which I’ve summarized and paraphrased based on what Michael E. Webber at the University of Texas had to say (as well as other research):
Generating electricity for electric vehicles will use a lot of water. Nuclear, coal, natural gas, and biomass fuels are the largest users of water in the United States – 49% of all water withdrawals (including saline), and 39% of all freshwater withdrawals – the same amount used by agriculture. Because most power plants in the U.S. electric grid use a lot of cooling water, electricity is about twice as water-intensive as gasoline per mile traveled. But unconventional fossil fuels such as oil shale, coal-to-liquids, gas-to-liquids, and tar sands require significantly more water to produce than gasoline, which only requires about 0.2 gallons of water per mile traveled.
Irrigated biofuels from corn or soy can consume 100 to 500 times more water than gasoline: 20 to 100 or more gallons of water for every mile traveled. By switching from imported petroleum to domestic biofuels, we are essentially substituting domestic water for petroleum. This may reduce oil price volatility, but we exchange that for risks to the production of biofuels – drought, floods, severe storms, and other calamities from climate change and weather.
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report ]
Senate 112-25. March 31, 2011. Hydropower. U.S. Senate hearing. 92 pages.
SENATOR JEFF BINGAMAN, NEW MEXICO, CHAIRMAN. Today we hear testimony regarding 3 pieces of legislation—S. 629, which is the Hydropower Improvement Act of 2011, S. 630, which is the Marine and Hydrokinetic Renewable Energy Promotion Act of 2011, and also the energy and water integration provisions from Title I, Subtitle D, of ACELA, the American Clean Energy Leadership Act of 2009, which was S. 1462 in the previous Congress. Today we will hear from administration and other witnesses about the potential we have to produce more hydropower in this country through improved efficiency at existing hydropower facilities and adding hydropower capabilities to existing structures. Developing additional energy from hydropower can help to decrease our dependence on fossil fuels. Developing new policies that integrate energy and water solutions will become increasingly vital as populations grow and environmental needs increase, and a changing climate continues to affect our energy and water resources.
MICHAEL E. WEBBER, PH.D., Assistant Professor, Department of Mechanical Engineering, Assoc. Director, Center for International Energy & Environmental Policy, UNIVERSITY OF TEXAS AT AUSTIN
My testimony today will make these main points: 1. Energy and water are interrelated, 2. The energy-water relationship is already under strain, 3. Trends imply these strains will be exacerbated
In California, where water is moved hundreds of miles across two mountain ranges, water is responsible for more than 19% of the state’s total electricity consumption.
Similarly large investments of energy for water occurs wherever water is scarce and energy is available. In addition to using energy for water, we also use water for energy. We use water directly through hydroelectric power generation at major dams, indirectly as a coolant for thermoelectric power plants, and as a critical input for the production of biofuels. The thermoelectric power sector-comprised of power plants that use heat to generate power, including those that operate on nuclear, coal, natural gas or biomass fuels-is the single largest user of water in the United States. Cooling of power plants is responsible for the withdrawal of nearly 200 billion gallons of water per day. This use accounts for 49% of all water withdrawals in the nation when including saline withdrawals, and 39% of all freshwater withdrawals, which is about the same as for agriculture.
Nuclear is the most water-intensive, while solar PV, wind, and some uses of natural gas are very water lean.
The Energy-Water Relationship Is Already Under Strain
Unfortunately, the energy-water relationship introduces vulnerabilities whereby constraints of one resource introduce constraints in the other. For example, during the heat wave in France in 2003 that was responsible for approximately 10,000 deaths, nuclear power plants in France had to reduce their power output because of the high inlet temperatures of the cooling water. Environmental regulations in France (and the United States) limit the rejection temperature of power plant cooling water to avoid ecosystem damage from thermal pollution (e.g. to avoid cooking the plants and animals in the waterway). When the heat wave raised river temperatures, the nuclear power plants could not achieve sufficient cooling within the environmental limits, and so they reduced their power output at a time when electricity demand was spiking by residents turning on their air conditioners. In this case, a water resource constraint became an energy constraint.
In addition to heat waves, droughts can also strain the energy-water relationship. During the drought in the southeastern United States in early 2008, nuclear power plants were within days or weeks of shutting down because of limited water supplies. Today in the west, a severe multi-year drought has lowered water levels behind dams, reducing output from their hydroelectric turbines. In addition, power outages hamper the ability for the water/wastewater sector to treat and distribute water.
Trends Imply These Strains Will Be Exacerbated
While the energy-water relationship is already under strain today, trends imply that the strain will be exacerbated unless we take appropriate action. There are four key pieces to this overall trend:
- Population growth, which drives up total demand for energy and water,
- Economic growth, which can drive up per capita demand for both energy and water,
- Climate change, which intensifies the hydrological cycle, and
- Policy choices, whereby we are choosing to move towards more energy-intensive water and more water-intensive energy.
Population Growth Will Put Upward Pressure on Demand for Energy & Water
Population growth over the next few decades might yield another 100 million people in the United States over the next four decades, each of whom will need energy and water to survive and prosper. This fundamental demographic trend puts upward pressure on demand for both resources, thereby potentially straining the energy-water relationship further.
Economic Growth Will Put Upward Pressure on Per Capita Demand for Energy & Water
On top of underlying trends for population growth is an expectation for economic growth. Because personal energy and water consumption tend to increase with affluence, there is the risk that the per capita demand for energy and water will increase due to economic growth. For example, as people become wealthier they tend to eat more meat (which is very water intensive), and use more energy and water to air condition large homes or irrigate their lawns. Also, as societies become richer, they often demand better environmental conditions, which implies they will spend more energy on wastewater treatment. However, it’s important to note that the use of efficiency and conservation measures can occur alongside economic growth, thereby counteracting the nominal trend for increased per capita consumption of energy and water. At this point, looking forward, it is not clear whether technology, efficiency and conservation will continue to mitigate the upward pressure on per capita consumption that are a consequence of economic growth. Thus, it’s possible that the United States will have a compounding effect of increased consumption per person on top of a growing number of people.
Climate Change Is Likely To Intensify Hydrological Cycles
One of the important ways climate change will manifest itself it through an intensification of the global hydrological cycle. This intensification is likely to mean more frequent and severe droughts and floods along with distorted snow melt patterns. Because of these changes to the natural water system, it is likely we will need to spend more energy storing, moving, treating and producing water. For example, as droughts strain existing water supplies, cities might consider production from deeper aquifers, poorer-quality sources that require desalination, or long-haul pipelines to get the water to its final destination. Desalination in particular is energy-intensive, as it requires approximately ten times more energy than production from nearby surface freshwater sources such as rivers and lakes.
Policy Choices Exacerbate Strain in the Energy-Water Nexus
On top of the prior three trends is a policy-driven movement towards more energy-intensive water and water-intensive energy. We are moving towards more energy-intensive water because of a push by many municipalities for new supplies of water from sources that are farther away and lower quality, and thereby require more energy to get them to the right quality and location. At the same time, for a variety of economic, security and environmental reasons, including the desire to produce a higher proportion of our energy from domestic sources and to decarbonize our energy system, many of our preferred energy choices are more water-intensive.
Nuclear energy is produced domestically, but is also more water-intensive than other forms of power generation.
The move towards more water-intensive energy is especially relevant for transportation fuels such as unconventional fossil fuels (oil shale, coal-to-liquids, gas-to-liquids, tar sands), electricity, hydrogen, and biofuels, all of which can require significantly more water to produce than gasoline (depending on how you produce them)
Almost all unconventional fossil fuels are more water-intensive than domestic, conventional gasoline production. While gasoline might require a few gallons of water for every gallon of fuel that is produced, the unconventional fossil sources are typically a few times more water-intensive.
Most power plants use a lot of cooling water, and consequently electricity can also be about twice as water-intensive than gasoline per mile traveled if the electricity is generated from the standard U.S. grid.
Though unconventional fossil fuels and electricity are all potentially more water-intensive than conventional gasoline by a factor of 2-5, biofuels are particularly water-intensive. Growing biofuels consumes approximately 1000 gallons of water for every gallon of fuel that is produced. Sometimes this water is provided naturally from rainfall. However, for a non-trivial and growing proportion of our biofuels production, that water is provided by irrigation.
Note that for the sake of analysis and regulation, it is convenient to consider the water requirements per mile traveled. Doing so incorporates the energy density of the final fuels plus the efficiency of the engines, motors or fuel cells with which they are compatible.
Conventional gasoline requires approximately 0.2 gallons of water per mile traveled, while irrigated biofuels from corn or soy can consume 20 to 100 or more gallons of water for every mile traveled. If we compare the water requirements per mile traveled with projections for future transportation miles and combine those figures with mandates for the use of new fuels, such as biofuels, the water impacts are significant.
Water consumption might go up from approximately one trillion gallons of water per year to make gasoline (with ethanol as an oxygenate), to a few trillion gallons of water per year.
To put this water consumption into context, each year the United States consumes about 36 trillion gallons of water. Consequently, it is possible that water consumption for transportation will more than double from less than 3% of national use to more than 7% of national use. In a time when we are already facing water constraints, it is not clear we have the water to pursue this path. Essentially we are deciding to switch from foreign oil to domestic water for our transportation fuels, and while that might be a good decision for strategic purposes, I advise that we first make sure we have the water.
Unfortunately, there are some policy pitfalls at the energy-water nexus. For example, energy and water policy making are disaggregated. The funding and oversight mechanisms are separate, and there are a multitude of agencies, committees, and so forth, none of which have clear authority. It is not unusual for water planners to assume they have all the energy they need and for energy planners to assume they have the water they need. If their assumptions break down, it could cause significant problems. In addition, the hierarchy of policymaking is dissimilar. Energy policy is formulated in a top-down approach, with powerful federal energy agencies, while water policy is formulated in a bottom-up approach, with powerful local and state water agencies. Furthermore, the data on water quantity are sparse, error- prone, and inconsistent. The United States Geological Survey (USGS) budgets for collecting data on water use have been cut, meaning that their latest published surveys are anywhere from 5 to 15 years out of date. National databases of water use for power plants contain errors, possibly due to differences in the units, format and definitions between state and federal reporting requirements. For example, the definitions for water use, withdrawal and consumption are not always clear. And, water planners in the east use ‘‘gallons’’ and water planners in the west use ‘‘acre-feet,’’ introducing additional risk for confusion or mistakes.
Energy for Water—US public water supply requires 4% of national energy and 6% of national electricity consumption
The energy-water relationship is already under strain: constraints are cross-sectoral • Heat waves and droughts can constrain energy • Energy outages can constrain water
SENATOR BINGAMAN. Your testimony highlights the need to investigate the water supply needs associated with electricity generation AND transportation fuels, which our legislation seeks to do. You have also indicated that a ‘‘switch from gasoline to electric vehicles or biofuels is a strategic decision to switch our dependence from foreign oil to domestic water’’.
MICHAEL E. WEBBER. Today, petroleum-based fuels supply more than 95% of our energy for transportation. Because of converging desires to switch to lower-carbon, less volatile, and domestic forms of transportation fuels, a variety of policy mechanisms support the displacement of imported petroleum with electricity, biofuels, unconventional fossil fuels, hydrogen, and natural gas. In general, gasoline and diesel are relatively water-lean to produce. By contrast, most of the alternative transportation fuels-in particular biofuels, unconventional fossil fuels, some forms of electricity, and some forms of hydrogen-are more water-intensive. Thus, by switching from imported petroleum to these domestic options, we are essentially substituting the use of domestic water for petroleum. While this tradeoff has important strategic benefits, it can be problematic from a water resources perspective.
SENATOR BINGAMAN. Many of us are familiar with the concept of ‘‘peak oil’’. Can you please elaborate on the concept of ‘‘peak water’’?
MICHAEL E. WEBBER. ‘‘Peak Water’’ is a reference to the concept of declining productions rates for fresh water. In contrast with ‘‘Peak oil,’’ which refers to a finite resource (petroleum), water is very abundant globally. However, most of that water is available in a form, location, or time of year that is inconvenient or unusable for many people. Consequently, significant amounts of energy are invested to move that water in place, time and form (through pipelines, storage reservoirs and treatment plants) such that it is clean, potable, and available when and where we want it. If energy sources become constrained or prohibitively expensive, then clean, piped water might also become constrained or prohibitively expensive in certain locations or particular times of year. Consequently, ‘‘Peak Energy’’ could trigger a decline in production of freshwater.
Traditional steam-electric (or thermoelectric) power plants, including many of those powered by nuclear, coal, biomass, natural gas, or concentrated solar power, use extensive amounts of water for cooling. Locating these power plants in arid or semi-arid regions, where water resources are scarce, exposes the plants to the risk that they will compete with other municipal, agricultural, industrial or ecological needs for that water. Ensuring that the water needs will be met by the power plants will be challenging if conventional cooling technologies and freshwater sources are used. However, novel dry-cooling and wet-dry-hybrid cooling systems require much less water for power plants, and therefore might be a promising option. For example, some new concentrated solar power systems that use dry cooling have been proposed in Nevada. While these types of systems significantly reduce the amount of water that is needed by power plants, they have a tradeoff of 1) requiring more capital up front to build the cooling systems and 2) reducing the operating efficiency of the power plant. Other options include the use of reclaimed water or saline water for cooling, or building power plants with water-lean combinations of fuels and technologies, such as solar PV, wind turbines, and natural gas simple cycle combustion turbines.
Generally speaking, the northern latitudes of the U.S. have more abundant sources of water available. However, even ‘‘water-rich’’ regions of the country can be exposed to periods of drought. In addition, water abundance can lead to flooding, which also puts the energy sector at risk. Thus, the risk of water problems are widespread.
The energy sector’s growing water use, primarily for irrigating biofuels crops, provides a benefit of displacing some petroleum use, but introduces a risk of competition for water resources. By displacing petroleum, we reduce our exposure to oil price volatility tied to geopolitical events. However, we exchange those risks for water-related risks driven by climate and weather systems. These risks can show up in the form of higher energy prices, which can impact economic growth. Developing more energy-efficient water systems and more water-efficient energy systems can be economically beneficial because they mitigate the downside risks.
Building more energy-intensive water systems and more water-intensive energy systems exacerbates the exposure to risk.
Using reclaimed water or saline water at power plants reduces the need for freshwater in the power sector and can save on water costs for plant operators. Such systems have been built. For example the Palo Verde nuclear power plant in Arizona, and the Sand Hill natural gas power plant in Austin, Texas both use reclaimed water. And, coastal nuclear power plants use saline water. However, these water sources can be more corrosive or cause mineral build-up and thus might require more expensive piping and heat exchanger materials and additional maintenance. Furthermore, in some cases the use of reclaimed water requires permitting approval from relevant agencies and significant up-front capital-intensive infrastructure investments to connect reclaimed water sources from wastewater treatment plants to the electricity stations.
JOHN SEEBACH, DIRECTOR, HYDROPOWER REFORM INITIATIVE, AMERICAN RIVERS. When it’s done wrong, hydropower can be far from clean. Hydropower is unique among renewable resources because of the scale at which it can damage the environment when it’s done poorly. Unless a hydropower dam is sited, operated, and mitigated appropriately, it can have enormous impacts on river health and the livelihoods of future generations that will depend on those rivers. Poorly done hydropower has caused some species to go extinct, and put others, including some with extremely high commercial value, at grave risk. That’s not something we should take lightly.
America is still blessed with many healthy, free-flowing watersheds, wetlands and floodplains that provide numerous services and values. We must preserve these intact systems and promote them as a vital part of our water supply and flood protection infrastructure. At the same time, we must rehabilitate rivers and streams that have been damaged by existing hydropower projects, and protect habitat from further degradation. A failure to improve the health of rivers now will doom more species to extinction as the world warms.
Hydrokinetic and Marine energy (S. 630) There has been a great deal of discussion about dam-less hydrokinetic technologies that use free-flowing rivers, waves, ocean currents, or other means to generate electricity. We have followed the development of instream hydrokinetic technologies closely. Moreover, since ocean and instream hydrokinetic technologies are often lumped together, we have participated in a number of policy discussions that have addressed both technologies. We are hopeful that these new technologies will eventually allow us to harness the power of moving water in a responsible manner that avoids the devastating impacts associated with dam-building. Unfortunately, there is still precious little information available about how these technologies interact in a natural setting. As of today, we are aware of only one instream hydrokinetic project that is currently licensed to generate in U.S. waters, and our understanding is that it is currently out of service. With so little information available, it is difficult to assess the environmental impacts of these technologies, let alone their commercial feasibility. We can only speculate as to what the costs and benefits of these technologies might be. It is clear, then, that there is a need for more testing, as well as for research into the potential environmental impacts and new and innovative ways that those impacts might be avoided. There is also a need for strong siting criteria that take into account environmentally sensitive areas or areas that are vital to economic activity (like transportation or commercial fishing), and consider the risk that the cumulative impacts of additional development may simply be too high in some watersheds that are already highly impacted by existing hydropower development.
Some of the potential environmental impacts of hydrokinetic energy technologies include (but are not limited to): • Aquatic Species’ interaction with devices and anchoring systems (including Marine mammals, sharks, fish, etc.). Potential risks include avoidance, behavior change, collision, entrainment, or mortality. • Effects due to the removal of energy from waves and currents. Potential risks include altered sediment transport and changes in flow velocity, tidal exchange, and water quality. • Effects of noise, vibration, lighting, EMF from transmission cables, and releases of chemicals (lubricants, oils, etc.) on aquatic and avian species. • Effects of exclusion / restriction zones on recreation, navigation, commercial fishing, etc.
For a much more detailed discussion of some of these impacts, we recommend the U.S. Department of Energy’s Wind and Hydropower Technologies Program’s December 2009 ‘‘Report to Congress on the Potential Environmental Effects of Marine and Hydrokinetic Energy Technologies.’’
Mr. Steven Chalk, Chief Operating Officer and Acting Deputy Assistant Secretary for Renewable Energy at the Department of Energy. The provisions being considered from ACELA address the interdependence of our energy and water consumption. Water is an integral component of many traditional and alternative energy technologies used for transportation, fuels production and electricity generation. Energy-related water demands are beginning to compete with other demands from population growth, agriculture and sanitation. This competition could become fiercer if climate change increases the risk of drought, making our water supply more vulnerable. The Department of Energy (DOE) has initiated many activities over the last few years to address this energy-water nexus.
About 45% of all hydropower in the United States is generated at Federally-owned facilities, providing clean, renewable power to the grid. DOE’s estimates indicate that there could be an additional 300 gigawatts of hydropower through efficiency and capacity upgrades at existing facilities, powering non-powered dams, new small hydro development and pumped storage hydropower.
Conventional hydropower represented 65% of U.S. renewable electricity generation in 2010, and 7% of total U.S. electricity generation. Conventional hydropower principally serves as a baseload electricity supply, but can also function as a dispatchable resource to balance variable renewable energy technologies such as wind and solar.
The Electric Power Research Institute indicated that its conservative estimate was that MHK power (from wave and tidal sources alone) could provide an additional 13,000 megawatts (MW) of capacity by 2025.
Power generation from thermal energy sources (which include coal, natural gas and nuclear energy) accounted for approximately 41% of U.S. freshwater withdrawals in 2005. Although most of the water withdrawn for cooling thermal power plants is subsequently returned to the source, this still can have disruptive effects on water flows and temperatures, which in turn negatively affect aquatic organisms, namely fish populations such as salmon.
We identify possibly 300 gigawatts of potential hydro. I would say roughly 12 gigawatts of capacity is from existing hydropower facilities from upgrading efficiency and capacity. A lot of these facilities are very old, so the turbines aren’t very efficient. So, if we can put modern turbines in there, we could get probably about 12 gigawatts of power. If we look at existing dams—and there’s 80,000 dams in the U.S.—most of those are not powered. But we could probably get an additional 12 gigawatts from 595 of those dams if we put powerhouses on those, as long as it can be done in an environmentally sensitive way. The big potential, we estimate about 255 gigawatts, is in small hydro, and this potential is all over the country. In fact, there’s 90 gigawatts of small hydro in Alaska. Incredible potential. Most of these locations have less than 5 megawatts of potential. So, that’s where most of the growth could occur if we would look to grow hydropower.
Then the last area is pump storage, which really is more of a capacity thing than energy. It actually uses more energy, because you have to pump the water back up the hill, and then it takes more energy to do that than you get when you need the power. But this is really important for backstopping and firming up intermittent renewables like wind and solar. So, this is a really important area. We estimate there’s roughly about another 34 gigawatts of this type of power that’s available.
The marine and hydrokinetic portion has gone down a little bit, but in that particular area, the marine and hydrokinetic devices are really where the wind program was 20 years ago. These device designs are just emerging. There’s been very little open water testing—almost no testing like you have wind farms today. We call them ‘‘arrays,’’ in the water. Almost no testing there. So, we feel like the amount of money that we’re putting into the marine and hydrokinetic is the right amount for the current state of development, which is rather immature.
There are a lot of synergies between offshore wind and some of these offshore water devices. Materials, for instance. We have to use composite materials to prevent erosion, corrosion, and other similar phenomena. A major barrier is ensuring that we have the transmission for offshore wind, and for these smaller ocean or wave or tidal devices. Perhaps they could be tied together. How to finance that transmission, and how to go about installing it would actually be a significant hurdle that we would have to address.
If you look at the challenges in siting a solar or thermal plant, it has a steam cycle to produce the energy, or a geothermal plant in the desert where there’s no access to water, you have to come up with ways of, what we call dry cooling. You have to minimize water use. That’s a tough R&D challenge because as you do that, a lot of times you reduce your efficiency in producing electricity. In biomass, for instance, if we’re going to grow sustainable energy crops, it’s a requirement that we have to use very little water—not like irrigating corn that we have today. We have to grow those crops with virtually just natural rainfall.
DOE’s pumped storage hydropower (PSH) initiative is focused on integrating variable renewable resources and identifying and addressing the barriers to deployment in the United States. In September 2010, DOE sponsored a PSH workshop where experts from the industry, manufacturers, laboratories, environmental groups, and government agencies were convened to identify the major PSH deployment barriers. The barriers identified in this workshop include permitting time and cost, lack of models that identify the full value of PSH, lack of uniform markets for ancillary services provided by PSH, high capital cost, and long payback period.
The CHAIRMAN. So, from your perspective, it’s not so much that the power from hydropower is more expensive than natural gas— it’s not.
Mr. MUNRO. Right.
The CHAIRMAN. But, it just takes so much longer to get the permits and to get it constructed, and online.
Mr. MUNRO. That’s true. Also, gas is a firm—it’s a real firm resource, meaning it’s there when you need it.
JEFF C. WRIGHT, DIRECTOR, OFFICE of ENERGY PROJECTS, FEDERAL ENERGY Regulatory Commission. The Commission regulates over 1,600 non-Federal hydropower projects at over 2,500 dams pursuant to Part I of the Federal Power Act, or FPA. Together, these projects represent 54 gigawatts of hydropower capacity—more than half of all the hydropower in the U.S. The FPA authorizes the Commission to issue licenses and exemptions for projects within its jurisdiction. About 71 percent of the hydropower projects regulated by the Commission have an installed capacity of 6 megawatts or less.
MICHAEL L. CONNOR, COMMISSIONER, BUREAU OF RECLAMATION, DEPARTMENT of the INTERIOR
Hydropower is very flexible and reliable when compared to other forms of generation. Reclamation has nearly 500 dams and dikes and 10,000 miles of canals and owns 58 hydropower plants, 53 of which are operated and maintained by Reclamation. On an annual basis, these plants produce an average of 40 million megawatt (MW) hours of electricity, enough to meet the entire electricity needs of over 9 million people on average. Reclamation is the second largest producer of hydroelectric power in the United States, and today we are actively engaged in looking for opportunities to encourage development of additional hydropower capacity at our facilities.