Water-Energy Nexus: Balancing Resource Use for a Sustainable Future

Did you know that over 40% of all water used in the U.S. goes to power plants? Electricity production consumes more than three times as much water as all the public water supplies in the country. This is just one example of how closely linked water use is with energy use. The connection between the two is called the water-energy nexus.

Understanding the connections between water and energy is important because all human societies depend on these two resources. We can’t build a sustainable future for our world without protecting them both.

Understanding the water-energy nexus

People often think of water and energy as separate resources—both important, but not really related to each other. But in the modern world, we rely on energy to produce water and on water to produce energy. A sustainable energy system depends on efficient use of water, and vice versa.

In addition, both these resources are critical for food production. Next to energy production, irrigating farmland is the biggest use for water in the U.S. The food system is a major user of energy as well, consuming over 12% of the nation’s energy. This means that as the world’s population and need for food grows, its need for water and energy grows too.

However, climate change is putting the squeeze on both water and energy resources. As the earth warms, droughts become more common, leaving less freshwater available for energy production. It’s possible to extract usable water from other places, but that requires more energy for pumping and water treatment. If that energy comes from fossil fuels, it creates more greenhouse gas emissions, warming the earth still faster.

In order to halt climate change, we need to get the world off fossil fuels and transition to clean energy as fast as possible. Unfortunately, clean energy sources aren’t created equally. Some of them require as much water as fossil fuels. If we focus on energy sources that are low-carbon but water-intensive, we’ll put more stress on our limited water resources. By contrast, if we choose water-light energy sources, that will ease the pressure on the world’s water supplies.

The role of energy in the water system

Every time you take a shower, the water has already consumed a lot of energy to reach you. Modern water systems use energy for:

• Pumping. It takes energy to pump water out of underground aquifers for irrigation. Additional energy is needed to get water intended for consumer use to and from treatment plants.
• Treatment. Household water may be treated both before and after use. In some areas, water must be desalinated (have salt removed) to make it safe to drink. This process requires a lot of energy to generate the pressure needed to force water through filters. Wastewater sent down the drain returns to treatment plants, which use energy to remove sewage sludge and other harmful chemicals.
• Heating and cooling. Once water reaches consumers’ homes, they use additional energy to heat it for cooking, bathing, and cleaning. Buildings may also use water and energy together in heating and cooling systems.

New technology offers various ways to reduce energy demand throughout the water system. For instance, water pumps can run on built-in solar panels. Advanced desalination methods can cut the amount of energy needed to remove salt from water. Water treatment plants can use the sludge they extract from wastewater as an energy source. And more efficient water heaters, like heat pump or tankless models, reduce energy use for heating.

Another useful strategy is to reduce losses along the water supply chain due to leaks, burst pipes, or theft. Less wasted water means less wasted energy.

The role of water in energy production

Just as we can’t produce water without energy, we can’t produce energy without water. The uses of water in our energy system include:

• Fossil fuel production. The extraction of fossil fuels generally requires water. It’s used for washing coal and for enhanced oil recovery—injecting water into oil wells to extract additional petroleum. Fracking to extract oil and natural gas also requires large amounts of water.
• Clean energy. Many forms of clean energy are also water-intensive. The most obvious example is hydropower. Damming a river to produce electricity doesn’t use up the water, but it does make hydropower dams dependent on rainfall. They stop working when rivers run low due to drought—an increasingly common problem due to climate change. Growing and distilling biofuels can also require large volumes of water. And green hydrogen is literally made by breaking apart water, destroying it in the process.
• Steam Turbines. Many power plants use steam-driven turbines. They heat water to produce steam, which turns the turbines to generate electric current. The heat source in this process can be fossil fuel, nuclear energy, concentrated solar power, or geothermal energy. These types of power plants use water not only to make steam, but also to keep the system from overheating. In the U.S., a severe drought in 2012 restricted the operation of some power plants because they lacked water for cooling.
• Carbon capture. Some fossil fuel power plants use carbon capture and storage (CCS) to reduce their emissions of planet-warming greenhouse gases. Unfortunately, this process uses large amounts of water. A 2021 paper concluded that relying on CCS to halt global warming would nearly double worldwide water use.

In 2010, the world’s energy system used 370 billion cubic meters (bcm) of water. That’s about 10% of all the fresh water used in the world. All this water use takes a toll on the environment. It worsens water shortages in dry regions, affecting plants, animals, and humans. In addition, discharges of cooling water from power plants cause thermal pollution that harm aquatic life.

As with energy use in water production, technological fixes can help with this problem. One solution is more efficient power plants that produce less waste heat, so they need less water for cooling. Power plants can also expend waste heat for productive uses, such as desalinating water. That’s an environmental two-fer, reducing energy use in the water system and water use in the energy system at the same time. Power plants can also reduce their water needs by recycling their cooling water or by cooling with air instead.

One of the most useful approaches is to rely on photovoltaic (PV) solar and wind power for electricity. These technologies don’t require steam to generate electricity, so they use very little water. And they’re also clean, with low emissions of greenhouse gases and other pollutants.

Water and energy resource management

In 2022, the world consumed about 179,000 terawatt-hours (TWh)—179 trillion kilowatt-hours (kWh)—of electricity. More than 155,000 TWh of that came from fossil fuels, hydropower, and nuclear energy—all heavy users of water. Wind and solar energy, the lightest water users, supplied just 6,430 TWh. And the Energy Information Administration predicts that world energy use will grow nearly 50% by 2050.

If all that energy continues to come from water-intensive sources, it will seriously deplete our already strained water resources. In 2014, the world used about 4 trillion cubic meters of water. That’s more than twice as much as it consumed 50 years earlier. And even now, we’re not using enough water to meet the world’s true needs. Billions of people worldwide still lack access to clean drinking water. Also, approximately 80% of all wastewater is discharged without treatment. Fixing these problems will require even more energy in the very parts of the world that currently lack reliable energy sources.

Our growing hunger for both energy and water has huge consequences for the environment. Fossil fuels, which provide about 77% of global energy, create air pollution that kills millions of people every year. Deaths due to fossil fuel air pollution exceed those from HIV, tuberculosis, and malaria combined. On top of that, fossil fuel use is driving climate change, which causes deadlier storms, droughts, flooding, and sea level rise. All told, fossil fuel use is costing the world an estimated $800 billion in health care costs per year.

The worldwide water system also creates environmental problems. Untreated wastewater contains a wide variety of harmful pollutants, including human waste, heavy metals, and drug residues. These pollutants damage aquatic ecosystems and can also spread disease. On top of that, flushing wastewater into rivers or oceans wastes a valuable resource. Today, nearly two-thirds of the world’s people face severe water shortages for at least one month out of every year. Climate change will only make that problem worse.

The good news is that the solutions to both these problems are often the same. Replacing fossil fuels with wind and solar will greatly reduce both greenhouse gas emissions and water use. Energy efficiency is also a two-fer, since the less energy we use, the less water we need for energy production. And better water treatment facilities can both reduce water pollution and conserve water. That, in turn, reduces the energy needed for water pumping and desalination.

Policy and regulations

Even though water and energy depend on each other, policy makers often treat them as separate issues. Utilities often site power plants without considering their water needs and the available supply. Politicians sometimes prioritize one form of energy over another without considering its water impact. And water utilities and regulators often make decisions about water without regard to energy use.

Organizations like the United Nations and the International Energy Agency (IEA) are pushing for a more integrated approach to water and energy. The IEA estimates that with current policies, global water use for energy production will increase 30 bcm by 2030. But with an ambitious policy agenda that considers both water and energy use, it could fall by 20 bcm. This agenda would include rapid increases in energy efficiency, wind power, and solar power.

Several countries, from Norway to Nepal, have already established joint agencies for dealing with water and energy. And within in the U.S., the Department of Energy is exploring the water-energy nexus and ways to address it. However, the country’s patchwork of state laws on water rights and energy use makes it hard to put solutions in place. Fortunately, some states, like California, are beginning to adopt a more integrated approach.

Sustainable practices for individuals

Water and energy use are often linked for individuals as well. Many steps you can take to save energy at home or at work will also conserve water and vice versa. Eco-friendly habits and choices like these benefit the environment twice. They save precious water and reduce fossil fuel use, air pollution, and climate change. And, as a bonus, they can also save you money on your utility bill.

Ways to reduce your water and energy consumption include:

• Conserving hot water. Every time you turn on the hot-water faucet, you’re using both water and energy. To reduce hot water use, try taking shorter showers and/or installing a water-saving showerhead. Add flow regulators to your faucets to save hot water in the sink. Do your laundry in cold water and run the machine only when you have a full load. Do the same thing with your dishwasher.
• Choosing efficient appliances. When it’s time to replace your water heater, consider a more efficient tankless or heat-pump model. That way, every gallon of hot water you use will require less energy to heat. Similarly, consider upgrading to an ENERGY STAR washing machine to save both water and energy.
• Changing your eating habits. About half your overall water consumption comes from the food you eat. Coincidentally, most foods with a large water footprint, such as meat and cheese, have a high carbon footprint as well. By replacing them with plant-based foods, you can reduce both footprints at the same time. Other ways to eat sustainably include reducing food waste and choosing local or organic food when you can.
• Using solar and wind energy. These forms of energy have both low carbon emissions and low water use. Conveniently enough, they’re also the cheapest ways to generate electricity. By installing solar panels or a residential wind turbine at home, you can produce clean power and save money too. Even easier, you can sign up for community solar. This allows you to lower your electricity bill by subscribing to a nearby solar farm. The Perch homepage can show you if there’s an available community solar project near you.

Providing water and energy sustainably

Energy use and water use are inextricably tied together. To build a sustainable clean energy future, we need to focus on both these resources together. We have to reduce energy use in our water systems and water use in energy production at the same time.

Fortunately, there are many ways for societies do this. They can build better power plants, desalination facilities, and wastewater treatment plants. They can increase energy efficiency in homes, businesses, and industries. And by replacing fossil fuels with wind and solar energy, they can cut air pollution, greenhouse gas emissions, and water use all at once.

Individuals have a role to play in this transition, too. We can make our personal lives more sustainable by choosing energy efficiency, plant-based foods, and clean energy. And we can let elected officials know that we support smart policies to protect our water and energy resources. Individually, each of us can only have a small impact—a drop in the bucket, you might say. But all those drops together can add up to a full bucket, with plenty of clean water for future generations.