California’s Water and Energy Systems Are Inextricably Linked

The effects of climate change on California’s environment are evident, especially when it comes to our water cycle. The state’s natural climatic volatility is increasingly characterized by hotter and drier droughts and less frequent but more intense rainy seasons. Not only are these shifts straining California’s water supply, they are also affecting energy supplies in important ways. For example, less water in reservoirs increases vulnerability to drought and also hinders hydroelectric power production.

There is also a connection between water and energy on the demand side: the water system uses more energy than many people realize for pumping, pumping and (especially) heating. This offers opportunities to conserve energy by conserving water—while helping to decarbonize the economy. Our new fact sheet examines the points at which California’s water and energy systems intersect and suggests ways to reduce risk and promote smart conservation.

California’s water system is a large energy consumer

The water system is a major energy consumer in California: According to the latest available data (dating back to 2001), one-fifth of the state’s electricity and nearly one-third of the state’s natural gas is used for pumping, production, treatment, heating, etc. and other energy-intensive water uses for homes and Company. Managing energy use in the water system will be important as California works to become carbon neutral by 2045.

Just reducing water use—already a key drought resilience strategy—can help conserve energy. For example, during the last drought, saving water resulted in significant energy savings.

Water heating is a very energy-intensive element of water infrastructure, accounting for a quarter of all household energy consumption. Water heating, along with other energy-intensive water uses in homes and businesses, accounts for almost 90% of water-related energy use – while treatment, pumping and transport make up the rest. Reducing hot water consumption and improving water heating efficiency could significantly reduce California’s overall energy use, and switching from gas to electric water heaters could help meet decarbonization goals.

Our energy sector is also heavily dependent on water

Water is a key component in power generation – it spins hydroelectric turbines, cools thermoelectric plants and aids in oil and gas production. And this water dependency makes California’s energy sector increasingly vulnerable: Thermoelectric plants that rely on surface water for cooling, for example, can face shortages during droughts.

The most vulnerable energy technology is hydropower, which accounts for an average of 15% of California’s power portfolio. Hydroelectric generation varies from 7% of California’s electricity in dry years to over 20% in wet years. As climate change exacerbates wet and dry seasons, hydroelectric power generation could become even more volatile, threatening the reliability of California’s energy supply.

Fortunately, there are ways to make the power system more drought resilient. Some thermoelectric plants already use seawater for cooling – a drought-proof supply. Many plants have also increased water efficiency (by moving to closed loop cooling) and switched to recycled water. And perhaps the biggest boon to drought resilience is the growth of solar and wind power, which use little to no water to generate.

Some priorities for better management of the water-energy nexus

Population growth and climate change are likely to increase pressure on California’s water and energy supplies. Better integration of decisions in these sectors can bring benefits. Here are some key efforts:

  • Update of 2001 water-related energy use estimates. Much has changed in both sectors since the country’s last detailed estimates. Updates on both energy demand and CO2 intensity of water use could give us a more accurate picture of the current situation and help take targeted action to better manage both.
  • Increase collaboration. Policy makers and managers should work together to anticipate the impact of new water and energy technologies such as desalination, recycled water and closed-loop cooling.
  • Incentives for conservation and electrification. Reducing household water use can save energy and money, and electrification of water heating systems can help decarbonize water use. The state and local utilities may offer rebates to expedite such efforts.

Water and energy are linked and these measures could benefit both sectors. As California works to improve its energy reliability and drought resilience while decarbonizing its economy, it becomes increasingly important to consider such connections and seek solutions whose benefits can be felt across multiple sectors.

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