Water and energy in California are linked in what is commonly called the water-energy nexus. A recent report by Pacific Institute and Next 10 looks at the importance of the water-energy nexus in the golden state.
Urban and Agricultural Water and Energy Use
Water suppliers to urban areas are increasingly using local water supply options, and many of the options are more energy-intensive than traditional water sources, the report found. However, they are less energy-intensive than imported water. The report’s other findings regarding urban water and energy use include:
- If urban per-capita water demand stays at current levels, urban water demand will increase 24 percent by 2035 with population growth.
- Increased water demand would lead to a 21 percent increase in annual water-related electricity use and a 25 percent increase in annual natural gas use for water heating.
- Greenhouse gas emissions will increase by two percent if water and energy use increases.
- Water-related energy use could decrease by 19 percent, natural gas use by 16 percent, and greenhouse gas emissions by 41 percent with more comprehensive water conservation and efficiency in urban areas.
Agriculture is dependent on groundwater pumping, and as groundwater levels have decreased in the state, pumping has become increasingly more energy-intensive. Climate change may accelerate the current trends. The report also finds the following for agricultural water and energy use:
- Under what the report terms the mid-case scenario, the Central Valley agricultural water use will decline by two percent by 2035 due to urban population growth encroaching on agricultural lands.
- The energy use under the mid-case scenario decreases four percent and greenhouse gas emissions decrease about 60 percent.
- If groundwater pumping stays at current levels and groundwater levels drop to the proposed minimum thresholds, the agricultural water system energy intensity for the Central Valley’s San Joaquin and Tulare counties would increase by 20 percent and six percent, respectively.
- Allowing groundwater levels to rise and pumping efficiency improvements can reduce the increase.
Urban vs. agriculture water and energy use
Improving urban water efficiency has the biggest beneficial effect on water-related energy use and greenhouse gas emissions in the state. The reason is that urban water is far more energy-intensive than agricultural water. The Central Valley’s agricultural water use under the mid-case scenario will be nearly three times that of urban water use by 2035. However, agriculture’s water-related energy use is only about half of the urban sector’s. Irrigation is less energy-intensive than water treatment and heating for urban uses. Greenhouse gas emissions for the urban water sector in the mid-case scenario will be nine times that of the Central Valley’s agricultural water sector.
Water-Energy Nexus and Greenhouse Gas Emissions
Water and energy trends affect the state’s greenhouse gas emissions. The state has a goal to transition to 100 percent clean energy by 2045 and water will play a key role in meeting that goal. To meet that goal, the state is both reducing its greenhouse gas emissions intensity and decarbonizing its energy. One example of how the state is working to decarbonize its energy is water heating, which is typically done with natural gas water heaters. The state offers programs to incentivize switching to electric water heating.
Water Conservation is Key
The report lists policy recommendations, including expanding urban water conservation and efficiency efforts. Given that all of California is under severe drought conditions, with some areas in extreme drought, water conservation efforts are key. The Natural Resources Defense Council found that California could reduce urban water use by 2.9 million to 5.2 million acre-feet a year. The measures needed to reduce urban water use require residents to adopt proven water-efficient technologies and practices such as repairing leaks, installing efficient fixtures and appliances, and replacing water-intensive landscapes with plants needing less water. Water utilities can identify and stop leaks and losses in underground pipes and other parts of their systems.