Climate-driven impacts on water in US West will raise the cost of grid decarbonization: Study

The western U.S.'s plans to decarbonize electricity grids by 2050 may be much more expensive than anticipated, as such targets fail to account for the effects of climate change on water resources, a new study has found.

Shifts in water availability due to warming could decrease hydropower production by up to 23 percent by midcentury, while electricity demand could rise by 2 percent annually, according to the study, published Monday in Nature Communications.

To bridge this gap, the western states would need to add up to 13 gigawatts of transmission capacity and up to 139 gigawatts of generating capacity between 2030 and 2050 — equivalent to almost three times California's peak demand and costing about $150 billion, per the research.

"Grid planning that ignores climate projections and water linkages underestimates the capacity and investment needed to achieve decarbonization and maintain grid reliability," the authors stated.

Today, hydropower comprises about 20 percent of annual average power production in the U.S. West, and electricity use for water makes up about 7 percent of electricity consumption, according to the study.

In the future, not only may climate change and associated groundwater pumping decrease water availability, but adaptation measures such as desalination and water recycling can also be energy-intensive, the authors explained.

"Failing to account for these changes in energy supply and demand via the water sector may overlook cascading vulnerabilities," the researchers stated.

Ignoring these threats could "jeopardize electricity system climate resilience, and make decarbonization goals elusive," warned the authors, who partnered across multiple federal research laboratories, the University of California and the University of Toronto.

To draw these conclusions, the scientists created simulations that connected the U.S. West's water supplies and electricity systems. They then assessed how the region could adapt to various climate change scenarios from 2030 to 2050, amid a shift to carbon-free electricity sources.

No matter which climate change scenario they evaluated, the researchers found that hydropower production plunged. A mix of renewable energy resources, such as wind and solar, complemented by flexible battery storage and geothermal power, would be necessary to compensate for these losses, according to the study.

At the same time, the authors observed that increased needs for air conditioning would drive up power demands, particularly in the Southwest. However, they noted that decreased electricity use for heating in the Pacific Northwest would offset this surge at least in part.

Moving forward, the researchers stressed the importance of integrating robust adaptation strategies into the power sector, with an emphasis on diversifying capacity investments and allowing for more flexibility in policy planning.

A failure on the part of grid planners to explicitly quantify how climate change and water interdependencies could impact electricity supply and demand could be detrimental to the region, the authors noted.

Incorporating these factors into grid expansion models, they concluded, could play a critical role in ensuring "a climate-resilient and zero-emissions grid of the future."