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Solar and wind energy: a secret weapon for keeping water in the ground

The Hill | November 13, 2019

Researchers discovered that increased use of solar and wind keeps more water in the ground — a benefit that can aid future droughts.

Renewable energy sources like wind and solar are crucial for reducing reliance on fossil fuels, and thus the greenhouse-gas emissions that contribute to climate change. But researchers have now found an added benefit of wind and solar: improving groundwater sustainability.

“Our study has found that there are unrecognized and underappreciated benefits of solar and wind energy,” says lead author Xiaogang He, a Water in the West postdoctoral fellow at Stanford University. “We found the synergies between maintaining groundwater sustainability and the benefits of solar and wind energy.”

New research published in Nature Communications uses California as a case study and reveals that increased use of solar and wind energy decreased reliance on hydropower. As a result, surface water that would have been used for hydropower can be used for irrigation. So overall, solar and wind energy keeps more water in the ground.

“What motivated me to do the study was to try to identify the water sustainability value of solar and wind energy,” says He. 

The researchers decided to use California as a case study because of its role as the largest agricultural producer in the U.S. They also note that California dealt with a severe drought between 2012 and 2017. Around the same timeframe, lower prices and state mandates allowed solar and wind electricity to surpass hydropower in California.

He explains that the state’s agricultural sector has been largely relying on groundwater stores that are unsustainable. The projections of future droughts plus intensified demand for water due to development means that burdens on groundwater storage will likely continue. But according to this research, solar and wind power have helped and will keep aiding groundwater sustainability. As their results show, it’s especially helpful to use two policies — increasing solar and wind energy as well as regulations on groundwater — simultaneously to ensure the sustainability of groundwater.

“Traditionally, the social value of solar and wind energy has mostly been focused on air pollution mitigation and carbon emission reductions,” He says. “However, if we look at the problem from a different angle — like the water-food-energy nexus — then our paper identifies … effects that have been overlooked in past studies.”

Ryan McManamay, an environmental sciences professor at Baylor University who was not involved with the study, points out that there are technological and economic challenges to expanding usage of solar and wind power. Unlike hydropower, solar and wind are intermittent renewables. As McManamay explains, “They’re great when the sun is shining and the wind is blowing.” The technology to store electricity generated from solar and wind over long-term periods is still developing, so it’s not a sure thing — at least not yet — that solar and wind power can be used without sources like hydropower also on the grid. Unlike sunlight and wind, water is easier to store as of now.

McManamay says he appreciated that the study considered multiple sectors and its interdisciplinary nature. He adds, “There’s a lot that they’ve taken into account and it’s a valuable paper for communicating this issue with policymakers.”

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