Nov 7 2019
Solar and wind farms are being set up across the United States to reduce carbon emissions. These renewables also have another vital effect—preserving more water in the ground.
Image Credit: Egan Jimenez, Woodrow Wilson School of Public and International Affairs.
A recent study led by Princeton University is among the first to demonstrate that wind and solar energy not only improve drought resilience, but also help in maintaining groundwater sustainability. Details of the study have been published in Nature Communications.
For the case study, the researchers used drought-prone California. They showed that increased wind and solar energy could decrease the dependence on hydropower, particularly during drought. As a result, this could help reroute more surface water from hydropower to irrigation, decreasing groundwater abstraction on the whole.
Although the focus of this research was the United States, it is possible to apply the framework globally, particularly for policymakers focused on meeting the U.N.’s Sustainable Development Goals, according to lead author Xiaogang He, who carried out the research as a PhD student at Princeton. At present, he is a Water in the West postdoctoral fellow at Stanford University.
Traditionally, the social value of solar and wind energy has mostly been focused on air pollution mitigation and carbon emission reductions. However, if we look at the problem from a different angle—like the water-food-energy nexus—then our paper identifies some unrecognized and under-appreciated effects that have been overlooked in past studies.
Xiaogang He, Study Lead Author and Assistant Professor, Department of Civil and Environmental Engineering, National University of Singapore
The researchers created a trade-off frontier framework to evaluate how wind and solar energy could be beneficial to groundwater sustainability. Trade-off frameworks are especially beneficial for policymaking as they examine many outcomes—such as how much wind and solar energy should be used to expand economic revenue, or how wind and solar power could guarantee groundwater recovery.
The scientists used the framework to compute the ideal pathways to maximizing the income from agriculture and hydroelectricity, while preventing groundwater depletion.
He and his colleagues used California as a case study since it is the largest agricultural producer in the United States. California also went through one of the most severe droughts on record from 2012 to 2017, which acted as a catalyst to control unchecked groundwater use. Together, solar and wind electricity started to surpass hydropower in the state because of state mandates and lower prices.
While the state’s agricultural industry still succeeded in earning $47 billion during that time by depending largely on unsustainable groundwater reserves, this approach is unsustainable going forward. With more droughts forecast in California—together with greater demand for water because of socioeconomic development—this will place an excess burden on groundwater storage, added He.
Wind and solar energy are helping though, and will continue their contribution, according to the team’s framework. The study outcomes show it is advantageous to concurrently deploy wind and solar energy and enforce regulations on groundwater use sooner rather than later. When these two policies work in unison, the overall advantage will be greater.
Our results also suggest that policymakers need to take the long-term outlook of groundwater depletion into consideration when planning further deployment of solar and wind energy. If groundwater aquifers keep getting depleted in the future, then the added value of penetrating solar and wind energy will largely decrease.
Xiaogang He, Study Lead Author and Assistant Professor, Department of Civil and Environmental Engineering, National University of Singapore
Still, the scientists call for exercising caution when generalizing these findings to smaller scale policy recommendations. They stress the need for integrated modeling across fields, which can help to tackle the intertwined problems associated with food, water, and energy.
He was involved in the study as a PEI-STEP Graduate Fellow at Princeton under the advisement of Michael Oppenheimer, the Albert G. Milbank Professor of Geosciences and International Affairs and the Princeton Environmental Institute (PEI) at Princeton and director of the Woodrow Wilson School of Public and International Affairs’ Center for Policy Research on Energy and the Environment.
Amy Craft, a lecturer of economics and international affairs at the Wilson School, offered guidance on the economic analysis presented in the paper.
He received his PhD in Civil and Environmental Engineering, and his advisors were Justin Sheffield, professor of hydrology and remote sensing at the University of Southampton in the United Kingdom, and Eric Wood, professor of civil and environmental engineering, emeritus, and senior scholar in the Department of Civil and Environmental Engineering at Princeton; both are co-authors of the paper.
The paper titled “Solar and wind energy enhances drought resilience and groundwater sustainability” has been published in the November 6th issue of Nature Communications. Apart from He, Craft, Sheffield, and Wood, the other co-authors include Kairui Feng, Xiaoyuan Li, Yoshihide Wada, and Peter Burek.
A portion of the study was developed in the Young Scientists Summer Program at the International Institute for Applied Systems Analysis in Laxenburg, Austria, with financial backing from the USA National Member Organization.
This study was also based on a research funded by a grant from the National Oceanic and Atmospheric Administration, and the STEP-PEI Fellowship at Princeton. Sheffield is supported by two U.K. Research and Innovation Global Challenges Research Fund projects (grant no. NE/P021093/1 and grant no. ES/P011373/1).