Impacts of climate change on our water and energy systems: it's complicated

So, in adapting to the consequences of climate change, how can we be sure that we aren't making problems worse?

Now, researchers at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), UC Berkeley, and UC Santa Barbara have developed a science-based analytic framework to evaluate such complex connections between water and energy, and options for adaptations in response to an evolving climate. Their study, "Evaluating cross-sectoral impacts of climate change and adaptations on the energy-water nexus: A framework and California case study," was published recently in the open-access journal Environmental Research Letters.

"There have been many analyses on how climate change could affect the water and energy sectors separately, but those studies were not typically looking at interactions and feedbacks between the two," said lead author Julia Szinai of Berkeley Lab's Climate and Ecosystem Sciences Division. "Our paper develops a generalized framework that identifies how climate change affects these coupled water and electricity systems, and potential adaptations to future gaps in supply and demand. By doing so, we illustrate often-overlooked tradeoffs and synergies in adapting to climate change."

"In developing this project, Julia led a remarkable effort to integrate the climate impacts and feedbacks between the energy and water sectors," said co-author Daniel Kammen, a professor of energy and resources at UC Berkeley. "What is critical to planning our future under climate change is to capture -- in both simplified and full dynamical models ¬- how interdependent are our infrastructure choices."

In applying the framework they developed to California, which relies on the snowpack for a good deal of its water and expends significant amounts of energy to transport water from the northern to the southern part of the state, they found that there are two possible adaptation pathways: one that is energy intensive and one that can actually save both water and energy.

"One of the most important points of the paper is that adapting our water system to climate change can either significantly exacerbate electricity grid stress, or on the flip side, it could help to alleviate it," said co-author and Berkeley Lab climate scientist Andrew Jones. "If we focus on adapting the water system by using big transfers of water across basins, or by using energy-intensive desalination, that's just going to make the electricity problem much more difficult. If, on the other hand, we adapt the water system by conserving water, it's actually a win-win situation because you're also reducing the energy required for water."

Currently, a staggering 19% of California's electricity consumption goes toward water-related applications, such as treating it, transporting it, pumping it, and heating it. Additionally, about 15% of in-state electricity generation comes from hydropower. Such interdependencies are referred to as the water-energy nexus. The state has already seen some impacts that climate change could have on these highly interdependent water-energy systems; for example, extended droughts and reduced snowpack have resulted in spikes in electricity consumption from groundwater pumping and hydropower deficits, which were made up by generating electricity using dirtier fossil fuels.

Looking ahead, the researchers integrated data across a number of fragmented studies to estimate the overall range of possible water and energy futures under various climate scenarios for the state at the end of the century. Their analysis found that the greatest direct climate change impact on the electricity sector in California will likely come from two factors: higher air conditioning loads and decreased hydropower availability. In the water sector, the greatest and most uncertain impact of climate change is on future water supplies. In the worst case, available water supplies could decrease 25%, and in the best case could increase 46%.

Applying their framework to California's water-energy future, they found that, if the state were to adapt to the worst-case water scenario by choosing the most energy-intensive technologies, it could result in an energy imbalance as large as that caused by climate change itself (increased air conditioning use and decreased hydropower availability being the climate change factors having the greatest direct energy imbalance impact).

"I think this is the first study to show that water sector adaptation can have as large of an impact on the electricity sector as the direct effect of climate change itself," said Jones. "So, if we pursued the energy-intensive path to water sector adaptation then it is as large as the direct effect of climate change, in the worst case."

Co-author Ranjit Deshmukh, a professor of environmental studies at UC Santa Barbara and faculty scientist at Berkeley Lab, noted, "Going forward, the electricity sector could leverage its close coupling with the water sector to enable balancing of increasing wind and solar generation in California as the state strives to meet its low-carbon-emission goals. For example, energy-intensive equipment such as water pumps or desalination plants, with adequate water storage, could be operated during times of plentiful solar and wind energy, and turned off at other times."

Next, Szinai, a UC Berkeley graduate student, said she plans to develop detailed models of both water and electricity systems so researchers can run simulations under various climate change and climate change adaptation scenarios, ultimately aiding planners in building out both the electrical grid and water resources.

"This study has highlighted the benefit of coordinated adaptation planning between the two sectors, so we're now linking a more detailed water resources management model and an electricity planning model that can demonstrate resilient pathways for building out electricity infrastructure in the Western U.S. when climate change impacts are included from the water sector," she said.