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Friday, September 24, 2021

Water conservation programs show potential to save water, energy and greenhouse gas emissions

Minimizing intensive energy operations in water systems can reduce water usage and costs comparable to current energy efficiency programs

In an innovative time where power and energy have evolved tremendously in the past few decades, efficiency and conservation have become new focal points, constantly being optimized in balance with costs. A study conducted by UC Davis’ Center for Water-Energy Efficiency illuminates the possibility of saving not only water but also energy and greenhouse gas emissions through water conservation programs.

Edward Spang—an assistant professor at UC Davis’ food science and technology department who played a pivotal role in starting the Center for Water-Energy Efficiency—explains the findings of a previous statewide study following the urban water conservation mandate back in 2015. Due to the mandate, all urban water utilities were required to reduce water usage by 25%. 

“We found that the cost [of water conservation programs] was competitive with direct energy efficiency programs,” Spang said. “That is to say that you can actually save water and energy at the same cost as saving just energy alone.”

In his most recent study, Spang conducted a case study on the Los Angeles Department of Water and Power (LADWP), a major water utility that has implemented water conservation programs, and by working with an individual public utility company, he reaffirmed the broad findings from his previous statewide study. 

“The study found that LADWP saved a considerable amount of energy through its water conservation programs,” according to a UC Davis press release. “Across the various scenarios, the estimated energy savings secured through water conservation programs (e.g., high-efficiency washing machines, toilets/urinals and irrigation systems) was cost-competitive with LADWP’s energy efficiency programs (e.g., more efficient lighting, HVAC and refrigeration systems).”

Though the findings offer a remarkably optimistic duality in saving energy and water, they highlight the complexity in measuring costs and energy savings purely due to water conservation programs—as Spang describes from a systems perspective—which, in turn, could be why many utilities have yet to adapt these programs.

“We’ve been working for a while to try to come up with methodologies to measure the amount of embedded energy in water systems,” Spang said. “This meant looking at a particular volume of water delivered to a customer, how much energy did it take to extract that water from groundwater, convey that water to a treatment plant, treat the water and then distribute it to the customer. You can actually trace the pathway of these water sources and come up with an energy footprint to deliver a particular quality of water to a particular location.”

Katrina Jessoe, an associate professor in the agricultural and resource economics department, offers an economist’s point of view as to why it can be difficult to adopt water conservation programs. 

“What the engineers find can differ from what the economists say,” Jessoe said. “The engineers tell us there are these huge savings from these programs, but the economist comes and looks at it, and finds that maybe that is not the case because behavior matters. Some water conservation instruments may yield energy savings, while some may not.”

Despite the many barriers and limitations that establishing water conservation programs may bring, the LADWP is a model that future conservationists and economists can follow to better understand and optimize energy and resource conservation in the future. 

According to Spang’s broad vision of what the future may hold for energy efficiency, California has done such a remarkable job with its programs that transitioning to another level of optimization of energy, and costs will be the next challenge.

“California, we have done such a good job that there’s not much low-hanging fruit as there used to be for these programs,” Spang said. “For example, changing out lightbulbs: We’ve done a really good job with that. And there are still lightbulbs we still need to change out, but at a certain point, we need to move onto the next phase of energy efficiency, which is a little bit more difficult. You can think of another analogy where you go from a lightbulb to the whole house, where you’re looking at window glazing and insulation.”

Indeed, water conservation may have opened a new door to this “whole house.” Jessoe highlights a holistic approach on water conservation, looking at agricultural users rather than just residential users, which may even further expand Spang’s findings.

“One thing we focus a lot on is residential water conservation. In California, urban users account for 20% of human water use while agricultural users account for 80%. The marginal cost of trying to wring out that last drop of water out of residential users is really high. So you might be able to, for the same cost, get a whole lot more conservation out of agricultural users.”

Written by: Brandon Nguyenscience@theaggie.org

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