UC Davis and LADWP Collaborate on Landmark Energy-Water Conservation Study

February 4, 2021

Conserving water goes beyond just saving water; it plays a vital role in conserving energy and reducing greenhouse gas emissions (GHGs). This is one of the main conclusions of a landmark study conducted by UC Davis in collaboration with the Los Angeles Department of Water and Power (LADWP).

The study, published in the journal Environmental Research Letters, shows that customer-focused water conservation programs are just as cost-effective (and in some cases, are more cost-effective) as energy efficiency programs in reducing electricity use, GHGs and other energy-intensive operations.

“In California we use about 20% of statewide electricity and 30% of non-power plant natural gas to move, treat, and heat water,” said author Edward Spang, an assistant professor in the UC Davis Food Science and Technology Department and the Center for Water-Energy Efficiency. “Using LADWP as a case study, we wanted to examine the energy savings secured through water conservation programs relative to energy efficiency programs.”

It Takes Energy to Move Water

Los Angeles receives its water from three main sources: the State Water Project, the Colorado River Aqueduct and LADWP’s Los Angeles Aqueduct. Unlike the LA Aqueduct which is completely gravity-driven and actually produces electricity as the water passes through hydroelectric plants, the State Water Project and the Colorado River Aqueduct are energy consumers. A system of water pumps delivers water to the LA basin from as far away as the Sacramento River in Northern California and Lake Havasu in Arizona.

UC Davis applied three different estimates of energy intensity (EI), which is the amount of energy embedded within water. The first directly assessed the LADWP service territory; the second had an expanded boundary that included LADWP’s imported water infrastructure systems; and the third was a broader estimate for the entire regional hydrologic zone. Researchers also analyzed data on the costs and estimated savings of LADWP’s water conservation and energy efficiency programs.

Unlike the gravity-driven Los Angeles Aqueduct, most water distribution systems in California convey water through energy-intensive pump and regulator stations. (photo LADWP)

Saving Water Saves Energy

UC Davis found that LADWP saved a considerable amount of energy through its water conservation programs. 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).

“Although LADWP has been focused on water conservation and the developing local water resources for quite some time, this study validates our efforts and really highlights the added benefit of reducing energy intensive water operations and related greenhouse gas emissions,” said Nancy Sutley, LADWP Senior Assistant General Manager of External and Regulatory Affairs and Chief Sustainability Officer. “This fruitful collaboration with UC Davis has given us valuable data we can use to effectively allocate resources and programs to better serve our customers.”

Cooperation is Key

LADWP’s Sustainability Office and the Water System administers customer programs offering residential/commercial rebates and incentives for installation of water and energy savings fixtures, devices, and equipment. Residential customers can order free bath and kitchen faucet aerators as well as shower heads by e-mailing WaterConservation@ladwp.com. Water-saving programs include rebates of up to $400 on high-efficiency clothes washers and up to $15,000 on the replacement of traditional lawns with California Friendly® gardens and landscaping. Commercial customers can also take advantage of rebates on industrial water conservation equipment such as cooling tower controllers and dry vacuum pumps.

Another key takeaway from the study is the importance of establishing an appropriate system boundary for evaluating program performance. While each local utility, such as LADWP, will gain a certain amount of energy savings by reducing energy-intensive water operations, these savings become more significant at the state-wide level. This study may serve as a framework for multi-agency, inter-regional water conservation programs.

“This study is highly relevant to both water and energy utilities, as well as government agencies with mandates to sustainably manage water supplies, achieve energy efficiency savings, and reduce GHG emissions,” said author Frank Loge, a professor in the UC Davis Civil and Environmental Engineering Department Department and Director of the Center for Water-Energy Efficiency. “We hope utilities and agencies will recognize this win-win scenario and allocate energy efficiency dollars to water conservation.”

UC Davis researchers conducted the study using data provided by LADWP’s Office of Sustainability, Efficiency Solutions Engineering and the Water System’s Resource Development & Watershed Management.

The study can be viewed at: https://iopscience.iop.org/article/10.1088/1748-9326/abb9de/pdf

Media contacts

Ali Loge, UC Davis Energy and Efficiency Institute, 530-302-5686, asloge@ucdavis.edu

Kat Kerlin, UC Davis News and Media Relations, 530-750-9195, kekerlin@ucdavis.edu

Vision and Research Gaps for a Low-Carbon, Biodiverse Future

By Kat Kerlin on December 18, 2020 in Environment

While the pressures of climate change bring a sense of urgency to renewable energy development, a new study serves as a roadmap toward uniting the goals of a low-carbon future with that of ecological sustainability and conservation.

The study, published in the journal Frontiers in Sustainability from the University of California, Davis, and John Hopkins University, aims to help decision-makers avoid the unintended environmental consequences of renewable energy development.

“Renewables aren’t always sustainable, but they can be if we think proactively,” said co-leading author Sarah Jordaan, an assistant professor at John Hopkins University’s School of Advanced International Studies. “There is a huge misalignment between United Nations Sustainable Development Goals and climate goals. This is a call to action for leaders to come together to address it.”

To develop the roadmap, the authors assessed public and private investments in renewable energy and analyzed the tradeoffs and synergies of clean energy. They also identified research themes drawn from a two-day workshop held by the Electric Power Research Institute in 2019 with 58 leading experts in the fields of renewable energy and sustainability from across academia, industry, government sectors.

Missing the forest for the GHGs

Among the key research priorities identified for sustainable solar and wind developments include site selection and understanding interactions with wildlife.

For example, Florida’s longleaf pine forests have, for centuries, helped store carbon, protect water quality and provide wildlife habitat. Now, only a fraction of the historical range of longleaf pine forests in the state remain. Yet a sliver of that remaining sliver is slated to be replaced by a solar installation.

Meanwhile, in the same state and just a few miles away, waterbirds squawk, preen their feathers, and hunt for food atop a floating array of solar panels – a “floatovoltaic” installation. Here, both wildlife and greenhouse-gas-reduction goals appear to coexist gracefully.

“We can’t pursue climate change mitigation blindly,” said co-leading author Rebecca. R. Hernandez, a UC Davis assistant professor and founding director of the Wild Energy Initiative in the John Muir Institute of the Environment. “We must consider the impacts of renewables on the few ecosystems we have left.”

Other key considerations and priorities the scientists identified were public acceptance of clean energy projects and the study of end-of-life management for wind and solar.  For instance, the composites in wind blades are not recyclable, and solar panels contribute to a growing electronic waste problem.

A heron stands next to a floating array of solar panels, or “floatovoltaics.” Such installations have the potential to serve both wildlife and clean energy needs. (Rebecca R. Hernandez/UC Davis)

Pushing forward

The authors said the work highlights how the field of sustainable renewable energy is in its infancy, with many of the questions and solutions unclear. The roadmap, they emphasize, is a living document, designed to change as the field matures.

“We’re pushing forward into maturation something that is really just being born,” Hernandez said of renewable energy. “Across its sectors, everyone is trying to figure things out as quickly as possible. This roadmap points to the fact that we all need to get organized and work together to share knowledge, innovation and results.”

Jordaan said while the roadmap highlights problems, they are solvable.

“We need to research the things we don’t know, implement solutions we do know, and develop technology as needed and ensure accountability,” she said.

Additional co-authors include Ben Kaldunski and Naresh Kumar of the Electric Power Research Institute.

The research was funded through grants from the Electric Power Research Institute, California Energy Commission, Department of Energy Solar Energy Technologies Office, Agricultural Experiment Station Hatch projects and a cooperative agreement with the Bureau of Land Management and a Catalyst Award from John Hopkins University.

Media contacts

Rebecca R. Hernandez, UC Davis Land, Air and Water Resources, 530-752-5471 , rrhernandez@ucdavis.edu

Sarah Jordaan, John Hopkins University, sarahjordaan@jhu.edu

Kat Kerlin, UC Davis News and Media Relations, 530-752-7704, 530-750-9195, kekerlin@ucdavis.edu

Jason Lucas, John Hopkins University, (202) 663-5620, jlucas27@jhu.edu

Study Comparing Energy Providers Finds Parallels to Local Foods Movement

By Kat Kerlin on October 12, 2020 in Environment

When you go to the grocery store, you can look at an apple and know if it was grown in Chile, Washington or somewhere closer to you by a quick glance at its sticker. But consumers have largely been in the dark when it comes to energy, and how far it has traveled to reach them.

A study published today in the journal Frontiers in Sustainability by the University of California, Davis, sheds light on the lengths alternative energy providers go to bring electrical power to customers.

Consuming electricity closer to its source can reduce greenhouse gases lost in the transport of electrons across the transmission and distribution grid. This can help increase efficiencies and create more self-sustaining, equitable communities. Similar goals are often shared by farm-to-table supporters.

“This study provides a quantitative foundation for a local energy movement, akin to the local food movement,” said co-leading author Rebecca R. Hernandez, an assistant professor in the UC Davis Department of Land, Air and Water Resources and a founding director of the Wild Energy Initiative in the John Muir Institute of the Environment, and Energy and Efficiency Institute.

The study compared three types of energy providers in California — community choice aggregations, or CCAs; cooperatives; and publicly owned utilities — to learn the distance purchased-energy sources travel to support their consumers, and the makeup of their energy resource portfolio, in 2017. Investor-owned utilities were excluded from the study.

Going the distance

Madison Hoffacker, a master’s student in the UC Davis Energy Graduate Group at the time the study was conducted, designed and hand-curated the study’s large, spatial dataset. She found that CCAs purchased more than 2.5 times as much renewable energy as other providers. Renewables comprised nearly half of their energy portfolios. However, CCAs also went 2.5 times farther to source that energy.

Hoffacker notes that CCAs are young, with beginnings around 2010, and it takes time to build energy portfolios. She hopes the research will help shape future goals of energy providers and raise awareness among customers and utilities alike of the need to look for both renewable and local sources.

“My study was trying to find a way to ensure accountability for different decision makers who have an influence over not only what type of energy is procured but also where we’re sourcing that energy from,” Hoffaker said.

Outsited and outsourced

The study found that only about 20 percent of purchased energy among providers was local. The remaining 80 percent is what Hoffacker terms “outsited” — energy generated from outside the provider’s jurisdictional footprint. In fact, 42 percent was drawn from out of state.

A figure from the study shows the distance California energy providers go to source various energy resources. On average, purchased energy came from 270 miles away. (Madison Hoffacker/UC Davis)

On average, purchased resources in California came from 270 miles away — as far north as Canada and as far east as Oklahoma. Further, 100 percent of coal and nuclear energy purchased by these providers was sourced from out of state.

“As we race toward a rapid energy transition to renewables, it can be deceptively attractive to impose large-scale energy infrastructure upon poorer, often rural communities that are far away,” Hernandez said. “Such communities are often disenfranchised from such development decisions or lack the socio-economic resources to voice how that infrastructure may impact their viewsheds, natural resources, and livelihoods — and we have seen this happen here in the U.S.

“By siting energy infrastructure as near as possible to those who directly benefit from it, risks and liabilities associated with environmental justice are often reduced.”

The food connection

While conducting the study, Hoffacker noticed several parallels between consumers’ increased interest in local, decentralized energy and the local food movement. One movement fuels interest in sourcing food from our own backyard, farmers markets, cooperatives and community supported agriculture subscriptions. The other features people installing rooftop solar panels and battery systems, and supporting providers like cooperatives and CCAs.

“People want to provide their own energy or have choices over where their energy resources are coming from, be they renewable or local,” Hoffacker said. “There’s a lot we know about the food sector regarding standards for producing organic food or distance metrics for local foods. There’s a similar movement underway that we can apply to the energy sector, as well.”

The study was funded by UC Davis’ John Muir Institute of the Environment; Department of Land, Air and Water Resources; Agricultural Experiment Station; and by the California Energy Commission.

Media contact(s)

Madison Hoffacker, UC Davis Energy Graduate Group, hoffacker@ucdavis.edu

Rebecca R. Hernandez, Land, Air and Water Resources, 530-752-5471 , rrhernandez@ucdavis.edu

Kat Kerlin, News and Media Relations, 530-752-7704, 530-750-9195, kekerlin@ucdavis.edu

Native Desert Plants Important to Indigenous Cultures Especially Vulnerable

By Kat Kerlin on July 20, 2020, in Environment

With their tough skins, pointy armor and legendary stamina, cacti are made to defend themselves from whatever nature throws at them.

But large solar energy facilities are one threat that cacti weren’t built to withstand, according to a study by the University of California, Davis.

The study, published today in the journal Nature Sustainability, chronicles the impacts of ground-mounted solar energy development in the Mojave Desert on native plants and their cultural significance to indigenous tribes in the region.

“We’re talking about iconic and threatened plants — cacti, especially, and Mojave yucca,” said co-leading author Steve Grodsky, an assistant research ecologist at UC Davis. “These are the plants most people envision when they think about the desert, and they’re also the most negatively affected by solar energy development.”

Location, location, location

Solar energy is a key strategy for reducing greenhouse gas emissions and the threats of climate change. But like any development, where it’s sited affects its overall environmental sustainability.

Ivanpah Solar Electric Generating System in the Mojave Desert. (Joe Proudman/UC Davis)

UC Davis Assistant Professor Rebecca R. Hernandez and Grodsky are exploring where renewable energy can best coexist with wildlife, biodiversity and the environment to achieve overall sustainability. Their work is part of their Wild Energy Initiative, a research initiative of the UC Davis John Muir Institute of the Environment, and of the Energy and Efficiency Institute.

“This is really our moment to double down,” said co-leading author Hernandez. “We need to not only build out renewable energy, we also need to develop it in the places that produce positive impacts. This isn’t just about saving the cacti. It’s about our need to achieve both climate change goals and sustainable development goals, which include protecting terrestrial ecosystems, at the same time.”

Native plants and native peoples

For the study, the scientists measured the impact of solar development decisions on desert plants at Ivanpah Solar Electric Generating System, one of the world’s largest concentrating solar power plants. They found negative impacts on the desert scrub plant community, including plants of cultural significance to 18 indigenous tribes.

Among them are the Mojave yucca, a Joshua tree relative. Its leaves and fiber historically were used for making shoes, baskets, and building structures. Its roots can be used for soap, hence its common name “soap yucca.” Other plants have provided medicine, tools and food, such as the fruits and pads of the beavertail prickly pear cactus.

Management options and impacts

There are a variety of ways to prepare land for solar installations, and some of these methods are more harmful to the desert plant community than others:

• Bulldozing, or “blading,” scrapes layers of earth away from the site. It’s the most damaging to cacti, Mojave yucca and other native plants. It also primes the site for invasive grasses like Schismus, which present a fire risk to deserts maladapted to wildfire.
• Mowing also destroys cacti and Mojave yucca, but creosote and perennial shrubs can recover from it.
• “Halos” are roped-off areas known to hold sensitive species that create islands of undeveloped areas within the facility. They can be effective for conserving native plants, including cacti and Mojave yucca.

“From a management perspective, there are things we can do to help conserve native desert plants at solar facilities,” Grodsky said. “But it’s best to develop solar energy in marginalized lands like urban areas, places where ecosystems are heavily altered, rather than undeveloped desert.”

Previous research by Hernandez, Grodsky and colleagues examined dozens of alternatives to installing solar on undisturbed lands. These include siting solar on contaminated sites (like Superfund sites), landfills and salt-affected lands. Other options include “agrivoltaics,” which co-locate agriculture and solar energy, and — perhaps most promising — on the rooftops of large commercial buildings, such as warehouses.

This study received funding from the California Energy Commission and the Bureau of Land Management’s California Office.

Media contact(s)

Steve Grodsky, John Muir Institute of the Environment, smgrodsky@ucdavis.edu

Rebecca Hernandez, Land, Air and Water Resources, 530-752-5471 , rrhernandez@ucdavis.edu

Kat Kerlin, News and Media Relations, 530-752-7704, 530-750-9195, kekerlin@ucdavis.edu

Media Resources

• Press kit of images.
• Video: How is solar impacting the environment it’s in?

UC Davis and Carnegie Mellon University received a $2.4 million grant from the U.S. Department of Energy’s Advanced Research Projects Agency–Energy (ARPA-E) to develop novel heat exchangers for high temperature and high pressure applications. Such heat exchangers can advance development of high efficiency modular power systems.

Heat exchangers transfer heat from one fluid to another without the fluids coming into contact with one another. They are widely used in power generation, space heating, refrigeration, air conditioning, and transportation. Professor Vinod Narayanan is leading UC Davis’ work as co-PI. Narayanan is a faculty member in the Department of Mechanical and Aerospace Engineering and Associate Director of the UC Davis Western Cooling Efficiency Center.

UC Davis researchers (from left to right -Aref Aboud, Adam Strong, Kha Ton, Ines-Noelly Tano, Vinod Narayanan, Erfan Rasouli, Caton Mande, and Zachary Delozier) at the Solar Thermal and Energy Enhancement Laboratory. Photo: Gregory Urquiaga/UC Davis.

Over the next three years, Narayanan will work with professor Anthony Rollett’s lab at Carnegie Mellon University to develop an ultra-high temperature recuperator for the supercritical carbondioxide thermodynamic power cycle. The project includes material science and engineering, additive manufacturing, thermal and fluidic design, and cost analysis.

The research team also includes National Energy Technology Laboratory, HEXCES, General Electric, Extrude Hone, and the Colorado School of Mines.

Many California Classrooms Don’t Have Sufficient Ventilation

Roughly 85% of recently installed HVAC systems in K-12 classrooms investigated in California did not provide adequate ventilation, according to a study from the University of California, Davis, and Lawrence Berkeley National Laboratory (Berkeley Lab).

For the study, published in the journal Building and Environment, researchers visited 104 classrooms in 11 schools throughout California that had been retrofitted with new heating, ventilation and air conditioning (HVAC) units in the past three years. They evaluated the HVAC systems, carbon dioxide (CO₂) concentrations, and indoor temperature and humidity through field inspections, monitoring, and a teacher survey.

“Previous research has shown that under-ventilation of classrooms is common and negatively impacts student health and learning,” explained lead author Rengie Chan, a research scientist with Berkeley Lab. “What isn’t known, however, is why this problem is so widespread and persistent.”

Indoor environmental quality matters

Ventilation helps remove indoor air pollutants such as volatile organic compounds, including formaldehyde, which can off-gas from building materials, finishes, and furniture. There is also increasing evidence that CO₂ exhaled by building occupants is an indoor pollutant that can affect cognitive performance. This is particularly important in classrooms, where lots of people gather in a small space.

Standards for ventilation rates balance indoor air quality and energy efficiency­­. ASHRAE, a global professional society that sets standards for building performance, specifies a minimum ventilation rate for classrooms of 15 cubic feet per minute per person. In California, the 2016 Building Energy Efficiency Standards, also known as Title 24, have the same ventilation requirement for classrooms.

HVAC problems are widespread

Using measured CO₂ concentrations and the number of people in the classroom, researchers found only about 15% of classrooms met the ventilation standard. Researchers characterized each HVAC system by documenting the number of problems due to its hardware, controls and filter maintenance. Classrooms with one or more HVAC problems tended to have lower ventilation rates and higher CO₂ levels.

Robert McMurry, an engineer with the UC Davis Western Cooling Efficiency Center, inspects an HVAC system at a California school. (UC Davis)

In addition to ventilation, thermal comfort impacts student performance. In this study, about 60% of the classrooms were warmer than the recommended average maximum temperature of 73°F. Also, 30% of the teachers surveyed were dissatisfied or very dissatisfied with the temperature in their classroom, and about 10% said the temperature interfered “a lot with the learning environment.”

A call to action

“Our study shows that proper installation, operation, and maintenance of HVAC systems is necessary to provide adequate ventilation in classrooms,” said co-author Theresa Pistochini, engineering manager at the UC Davis Western Cooling Efficiency Center.

The Division of the State Architect provides oversight of construction projects, but many HVAC replacement projects are exempt from their review. Yet these projects must still meet Title 24 requirements. This puts the onus of ensuring compliance on school districts.

“There are nearly 1,000 school districts in California,” Pistochini said. “With limited resources, it is unrealistic to expect that school district personnel be adequately trained to ensure compliance. Increased oversight of HVAC replacements, or other ways to address widespread inadequate ventilation in California classrooms, are needed, likely through state intervention.”

Researchers recommend the following actions to improve ventilation rates in classrooms:

• Complete commissioning and acceptance testing of new HVAC systems as required by Title 24.
• Run HVAC fans when classrooms are occupied to bring in fresh air.
• Replace filters 2-3 times per school year.
• Monitor classroom CO₂ concentrations. Thermostats with CO₂ sensors and stand-alone sensors are widely available.
• Test ventilation rates in existing HVAC systems and make corrections when needed.

Millions of California children spend a large portion of their day indoors at school. Ensuring adequate classroom ventilation will help protect and support the health and well-being of students and teachers.

Authors and funding

Additional study authors include Xiwang Li and Brett Singer of Berkeley Lab, and David Vernon, Sarah Outcault, Angela Sanguinetti, and Mark Modera of UC Davis.

The study was supported by the Electric Program Investment Charge, managed by the California Energy Commission.

Media contact(s)

Theresa Pistochini, UC Davis Western Cooling Efficiency Center, 530-752-3262, tepistochini@ucdavis.edu

Kat Kerlin, UC Davis News and Media Relations, 530-752-7704, kekerlin@ucdavis.edu