Sustainable LA Grand Challenge

Los Angeles County contains 215 community water systems that are disconnected and fragmented. These water systems vary greatly in their local water resources including access to groundwater storage, stormwater capture, water re-use, infrastructure and potential for conservation. For instance, some systems contain more water resources than they need to meet their local demand. Other systems have limited resources and depend on a single source of imported water or groundwater aquifer. As a result, households face unequal access to affordable drinking water that is mainly determined by their geographical location. A feasible strategy to integrate these fragmented water systems is needed to address the inequities in pricing and ensure Los Angeles County can achieve 100% local water. 

Solar energy is the world's most abundant clean source of energy. The research objective of this project is to develop a tandem device capable of providing both energy generation and storage by combining the functions of a photovoltaic and rechargeable battery. Although both systems individually have been studied in-depth and developed, a tandem device that both generates and stores electricity had yet to be explored. The Sustainable LA Grand Challenge provided a unique opportunity to create an interdisciplinary research and design team to exploit this resource and significantly enhance energy self-sufficiency in Los Angeles and beyond. 

Direct Potable Reuse (DPR) is a water recycling technique that uses treated wastewater as a source of drinking water. The State Water Resources Control Board (SWRCB) of California is currently tasked with developing regulations for DPR by the end of 2023. In this project, UCLA researchers focus on ways to clear the legal path toward the adoption of DPR in Los Angeles County and California. The ultimate goal of this project is to facilitate the adoption of DPR in a manner that is timely, secure and protective of public health. 

Nearly 60% of Los Angeles County’s water demand is fulfilled by imported water from hundreds of miles away. Securing a sustainable local water supply via recycled wastewater can help save the enormous amounts of energy required to transport water and make the region more resilient to climatic change. Over the years, the use of bioreactors (a type of membrane filtration) combined with wastewater treatment has significantly contributed to ensuring local water supplies.   However, it has also raised concern for biofouling, which is a phenomenon that occurs when microorganisms in the wastewater adhere to the surface of the membranes and restrict water flow. Membrane surfaces must be cleaned periodically by discontinuing the bioreactor operation, which limits the economic advantages of using this approach. Thus, for the use of bioreactors in wastewater treatment to become widely adopted as a fully sustainable and economical technology across Los Angeles County – the membrane biofouling issue must first be resolved. 

Reducing water consumption in Los Angeles County so that the region can achieve 100% local water, as well as enhancing ecosystem health, are two key targets of the Sustainable LA Grand Challenge. However, an apparent contradiction exists between increasing urban vegetation and reducing water use in the Los Angeles Basin. Therefore, the interconnections between the L.A. region’s water use and urban ecosystems need to be better understood. In this project, researchers reconstruct historical urban ecosystem changes in the region over the past several decades to inform future landscape and water management practices. 

For Los Angeles County to achieve 100% local water, increasing local water supply and reducing local demand for water must occur simultaneously. Numerous water conservation efforts exist and have been proposed to serve this purpose, but there is a lack of quantitative data on how each of these water conservation efforts functions in the county. Thus, there is a need to evaluate the full portfolio of potential conservation options to identify practices that would maximize benefits. The UCLA research team carried out this evaluation, taking into consideration Los Angeles-specific conditions such as the local climate and the inability to reduce customers’ water demand (often termed, “demand hardening”) due to previously implemented programs. 

Wastes and biomass residues from agricultural, dairy, forestry and household activities are sustainable energy resources that are widely available and replenishable. They can be used to derive alternative energy products like electricity, heat and bio-jet fuel. However, the transport and storage of waste are costly and processing it requires substantial energy. In order to consider wastes and biomass residues as potential alternative energy sources, there needs to be a holistic assessment of their potential energy production, net energy gain, and greenhouse gas emission reductions. This project aims to undertake this assessment in the contiguous United States.

California’s water infrastructure is set up for flood control, with conveying streamflow to the ocean as efficiently as possible as its primary aim. Capturing and using more stormwater is one key way that Los Angeles County can decrease its dependency on water supplies sourced from hundreds of miles away. In adapting the state’s infrastructure for stormwater capture, storage and use, it is essential to plan carefully for the precipitation extremes of the future, which will become more intense and frequent due to climate change.  Atmospheric rivers—long corridors of water vapor traveling from the Pacific Ocean to California—are responsible for producing heavy precipitation and determining the state’s flood risk. Given this context, it is critical to understand how atmospheric river events will change in a warming world. In this project, researchers quantify projected changes in future precipitation driven by extreme atmospheric rivers in California by combining global climate model (GCM) with regional modeling.