The critical role of humidity in modeling summer electricity demand across the United States

Nature Portfolio (Springer Nature) | April 3rd, 2020

Cooling demand is projected to increase under climate change. However, most of the existing projections are based on rising air temperatures alone, ignoring that

Cooling demand is projected to increase under climate change. However, most of the existing projections are based on rising air temperatures alone, ignoring that rising temperatures are associated with increased humidity; a lethal combination that could significantly increase morbidity and mortality rates during extreme heat events. We bridge this gap by identifying the key measures of heat stress, considering both air temperature and near-surface humidity, in characterizing the climate sensitivity of electricity demand at a national scale. Here we show that in many of the high energy consuming states, such as California and Texas, projections based on air temperature alone underestimates cooling demand by as much as 10–15% under both present and future climate scenarios. Our results establish that air temperature is a necessary but not sufficient variable for adequately characterizing the climate sensitivity of cooling load, and that near-surface humidity plays an equally important role.

The effect of reducing per capita water and energy uses on renewable water resources in the water, food and energy nexus

Nature Portfolio (Springer Nature) | May 9th, 2022

This study assesses the feedbacks between water, food, and energy nexus at the national level with a dynamic-system model, taking into account the qualitative and quantit

This study assesses the feedbacks between water, food, and energy nexus at the national level with a dynamic-system model, taking into account the qualitative and quantitative environmental water needs. Surface and groundwater resources are considered jointly in the water resources subsystem of this dynamic system. The developed model considers the effects of reducing the per capita use water and energy on its system’s components. Results indicate that due to feedbacks the changes in per capita uses of water and energy have indirect and direct effects. About 40% of the total water savings achieved by the per capita change policy was related to energy savings, in other words, it is an indirect saving. Implementation of per capita use reductions compensates for 9% of the decline of Iran’s groundwater reservoirs (non-renewable resources in the short term) that occur during the five-year study period. The Manageable and Exploitable Renewable Water Stress Index (MRWI) corresponding to water and energy savings equals 214.5%, which is better than its value under the current situation (which is equal to 235.1%).

The Future of California’s Water-Energy-Climate Nexus

Pacific Institute | September 9th, 2021

Water and energy are inextricably linked in California and, as one resource faces constraints or challenges, so does the other. With the state looking to both reach its c

Water and energy are inextricably linked in California and, as one resource faces constraints or challenges, so does the other. With the state looking to both reach its climate change goals and decarbonize its economy through a transition to 100 percent clean energy, water will play an integral role. Water is a key input for energy production, and energy is integral to all aspects of water management and use in California—including collection, treatment, heating, and wastewater management. Prior studies have estimated that about 20 percent of California’s total statewide electricity use, a third of non-power plant natural gas consumption, and 88 billion gallons of diesel consumption are related to water—from collection and treatment to use and wastewater management—with a large share associated with heating water. These interdependencies between water and energy supplies are commonly referred to as the water-energy nexus.

The importance of system configuration for distributed direct potable water reuse

Nature Portfolio (Springer Nature) | April 27th, 2020

Water and wastewater infrastructure worldwide faces unprecedented demand and supply conflicts that require unconventional solutions. In this study, we develop a novel mod

Water and wastewater infrastructure worldwide faces unprecedented demand and supply conflicts that require unconventional solutions. In this study, we develop a novel modelling framework to assess the environmental and economic implications of a hybrid water supply system that supplements a centralized surface water supply with distributed direct potable reuse (DPR) of municipal wastewater, as a strategy to address such challenges. The model is tested with real water and wastewater systems data from the City of Houston, Texas. Results show that supplementing the conventional centralized water supply with distributed DPR would reduce water age in the drinking-water distribution network and hence improve water quality; properly designed system configurations attain system-wide net energy savings even with the high energy consumption of existing technologies used for advanced treatment of the wastewater. A target energy efficiency for future advanced treatment technologies is identified to achieve net energy saving with all hybrid system configurations. Furthermore, distributed DPR remains financially competitive compared with other unconventional water supply solutions. The modelling framework and associated databases developed in this study serve an important research need for quantitatively characterizing distributed and hybrid water systems, laying the necessary foundation for rational design of integrated urban water systems.

The Steam Wells of California

Nature Portfolio (Springer Nature) | May 5th, 1928

The utilisation of the steam of the soffioni of Tuscany as a source of mechanical power has steadily developed since 1904 when the first pioneer experiments were

The utilisation of the steam of the soffioni of Tuscany as a source of mechanical power has steadily developed since 1904 when the first pioneer experiments were carried out at Larderello by Prince Ginori Conti. The remarkable results which have since been achieved were described in NATURE of Jan. 14 last. Similar sources of geothermal energy were first tapped in California in 1921, and since then several deep wells have been successfully sunk, some of them being superior both in pressure and steam output to any yet reported from Italy. The active region is known as ‘The Geysers,’ and lies on the western side of the St. Helena Range, one of the coast ranges of California. Along a line some twentyfive miles in length, which appears to mark a fault or shatter belt, hot springs, some of which are associated with quicksilver deposits, occur at intervals. There are no actual geysers at ‘The Geysers,’ but over an area of thirty-five acres the ground is dotted with hot springs and fumaroles and salt patches, and steam and gases are constantly seeping through the surface. A thorough investigation of the locality has been made by Dr. E. T. Allen and Dr. A. L. Day, and the results, beautifully published by the Carnegie Institution of Washington,1 add very materially to our knowledge of subterranean supplies of magmatic steam.

The Water Footprint of California’s Energy System, 1990–2012

Pacific Institute | February 1st, 2015

A new article by Julian Fulton and  Heather Cooley  evaluates the amount of water consumed in meeting California’s energy needs – also referred to as the water foot

A new article by Julian Fulton and  Heather Cooley  evaluates the amount of water consumed in meeting California’s energy needs – also referred to as the water footprint of energy. The article, published in Environmental Science and Technology, examines how the water footprint of energy changed between 1990 and 2012 – finding that the amount of water consumed substantially increased over recent decades without utilizing more of the state’s water resources, but rather by relying more heavily on water resources from outside the state. Much of that increase is attributable to the production of bioethanol, which recent energy policies have promoted to meet state greenhouse gas targets. Fulton and Cooley demonstrate that while efforts to mitigate climate change in California have been successful in reducing greenhouse gases, these policies may have shifted burdens from energy to water, rather than alleviate them. They conclude that more integrated analysis and planning of water and energy systems are needed to ensure that climate adaptation and mitigation strategies do not work at cross purposes. Abstract: California’s energy and water systems are interconnected and have evolved in recent decades in response to changing conditions and policy goals. For this analysis, we use a water footprint methodology to examine water requirements of energy products consumed in California between 1990 and 2012. We combine energy production, trade, and consumption data with estimates of the blue and green water footprints of energy products. We find that while California’s total annual energy consumption increased by just 2.6% during the analysis period, the amount of water required to produce that energy grew by 260%. Nearly all of the increase in California’s energy-related water footprint was associated with water use in locations outside of California, where energy products that the state consumes were, and continue to be, produced. We discuss these trends and the implications for California’s future energy system as it relates to climate change and expected water management challenges inside and outside the state. Our analysis shows that while California’s energy policies have supported climate mitigation efforts, they have increased vulnerability to climate impacts, especially greater hydrologic uncertainty. More integrated analysis and planning are needed to ensure that climate adaptation and mitigation strategies do not work at cross purposes.

Trade-offs across the water-energy-food nexus: A triple bottom line sustainability assessment of desalination for agriculture in the San Quintín Valley, Mexico

Environmental Science & Policy (Elsevier) | September 30th, 2020

This paper introduces a novel triple bottom line sustainability assessment to evaluate the water-energy-food nexus of desalination for agriculture. Falling technology cos

This paper introduces a novel triple bottom line sustainability assessment to evaluate the water-energy-food nexus of desalination for agriculture. Falling technology costs and rising water scarcity worldwide make desalination an increasingly attractive proposition, and agriculture is one of the main sectors grappling with its potential impacts. To explore this issue, we combine a wide range of primary and secondary environmental, economic, and social data with a triple bottom line / WEF nexus analysis, to demonstrate both the holistic sustainability impacts of desalination for agriculture, and the multi-sectoral policy environment within which desalination is adopted. We apply this approach to 54 privately-owned desalination plants that treat brackish groundwater for agricultural use in the San Quintín Valley of Baja California, Mexico. We find that subsidized energy for local agribusinesses plays an important role in making desalination economically viable in the region. This in turn fuels a large agricultural export industry that represents a significant virtual water transfer to the US market. Rapid population growth in the area driven by agricultural labor needs exacerbates the issues of social equity and sustainability that these subsidies and transfers raise. We conclude with a discussion of how to manage these identified trade-offs across the water-energy-food nexus.

Trend analysis of ground-water levels and spring discharge in the Yucca Mountain region, Nevada and California, 1960–2000

U.S. Geological Survey (USGS) | July 1st, 2002

Urban water and electricity demand data for understanding climate change impacts on the water-energy nexus

Nature Portfolio (Springer Nature) | January 23rd, 2024

Water and Energy in California

Public Policy Institute of California (PPIC) | December 6th, 2022