Scenarios to decarbonize residential water heating in California

Abstract

A B S T R A C TThis paper presents the first detailed long-term stock turnover model to investigate scenarios to decarbonize the residential water heating sector in California, which is currently dominated by natural gas. We model a mix of water heating (WH) technologies including conventional and on-demand (tank-less) natural gas heating, electric resistance, existing electric heat pumps, advanced heat pumps with low global warming refrigerants and solar thermal water heaters. Technically feasible policy scenarios are developed by considering combinations of WH technologies with efficiency gains within each technology, lowering global warming potential of refrigerants and decreasing grid carbon intensity. We then evaluate energy demand, emissions and equipment replacement costs of the pathways. We develop multiple scenarios by which the annual greenhouse gas emissions from residential water heaters in California can be reduced by over 80% from 1990 levels resulting in an annual savings of over 10 Million Metric Tons by 2050. The overall cost of transition will depend on future cost reductions in heat pump and solar thermal water heating equipment, energy costs, and hot water consumption.

Energy use for urban water management by utilities and households in Los Angeles

“…Second, in case study cities, what are the relative contributions of utility and end-use energy consumption for water management in cities across diverse climate and geographic regions? Simultaneously evaluating these through a comparable quantitative framework can build on existing research and quantify the relative energy used for water management by utilities in buildings (Kenway et al 2015, Sanders and Webber 2015, Raghavan et al 2017, Kenway et al 2019.…”

Boosting Energy Efficiency and Solar Energy inside the Residential, Commercial, and Public Services Sectors in Mexico

“…In the case of solar energy options for this same sector, the study by Reference [67] proposes for Brazil in its Low-Carbon Scenario that 0.7% of electricity consumption comes from SFV installed in the residential sector in 2030, a goal very similar to the one considered in this article of 1% in 2035. As for the option of solar heaters, the study by Reference [11] proposes in its Advanced Technology scenario that in California, 15% of residential water heating is carried out with solar heaters in 2035 and 44% in 2050. The proposal, analyzed in this article, considers that this value is 12% in 2035 with average annual growth rate of 18% for the period 2011-2035, a rate lower than the 22% achieved by China, during the period 1998-2009, according to Reference [68], which has been one of the most successful dissemination of this technology worldwide.…”

Electrification of buildings and industry in the United States: Drivers, barriers, prospects, and policy approaches

“…A recent University of California Berkeley/Berkeley Lab study on water heating decarbonization in California (Raghavan et al 2017) describes several scenarios to decarbonize residential water heating in 2050 to meet the state's 80% greenhouse gas reduction target in 2050. The study estimates customer life-cycle costs (capital, fuel, and maintenance costs) for several water heating technologies: conventional natural-gas heating, tankless natural-gas water heating, heat pump-based water heating, advanced heat pumps, electric resistance heating, and solar thermal water heating.…”

“…NGWH is natural gas water heater; INGWH is instant (tankless) natural gas water heater; ERWH is electric resistance water heater; HPWH is heat pump water heater; AdvHP is advanced heat pump water heater; STh is solar thermal water heater. Source: Raghavan et al (2017) All three of these studies were conducted in California and may not be broadly applicable to other parts of the country. 37 California experiences mild winters, and heat pump technologies are more efficient in these climates.…”