Integrated water-energy-emissions analysis: Applying LEAP and WEAP together in California

This policy brief describes the integration of the Water Evaluation and Planning (WEAP) and Long-range Energy Alternatives Planning (LEAP) systems to analyze the water-energy-climate nexus. Using a case study in California, the document demonstrates how integrated modeling can quantify the tradeoffs between reducing water imports through desalination and the resulting increases in electricity demand and greenhouse gas emissions.

• The Stockholm Environment Institute (SEI) has integrated two of its decision support systems—the Water Evaluation and Planning (WEAP) system and the Long-range Energy Alternatives Planning (LEAP) system—to allow users to model evolving conditions in both water and energy systems and examine cross-sectoral impacts of policy choices.
• In California, the water sector is a significant energy consumer, accounting for 19% of the state's electricity consumption. The State Water Project (SWP) is the single largest power consumer in the state, utilizing 3% of total electricity to pump approximately 4 billion cubic meters of water annually.
• California's Global Warming Solutions Act (AB32) of 2006 mandates a reduction of greenhouse gas (GHG) emissions to 1990 levels (427 million tonnes of CO2e) by 2020. To support this, the Renewables Portfolio Standard (RPS) requires that 33% of electricity come from eligible renewables by 2020.
• An analysis of the Renewables Portfolio Standard (RPS) suggests that meeting these targets could increase water consumption for power generation by 219 million cubic meters compared to 2010 levels, although this increase could be mitigated by choosing different technologies, such as solar photovoltaic over solar thermal.
• A case study simulating the use of desalinated seawater to meet roughly 5% of Southern California's current urban water demand through 2049 found that while it could reduce water imports by about 300 million cubic meters per year in normal years, it would increase the water sector's electricity use by approximately 3 terawatt-hours per year and emissions by 1.4 million tonnes of CO2e per year by 2049.

APA

Stockholm Environment Institute (2012). Integrated water-energy-emissions analysis: Applying LEAP and WEAP together in California. https://leap.sei.org/documents\LEAPWEAPPolicyBrief2012.pdf

Chicago

Stockholm Environment Institute. Integrated water-energy-emissions analysis: Applying LEAP and WEAP together in California. 2012. https://leap.sei.org/documents\LEAPWEAPPolicyBrief2012.pdf.

Wikipedia

{{cite report |author=Stockholm Environment Institute |title=Integrated water-energy-emissions analysis: Applying LEAP and WEAP together in California |date=2012 |url=https://leap.sei.org/documents\LEAPWEAPPolicyBrief2012.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stockholmenvironmentinstitute2012integrated, author = {{Stockholm Environment Institute}}, title = {{Integrated water-energy-emissions analysis: Applying LEAP and WEAP together in California}}, institution = {Stockholm Environment Institute}, year = {2012}, url = {https://leap.sei.org/documents\LEAPWEAPPolicyBrief2012.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }