Energy transitions on the Hawaiian Islands : water resources implications for Hawaii's electrical power system

Imported fossil fuels currently supply over 90% of the Hawaiian Islands' annual consumed electricity, the majority of which is produced by petroleum-fired power plants. The state of Hawaii has a goal to dramatically reduce this reliance on imports and achieve 30% locally sourced, renewable power use by 2030. This goal signals an energy transition for the state that is achievable through decommissioning, repurposing and new development in power generating technologies and infrastructure. In addition to dependencies on imports and fossil fuels, Hawaii's electrical industry is also currently the largest water user in the state of Hawaii with over 75% of all surface water and groundwater withdrawals attributed to thermoelectric generation and cooling. Transitions in Hawaii's fuel mix from a petroleum dominant mix to renewable fuel for power generation could have significant impacts on water use and availability: a small change in energy resources could mean significant changes in water use. Integrated planning and management for these two resources is needed. A successful energy transition for Hawaii in the next 15 years will involve precise planning, and strategic decision-making for both energy and water. This research adopts a systems view to evaluate energy-water interdependencies within Hawaii's electrical system, comparing the current fuel mix and projections for energy trends on the islands with the continental United States. A power plant database built from Hawaii-specific utility-scale data combined with national averages for thermoelectric water use reported in the literature provide an overview of Hawaii’s current electrical sector and its water use. This snapshot identifies critical resource management needs and reveals disparities between the electrically detached islands. Scenario analysis of projected change in Hawaii’s electrical sector is used to assess the implications for water use intensity across a range of locally sourced power capacity and generation options. Results indicate that, because it displaces petroleum power production, increases in renewable energies on Hawaii will produce substantial water savings, especially in total operational water withdrawals.