The need to keep climate change within safe thresholds will require rapid emission reductions, and widespread deployment of low-carbon technologies to help achieve them. Yet many low-carbon energy sources require considerable amounts of water – and given competing demands, resource depletion and projected climate impacts, sufficient water may not be available to meet all needs.
The authors start by describing how water is used in electricity generation in particular, looking at both conventional sources and renewables. Then they outline the findings of a case study in California, focusing on the water and emissions implications of the state’s renewable energy portfolio standard (RPS).
The case study shows that under business as usual (BAU), greenhouse gas emissions, water withdrawals and water consumption all increase. Under the RPS, which would boost the share of renewable electricity from 25 to 34 per cent by 2020, emissions and water withdrawals drop, but water consumption (the water that is not reused or returned to the source) increases.
Adjustments to California’s RPS could significantly reduce water demand, however: A scenario the authors call RPS+Technology, using more photovoltaics and less solar thermal power, and incrementally switching once-through to wet-recirculating and dry-cooling systems, reduces both water withdrawals and consumption. This would also somewhat reduce plant efficiency, however.
The policy brief ends with a list of potential strategies for reducing water demand for electricity generation, in the context of renewables and beyond.
Download the policy brief (PDF, 533kb)
Note: This document was corrected on 4 May. Earlier versions contained errors in Figure 1 and Figure 4.