Considering it composes roughly 80% of our body, water is humanity’s most important resource. With more than 7 billion people on the planet, water is becoming increasingly more precious. Given its absolute value, the Stockholm Energy Institute (SEI) recently published a report evaluating the potential impact of renewable energy technologies on water resources.
The findings? It’s simple, we need to be more judicial in our water consumption in all areas of the economy, including energy. Like the body, water is intrinsic to energy production. It is used for electricity generation, production and processing of fuels, energy storage, and as a coolant for power plants.
As the SEI points out, low-carbon energy technologies are essential to reduce greenhouse gas emissions and mitigate climate change. However, some clean energy technologies require considerable amounts of water. And, as the Institute reminds: “given competing demands, resource depletion and projected climate impacts, sufficient water may not always be available.”
Conventional power generation through fossil fuels and nuclear energy currently accounts for 90% of the United States’ electricity production. In 2005, they accounted for 41% of freshwater withdrawals — removing water from a source and either returning it ot the source, or making it available elsewhere — the single largest share. By far, conventional energy sources such as coal and nuclear require more water withdrawals than alternatives. Although, some renewable technologies such as biofuels are not far behind.
Using California as a case study, the international research institute created three models to evaluate the environmental and water impacts of energy production and consumption from 2010-2020.
Under the first model, Business As Usual, emissions, water withdrawals, and water consumption all increase. In the second model, the Renewable Portfolio Standard scenario, emissions and water withdrawals remain constant, and do not increase. Water consumption, on the other hand rises sharply, due to increases of geothermal, biomass, solar thermal, and reciruclating systems.
The final scenario, which the SEI dubbed, RPS+Technology, assumes the same fuel mix as the RPS model, but switches technologies. California’s solar portfolio is altered from its current state of 70% solar thermal and 30% photovoltaic to a 50-50 mix by 2020. The scenario also incorporates changes to make cooling systems less water intensive. In this scenario, emissions are cut even more than the RPS model, water withdrawals drop, and water consumption increases minimally — nearly ten times less than the RPS model.
So, under the lens of water usage, not all alternative energy technologies are created equal. As a result, the SEI recommends that energy planners and policy makers prioritize renewable energy technologies such as solar PV, wind, small hydro and binary-cycle geothermal, as they use relatively no water. Other recommendations include reducing energy demand through greater efficiency measures, developing more effective energy storage systems, and using wastewater for power plant cooling.
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