“Think you need 8 glasses of water a day? Think again.” reads an infographic on The Nature Conservancy website. All the things we consume – the food in our pantries, the clothes in our closets, the appliances in our homes and the gadgets in our pockets – have gallons of embodied water in them.
Save water by turning off lights and unplugging unused chargers
The average light bulb consumes 1.4 gallons of water per hour (Last Call at the Oasis). “Water is needed for energy production and energy is needed for water supply.” say Mekonnen et al. in their recent paper on the consumptive water footprint (WF) of electricity and heat. “The consumptive WF of electricity, expressed as the total volume of water consumed over the supply chain, per unit of gross electricity produced, primarily depends on the energy source.”
Water and energy are intimately interlinked
Recent research shows that the energy can also be produced during water treatment [1,2,3,4]. At the same time, reducing our energy consumption would also reduce our water footprint. But how much would our reduced energy consumption absolve us of our environmental sins depends on what keeps our lights on – fossil fuels, solar energy, hydroelectricity, wind energy or biofuels.
How green is renewable energy?
Renewable energy sources such as solar and hydropower are often promoted as low-carbon alternatives to fossil fuels. But Mekonnen et al. deliver some sobering news: “The WF of solar energy from CSP [concentrated solar power] is in the same order of magnitude as the WF of electricity from fossil fuels and nuclear energy, because of the need for cooling.” What does this say about massive fields of solar panels in deserts and other water stressed areas?
Wendy Wilson, Executive Director of Advocates for the West has said, “[E]ach day, enough water to meet the demands of more than 50 million people evaporates from reservoirs behind hydroelectric dams.” So what is the carbon footprint of water?
Rethinking green
Buying green and installing solar panels on our rooftops may give us the warm fuzzies, but we need to reassess what we mean by ‘green’. Of course, a single metric (such as carbon footprint or water footprint) cannot capture the complexity of the life cycle impacts of a product or a process. We need an array of complementary metrics and life cycle assessment to analyse the sustainability of renewable energy [5]. Nonetheless, Mekonnen et al. have provided ample fodder for us to chew on and think about the intertwined challenges of sustainable energy and water.
What is your water footprint?
Find out by using this personal water footprint calculator and the statistics and infographics developed by the Water Footprint Network.
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You can read the full paper for free* using the link below:
The consumptive water footprint of electricity and heat: a global assessment
Environ. Sci.: Water Res. Technol., 2015, Advance Article
Mesfin M. Mekonnen, P. W. Gerbens-Leenes and Arjen Y. Hoekstra
DOI: 10.1039/C5EW00026B
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About the webwriter
Paramjeet Pati is a PhD Candidate at the Virginia Tech Center for Sustainable Nanotechnology (@VTSuN).
You can find more articles by him in the VTSuN blog, where he writes using the name coffeemug.
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*Access is free through a registered RSC account.
