The Water Footprint of Energy: Summarising 10 Years of Research
It's now about ten years ago that my research group in Twente - the Netherlands - started to study the water footprint of energy. Time for a summary!
Keeping in mind your limited time, I keep it short. Our main findings:
- Water use in the world is highly unsustainable in many regions of the world.
- Agriculture is responsible for 92% of humanity's water footprint and thus the largest contributor to water scarcity.
- Replacing fossil fuels by biofuels from crops is a bad idea given the enormous additional water demand for producing biofuels.
- Biofuels from algae are only slightly better, also requiring substantial amounts of water. Reference: http://ayhoekstra.nl/pubs/GerbensLeenes-et-al-2014.pdf
- Biofuels from crop residues are a better idea, because they don't result in additional water use, but the potential is limited, because crop residues need to partially stay on the field and are used already for other purposes as well (like animal feed).
- Hydroelectricity is relatively clean, but dams often have big ecological and social impacts; the potential for more dams is limited. The water loss from reservoirs is also enormous.
- A sustainable energy future will be primarily based on solar and wind . This is the only way to reduce both the carbon and water footprint of our energy supply.
- The best energy scenarios of the International Energy Agency in terms of carbon footprint reduction are worst in terms of their water footprint increase, because of the bet on firewood and biofuels. It is possible to reduce both carbon and water footprint, but policies need to radically shift towards photovoltaics and wind energy.
- The future of energy is solar and wind powered and thus electric. Efficient energy storage to match supply and demand in time will be one of the key challenges.
Energy for thought.