Over 80% of the world’s energy currently comes from burning fossil fuels. We get another 12% from burning ‘biomass,’ 3% each from hydro-electric and nuclear plants, and less than 1% each from wind, solar, and geothermal sources. Said another way, we get more than 90% of our energy from burning things that grow.
Fossil fuels don’t consume significant amounts of today’s water. But the availability of these fuels trick us into lifestyles that won’t be sustainable when the fossil fuels become scarce. As consumers, this might lull us into buying homes and appliances that require large amounts of fossil fuel in communities that also require inhabitants to expend large amounts of fuel to travel to shops, schools, and work. If fossil fuels become scarce, these fuel-hungry homes and communities will plummet in value.
Some folks insist that fossil fuels will remain abundantly available for decades and even centuries to come. They point to new technologies, like hydraulic fracturing (or fracking), which will allow us to extract fossil fuels that otherwise don’t easily come to the surface. But if these methods increase pollution of ground water, they no longer enjoy a low water footprint.
Biofuels, sometimes considered renewable and therefore sustainable fuels, derive from things that grow. So ethanol from corn or rapeseed will have a water footprint based on that crop. Logs and wood pellets also consume water. As these trees and fuel crops grow, water must evaporate or ‘transpire’ from their leaves in order to suck water and nutrients up from their roots. This evaporated water is lost until it comes back out of the atmosphere in rain, snow, or some other kind of precipitation.
Electricity from hydro-electric plants use dammed rivers to produce water pressure. This water pressure turns the turbines that create electricity. But a certain amount of water trapped behind the dam evaporates, and is also lost until it comes back out of the atmosphere.In dry climates, this water evaporation can cause thousands of liters of water to be lost for each Megawatt of energy produced.
Nuclear power is frightening to many, particularly since the 2011 tsunami in Japan that caused meltdowns at the Fukushima Daiichi Nuclear Power Plant. Nuclear power itself doesn’t have a large water footprint. But in case of a meltdown, mere addition of water won’t be able to ‘dilute’ local waters back to acceptable concentrations of radioactivity.
Electricity and heat from solar, wind, and geothermal systems creates the lowest water footprint per unit of energy, but currently these three together provide less than 1% of the world’s energy.
In summary, saving water might not seem aligned with reducing carbon footprint on the face of things. However energy sources that produce a significant carbon footprint either consume water now, or at the least create an energy appetite that cannot be sated once fossil fuels become scarce.
Meg is an engineer with a BS in Physics from George Mason University and a MS in Product Development (combined Systems Engineering and Masters in Business Administration curriculum) from Naval Postgraduate School.