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Clean Power Water used for power (1BOG.org)

Published on March 22nd, 2014 | by Sandy Dechert


Solar Power Is A Huge Water Saver (World Water Day Infographic)

March 22nd, 2014 by  


Every year on this day since 1993, the community of nations has focused on the importance of fresh water and advocated for the sustainable management of freshwater resources. Severe droughts experienced recently in places like the American West, the Horn of Africa, Russia, China, and Australia have highlighted the fact that humans are rapidly using up the world’s freshwater supplies—and when they’re gone, they’re gone. We are spending one of our most vital resources in greater volumes every day.

Worldwide drought (FAO)

WWD posterThis year, the UN’s Water Day theme rests on a crucial link largely invisible to most of us: water and the production of energy.

“Water and energy are closely interlinked and interdependent. Energy generation and transmission requires utilization of water resources, particularly for hydroelectric, nuclear, and thermal energy sources. Conversely, about 8% of the global energy generation is used for pumping, treating, and transporting water to various consumers.”

We wrote about water to make power and energy efficiency a few years ago in CleanTechnica:

“If you didn’t know, we use water to pump crude oil out of the ground, remove pollutants from power plant exhaust, flush residue after fossil fuels are burned, cool power plants, and much more. Our energy resources rely on water, much more than we probably realize. Exactly how much water?”

Here are two tables on water usage by power source from that post:


Technology gallons/kWh liters/kWh

Wind [1] 0.001 0.004
PV [2] 0.030 0.110



Technology gallons/kWh liters/kWh

Nuclear 0.62 2.30
Coal 0.49 1.90
Oil 0.43 1.60
Combined Cycle 0.25 0.95

One Block Off The Grid recently developed a cool infographic (below) to illustrate how energy production depends on water. It shows water use by four of the most common energy sources: coal, nuclear, oil and gas, and solar. Solar comes out on top big time.

Water used for power (1BOG.org)

Impressed? We also need to consider how energy industries have water expenditures even after power is generated, all the way through to decommissioning of the power sources.

The analysis gets complicated at this point. No one has yet come up with solid numbers for the storage and post-generation stages of energy water. Here are some guesstimates from solarenergy.net:

Coal: A typical 500-MW coal-fired power plant will create close to 200,000 tons of sludge waste per year, according to the Union of Concerned Scientists, as well as 125,000 tons of coal ash. This waste leaps into the headlines when it spills into waterways, destroying rivers and polluting drinking water, as it has at large scale in Tennessee and North Carolina in recent years.

Natural Gas: The post-generation water impacts of natural gas are negligible, although the EPA notes that “pollutants and heat build up in the water used in natural gas boilers and… is often discharged into lakes or rivers.”

Nuclear: There are no hard data, but one estimate—which may be on the low end—puts nuclear waste disposal’s water use at 3 gallons per MWh of energy generated.

Rooftop Solar: Another instance where hard data don’t exist, especially not on a per-MWh basis, but several studies have shown that both solar panel manufacturing and disposal can create toxic waste that affect water supplies, such as when lead or cadmium seep into groundwater when end-of-life panels are sent to landfills. However, the Silicon Valley Toxics Coalition, which has studied these issues extensively, notes that those wastes can be reduced and avoided through responsible recycling practices, and that state and federal laws govern proper disposal of solar panels.

Wind uses a bit less water than solar, but both are exponentially more water-efficient than other energy sources.

So now you know. You need water to make power. Using solar won’t just save you $84 per month (on average). It will also help all of us conserve precious fresh water and switch over to less wasteful and less dangerous energy from renewables.

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About the Author

covers environmental, health, renewable and conventional energy, and climate change news. She's currently on the climate beat for Important Media, having attended last year's COP20 in Lima Peru. Sandy has also worked for groundbreaking environmental consultants and a Fortune 100 health care firm. She writes for several weblogs and attributes her modest success to an "indelible habit of poking around to satisfy my own curiosity."

  • JP

    According to your description, wind uses even less water than Solar. Why did you feature solar power in your headline and closing statement?

  • Are there many natural gas boiler power generation plants? My experience is only with natural gas turbine power generation.

    • Bob_Wallace

      Combined cycle natural gas plants have a boiler.

  • Geneki

    Some solar plants use water.

    • Bob_Wallace

      Got any data on how much they use per MWh compared to coal and nuclear?

    • UKGary

      According to this article from 2011, concentrating solar thermal uses around 0.9 gallons (around 3.4 litres) per kWh when wet cooled i.e. cooling tower and 0.1 gallons when dry cooled.


      Of course the technology is still being refined so my guess is that water use may be reduced as systems are developed with higher running temperatures and better Carnot efficiency.

      This is a major concern in regards to the proposed Desertec initiative as concentrating solar thermal plants are inherently most likely to be constructed in desert areas which are by their nature water stressed. In the Desertec case within the Sahara desert.

  • No way

    How much of the water is actually being wasted? I mean, there is quite a difference between water being polluted by toxic waste or pumped down into cavities and you won’t get it back compared to water for cooling that you pump back unaffected except for some temperature increase (or not so much so if you use cogeneration).

    • Ross

      Assuming you have enough water for cooling and the temperature of it isn’t already elevated a little by global warming.


      • No way

        Interesting, thank you for that one.

    • Matt

      A lot of the cooling water is “placed back” but in the air. And yes it will rain back some where. But in a area that is short on water, that water is gone. If you look at gas tracking all the water used is gone, or at least that is the hope of the tracking Industry because it is way to costly to clean back up again.

      • No way

        Oh, yes. Assuming cooling towers are used. I forgot that different solutions are used in different places. Then there is a lot of water being displaced (even though you get it back it might not be where you want it to be).

        Yes, the gas fracking (if you actaully meand gas tracking then I don’t know what it is…I’m assuming autocorrection) is totally terrible. I can’t understand how anyone anywhere could let that happen.

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