Water used for four power sources (1BOG.org)

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

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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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