Originally published on PV Solar Report

Want good beer? You need clean water.

Now, there’s strong motivation to keep our water supply clean -- whether you prefer drinking water or beer. And that makes a good case for moving away from coal and gas production.

According to the EPA, more than half of all toxic water pollution in the U.S. comes from coal-fired power plants. And stories about water contamination from fracking have become common.

But what if your problem isn’t dirty water? What if your problem is not enough water?

How to deal with severe droughts?

Everyone seems to be aware of energy issues these days. But we don’t think about water much until we don’t have it. Yet energy and water are intimately connected. We need water to produce energy, and we need energy to get our water.

California could be facing a water shortage sooner than expected. The state is in the midst of the worst drought in 500 years. Reservoirs are facing critical shortages. And with severe weather patterns prevalent everywhere, more frequent and serious droughts are expected in California and other western states.

This can seem like a bleak situation. But there’s something that can help with both the cause and the symptoms. That something has to do with energy. That something is solar power.

Even the staunchest of us solar advocates wouldn’t suggest that solar power is the only solution to our energy problems. We need a mix of renewable energy sources, coupled with energy-efficiency measures. But solar has some important advantages when it comes to water.

How much water do we use to produce energy?

When a drought hits, we hear a lot about taking shorter showers. Then we start hearing that agriculture accounts for a lot more water than home use. What we don’t hear about as much is the biggest use of water in the U.S.: electricity production.

Source: Union of Concerned Scientists

While percentages vary by region, overall, electricity generation uses more water than even agriculture. (California, America’s agriculture leader, is an exception.) Coal-fired and nuclear plants use it for cooling, extraction, and storage. And water also figures prominently in biofuel and natural gas production -- not to mention hydropower.

According to the Union of Concerned Scientists, this means that for each load of hot-water laundry you do using electric appliances, 3 - 10 times more water must be withdrawn at a coal or nuclear plant than you use to wash the clothes. Overall, an average family of four goes through 400 gallons of water in their home per day. If their power comes from coal or nuclear, they’re indirectly using 600 to 1,800 gallons for their energy.

In a state like California, the mix is a bit different. It’s not a big coal and nuke region, so power generation there doesn’t take as much water as agriculture, which is big in the state. But California does use a fair amount of natural gas and hydropower.

Natural gas has come under attack lately because of fracking procedures, which do more than contaminate water. Fracking also accounts for significant amounts of water consumption in arid regions.

Hydroelectric power is obviously going to be an issue in a drought, and it’s now at risk in California The state’s hydroelectric plants depend on rivers and reservoirs that are running extremely low.

Advantages of solar power

However, the same dry weather that’s bad for hydropower is good for solar power.

In spite of shorter winter days, California keeps breaking records for solar generation. Last year, California kept its place as the leading state for installed solar PV, increasing its rooftop solar installation capacity from 1,000 MW to over 2,000 MW. In addition to rooftop solar, California now has 2,926 MW of utility-scale solar in operation, according to the Solar Energy Industries Association.

So can solar take over where hydropower leaves off? Solar PV is definitely a good candidate. The case is a bit murkier when it comes to solar thermal plants, which are getting big in California. The plants use large fields of mirrors to concentrate sunlight and heat water, producing steam that spins power-plant turbines. And they use large amounts of water for cooling.

Technology to the rescue

According to the MIT Technology Review, a technology called dry cooling has started to become more common at solar thermal plants. Though it’s more expensive, researchers are working to improve the technology and reduce its costs. And even though dry cooling still costs more than conventional cooling, it represents only about 5% of the total cost of a solar thermal plant.

Another interesting idea that’s come up recently is using solar power to desalinate water. A startup called WaterFX is pioneering just that. Since California’s Central Valley has a lot of salty water that can’t be used, desalinating it has the advantage of not only increasing the water supply, but also getting it locally. That saves the energy used to pump water to the farmlands. The desalination method being used by WaterFX has another advantage: instead of leaving a lot of harmful waste, it transforms most of the salt waste into something useful, like gypsum or epsom salts. And it’s powered by solar!

And then, of course, there’s good old solar PV. While some water is used to produce the panels, as in all manufacturing processes, once they’re in place, PV panels don’t use water to generate energy. Notice that solar doesn’t even come up in this illustration of projected water needs from the International Energy Agency (IEA):

And solar, whether thermal or PV, confers another very important benefit. It helps reduce the greenhouse gas emissions that have led to the extreme weather we’re now facing around the country -- and around the world.

So it makes sense to move to solar and other renewables, like wind power. Making that change can help preserve our water and help protect our climate. That seems like a high ROI.