Where Two Big Thirsts Collide: The Nexus of Energy and Water

August 5, 2013 | 2:46 PM

By Terrence Henry

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A Conversation with Michael Webber

We’ve arrived in the dog days of summer in Texas, when air conditioners across the state stretch our power supplies thin. It’s also dry: the state is in a third year of drought, with reservoir levels at 63 percent full overall, down significantly from a year ago. In short, Texas needs more water and more power, and the two are highly dependent on each other.

Where those thirsts for more power and water collide is referred to as the ‘Energy-Water Nexus,’ and it’s a subject University of Texas at Austin professor and Deputy Director of the UT Energy Institute Michael Webber has spent a lot of time on. “Energy uses a lot of water, and water uses a lot of energy, and this fact is surprising for a lot of people, just how much they use of both,” Webber says.

For instance, energy needs water to grow biofuels, drill and produce oil and gas, cool power plants and power hydroelectic dams, Webber says. And water needs energy to be heated, treated, cleaned and moved. Getting water cleaned up and into our homes makes up over 12 percent of our nation’s energy use, Webber says.

We sat down with Webber to talk about these issues in advance of a lecture in Austin Tuesday, August 6 about “The Global Nexus of Energy and Water.” The talk is free and open to the public, at 5:45 pm at the AT&T Conference Center. (More details here.)

Q: So energy needs water, and water needs energy, and I would imagine that this nexus is even more pronounced here in Texas.

A: These days in Texas, it seems like we’re worried about the grid being on edge. We’re worried about drought, and these things sort of play into each other’s hands in a bad way. As we have more drought, we have less water available for our dams to make electricity, we also have less water available for cooling our power plants. And as that water gets hot from heat waves, water is less effective as a coolant, and so the power plants perform with lower efficiency. So a water strain or water constraint becomes an energy constraint, so it’s true also that if you have an energy constraint – if you have a power outage or a rolling blackout, your water infrastructure might be hindered as well. So the energy-water nexus means they rely on each other, and that means — bad news — they inherit each other’s vulnerabilities. A constraint in one becomes a constraint in the other.

There’s several things going on over the last few years as we’ve had massive droughts and massive heat waves, which is power plants that never felt vulnerable now feel vulnerable and they might not have the water they need. So they go to great effort to get the water by piping it long distances, or by cutting down trees around the reservoirs so they get more cooling of the reservoir and less evaporation they hope. Or other sort of tricks of the trade to keep the water in hand to keep the power plants operating, sometimes turning the power plants off at night or curtailing them during the day if you need to.

So that strain is already in place and has been for a couple years. And we’re feeling it more than ever because a lot of these water rights allocations were made decades ago before our population boomed so much.

Q: Let’s tackle maybe one major slice of this issue: the power plants. If you were to reduce water use by power plants, what are some of the solutions there?

A: There are a couple different ways to reduce water use at power plants. There’s technology switching, you could switch to cooling tower designs or you could switch to more efficient power cycles, maybe better turbines or controls, that kind of thing. As your power plants are more efficient, they have less waste heat and they need less cooling. So you could do technology switching, or you could also do fuel switching.

In Texas, this is particularly interesting. Coal power plants use about twice as much water per kilowatt hour of electricity that’s generated, compared to a new, modern, efficient, natural gas combined-cycle plant. So if you go to a natural gas combined-cycle system that’s relatively new instead of a relatively old and less efficient coal system, then you can save a lot of water there, at least in terms of consumption at the power plant for cooling.

Q: I think an immediate concern that comes up when you hear that is cost. And one of the things that you’ve argued is that we don’t pay enough for water, and that we get it too cheaply, and it leads to these inefficiencies.

A: One of the things I complain about in energy and water is that they’re too cheap, and in particular water is too cheap. There’s a human right to water, and that human right to water has expanded into a sense of ‘Water should be infinitely available, perfectly clean, and free or cheap.’ And that creates all sorts of weird behaviors, where large water users who don’t have to pay for the water because they paid for it maybe 100 years ago, or 50 years ago, don’t have an incentive to conserve. We tend to conserve things that are valuable or expensive, and while water is valuable, it’s not expensive. Sometimes it’s cheaper to waste it than to pay for the expensive water-saving equipment that might conserve it. So that’s one of the challenges, that we have highly dysfunctional water markets, or no water markets at all, and therefore a water price signal that does not inspire conservation.

Q: It’s interesting, because it seems like we’re looking at fewer and fewer supplies of water, less and less clean water. The water that we want to get, it’s expensive to get to, and we don’t value it enough. But just five years ago, we were reading articles about Peak Oil, but the paradigm has really shifted rather rapidly with that. Now there’s talk of Peak Water — is there any chance of a similar, unexpected shift happening with water?

A: One of the things we see in the world of resources is that our long-term ability to predict trends is spectacularly bad. So we were convinced we were running out oil in the seventies, and then we weren’t, but prices went up, and we’ve had these various predictions at various times. The latest one being peak oil and gas.

But now we’ve got a shot in the arm of at least a decade or two of abundant gas reserves from shale formations in just the Barnett Shale alone. So now the sort of new view about energy abundance, and then the same concepts are translating over to water, do we have Peak Water?

Well really, no, water is different. Water is a closed hydrologic cycle. We really never get rid of the water, we just move it around. But the moving around has consequences, because we move it to locations that are further away or we move it to a form or quality that’s less acceptable or less convenient. And the consequence is energy. We have to spend energy to move it closer in quality or closer in location to what we need it for. And so our water shifts have this energy implication that we have to be ready for. And because energy is available in a different way maybe the water will be as well, and maybe there’s an analogy in the energy world for water. Where, for many decades, we had this degraded energy resource beneath our feet, shale, and we didn’t think it was economically feasible, or technically feasible, or environmentally responsible to get, and now we’re finding that it actually is economically feasible, it is technically feasible, and in some ways it is an environmentally preferred solution if that cleaner gas displaces dirtier coal.

So maybe there’s the same lesson with the ocean under our feet of all that dirty brackish water we have in Texas. It’s not the kind we want to drink, but it’s abundant, it’s there, and it’s not technically feasible or economically feasible to extract. But if we integrate wind power or solar power in West Texas with all the brackish water, maybe we can get that brackish water cleaned in a cheap way and an environmentally responsible way to change the story. So who knows? Maybe our brackish water resource today is just what shale was a decade ago.

Q: It seems like there’s a lot of decisions to be made here at the larger policy level. But what about the individual? How could they reduce their role in the energy-water nexus?

A: There’s a lot individuals can do to conserve energy and conserve water. We have more power over this than we think. There’s 315 million stakeholders in America making decisions about energy and water, and there are a couple easy options we can do.

First of all, the most energy-intensive water is the treated, clean, drinking water that we heat in our home. So if you want to save a lot of energy, save the heated water. Shorter hot showers, more efficient dishwashers, more efficient washers, that kind of thing. And surprisingly, saving that heated water is a pathway to saving energy.

That’s one of the good news bits about the energy-water nexus: saving water saves energy, saving energy saves water. In fact, the irony is if you want to save water, saving energy is a cheaper, faster, way to do it, and if you want to save energy, saving water is a cheaper, faster, way to do it.

In our homes, we spend an incredible amount of energy heating our water and that’s sort of ironic given that we have so many photons and so much sunshine that will heat the water for us for free. And so an easy option for those homes that have rooftops that are not shaded is to get solar water heaters installed. My household had its solar water heater installed in the ‘80s, and it’s still working great and it saves us a ton of money and it helps reduce our energy consumption overall. It works great. So that’s an easy solution, an easy option for a lot of people.

We can also reduce how much water we use on our lawns. Especially how much treated drinking water we use on our lawns. Lawns are particularly thirsty — well over half our water usage is for irrigation, generally. And so getting different strains of grass, less grass, watering it with something like rainwater we collect or reclaimed water instead of fresh, treated drinking water is a way to save a lot of energy and water.

Then if we turn off our lights and things in our homes, we can save water at the power plants. We use more water through our light switches than our faucets, and that’s a surprise for many people. So just turning off your light switches and reducing your energy consumption in the home will be a pathway to saving water as well.

In Texas, we care a lot about energy and water. We make a lot of money from energy and we feel like we don’t have enough water all the time. And these water issues in particular become interesting in times of drought or heat wave, and if we think we’ll never have a drought or heat wave again we probably can quit worrying about it. But in Texas, we tend to have these a lot.

Michael Marks provided transcription. This interview was edited for clarity and content.