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[Episode #25] – The Energy-Water Nexus


Energy and water are inextricably linked: It takes energy to supply water, and it takes water to supply energy. And those processes consume vast amounts of both. Yet we have only really begun to study the energy-water nexus and gather the data that policymakers will need to understand the risk that climate change poses to both power and water. As rainfall and temperatures continue to depart from historical norms, forcing conventional power plants to throttle back or shut down, we may need to invest more heavily in wind and solar PV just to keep the lights on. Even more radical solutions may become necessary, like switching to more dry-cooled power plants, and desalinating brackish groundwater. Ideally, we would treat the challenges of the energy-water nexus in an integrated way, deliberately reducing our energy and water demands simultaneously as part of our energy transition strategies, but our governments aren’t typically set up for that, and much more basic research and analytical work is needed.

Guest: Jordan Macknick is an Energy and Environmental Analyst at the National Renewable Energy Laboratory (NREL). Jordan leads NREL analysis research on the interface of energy, water, and land issues in policy planning.  In addition, his research addresses energy deployment in developing countries, technology characterizations, and global energy and carbon systems. Prior to joining NREL in 2009, he worked as a research associate at the International Institute of Applied Systems Analysis (IIASA) in Austria. He holds a BA in mathematics and environmental studies from Hamline University and a Master’s of Environmental Science from the Yale School of Forestry and Environmental Studies.

On the Web: NREL: The Energy-Water Nexus

Recording date: August 29, 2016

Air date: September 7, 2016

Geek rating: 6

Chris Nelder: Welcome Jordan to The Energy Transition Show.

Jordan Macknick: Thanks for having me.

Chris Nelder: When I first wrote about the energy-water nexus in 2009 I found it really difficult to track down solid data on exactly how much energy is consumed for water and how much water is consumed for energy. There just didn't seem to be that much data available. And it turned out to be actually a very complex question to answer because rainfall can be so variable and water use can be so different from state to state. For example at the time I was living in California and I looked at the water use of California, which is of course where most of the fruits and nuts and much of the vegetables consumed by the rest of the country comes from, and it has a much higher agricultural water use than the other states and consumes a lot more energy to meet its water demands. So the rough conclusion that I came to after looking at this really noisy data was that about one fifth of California's total energy use is related to pumping, treating, transporting, heating, cooling and recycling water which I just thought was stunning. So let's start with some gross numbers. On a national basis, how much energy to use for water and how much water do we use for energy?

Jordan Macknick: So that's a great question and I think California certainly is unique in its large energy consumption for water transport, but it's not that different from the rest of the country where approximately 12 to 13 percent of all of our primary energy for the U.S. goes towards that pumping, treating, transporting and especially heating water. And so that's something that is a surprise to most people. It's about 12 quadrillion BTUs of energy we use every year just to manage our water resources. Even more shocking though is on the water for energy side, where on a national basis most people are surprised to hear that the number one user of water in the nation is the energy sector. Approximately 38 percent of all of our water withdrawals, or that's about 130 billion gallons every day, are used for the energy sector. Now that brings up an important distinction though between water withdrawal and water consumption, because water withdrawal is the act of taking water out of a water body and using it. Some of that water you might use in and evaporate but other water you might actually use and then put it right back into that system. And so the water that you take out of this system is water withdrawal and the water that you evaporate or that you use up and do not put back into the system is water consumption. And the energy sector, although being the number one water withdrawer, is not the number one water consumer. That's agriculture. So whereas approximately 38 percent of all our freshwater withdrawals come from the the energy sector, only about 3 percent of all of our water consumption comes from the energy sector. Still it's about three and a half billion gallons per day that we consume in the energy sector.

Chris Nelder: And about 73 percent I think of the surface water withdrawals are actually from freshwater sources.

Jordan Macknick: Right. Yeah.

Chris Nelder: OK. So at about three quarters of the water that's being withdrawn and used in the power sector is actually coming from the surface and the other quarter is groundwater.

Jordan Macknick: Right.

Chris Nelder: OK. So you and your colleagues wrote a paper in 2012 which was kind of a review of the lit which looked at the water consumption withdrawal for electricity generation and that seemed like a very handy paper to me. In fact it was the kind of thing I was looking for in 2009 but couldn't find. Why do you think that is? Was there in fact a dearth of good research on the energy-water nexus in 2009? Or do I just suck as a researcher?

Jordan Macknick: Yeah I don't think it was your fault sucking as a researcher. We actually you know we came across that research because we tried to answer a simple question which was how much water does a coal plant require? How much water does a solar plant require? How much water does a nuclear plant require? They seemed like very straightforward simple questions.

Jordan Macknick: Yeah like you ought to be able to just quickly look it up somewhere right.

Chris Nelder: Right. And as it turned out there was no simple answer. One of the reasons was was that we would find one source published 20 years ago that would say the water intensity of a coal plant is 400 gallons for every megawatt hour. And we would come across another report from 10 years ago that would say you know the water intensity of a coal plant is fifteen hundred gallons for every mega watt hour. And so we had this large large range of values and estimates that people had reported on for how much water different types of energy generating technologies required. And it was frustrating to see because there hadn't really been a comprehensive literature review that had brought all of the data together, tried to parse them out into the appropriate categories and try to understand why there was this variation and variability in the water requirements of these energy technologies. And so that report really was designed to provide a little bit more clarity to the field and provide a little bit more definitive answers for researchers like you and actually for state and federal researchers as well who wanted to know very simple questions like how much water is used by different energy technologies. And I think that's really a function of the fact that this issue you know the idea that water can be really important for the energy sector wasn't really on the front of people's minds at that point. People had thought that you know they had recognized that there was a lot of water being used but they hadn't really thought about it or done a lot of efforts in order to quantify it in such a way because they hadn't really recognized it as being so much of a critical issue for energy security.

Chris Nelder: Wow that's amazing that you know that kind of data was only compiled like five years ago. That's remarkable considering how huge numbers are. OK, so there were a few things in that paper that surprised me. One was concentrating solar thermal power could actually use as much water as a nuclear plant because I was under the impression that nuclear was by far the most water in terms of kind of power generation. And I was surprised to learn that geothermal can actually be a big water user too. And I guess maybe that depends on what kind of technology you're looking at because I had in mind the kind of organic Rankine cycle geothermal technology where you're basically circulating a conventional refrigerant fluid based on CFCs or HFCs in a closed loop and then running it through a heat exchanger to transfer the heat to the engine. And so the water wouldn't be needed in that design. So can you outline some of the nuances here.

Jordan Macknick: Sure. And geothermal is a special case that you know requires pages and pages and pages of research to fully understand. Partly because there's so many different configurations of geothermal technologies that are also partially dependent upon the temperature of your resource that you're working with. And so all of these factors, the resource quality, the geothermal technology you are using, the cooling system you're using, as well as the water that you're using will affect what your water intensity is for different geothermal technologies. So for example, in geothermal technologies water is required for drilling the bore hole, for stimulating the reservoir, for circulation and testing during the plant construction phase. But then during operations it's also required for things like dust control maintenance, any domestic needs onsite. But then importantly we have the operational water requirements that are really the lion's share which are cooling, whether or not cooling is being used, and then also whether or not you need to replace water in the resevoir that you're using in that cycle as you will lose some of that water through that process. So in many cases for geothermal technologies you're actually able to use that reservoir fluid as your cooling water. And so in that case you could potentially require large quantities of water because the efficiencies are overall pretty low due to the temperature of the fluid, but you're able to not use fresh water you're able to use this geothermal brine.

Chris Nelder: The produced water.

Jordan Macknick: Yeah exactly. You can use that so you're not really affecting the freshwater amounts. However if when you are using this geothermanl fluid and you are operating this plant long enough and the reservoir is not as full I guess as you thought it might be, you start to lose some of that water in that reservoir and it might leak, it might go somewhere else that you're no longer able to use it. So you might have to replenish your water supply with an alternative source. And so there is examples of using municipal waste water in California for example to help replenish that reservoir to make sure you have enough water and it's at the right pressure to operate.

Chris Nelder: That reminds me they're actually taking some of the wastewater from the wastewater treatment plants and pumping it down into the Geysers facility.

Jordan Macknick: Exactly. Yep. And that's due to the fact that you have a loss of reservoir pressure because you're losing water whether through evaporation or underground leakage. And so then or it's a great use of of that municipal wastewater and it allows the geothermal facility to keep operating.

Chris Nelder: So what about concentrating solar thermal, why does that need so much water?

Jordan Macknick: So concentrating solar thermal power it also needs a lot of water due to its lower thermal efficiency. One of the reasons is due to the limitations of our existing metals and technologies, we're not able to get as high of a temperature as we might want to have in order to power that steam cycle process. And so just inherently we're going to have a lower temperature and a lower efficiency to start up. In addition to that though, concentrating solar power facilities are often located in very hot very arid environments and that puts a lot more stress on the thermal efficiency of these different power plants. And so any time you have any sort of power plant that's operating in the middle of the Mojave desert, it's going to be less efficient than if it's operating in northern Minnesota where you have much cooler ambient conditions, and so that's really a function of the technology constraint in itself and of the regional climatic and ambient conditions.

Chris Nelder: OK. So it's really about the size of the temperature delta.

Jordan Macknick: Right.

Chris Nelder: OK. That makes sense. I never thought about that. So an important benefit of energy transition is that by transitioning from conventional thermal plants to wind and solar PV we'll reduce the water demands of energy because wind and solar PV don't consume any water. Now most solar thermal plants like the concentrating solar thermal plants were just discussing do consume as much water as a coal or nuclear plant because they're cores they're still using conventional Rankine cycle generators to generate electricity. But some of the newer solar thermal plants like the Shams 1 plant in Abu Dhabi, which I have visited, are actually air cooled. So how significant do you think that aspect of energy transition is? How much can switching to air cooled plants and wind and solar PV help reduce our water demands?

Jordan Macknick: First off, it can have a major impact for individual technologies. If we're talking you know having a concentrating solar power facility that's air cooled versus one that's wet cooled, you're looking at a 90 percent reduction in water usage. Similarly if we have natural gas or coal fired facilities that are air cooled, we're also looking at about a 90 percent reduction in their water. So individual plant level can have a major impact on reducing that water intensity. The important thing to consider with air cooled facilities though is the fact that there are going to be costs in efficiency tradeoffs. And so you are looking at a cost penalty and an efficiency penalty when implementing dry cooling, and unfortunately for concentrating solar power the efficiency penalties are happening during the summer months when it's hotter and dryer than it is throughout the rest of the year. So you're looking at you know five to 10 percent impact on your efficiency happening during the summer times. And so that can become an issue and is something that power plant operators and planners have to consider when looking at what is the best type of generator for my area. And when you look at dry cooling a coal facility or natural gas facility you have to also recognize that those efficiency penalties then correspond to greater emissions of carbon dioxide because you're essentially burning you know the same amount or more coal to get the same amount of generation with an air cooled facility as with water. And so you always have to be considering these climate and water and energy tradeoffs when we look at the push and the move towards dry cooling. But I do think we are going to see a lot more instances of power plants being built with air cooled condensers. I think one of the benefits that you do have with air cooled condensors despite the efficiency penalty, despite the capital costs intensity, is the fact that you now have a drought proof power plant and that can be worth much more money than than the initial amount of cash because you might say from the beginning. And so we are seeing certain institutions certain utilities moving towards more dry cooling because it gives them that buffer and that safety net if there is a drought, if there is something that happens to their supply of water.

Chris Nelder: So another important implication of the energy-water nexus is that as climate change continues to diminish the amount of rainfall and snowpack around the U.S. it will actually reduce the amount of energy we can generate. I believe the Pacific Northwest actually had problems with this where they had to temporarily shut down some of its hydro plants this past winter due to a lack of rainfall, which of course was unheard of in a place like Seattle. It was the first time that it ever happened there. And over the past decade or so we've actually seen numerous instances of coal and nuclear fired power plants being forced to shut down because they had insufficient or insufficiently cold water available. Offhand I actually remember nuclear plants in Connecticut and Florida having to shut down for lack of cold water in the past several years. So with record heat temperatures being set year after year now and rainfall becoming less predictable, it seems like this is a risk that's only going to increase. So what's your outlook for how much of our power supply is actually at risk of being shut down in the future for lack of water?

Jordan Macknick: And that's a great question. And that's something that the Department of Energy has recognized is an important issue to consider going forward and we helped the Department of Energy with the report looking at climate change impacts on the energy sector and how the energy sector might be affected in the future. Now it's a very very difficult to predict for specific power plants whether or not they will be shutting down due to elevated water temperatures or there not being enough water because there's a variety of factors that are playing into those decisions and into the conditions that might lead them to shut down. One of the issues that we've been exploring at the lab is what happens if there is a heat wave or a drought or a concurrent drought or heat wave which power plants will be affected. And if there are cascading effects from one power plant leading to another. And so in many places especially out in the Eastern and the Midwest you do have power plants that are located on the same river and one might be downstream from the other, and so if another power plant is releasing hot water into the system, the power plants downstream will be affected by those upstream power plants. And so then it becomes a game almost you know especially if they're owned by the same utility of changing the output of one power plant to affect our plants downstream less. And so this is an active area of research that we're looking at which is the how to best quantify what conditions really lead to certain power plants having to shut down. Almost more importantly than than just one power plant shutting down, we have to look at what happens if we have a whole system or a whole series of power plants that go down in one region. And so our energy system is designed to be resilient and we have a lot of backup power that can handle power plants when they have to unexpectedly shut down. But if we're looking at a number of large generators let's say coal and nuclear facilities that are large baseload facilities that has to shut down or curtail generation due to the elevated water temperatures or not being enough water, that's a stress on the system that you know we really haven't seen yet. But what we're doing right now is exploring different climate scenarios to see what's really a tipping point and what conditions might lead us to one of those cases where we could have multiple power plants in one region having to shut down.

Chris Nelder: So are we not quite to the point yet where we can aggregate this data and really quantify it?

Jordan Macknick: So we are not at the point where we can really say that there are 75 power plants that we'll have to curtail or shut down in the year 2020. What we are at the point though is, what we can say is that there are a certain number of power plants that are high risk. And we know this because we've done some research looking in the past is about 40 different power plants that have had to curtail or shut down due to these water issues in the past decade, and so those power plants are certainly at risk. And there's other power plants that are either downstream from there or in other areas where we really see that water will play a role in their successful operations. But it's hard to say in the year 2025 or 2030 this number of power plants will have to shut down. We just know that they are at risk. And when the conditions align in terms of a drought and a heat wave you know that's when we know that there were much more likely to see curtailment events. But I will say the energy sector is moving in a way to become a little bit more resilient in terms of these water related curtailments and shutdowns and that's partly due to the fact that there are EPA regulations through the 316B of the Clean Water Act that are leading to a less dependents on once-through cooling. So once-through cooling are cooling technologies the types that withdrawal large quantities of water and then discharge that water back into the system at a much much higher temperature than what it was withdrawn. These withdraw 50 to 60 thousand gallons for every megawatt hour of electricity generated. So it's a lot of water that's being withdrawn and then a lot of water gets put back in the system at temperatures approaching 100 degrees in many cases. And these types of systems also have a large impact on aquatic habitat and aquatic life, and the EPA has been moving towards retiring these sorts of cooling systems. And so these cooling systems are the ones that are generally most at risk due to the water temperature concerns. And so I think we will see two opposing trends as we go into the future. One is the climate trend which is making the water hotter, making the water less available for the power plants, making the power plants less efficient through the higher ambient temperatures. But counteracting that is the trend in the power sector towards removing once cool facilities and moving towards the recirculating cooling or the cooling tower cooled facilities. And so these have a much lower water requirement and also have a lower impact on water temperature. And many of the facilities that are once-through cooled are coal facilities that are scheduled to be retired in the next 10 to 15 years in any case. And so I think we're going to see some opposing trends where in some areas you might see more curtailments, in other areas those power plants that we're curtailing in the past will be retired in the next 10 to 15 years.

Chris Nelder: Interesting. So let's switch context a little bit and talk about oil and gas. We use a lot of water to produce energy through fracking. Millions of gallons of water down a single well and fracking operations. And of course we now have tens of thousands of these wells across the country. Producing synthetic oil from tar sands also consumes a vast amount of water and petroleum refining consumes a lot of water. Even coal mining requires billions of gallons of water a year. So have you looked at the water demands of producing fossil fuels and do you see any particular risks in our ability to produce fossil fuels in the future if water supply diminishes?

Jordan Macknick: So that's a great question and it's an area that we have been exploring in the past couple of years. Although millions of gallons are required for hydraulic fracturing, although billions of gallons are required for coal mining, coal washing, etc, when we look at the total amount of water use on a per energy produced basis, so the total gallons of water used every megawatt hour of electricity that could be produced with that primary energy source, what we're seeing is that the water consumption requirements in the power plant are still about 10 times greater than the water requirements at the mine or at the wellhead. And so that's something that hopefully will put into perspective how much water is actually used at power plants and why is such an important consideration. You know we have definitely seen certain areas in Texas where there is a concern over the amount availability of water for hydraulic fracturing and that really brings home true the statement that water is local. In some areas there will be sufficient amount of water to handle water requirements for coal mining, for uranium mining, for hydraulic fracturing, for conventional gas development. But in other areas there is not sufficient water. And so what happens then is that the developing companies have to find a way to transport water to that wellhead, which could be through trucks or through pipelines, both of which can be challenging from a permitting perspective and from a community engagement perspective. Or they have to move elsewhere or come up with some other creative infrastructure project. And so there are plenty of examples in Canada also in Texas where there's a lot of water that's being reused from oil and gas operations, so the produced water that comes out of the well can be treated and can be transported to other facilities which has the effect of reducing the freshwater demands in the area. But again what we try to do is put this in context and we do note that although 10 times more water is used at the power plant than at the mine or at the wellhead, in many cases there are stresses at the wellhead because for hydraulic fracturing in particular almost all of the five to six million gallons per well that are used are used all basically at the same time over the course of a couple of days. And then that one time water use basically will be enough to supply the gas development for the rest of the lifetime of that well. So that's a lot of water that happens in one particular area all at once. And so there can be very important regional stresses and regional implications of that water use. And so although we talk a lot about gallons per megawatt hour in terms of the water intensity, one thing that that doesn't capture is that important local piece of that water use as well as the the timing of that water use. Is it use over the course of 30 years like water for coal mining is or is used over the course of three days like it is for hydraulic fracturing.

Chris Nelder: Well yeah and the one part of the fracking complex in the United States that's still doing alright. There's the Permian Basin in Texas. So this is an arid area. Likewise for some of the shales in the Denver Julesburg basin here in Colorado. You're talking six million gallons of water per well and contaminating it basically in one shot and then it generally goes off to a disposal well where they're injecting it into the ground and planning to just leave it there because it's now contaminated. I mean although you're correct that the water can be taken out and cleaned up and then reused in other fracking operation, I'm not aware of that happening almost anywhere because it adds cost. And right now all the frackers are struggling to make a dollar at all. So they're not actually looking to add cost and of course the states where all this fracking operation is going on are dependent on the revenue from those oil and gas producers and they're not eager to lard on some costs for these guys either. They don't want to kill the goose right. So you know I'm not even seeing any regulations being suggested that would require the water to be cleaned up and reused instead of just disposed.

Jordan Macknick: You're right about that that the regulations are not always requiring the water to be reused but there are a number of companies throughout Texas and in Colorado that are reusing it and they're reusing it voluntarily and they're reusing it voluntarily partly because it might be the best cost option for them given how far they might be from a disposal well. But it also might be a result of some of their community engagement. So in our work with oil and gas industry we really notice that they've been putting a lot of effort towards community engagement, really understanding what will local communities might want or need. And in many cases that is a productive use of that water. And so although they're not very good statistics or good data available on it many companies are reusing their water for additional hydraulic fracturing jobs. The challenge though is that with all the amount of produced water that's produced it's still not 100 percent enough to cover the amount that you would need for a new well. And so there's still going to be some sort of additional water that's going to be required whether it's fresh water or municipal waste water that's used in those operations. So their reusing the water doesn't 100 percent negate the need for new fresh water but it certainly reduces the amount required. And I will say another issue that I think the oil and gas industry is facing is the risk and liability issue over the reuse of that water. In many cases due to the existing regulations and existing risks associated with transporting water that does have contaminants in it there is a risk if there is a spill you know that they could be liable or if the water treatment that was used on it was not sufficient and the water was used for a productive use and someone got sick or something got contaminated. You know they're looking at a lot more risk and you know they could face heavy fines and so in many cases the safest that for them is to dispose of it in a disposal well. Like I said a lot of them are looking for any way in which they can to reuse this water and in some areas they have developed partnerships with local farmers who are using water productively not for growing food crops for humans but for growing other types of crops that humans won't consume. So there are some productive uses of this water that are being used but oftentimes it's a difficult challenge for them to figure out liability and the risk management.

Chris Nelder: But that doesn't sound like we're quite at the point where we're actually looking at water as a real constraint on oil and gas fracking.

Jordan Macknick: No. And one of the reasons why that is is that in Colorado but in basically the western states if the oil and gas sector wants to get water it's very willing to pay for it. And you have a number of different agricultural communities where you might have aging farmers whose kids or grandchildren that don't want to take over the farm and they could keep struggling it out or they could sell their water rights at a price that's three to four times what another farmer might pay for those water rights and it comes across as a bargain for oil and gas companies. And so there's plenty of opportunity for oil and gas companies even in arid areas to get water from the local agricultural communities.

Chris Nelder: That's incredibly complicated stuff there. There's a lot of moving parts there. OK. So we have several ways to generate electricity without fossil fuels or nuclear plants. But when it comes to water we don't really have many options other than conservation. I mean even drilling deeper has its limits, we can actually actually become a dangerous dependency as we're discovering with the Ogallala aquifer. Once you've consumed fossil water, it's gone forever. The only real option for producing more water is desalination. And I've written off desalination as being impractical in all but the most desperate and extreme situations like in the Middle East where they consume millions of barrels of oil per day and billions of cubic feet of gas per to desalinate water. It's incredibly expensive to do. And I haven't seen it as a practical option except where there aren't any other options. But there seems to be more interest in desalination now including desalination powered by renewables. So what are your thoughts about that? Is it an economically viable pathway for energy transition?

Jordan Macknick: So the key factor with desalination is that it gives you a very reliable source. It might not be the most economically attractive option but it can be considered one of the most reliable options because that ocean water will always be there or the brackish water underneath us will also basically always be there as well. And so I see seawater desalination as becoming important globally. I don't see seawater desalination as becoming as important in the United States over the next couple of decades. What I do see becoming important United States for the next couple of decades is brackish water desalination. So this is groundwater that is naturally brackish, naturally a little bit salty, it might be about a mile down below our water table, but it's about half or less salty as seawater itself. And what that means is that it takes about half to a fifth to a tenth of the amount of energy to desalinate as seawater. And so in many areas of the arid Southwest such as Arizona, New Mexico, Texas, you know especially, they have vast reservoirs of brackish groundwater that they could use and that they likely will be moving towards going forward. And you know as I mentioned it requires a lot less energy to produce, it's a lot less stress on some of the membrane technologies that are used for desalination and so I see this as an area where there certainly will be more focus being put on this because right now Arizona you know is basically surviving through the Central Arizona Project, the CAP, which transports a lot of Colorado River water to feed places like Phoenix and Tucson. And they're predicting by the year 2050 to essentially need another Central Arizona Project to supply all their water needs and building another Central Arizona Project could be politically untenable as well as extremely expensive. And so a feasible option for them could be moving towards pumping up the brackish groundwater and then treating it and using that for all of its different purposes. And one of the things that we're looking at at NREL is how do you use renewables to smartly power these types of desalination. So we're looking at actually integrating renewable energy with not only with seawater desalination but also with brackish water desalination systems. And this could be through solar power, can be through wind power, can be through geothermal power, using basically using both electricity that's produced from wind PV and solar and geothermal technologies as well as the thermal energy that's produced from concentrating solar power and geothermal technologies to power these desalination activities. And it certainly is a challenge because you have variable renewable generation that you are trying to integrate with the water treatment system that generally likes to operate either on full power on and then shut off and is not entirely used to ramping up and down when you have very little renewable generation on the system. But we see it as a very promising area and especially as we see more and more renewable deployment there are many areas in California and in Arizona especially where during some months you might have too much rooftop solar power on a system that it starts eating into your base load power like your nuclear generation or natural gas generation depending on where you are, And there is one approach to having too much solar on a system is to curtail that generation and to you know basically shut it off. What we've been looking at though is how can we use basically a smarter grid to use that excess generation to power desalination technologies. It could be any industrial process really but we've focused on for the state of Arizona how to use excess solar power to power desalination technologies during that time. And you can do the same with wind power at night, you can do the same with concentrating solar power as well. So there's a lot of different opportunities that we see that I think are really exciting and that are really at the forefront of the research. You know it's certainly going to be an issue internationally. There's a lot of areas that do not have sufficient infrastructure or sufficient water resources for their populations and they are in those desperate situations where desalination really make sense. In the U.S., like I said, it's going to be a much more localized process and we're probably going to see much more brackish water desalination in the U.S..

Chris Nelder: Yeah that's interesting that you bring up the concept of using water treatment and water processing as a flexible demand asset. You know something that we've discussed in a couple of previous episodes, I think it's an interesting question as is the question of how we really should be using the water. Like I grew up in Tucson. The whole time I was growing up researchers at the University of Arizona would put a big loud warning that would appear in the newspaper about every six months saying our groundwater water table is dropping, it's dropping, it's dropping. It's going to be gone by X year, right. We've got to do something about this. And of course no one ever did. No one ever did anything about it and we continued building golf courses. And so you're out there irrigating golf courses and a place where the temperature gets to 115 degrees in the middle of the day, which just seems like utter insanity. I mean if you're going to be doing brackish ground water desalination for household uses in Tucson, I could maybe see where that would be you know an economically viable alternative, but you can't really go down that path without also looking at all those freakin' golf courses. What are we really trying to do here? What are we using these water for? I mean I think that's an important question here.

Jordan Macknick: Yeah and that really gets to the point of policy planning and thinking about if we do have a limited resource of water what are the best uses of it. In the West we face a challenge with prior appropriations system for water rights where first in time first and right. And so if someone stake the claim and wants to grow cotton in the arid Southwest because they've had the water rights and had been doing that for the last 120 years, they are allowed to do that. And I think that rubs some people the wrong way because they think well you know look at all that water being used for cotton that's really benefiting that one farm where that could supply enough water for a small city for example. And so that certainly is a major concern and it's a very touchy subject in the West and it's something that we are addressing when we look at developing concentrating solar power projects in the Southwest because those as we talked of before if they're wet cooled can have a higher water intensity than the nuclear power generation. But when we actually compare the amount of water that's use per acre per year with things like golf courses or fruit orchards or alfalfa or cotton growing, we see that developing these energy projects actually saves water in that area. So it's a bit of a shock to people because they don't really think about how much water goes into agriculture. And so in this specific example with concentrating solar power, although we say it consumes relatively a lot of water, it's still a small amount of water compared to how much is used per acre on golf courses and in many agricultural fields. So it becomes a very difficult policy challenge as well as you know a cultural challenge because there's many areas that are very proud to be agricultural in nature and it's not going to sit well with them if you try to remove agriculture operations from that area.

Chris Nelder: Well exactly. I mean you know you think about fourth generation cotton farmer in southern Arizona potentially losing his livelihood. You know and then you have to think about well gee, that's not like a fourth generation coal miner in West Virginia being threatened with losing his livelihood now. I mean this transition stuff is difficult on a lot of people in a lot of ways but it's clear enough to me that our energy transition strategies should be grappling with these challenges especially the energy-water nexus in an integrated way you know where we're as you say we're thinking about all the different uses and all the different aspects here and trying to come up with some sort of an integrated policy that deliberately reduces our energy and water demand simultaneously. And I think there's a huge untapped opportunity for example in using water pumping in wastewater treatment facilities as demand response assets as we were just talking about not just to absorb excess solar production in the middle of the day for example but as a grid balancing asset more generally, particularly as renewables make up a growing share of power supply. So do you think there's a need for this kind of integrated system modeling for looking at things like demand response from a water angle? And if so what kinds of water related research per pilot projects do you think we should be undertaking as a part of energy transition?

Jordan Macknick: I absolutely think we need to do more on this. It's an area we've just begun research on actually. But it's really in its infancy. We have put out one paper at the lab looking at the Energy Services that different water and wastewater treatment facilities can provide to the grid. And we've also been partnering with local utilities and exploring how different water and energy utilities can interact better and coordinate better. Because there have been some examples where water utilities have taken advantage of demand response programs by an energy utility, but you know these are mainly opportunistic for the water companies. You know they shift their pumping or some of their treatment to a different time of day in some cases.

Chris Nelder: Because they're on a time of use rate and they can save some money by doing so.

Jordan Macknick: Right. But it's not really optimized for the grid. And so that's the challenge that we're trying to undertake is how can we help water utilities and energy utilities work together so they can co-optimize their energy and water systems. So water utilities have a very important job of providing a clean reliable supply of water. They do not want to do anything to jeopardize that primary mission. Energy utilities on the other hand have had a similar mission to produce energy that's reliable and always available to customers. They don't want to jeopardize that. So we have been brokering you know some of these conversations where we're looking at how can we recognize and quantify the benefits that water utilities can provide to the grid that still allow them to meet their primary mission. And how can the energy sector really benefit the best from these water utilities. And I think there's a number of things that have to happen and these can happen sequentially as well as concurrently. And we're in the process of doing some of these right now. And one of the things that needs to happen is just modeling of energy and water systems. And I think it would be shocking to most people to realize how complicated, how many different miles of pipes and how many different pumps there are for a water utility and how challenging it is for them to manage all these pumps and pipes and reservoir levels to make sure that they do have fresh tasting clean good water available for people at any time of the day. And so there's a lot of modeling needs to happen in terms of modeling their system and linking that up with energy utilities system. And then where we'd start getting interesting in where we start talking about testing. So let's say we can model a system, then we want to use some actual equipment to test to see if oh can we change the operations of this pump or change the operations of some of this water infrastructure and see how it affects different parts of the grid and see how it can affect the regulation characteristics of the grid. And we can do that without actually using their equipment themselves, but if we have a test or a pilot scale laboratory, we can actually use real water equipment and link it up with a real grid and see how this equipment actually performs and functions and affects the grid. And at NREL we do have our Energy Systems Integration Facility, or ESIF, building where we do have capabilities for having hardware in the loop in a little electrical micro-grid that we have there where we can look at actually implementing certain types of water treatment technologies or pumps or other sorts of water equipment in the system and actually operate it at the grid scale level. And so that's you know what we see is kind of the second step after that first modeling happens. And then the last step that we see is partnering with facilities on the ground and having some test cases with actual equipment with those utilities themselves. And so that's what we're trying to gear up for. We're all prepped and ready for the other pieces. But I will say that one of the major challenges that you face is that water utilities and energy utilities have these primary missions that they do not want to jeopardize at all. And so they are very reluctant to try new things, new technologies, unless they're you know 100 percent certain that it will work. They don't want to be the first one to test it out, they want to be the 14th and 15th one to test it out after it's already gone through its testing phases and it's been demonstrated to be successful elsewhere. And so I think it's something that we will get around to and it's something that I think if we can find the right progressive and the right forward looking water and energy utilities it's something that we can certainly demonstrate because we do think that there is a lot of opportunity for water utilities to improve their energy management, so they save money, the water ratepayers save money and a lot of opportunities for energy utilities to get energy services from water utilities which you know really helps them with their grid management and with the maintenance of their facilities. And so it's only a matter of time before we can do some demonstration pilot studies.

Chris Nelder: That's a great point and it's a good thing you've got that snazzy facility that I toured over there ay NREL you can actually do those kind of real world testing of you know grid scale power and see how this stuff actually works. Because you're right, I mean these are fundamentally conservative organizations. Their number one remit is total reliability and availability and no interruptions. And so they're not eager to get out there and start testing some of those stuff. You know on a similar note of integrated planning, should we not be including water now in our planning for energy. We haven't done any serious national energy planning in this country since the 1970s, but such as it is shouldn't we be pushing for wind and solar PV and air cooled thermal plants as a deliberate policy priority, particularly in light of climate change. Or more generally what kind of policy prescriptions does the research on the energy-water nexus suggest?

Jordan Macknick: So this gets back to the fact that water is local. In some areas, yes, they are drought prone. There's not a lot of water available for any users and so the water used by the energy sector has an even more important role. And so that case it could make a lot of sense to have load zero water using technologies. In other areas so that they might not be as stressed out with water and so there might be sufficient water that's available to operate wet cooled facilities. And as we mentioned earlier those wet cooled facilities have a higher thermal efficiency than the dry cooled facilities, and so you know it would be more cost competitive to do that. But also when we start factoring in climate change, if we're talking about natural gas or coal facilities, you're going to have lower emission rates with these wet cooled facilities than you will with air cooled facilities. And so there's always tradeoffs that have to be considered but I think you're right that they have to be considered together, and that's something that we're not seeing happening enough is that we have an energy policy in a state or we might have a water policy but there's not a lot of coordination among them. And we might see some unintended consequences or tradeoffs where we you know we have a water policy that then conflicts with a climate or carbon policy or vice versa. And so what we're seeing from our research is that the water characteristics on water constraints are very local. And so we need to make sure that when we are developing coordinated policies you know they are really taking into consideration those regional dynamics. And there's some good examples we can look to and I think internationally, for example, South Africa has had a coordinated energy and water policy for a while now, and all of their new power plants that are being built are required to be dry cooled and they've gone through that. In many areas of the Middle East they have water and energy ministries that are the same ministry that handle the water energy because they are so linked and they are so important. And so I think one of the challenges in the U.S. though is that there are so many different agencies on the federal and state level and local level that have their finger in water. And so there's all these different agencies and groups that must coordinate and that makes it difficult for them to come up with a coherent water policy, much less linking that water policy with an energy policy that is also consistent. So I think there is a lot that can be done and I think people are starting to recognize it and I think really the drought in Texas in 2011 and the recent California drought actually brought a lot of these issues to the forefront and made people outside of just Texas and California start considering these issues. And we're seeing a little bit more effort by states in areas to actually focus on how can we incorporate these water concerns into our energy policy because I think when they're looking out to the year 2050 and they are seeing wow our population is going to be double, we're going to require a lot more water and a lot more energy, and where are these resources going to come from. I think it makes them a little bit nervous. And so you know I think this especially highlighted in the state of Colorado too where you know the recent Colorado water plan that came out you know had an explicit section on the water needed for the energy sector. And I think that's great that many states are starting to really get very explicit and very focused about these connections between energy and water sectors.

Chris Nelder: Well I guess that raises the next obvious question which is if we're going to start as a matter of energy policy switching over to air cooled plants, how much does it cost? I mean is this even an economically feasible strategy especially if you're talking about big coal and nuclear or natural gas plants?

Jordan Macknick: So the cost is a concern, but you know that the cooling system can probably take up about 10 percent of total capital costs for a new power plant. And so even if you're doubling the cost of the cooling system, it can be a major investment, you know but those costs are also you know looped in and wrapped in and advertised over the course of the lifetime of the plant. And so I don't see cost as really necessarily the ultimate barrier to air cooled condensers or to dry cooling if there's a significant enough water challenge. You know, if there needs to be power in a certain area, utilities will make that investment to build air cooled condensers. What we're seeing though is that oftentimes that only happens really in the most desperate of situations. What we're seeing much more frequently is that if there's not enough water available in an area, either now or if the availability could be at risk in the future, what we're seeing is that the utilities might just develop that power plant in another area that has a more reliable supply of water and then build that extra transmission if it's needed. And so in many cases that might be the more cost effective option than actually building a dry cool facility.

Chris Nelder: Interesting. So if it's only, yeah, if it's only 10 percent of the capital cost of the plant then probably the bigger impact would be the reduced efficiency of the plant over a long period of time, you know from an economic standpoint.

Jordan Macknick: Right.

Chris Nelder: OK. So borrowing from the concept of megawatts, energy you don't consume, I wonder if we shouldn't be looking at water in a similar way. For example instead of investing in desalintion in Southern California, maybe it would be better to reduce the freshwater demands of the energy sector by investing in more solar PV? I mean are there any interesting models or pilot projects looking at mega gallons?

Jordan Macknick: So you bring up the example with California, which I think it's a good opportunity to really put the energy use, the energy sector's use of water in perspective. You know I think a better option, or potentially a more effective option than reducing the amount of water that's being used in the energy sector might be to look at how can we reduce the amount of water being used in the largest user of water in that area which is agriculture. You know how can we be more efficient? How can we not necessarily reduce the amount of agriculture that we have in that area, but how can we be more efficient in those areas and how can we look at being flexible with the water rights situation in that area to use water more effectively. And I think that's because you know in that area the water requirements of the energy sector are minuscule compared to domestic demands as well as to the agricultural demands. And so the challenge with dealing with the energy-water nexus is that you know water is used by so many different sectors and energy is just one of those. In some areas energy is the you know the dominant users, in other areas energy is very much a marginal user. So it's really helpful to look at what are all the different water users in these areas and really look at water management from a holistic perspective looking at all the different water users in that area. So energy plays one role in that, but is not really the driving factor, at least in that southern California area. But in any case I think that there are a lot of interesting programs where you can look at what are the water savings of my energy efficiency actions? Or, similarly, what are the energy benefits of my water reduction strategies? And so this is an area where I think California is probably leading the way in terms of linking these sectors and really trying to make that connection that if you save water, you're saving energy. And if you save energy, you're saving water. And really looking at how can we quantify the water savings from energy efficiency options and quantify the energy savings from water saving options I think remains a challenging area and an area that if we could find great quantitative data on it, I think we would see more and more states adopting policies and adopting incentive programs that would encourage this simultaneous reduction of both energy and water.

Chris Nelder: Well OK, so if data is the key thing then what's your view of the state of research today on the energy-water nexus?. Do we have the data we need? Is the data getting through to policymakers? Are we adequately taking water into account when we make policy decisions about energy? And are we actually taking energy into account we make policy decisions about water?

Jordan Macknick: Data is one of the biggest challenges we're facing in the energy-water research world, in the water world especially. Fundamental data related to how much water is in the stream, what is the temperature of that water, how much water is being used by different sectors is oftentimes not available, not reliable, not at the resolution that you need, not at the time frame that you need. And so that has been one of the biggest challenges we face is that availability of water data. And this is not to say that there's not a lot going on. The USGS does a great great job collecting data. States do a lot of work. Regional Water offices do a lot of work as well. But oftentimes the data that they collect is not consolidated in the same location, they might be using different or inconsistent spatial units and linking them together remains you know a terrible terrible challenge. And so that's one area that we see could really really benefit energy research, and I think overall water management in states as well is having improved data collection and data monitoring on the amount of water that's there that's available that's being used et cetera. I think that piece could really help out not only researchers but then also policymakers. And so policymakers you know will get certain summaries of data, but I still don't think it's really at that level that it needs to be for this integrated policy and integrated planning that we are just talking about. I think the level of the quality of data for the energy sector is very high. You know we collect a lot of data, it's monitored, it's measured. That's partly because we pay for it, we pay a lot for it. And you know it's measured and we can get real time data of how much energy we're using in all of our homes right now. That same level of technology and interest is not there for the water sector right now. Part of that is due to the pricing of water. Part of that is due to there being legacy infrastructure where we just don't have the ability to capture that granularity level of detail. But I think going forward we're going to need to have that granularity. And I see it as we move towards a connected world of connected homes. And I see when we have a real smart grid you know where you're plugging your electric car into your home and it's charging or discharging, depending on what's needed, I see water as a crucial part of that smart home and of the smart grid. And in order to make that happen though we need to have improved data collection, data monitoring, data availability on that water side to really link it in so it's up to par with the level of quality of data collection that we have on the energy side.

Chris Nelder: Sounds like an important opportunity maybe for the academic world.

Jordan Macknick: Yeah. Academic world, utilities, I think, labs. I think there's a lot of different people, a lot of institutions that could really play an important role in this future direction.

Chris Nelder: All right one final question. Does it bug you as much as it bugs me when people say desalinization?

Jordan Macknick: There are some very very well known and high level people who do say desalinization, so I try not to publicly criticize it.

Chris Nelder: I don't know how the Z gets there, man. It drives me nuts.

Jordan Macknick: Yeah.

Chris Nelder: Well listen Jordan, this was a lot of fun. Thanks for talking today. You've got a wealth of knowledge there and it's such a deep subject. I feel like we just barely scratched the surface of it. Might have to have you come back and talk about some new research in the future.

Jordan Macknick: I'd love to. This area is just getting started. It's in its infancy. There's got to be a lot more year after year after year.

Chris Nelder: Awesome. All right thanks a lot Jordan.

Jordan Macknick: Thank you.