[00:00:22] Bridget Scanlon: I'm pleased to welcome Nathalie Voisin to the podcast. Nathalie is the Chief Scientist for Regional Climate Energy Dynamics at the Pacific Northwest National Lab, which is a US Department of Energy Research Center. And today we are going to talk about linkages and interdependencies between water and electricity within the context of droughts and floods and climate extremes, as well as evolving infrastructure .
Thank you so much, Nathalie, for joining me. I really appreciate it.
[00:00:59] Nathalie Voisin:Oh, thank you, Bridget. I'm really excited to join your podcast.
[00:01:02] Bridget Scanlon:So Nathalie, we've known each other for quite a while, and I really admire the work that you do at the interface between water and electricity and look at all sorts of aspects. I think you were recently visiting Kosovo as part of the US delegation. I would love to hear a description of what you all were doing there and what the challenges were.
[00:01:24] Nathalie Voisin:Oh yes. That was back in 2020, so there was COVID, but there were also other things happening. And this is a water-energy nexus story, really. At the time, there had been a Washington agreement between Kosovo and Serbia and they agreed to coordinate, and one of those areas of coordination was the management of a lake. And that lake is Lake Ujmani/Gazivode, which is a 15-mile-long reservoir that crosses the border between Serbia and Kosovo. It was built in the sixties, but it was managed without a transboundary cooperation agreement. This is where the US DOE (Department of Energy) Office of International Affairs came to PNNL (Pacific Northwest National Laboratory) because we had this expertise. They asked us specifically, "Can you evaluate the opportunities for managing this lake and then provide some recommendations?" I got the opportunity to join a US delegation and go there. This was the trip-of-a-lifetime where you get to visit the reservoirs, the power plants, and meet all of those different users.
Let me talk a bit more about what was happening here, like what is the water-energy nexus? This reservoir here is really managing water coming from different countries. The hydropower coming from this reservoir isn't much—it's only 2% of the electricity generation for meeting Kosovo's electricity demand. The story is in the release from those reservoirs: about 30% goes into a canal that runs south for hundreds of miles and feeds major cities in Kosovo, and most importantly, two thermo-electric plants. Those two electric plants provide 95% of the generation for Kosovo's electricity demand. Just from those three plants, 97% of the Kosovo electricity demand is met.
So, our role was to look for recommendations. We met with operators and users, and visited sites. I think that it really helped to be versatile in both water and electricity to truly value the services provided by the reservoir; because water is providing cooling, as well as water supply and irrigation to the population, and contributes to electricity and potential energy transition in the region.
At the end of the day, we provided recommendations. I thought we would go in with new optimization approaches, but in reality, it was more basic: maintain the canals to prevent losses; build resilience in the water system by adding another reservoir to ensure reserves; improve predictability of inflows; and most importantly, establish a River Commission. You can have all the engineering and optimization tools you want, but for people to make decisions, they need trade‑offs. Beyond recommendations, the report provided ways to jointly evaluate the river services and electricity services for this River Commission, which was essential [for future success].
\[00:04:49\] Bridget Scanlon: That sounds like a lot of fun — going over there, seeing all this in action. The reality is that we can develop sophisticated models, but ultimately, decisions come down to people and fundamental analysis. It sounds like it was a great opportunity. You work on a lot of hydropower. Much of the electricity you focus on is hydropower, which is strongly linked to water. I was working on the Colorado River for a couple of years and looking at the data. It has been subjected to long‑term drought — a “megadrought” since around 2000.
Currently Lake Powell is at 25% of capacity and Lake Mead at about 33%. People often say that if water levels fall below critical levels, hydropower generation could stop. But when I looked at how much electricity those reservoirs produce, it seemed small compared to other sources in the region. Maybe you can explain why hydropower from those reservoirs is so important.
\[00:05:57\] Nathalie Voisin: Yes, and something I’ve read in the media that I want to clarify is that it’s not because one reservoir goes below the intake to the penstock that the grid is going to go black. There are two misconceptions: Does hydropower matter? Yes, it does. And don’t worry — the grid is still going to function without it [one hydropower plant].
Hydropower is very important. I’d like to refer to a book that many water resource managers have read — Cadillac Desert by Marc Reisner. It explains the role of the man‑made reservoirs in the West, built to support settlements and provide river services like flood control and water supply, especially for irrigation.
Hydropower [in the West] is a byproduct, but an important one. The electricity it provides supports the conveyance of irrigation water at a preferred price. The dams also subsidize flood control, recreation, tourism — a billion‑dollar enterprise — and maintain reservoir levels. All of this maintenance is funded by hydropower revenue. So hydropower is an entire enterprise. And that's why hydropower is important for many applications for the local economies.
\[00:07:52\] Bridget Scanlon: Right. The electricity they generate, and the revenue from it, supports reservoir operations and maintenance. These are Bureau of Reclamation reservoirs, right?
\[00:08:03\] Nathalie Voisin: That’s correct. And the same applies to privately owned reservoirs — they’re self‑sustained.
\[00:08:11\] Bridget Scanlon: We often talk about the water intensity of electricity production for hydropower. People sometimes assign all evaporation losses from a reservoir to hydropower, even though those reservoirs serve many other objectives.
Is it fair to assign all evaporation to hydropower and conclude its water intensity is off the charts?
\[00:08:44\] Nathalie Voisin: This question is a sensitive one. Hydropower subsidizes a number of services. The same issue applies to greenhouse gas emissions from lakes. Those impacts should not be fully allocated to hydropower because the reservoir provides recreation, flood control, and other services. Flood control in particular requires large reservoir fluctuations.
So no, I don’t think it’s fair.
\[00:09:22\] Bridget Scanlon: Many reservoirs supply water for irrigation, so it seems unfair.
\[00:09:28\] Nathalie Voisin: It is a bit unfair, but there’s no consensus yet on how to allocate these impacts.
\[00:09:36\] Bridget Scanlon: Right. I was reading Kevin Fedarko’s *The Emerald Mile* about the Colorado River — fascinating book. He describes how close they came to losing Glen Canyon Dam during the high flows of 1983 due to a small structural defect that kept expanding.
Our reservoir fleet is old — built mostly in the sixties and seventies — so reservoir upkeep is a big issue. I also remember the Oroville Dam incident in 2017 with the atmospheric rivers and evacuations. The Bipartisan Infrastructure Law provides funding for dam upkeep and infrastructure. Has hydropower been part of those programs?
\[00:10:40\] Nathalie Voisin: I’ll deflect a bit on whether the infrastructure is upkeep. Overall, infrastructure — river systems, the grid — was built decades ago and needs to be retrofitted and updated. One challenge for hydropower, compared to wind, solar, or thermoelectric plants, is lifespan. Other plants live 20–30 years. Hydropower plants last up to 100 years.
It means that right now, when we are looking into features for those dams, should they have a higher, bigger storage, a bigger capacity, or what will be the combinations of turbines; because there is more variability in the water. Should they be the same size? Should they be at the same height? What are the ways that you can get there? And there is a little bit of a disconnect on what the projections are across generation technologies.
We’ve been moving forward with the Secure Water Act. We released the third version recently, led by Oak Ridge National Laboratory, with PNNL contributing to the hydropower‑specific components. Long‑term projections are important because the hydropower infrastructure is there for a 100 years. The projections focus on future potential generation, but another uncertainty is how people will want to use hydropower. Hydropower is not just for generation; it helps operate the grid — providing flexibility, ramping, maintaining 60 Hz, and offering black starts. There are about 50 grid services that hydropower can provide. And different types of turbines are needed for different services.
Long-term planning for hydropower infrastructure is really challenging because it's not just the change on the grid, it's also the change on what the electricity demand will be. What will the different markets be like? What are the other technologies that hydropower is going to support? And what are the different water uses? What are the different institutions?
It's enough for a lot of researchers to work on it.
\[00:13:11\] Bridget Scanlon: Managing many functions is hard. You’ve been working at this interface most of your career — between water and energy — which means working with communities that use different terminology and projection periods. Can you describe a little bit, how that has evolved through your career? And how you got to understand how all of these different actors play together or trying to bring them together?
\[00:13:52\] Nathalie Voisin: My background is in water resources engineering, so I was pretty set on how it works on the water side. You get to understand the engineering compoent, but also what's important is the institutions. What is long-term planning, what does it mean for water? What is medium-term and short-term planning? What are the drivers of planning? Who are the players for each horizon of the decisions? And when I joined PNNL a couple of years ago, I was working on developing forecasts for hydropower reservoirs. I was working on further research proposals. I kept proposing more forecasting and modeling, and I was challenged [at the time] on why it [water forecasting] is important for energy systems [with respect to other drivers]?
So I got to learn in the field, and it was just really an opportunity [to grow] and I had great colleagues who helped me understand and guided me. I learned by analogy, connecting that hydropower is part of the river system, which is my training background, but discovering that hydropower was also part of a network, through the grid, where you also manage different resources. The grid also manages different institutions. I'm still learning! The grid is dynamic, because the institutions change. That's really how I learned, through colleagues, through great teams.
And yes, I lost my thought on that.
\[00:15:07\] Bridget Scanlon: It’s okay. It took me a while to understand the interface between water and electricity, and the fact that you can store water in reservoirs or in the subsurface or whatever. You can store water fairly easily but transporting it is difficult. Electricity is the reverse — easy to transport, hard to store. You work a lot with the Western Electricity Coordinating Council (WECC). Can you describe how that [interface] helps manage demand and supply? You mentioned earlier demand needs to meet supply at 60 hertz and the buffer is very small at microsecond level. When I went to ERCOT and I saw that big thing- 60 hertz, 50 whatever- it's pretty scary.
\[00:15:56\] Nathalie Voisin: Yes. I often describe the grid as a form of virtual water transfer. Hydropower provides many services, including storage — likely the most efficient long‑term storage because there’s essentially no efficiency loss between storage and operations.
\[00:16:27\] Bridget Scanlon: Just to make sure to resolve any disconnects between supply and demand load and whatever you call it.
\[00:16:33\] Nathalie Voisin: For that assessment, water is represented through assessment studies. There are multiple steps into understanding the long-term planning. There is resource adequacy and then there is reliability.
In the resource adequacy step, [important dynamics] are short in time over representative periods, the exercise is really going to be a bit about available capacity. So with hydropower, it's going to be understanding the operational capacity at strategic times. When it comes to reliability, this is where storage is going to be very important .
It took years [to learn about it]. I started engaging with WECC in 2015, attending meetings and working with their teams to understand how hydropower fits into the broader power system and understand tradeoffs justifying the modeling representation. Hydropower is one part of all of the other technologies that they have to plan for and consider. Initially, I thought we’d fully couple power system models with water management models, working on optimization. But the computational cost was too high and not needed for all regions. It took several years to build trust and understand what would be the level of representation with computational fidelity and cost that they would be okay experimenting with.
We came up with data sets. At the time they would only use observations and they were bringing data from different regions. We've been working and honestly, I have been growing with them on developing this business case and first demonstrating that a normal year, a median year, is very difficult to find. It's actually always wet somewhere and dry somewhere else. That reality was important for their reliability studies because if they were merging different water years together for test cases to be average everywhere…. what would happen is that, from the generation side on hydropower, it would be median generation, but studies would lose the quantification of cross-regional transfer needs. Like the virtual water transfers I was talking about. Here, such “median case” would mean that any science questions about reliability of the grid including transmission as a reliability asset would not be robust.
Things have evolved, and then we made the case on, how you have 20 years of drought, how to make a consensus on the selection of what is a representative drought. And this is really what is motivating a lot of my work with my team right now, the development of data sets that provide this inter-annual variability.
Also the selection, the guidance on selecting events that are going to be relevant for. Do you want to test how much storage you need in specific regions or do you want to evaluate what are going to be the transmission needs between virtual water transfer needs through transmissions between regions?
And so it's very rich.
\[00:19:26\] Bridget Scanlon: It gets complicated. Looking at WECC, California’s net imports account for about 20–30% of their electricity. So across the Western U.S., how many states are included?
\[00:19:40\] Nathalie Voisin: Eleven.
\[00:19:41\] Bridget Scanlon: Eleven, plus parts of others. Having that large interconnection increases reliability, right? You can bring power from elsewhere. But also, people talk about the reserve margin, you have capacity that exceeds your peak demand. I think most states try to aim for maybe something around 15% reserve margin. These are ways to make sure that you can tolerate different stresses.
\[00:20:11\] Nathalie Voisin: Yes. Maybe I can provide some background on this: What's happening is that on the water side, we're very familiar with the watersheds and the fact that all the precipitation that falls there is going to go out one outlet. With the grid, they have what we call balancing authority. In many other regions across the world, it will be one country. In the U.S., because it’s so large, each balancing authority must meet its own local load with local generation first, before relying on transmission. And that's pretty important because as you bring more wind and solar and technologies that vary and are very intermittent, it's very difficult to use the transmission. The transmission is a big machine and you can't go back and forth. You have to schedule- I'm simplifying- but you have to schedule certain directions. It means that depending on the generation portfolio for specific balancing authorities, you're going to have a need for specific reserve margin. That reserve is very regional. Regions with lots of wind and solar typically have higher reserves. In the Northwest, reserves are lower; in Texas, I believe they’re among the highest.
\[00:21:44\] Bridget Scanlon: With the deregulation, I'm not sure that ERCOT aims for 14, 15%, but I was just looking. So, you have a much different electricity portfolio and say for example, Washington State, you've got 60% hydro, 20% nuclear is it or something like that, and then thermo electric. ERCOT in Texas, we are a lone ranger. ERCOT is on its own, we have very few interconnects. I just wonder the Western interconnection and the Eastern interconnection a huge number of states and maybe that helps with reliability?
\[00:22:17\] Nathalie Voisin: Absolutely. The footprint matters. I mentioned earlier how you don't have a median year. It's always wet somewhere and dry somewhere, and that provides some of the early research I did. I demonstrated that the transmission between the Pacific Northwest and California, those interconnect transfers were actually linked with those wet and dry states. Very recently we updated that study showing the opportunities to provide climate information on how you could predict stress on the reliability [of the Western Power Grid]. So we evaluated El Niño and La Niña, where during a La Nina, typically it's wet in the Northwest and dry in California, and then El Niño is the reverse. Typically, you hear in the region, " Oh, we have La Niña or El Niño, it's going to impact our region." For their region, that is very true. It means that there will be, for example, less water over the Northwest. It doesn't mean that there will be issues with the reliability; it's just going to be more expensive because there will be less hydropower. But when it comes to adequacy and reliability, it just means the electricity will come from somewhere else. Actually, what we were showing is that it's during the neutral El Niño, when everything is dry everywhere, it was more a challenge for the grid. That was the grid from 2010 at the time. But the principle holds. Neutral El Nino is when you had the most stress because you could not rely on that regional variability to provide reliability.
\[00:24:04\] Bridget Scanlon: Interesting — we always hear about El Niño and La Niña, but the ENSO‑neutral years were the most challenging. We’re used to talking about meteorological and hydrological droughts, but you’ve described renewable droughts in wind and solar. Can you explain those?
\[00:24:33\] Nathalie Voisin: Yes! The research is very important and we've moved forward with describing and characterizing droughts and their impact on hydropower and thermoelectric plants at the same time. I've mentioned how the grid manages multiple resources. Considering hydropower and thermal electric plants at the same time was really important to show the vulnerability of the grid to water. But the power grid infrastructure has changed tremendously since 2010, with now much, much, more wind and solar. So it was time to also ask "What about those compound energy droughts in wind and solar?" And in particular - I always come back to water- the contribution of water, and hydropower, has changed from generation to ramping, to accommodate those renewable energy plants because hydropower provides storage as well.
It was strategic to understand and characterize what we call energy droughts, with the end goal to understand what the value of storage is. For energy droughts, we especially use the concept of the balancing authority. That's the right scale because of the implication on the decision making.
Cameron Bracken is on my team and has been implementing this work, doing great work, and showing how the energy droughts don't necessarily have the same duration across the US. ALso understanding the coincidence between those energy droughts across balancing authorities helps derive the need for transmission. It's not just about the future climate trends. Other people are asking us; are energy droughts going to be more intense moving forward? And the same thing with hydropower droughts. The difference with wind and solar is that the infrastructure is changing exponentially every year. And what we're finding is that, yes, those energy droughts are going to be more intense, because they're going to be more wind and solar. This research is opening the question of how to design and where you put wind and solar; not because this is where there's a lot of wind and solar potential, but in a way to reduce the intensity of those energy droughts.
Some places may seem less attractive from a single‑plant perspective, but from a system perspective, they provide diversity and reduce stress on the grid.
\[00:27:05\] Bridget Scanlon: That’s interesting. I usually think about wind and solar in terms of land access and permits, not system strategy. I liked your paper on water security, where you describe options for improving reliability at the plant scale and grid scale. Could you describe that?
\[00:27:45\] Nathalie Voisin: Yes. There’s a story behind that work. Fred Boltz was developing a special issue on water security with the theme that water is the master variable for resilience. He reached out and said, “Nathalie, water is the master variable for the power grid.” I said, “Well, you’re preaching to the choir, but many people will disagree. Let’s evaluate it.”
This paper is on water security, and we reviewed it at different scales. First, you have individual power plants, and then you have a regional scale, which could be watershed or urban scale which is the scale for water management, and then the scale of the entire grid. What are the connections with water? How do they respond to water stress? What are the tipping points for each of those scales where they might decide to disconnect from water? Or not? Then it gets more complex [on how to disconnect]. Let’s review. At an individual plant, there's going to be less generation, but you're going to maintain the different services and so on. Eventually, and this is something that we started seeing, when a plant, a one single hydropower plant, is not producing as much as expected and the overall river services are not worth it- as deemed by a commission, then it will be removed.
We've seen some of those instances; the Elwa River for example, was one of the first with these big discussions. For the thermoelectric plants, a tipping point is going to be switching from what we call wet cooling to dry cooling. This is a big decision. Wet cooling,- especially once- through cooling- is very efficient and cheap. And as you switch to dry cooling, a whole discussion is needed on the overall substantially decreased efficiency, to the point that you might actually need another plant.
For the watershed scale, the first response to stress is a redistribution of resources. At the grid scale, it's going to be more management across resources.
Maybe something that is important to me, that I want to mention, is [the disconnect between the interpretation of sensitivity and vulnerability study of power grid to water, and how power system planners may interpret the take aways]. The energy sector has a lot on its plate. The major stressor is load -electricity demand-, and eventually technology innovation. With all the science and the knowledge we have about climate, the Earth system community has been promoting, "What are the opportunities to really inform more of this long-term planning and operations with this knowledge?" As done in any business of science, we need to get the business case and we have to say why it matters. To do that, we often highlight worst‑case scenarios, with an emphasis on water as a threat to the power grid, which can lead energy planners to consider disconnecting from water. But we [Earth systems scientists] are actually identifying opportunities for joint management.
And I'm just bringing this up because there's a lot of opportunities to bring a lot of the earth system science and forecasting. Trying to ponder some of the language here. Socioeconomic studies show that using resources smartly with better information is often more beneficial than disconnecting completely.
\[00:31:40\] Bridget Scanlon: Right. Texas experienced probably one of the worst drought years on record in 2011, and I was wondering why we didn't have any blackouts or things like that. So I looked at reservoir levels for once through cooling; sometimes they had cooling towers.
It was amazing how many different things they could turn to survive. A pipeline had been completed the year before that brought water and each case that we looked at, individual plant level it seemed like that they had multiple backups, and, what you describe for thermoelectric, maybe they could just go disconnect. But as you say, then having water cooling makes it less energy intensive. It's more energy efficient, and so you use less energy and you have less greenhouse gas emissions and other things. Going to dry cooling, you need more land and then it might not, is not as effective, so there's an energy penalty. A lot of times, I guess with these discussions and then optimizing, it's looking at trying to manage the tradeoffs. At the grid scale in that paper you mentioned reserve margin and increasing that maybe, or transmission planning. But a lot of these things will be costly and increase your cost of electricity. So how much insurance do you want to buy? What type of drought do you want to prepare for?
But it's interesting to hear that you're not just relying on the observational record because that's just one set of data and as you say, one place might be dry and the other place wet. So how do you develop these synthetic scenarios then, to evaluate the reliability of the grid?
\[00:33:12\] Nathalie Voisin: A lot of the resource adequacy effort is based on probabilistic metrics, similar to metrics for flood probability. With wind and solar and temperature, there are some synthetic weather generators. But you can also use historical weather. Scenarios are developed for a specific infrastructure set and you can have a lot of ensembles because of the short term nature of high load and low wind-solar. When it comes to water, it's a little bit more complex because it's difficult to get the probabilities using only 40 years of historical weather and get those probabilities. You need a synthetic generator. Your initial observation dataset is just not long enough.
This challenge is one that we address in a new initiative that I lead, [Nathalie pointing out the FORESIGHT logo in the background]. So far, when we've been doing the long-term planning, we were looking at using climate change projections and going to long horizons up to 2100. The uncertainty was focused on trends. The feedback from the community was that we need to pay attention to the extreme events. Hence, some of the probabilities. In FORESIGHT, it's a team of 40 staff contributing to it, one of the activities is focusing on developing probabilities of extremes in the near term. Near term .. that's also something we learn is that long-term electricity planning, except for hydropower design, really means near term in the climate field. At the grid scale, long term is the next 10 years and 20 years, so all of the probability should be about the extremes around that horizon.
\[00:34:53\] Bridget Scanlon: Right. And for listeners who might not see the visuals, Nathalie, you were referring to FORESIGHT.
\[00:35:03\] Nathalie Voisin: Oh, thank you!
\[00:35:05\] Bridget Scanlon: And that acronym stands for Framework for Optimizing Reliable Energy Systems and Infrastructure Given High‑Uncertainty Trajectories.
You need large ensembles in order to capture the extremes, and we have the same in hydrology with droughts and floods, we cannot just rely on observations. But another aspect of your work that I really like is these Sankey diagrams. I don't like them just because Sankey was an Irish guy, but I like how it explains from the energy source to the uses and the applications and the waste heat. It is a bit a budget type of thing. Maybe you can describe those and you have them for the WECC and the Eastern interconnection and ERCOT and these different regions.
How do you guys use, I mean, they're pretty difficult to compile, right? It's a lot of information
\[00:36:04\] Nathalie Voisin: Those were compiled by my colleagues Kendall Mongird, Jennie Rice, and Juliet Homer, published in *Utilities Policy* (2023). They're updating those Sankey diagrams. It took them a lot of work to develop them. Sankey diagrams are all those flows where you have all of the energy sources, and all of the different water uses associated with energy sources. The diagrams quantify the interconnection. They have been very successful for establishing and quantifying the differences for different states and different power grids. They are very critical for understanding the water energy nexus, which is regional. Those inspire discussions, for example, disconnecting from water. When you look at those Sankey diagrams, you can see that over the Western US, we have a lot of hydropower, and for all of the other technologies, they are already very disconnected from the water sector. Over the eastern US, where you have plenty of water, the Sankey diagrams reveal how the energy sector was designed around this abundance of water. Early recommendations are going to be around those Sankey diagrams. I think they also have them as a time series to see on how [the water-energy nexus] has evolved across the years.
[00:37:31] Bridget Scanlon: Oh.
[00:37:31] Nathalie Voisin: And that really allows us to provide some lessons learned on how the infrastructure has changed. When I say it's been designed around water, that's all there, where you can see that.
[00:37:42] Bridget Scanlon: and you can really see the uses then. It talks about transportation, irrigation, and all sorts of things. With the evolution of the grid, do you see increasing electrification, more EVs, more load in the future, and then trying to meet that load? That's a big, big issue for the power grid.
[00:38:02] Nathalie Voisin: Projecting what the load is going to be is likely the elephant in the room. Depending on the changes in policy . And currently, the data centers are also one of the big challenges with respect to what we have talked about. It's important to understand the implications of an increasing load. With this increasing load there is the question of where [the data centers] go, and who needs to build the capacity and the power plants to balance this load. The question of where? There's the concept of balancing authority again. Will the data centers balance their own load , because it will be very intermittent as well.
Also, there are different types of investors— public utilities, private utilities, and markets — which have different mechanisms for who pays for what. There are places where you're planning to rely on transmissions and buy from the market. There are places where it's a publicly or privately owned utilities; There are many ways to invest into those extra power plants, implying a very different financial mechanism.
The challenge is to follow the load [growth] and then how to make it happen. How do you evaluate how … I think you were mentioning before : is there going to be enough land or, what will be the impact on the power grid, not just from a reliability perspective, but also from a financial perspective.
[00:39:27] Bridget Scanlon: Right, right. And, getting back to your water security paper. I mean, there's a lot of discussion these days about the water demands for the data centers. And I know you're not working on it. You have a separate team working on data centers. So I don’t want to probe too much. But I think, when in that water security paper, you can say they could disconnect, and some people say, well, they, they will use a single cycle of gas, without water for cooling or, or whatever. So they could disconnect. But then there's the energy penalty and loss in efficiency and everything. So. there are different ways of managing things and I guess it's early days and so there's a lot of uncertainty and a lot of discussion. But yeah, challenging times. But the other aspect that I wanted to mention, I really appreciate all the data sets that you guys are developing, and I really like the hydropower data set that you developed with Sean Turner at Oak Ridge National Lab.
And maybe you can describe that a little bit.
00:40:27] Nathalie Voisin: YEs. Actually, those [datasets] were developed when he was at PNNL and they are in continuity of the research I have discussed so far. With work I had with the WECC, I had already made the landscape for what the power system models were willing to take into their power systems. And also what was the data availability. So, at the time I had a project to develop that first set of multi-year hydropower data sets that was based on simulated monthly hydropower. That's the scale where the representation of the water management was good enough that we could go to monthly. And then we had planned to use observed stream flow to go from monthly to weekly, and we were moving forward. So Sean Turner was implementing the idea and then he came one day and said, "Those monthly observed data, they don't make any sense. And he went on and he tracked where the problem was. So we found that a lot of the EIA monthly data were actually imputed [from annual values]. And so, what we had planned to do on the simulations, [from simulated monthly to weekly], we ended up doing it on the observations to go from annual to monthly. And then PNNL continued working on this, going from monthly to weekly. And we have a range of datasets at the weekly timescale where we are paying attention to always have enough power plants so that it can go into the power grid models. We are focusing on developing those power systems relevant data sets spanning over multiple years. We have datasets that are based on observation, that we keep updating, bringing more and more data as they come in. We also have simulations- based datasets where we call it GODEEEP Hydro. That was the name of the project I was leading. The point is that we have 40 years of historical data based on simulations, historical period. And then the particularity of the future period is it has the same sequencing as the historical period. So it allows us to say, what was the drought in 2001, -which was a drought record- , how would it be in the future? How more intense would it be? Those datasets reflect the engagement with stakeholders, who are not necessarily yet ready to use projections [simulations]; this framing is very important because they can relate to what happened then and what it would be in the future. And finally, we keep developing other weekly datasets, available for the entire country at this time, based on the Secure Water Act. So we're developing them and then we'll have more as we continue going.
\[00:43:01\] Bridget Scanlon: Well, that's fantastic. I mean, it is great, the data sets and the modeling are continually improving, so we can better understand. But the challenges are also increasing it seems like with the different portfolios of energy electricity systems. Yeah. Well thank you so much Nathalie
Our guest today was Nathalie Voisin and she's the Chief Scientist for Regional Climate Energy Dynamics at Pacific Northwest National Lab. So good luck with your work and really appreciate what you do.
[00:43:31] Nathalie Voisin: Thank you so much and thanks for the opportunity to share what we do on that water energy Nexus. I hope people enjoyed it.
