Our electric sector has a significant water problem. This is not news to much of us in the industry, particularly those of us who think about the energy/water nexus. A couple of my favorite Texas energy/water nexus experts I like to follow are here and here.
I was working on a presentation for a talk at HARC and HTC’s Innovator in the Woods series and was struck by this water dependency. One of the first slides I included was this EIA slide that shows the current US electricity generation source by fuel type.
It appears pretty uninteresting regarding water at first glance. We see a sliver of hydropower and think that there is not much to see here in regards to water. However, if you take a closer look and think about what is the one thing that keeps all of these power generation systems operating, you realize that the one thing that 90% of our power sector is dependent upon is water. We talk a lot about the diversity of fuel sources. In this case, we have a diversity of fuel sources, coal, natural gas, hydropower and nuclear, but we have very little diversity in a very key component. Our power supply is highly dependent on water. Water dependency for cooling in regards to coal, natural gas and nuclear and water dependency for actual power production in terms of hydropower. The lack of diversity of our power sector in regards to what keeps it running and humming along is rather frightening.
A better look of our dependency on water can be found in this hybrid sankey diagram provided by Lawrence Livermore National Lab.
This diagram is a few years old and the Lab has actually produced some newer energy specific ones. The reason I use this map is to show not only the tremendous energy waste we have in this country (an argument for more energy efficiency and distributed generation), but also to better show the interconnect between water and our power sector. Here we see that on a daily basis the power sector uses 196 billion gallons of water. Most of us think, it is the agricultural sector is the largest user. They are the largest consumer, not the largest user.
In any case, as we bring it closer to home, we can check out this heat map for water consumption across the United States, what we see here is that one of the more politically red states, is very blue when it comes to water consumption. Texas is the bluest state west of the Mississippi.
This can be a problem when the Water Sustainability Index looks like this for Texas in the year 2050. This image is brought to you by a joint Tetra Tech and NRDC water risk study.
Of course, by 2050, the expectation is that we will have a lot more solar and wind and our dependency on water will decrease. According to the Bloomberg New Energy Finance report “New Energy Outlook,” 34% of global power production will be renewables, largely solar and wind. Further, when you look at ERCOT’s summary of generation interconnection requests as of December 2016, of the nearly 60 MW that are in some part of the interconnection queue, almost 70% are wind and solar interconnects. Of course not all of these will go forward, but that looks pretty promising in regard to the water concerns. In the next couple of decades, we should be out of the woods. Problem solved. Except, when you see this…
This is the Texas drought map in September 2011. For those not familiar with this map, dark red is not good. It is a D4 on the scale, the highest score you can get, which means exceptional drought. Exceptional means this…
Much of the reservoirs and rivers that cool our power plants were getting too low to provide cooling or the water that remained was becoming too warm. During 2011, ERCOT, the organization that manages the Texas grid, was concerned about losing “potentially several thousand megawatts” if the drought did not end. There were also plants during this time curtailing operation at night so they would have plenty of water to provide power during the day, as well as plants that were piping water from other sources to ensure they could operate.
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Fortunately, we are already moving in the right direction as far as reducing our water dependency in the power sector. We do see growing deployment of solar and wind. Solar installations were up 95% from 2015 to 2016 and wind looks to continue to grow at a considerable rate. Battery prices continue to fall, which will help with the intermittency of our renewable energy resources. We also see increasing deployment of microgrids, which use battery, solar, as well as air cooled combined heat and power. This market is expected to reach 3.71 GW by 2020.
In the meantime, as we wait for the deployment of this less water intensive power infrastructure, what we all could be doing is using less of it. Energy efficiency is still the best resource we have to hedge against this problem of water dependency of our power infrastructure. If we do not need the energy, the system does not need to produce it. If less energy is needed, less water is needed. Energy efficiency provides the best bang for the buck for all of these resources. It has the lowest levelized cost of energy, it is proven and it is easily deployable. So, let’s keep building the new sexy renewables and microgrids, but let’s now forget our greatest water saver, energy efficiency.