Future Power Sector…you still have a water problem

I wrote last week about the dependency of our power sector on water to keep the power plants cool and to produce power. The ways to reduce this dependency are to move toward more sources that are air cooled, such as combined heat and power, renewables, such as solar PV and wind or what I think is one of the key options, energy efficiency. The less we use, the less dependent we are on our generation resources.

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As we look into the future, there is considerable expectation that we will deploy more of this less water dependent power infrastructure. The first is from the DOE’s Wind Vision study and the second is from SEIA.

DOE Wind projections

solarPV growth

This looks like some good news for the deployment of these resources. We see some significant growth, however, when we look at DOE’s Annual Energy Outlook for 2017, we still see a  generation sector that is heavily dependent on water.

electricity generation AEO 2017

What we see from the above chart is that renewable energy roughly makes up 27% of the total generation in 2040. This includes hydropower, biomass, solar, wind and geothermal. Now if you take out the hydropower, (see breakdown below of AEO 2017 study below) which makes up about 23% of the total renewable energy amount, you end up non-water using sources of power of about 21% of total generation.

renewables AEI 2017

What we have done between the present generation mix to 2040, is cut our water using sources of power by 10%. In my previous blog post, I referenced water using sources of power to be 90% of total generation.

Looking at these projections from AEO 2017, I feel it is important to think what is the vulnerability we face with our grid if our water outlook to 2050 looks like this…

drought sust index

Most of the concern is in the west and southwest, with a bit in Florida. A large portion of our industry and population centers live in these areas, are seeing significant growth and will have to build generation to meet demand. Of course, less generation if we are smarter about building codes and energy efficiency. I digress.

The reason I have started focusing on this issue and why we are working developing some related projects at HARC is due to a couple of papers I recently found on the subject of vulnerability of Texas ERCOT generation due to climate variability and one on water demand projections for generation in Texas.

In the water demand projections research, there is a discussion of how water withdrawals will change over time in a variety of different generation scenarios. The projections below show water increasing by 100% to 200% depending on the scenario under consideration. The scenarios consider different natural gas price environments and carbon price scenarios.

TX Water Consumption Projection

This possibly significant increase in water consumption should then be looked at in relation to Texas ERCOT power generation study by DOE and UT Austin. In this study, different water sources are considered to help determine the vulnerability of the power sector. The study considers potable groundwater, brackish groundwater, municipal wastewater, appropriated water and unappropriated surface water. The study considered not only the availability of water sources and their costs but also water temperatures and the impact on cooling power plants. Very simply, the report concludes that water supplies for new power plants will need to come from already appropriated water sources and that water prices for power plants will be significantly higher than historically the case. The lowest cost water supply could come from already appropriated low-value agricultural sources, at about $18 per acre-foot. Getting this water could be a bit difficult based on what we learned and experienced during the 2011-2012 drought. In contrast, the more bountiful brackish water, that has fewer claims on it, must be treated and will cost significantly more at about $500-900 per acre-foot. This could potentially make the ownership and operation of a plant relatively costly and not able to compete in the ERCOT market.

This issue needs careful study across Texas and the western United States. Based on what I have seen so far, there has not been enough consideration of water when we look at future generation mixes. The two studies I mentioned, do a great job discussing water issues faced by the electric sector but do not discuss what viable solutions would be to mitigate these water issues. This post is the first of an anticipated longer discussion of how we need to build out an electricity sector that can reduce water dependency and keep the lights on.



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