As someone who has written a lot about renewable energy and working towards a post-fossil fuel future I have been disheartened by the strong anti-nuclear stance of much of the environmental community. As has been noted more times than I can discuss (but was best summarized by Brad Plumer at Vox.com) nuclear power and renewables don’t have to be enemies. Moreover as Jesse Jenkins and Samuel Thernstrom have recently written the most cost-efficient deep decarbonization systems require some dispatchable low-carbon baseload. In their paper on the topic they point to nuclear energy as being a prime example of a low-carbon technology that can be used to fill the need for baseload power. The nuclear industry does have its critics in the renewable energy community with Dr. Marc Z Jacobson being a notable example. The arguments made by Dr. Jacobson against nuclear include issues like nuclear proliferation, thermal pollution from cooling tower return water and the potential for disruptions to power supply by terrorists? I have addressed two of these (terrorism and nuclear proliferation) in a previous post and today I want to address the final one “thermal pollution” and its associated issue water use. More specifically in this blog post I want to see if we can turn some of the biggest criticisms about nuclear energy into opportunities in a post-fossil fuel energy system.
Coupling Nuclear power facilities to underground thermal storage systems
One of the most commonly discussed complaints about nuclear power is water use. There is a stat I have read in blogs and articles by anti-nuclear activists, that about 40 percent of the nation’s fresh water use goes toward energy generation. To be clear, this water is not consumed, rather enters the system at one end and leaves the plant at the other to siphon off heat (via once-through cooling systems). The water is not chemically changed it is just used to dump thermal energy. It enters at a lower temperature and leaves at a slightly higher temperature. Technically the water is used but not in the manner most associated with industrial process where the water is consumed and doesn’t re-emerge on the other end. In some places this warmer water is good for the environment (manatees love the heat) but in others it can be a serious problem. Thermal waste is a serious concern for the nuclear industry but it is a problem that provides a wonderful opportunity in a post-fossil fuel economy. If that heat was treated as a valuable commodity rather than a waste product nuclear could turn a recognized weakness into a strength. This could be done by coupling nuclear facilities with thermal storage facilities.
Coupling nuclear with thermal storage is not a new idea as scientists have previously suggested linking nuclear to thermal storage blocks and even underground storage. Unfortunately, in my research to date most of the cases I have found involve storage of the primary heat from the system. In my searching, I have not found a lot of examples of a much simpler idea: coupling nuclear power station process water to underground thermal energy storage (UTES) systems. I’m sure someone has written a lot about this and assume that shortly after I post this blog I will get a stream of links sent to me but as I write this I cannot easily find plans for these apparently straightforward adaptions to existing technologies.
To explain for the lay reader, underground thermal energy storage (UTES) is a form of energy storage that provides large-scale seasonal storage of cold and heat in natural underground sites. Three common types of UTES are aquifer thermal energy storage (ATES), borehole thermal energy storage (BTES) and rock cavern thermal energy storage (CTES). Essentially what you do is you take waste energy in the form of heat from your system and store it underground until you need it at some later date. Readers of this blog will surely remember the Drake’s Landing solar community in Alberta as I have written about it regularly. At Drake’s Landing the community is connected to a solar energy system which provides electricity during the day but the system also stores excess energy via BTES. The BTES energy is then used in winter to help heat the houses within the community. According to the Drake’s Landing website over the 2015-2016 heating season 100% of the heat required for space heating was supplied by the combination of solar and BTES. Sure setting up a system like Drake’s Landing can be expensive but in the end it provides a useful model for how we can eliminate dependence on fossil fuels for household uses.
So I asks, why haven’t we done this at any nuclear plants? Why are they just dumping their excess heat into the environment when they could instead store it for the winter? By storing that heat the nuclear plants could eliminate their thermal pollution issue and increase the amount of energy generated by their facilities. As for the critics in the 100% Wind, Water and Sunlight (100% WWS) community I can’t see them raising a fuss. After all, in his 100% WWS plans Dr. Jacobson suggests building all sorts of energy generating systems with thermal storage so thermal storage associated with a nuclear plant would not appear to be a major concern for the renewable energy community.
Coupling Nuclear power facilities to hydrogen generating facilities.
My second suggestion is one that has been better studied and discussed but once-again not to the extent I believe it should: the use of off-peak nuclear energy to produce hydrogen. One of the big complaints from the environmental community about nuclear energy plants is that they are not very flexible. They take a while to get running and so need to be kept running most the time. They argue that this is a bad thing as it makes it harder for renewable energy to find a foothold. Moreover, in an electrical system that is heavy with renewables there are peaks during the day when there is virtually no demand for the energy produced by the nuclear plants (see the duck curve). This challenge for the nuclear power industry could potentially provide another useful opportunity in a post-fossil fuel future: hydrogen generation.
As anyone who has followed the energy discussions around climate change knows one of the biggest challenges to moving off fossil fuels is the transportation industry. I have written numerous blog posts discussing the issue (most recent here) and while electric vehicles seem a reasonable alternative for most commuting needs the one place where electric engines are struggling is in the air. Put simply electric storage devices are too heavy and simply don’t carry enough juice to power a modern airliner. One alternative to fossil fuels in the air could be hydrogen but even minimal attempts to use the gas have stumbled on the issue of a limited supply of hydrogen. The problem with hydrogen is that it is not an energy source but rather an energy storage medium. Like a battery, hydrogen acts a carrier of energy from other processes like nuclear, solar or wind power via fuel cells or combustion into electricity.
The Alternative Fuels Data Center of the US Department of Energy has lots of info on hydrogen but notes that a challenge for the hydrogen economy is production near where it will be used. This seems like another opportunity where nuclear can be useful. By coupling nuclear plants with hydrogen generating facilities we could kill two birds with one stone. During the low demand times the nuclear plants could provide energy to the coupled hydrogen facility to generate hydrogen. When demand for electricity ramped up in the evenings the nuclear energy could be used to supplement the renewable supply. In this manner, the nuclear facilities could continue to run at a steady output sometimes producing hydrogen, sometimes producing electricity for the grid, always with little energy being wasted and without the need to ramp up or down, thus reducing wear and tear and increasing capacity.
Once again, the renewable energy community has repeatedly suggested that hydrogen is a necessary fuel of the future and Dr. Jacobson and his team have suggested building numerous facilities to generate hydrogen. But who needs to build new facilities when we have all these nuclear plants waiting to provide the electricity necessary to produce hydrogen.
To conclude, I am by no means a nuclear engineer and I am sure that there are some pretty significant hurdles to my suggestions but decarbonizing the North American energy system is going to be full of technical hurdles. As I pointed out earlier, I’m betting that nothing I have written above will come as a surprise to the informed (like the people at the Breakthrough Institute) but I continue to wonder why I’m not reading about these ideas as part of the battle to preserve the existing nuclear infrastructure and as a selling point for the next generation of facilities. It is clearly time we started talking more about these topics since opponents of nuclear power are making themselves heard and it is time that we turn some of their biggest complaints about the nuclear industry into some of the biggest selling points for keeping the nuclear industry.