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> Safety isn’t the only reason I’m excited about the Natrium design. It also includes an energy storage system that will allow it to control how much electricit

by kyrofa 3y ago

> Safety isn’t the only reason I’m excited about the Natrium design. It also includes an energy storage system that will allow it to control how much electricity it produces at any given time. That’s unique among nuclear reactors, and it’s essential for integrating with power grids that use variable sources like solar and wind. I'm surprised this is all he says on this matter. As far as I'm aware, this problem is largely unsolved, and one of the reasons dams can't go away: they're the only power generation technology that we can spin up and down in response to fluctuation in wind power and so on. That's because we don't have a good solution for storing energy on this scale, and thus must use the energy we generate. Have we finally come up with one? A water battery (pumping water into a reservoir behind a dam) is the only one I know of, which doesn't seem to scale well.

p1mrx 3y ago
Any of the high-temperature reactor designs (sodium, molten salt, TRISO, etc.) can be combined with thermal energy storage. Light water reactors only get up to 300°C, which is barely hot enough to spin a turbine. At >600°C, you can heat an intermediate fluid, lose some energy, and still spin a turbine.
- kyrofa 3y ago
  So the idea is that there are chambers of molten salt (or similar) that can be heated when a spinning turbine is not needed, and it'll stay hot enough to spin one later? Any idea how long it stays hot? What happens when they're all already heated?
  - p1mrx 3y ago
    12-24 hours of molten salt storage should be enough to generate power all day, and sell it at times when electricity is most expensive. There's not much point storing for multiple days, when the reactor itself behaves like long-duration storage. If your reactor is producing energy with no buyers, and your thermal storage is full, then you probably should've built it somewhere else, but in that case you can just power down the reactor.
aksss 3y ago
> which doesn’t scale well It also has the problem of only being applicable to geographies with abundant water and the topography suited to create giant reservoirs.
- kyrofa 3y ago
  Right, I don't mean that individual water batteries don't scale well, but that the concept in general doesn't scale well as a solution to this problem. That's definitely one of the reasons.
godelski 3y ago
Interestingly there has been a lot of discussion about hydrogen lately[0] because the Inflation Reduction Act provides a tax credit for production of clean hydrogen (e.g. hydrogen not from methane). Nuclear is one of the best possible methods to ways to generate this (high electricity, high heat) given that its operation does not generate carbon (just like renewables). The problem? Nuclear power generates $30/MWhr and will make between $60-$70MWhr producing hydrogen. Sounds like a win, but reactors are already at 90% capacity and supply ~20% of the US's energy and half of our zero emission energy. Variability isn't that much of an advantage. Excess energy can often be sold off as well, reducing other areas' reliance on fossil fuels. France, Norway (almost all hydro), and Sweden (also a major nuclear player) and the main energy exporters in Europe (also lowest energy based carbon emitters)[1,2]. We see a similar thing with Quebec (major nuclear). But it is concerning given that nuclear is the main source of zero emission energy in the American South East[3]. Gates probably isn't concerning himself with the variability since there's no shortage of regions where selling a zero emission source isn't going to help reduce its neighbors energy emissions. The only areas where there is a shortage is where regions already rely heavily on either nuclear or hydro (or a combination). There's no reason to not run at max load. You either sell the energy or your produce hydrogen. This is also a big reason that a carbon tax makes nuclear a viable option. Just for reference, here's an annual solar radiance map[4], wind (10m)[5], and hydro[6] as they might help explain the situation in the South East. [0] https://heatmap.news/economy/the-nuclear-hydrogen-conundrum https://heatmap.news/economy/the-nuclear-hydrogen-conundrum [1] https://www.enappsys.com/interconnectorreview/ https://www.enappsys.com/interconnectorreview/ [2] https://app.electricitymaps.com/zone/FR https://app.electricitymaps.com/zone/FR [3] 80% of TVA's zero carbon, 77% of SCS, 86% of Duke Carolinas, 81% of Duke Ease, 80% of PJM(looking at 12 months) [4] https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018-usa-scale-01.jpg https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018... [4.5] find other maps -- look at DNI -- for different months and energy sources here https://www.nrel.gov/gis/solar-resource-maps.html https://www.nrel.gov/gis/solar-resource-maps.html [5] https://www.nrel.gov/gis/assets/images/wtk-10m-2017-01.jpg https://www.nrel.gov/gis/assets/images/wtk-10m-2017-01.jpg [6] https://www.nrel.gov/gis/assets/images/map_hydrogen_kg_county.jpg https://www.nrel.gov/gis/assets/images/map_hydrogen_kg_count...

by kyrofa 3y ago

p1mrx 3y ago

Any of the high-temperature reactor designs (sodium, molten salt, TRISO, etc.) can be combined with thermal energy storage. Light water reactors only get up to 300°C, which is barely hot enough to spin a turbine. At >600°C, you can heat an intermediate fluid, lose some energy, and still spin a turbine.

kyrofa 3y ago
So the idea is that there are chambers of molten salt (or similar) that can be heated when a spinning turbine is not needed, and it'll stay hot enough to spin one later? Any idea how long it stays hot? What happens when they're all already heated?
- p1mrx 3y ago
  12-24 hours of molten salt storage should be enough to generate power all day, and sell it at times when electricity is most expensive. There's not much point storing for multiple days, when the reactor itself behaves like long-duration storage. If your reactor is producing energy with no buyers, and your thermal storage is full, then you probably should've built it somewhere else, but in that case you can just power down the reactor.

aksss 3y ago

> which doesn’t scale well It also has the problem of only being applicable to geographies with abundant water and the topography suited to create giant reservoirs.

kyrofa 3y ago
Right, I don't mean that individual water batteries don't scale well, but that the concept in general doesn't scale well as a solution to this problem. That's definitely one of the reasons.

godelski 3y ago

Interestingly there has been a lot of discussion about hydrogen lately[0] because the Inflation Reduction Act provides a tax credit for production of clean hydrogen (e.g. hydrogen not from methane). Nuclear is one of the best possible methods to ways to generate this (high electricity, high heat) given that its operation does not generate carbon (just like renewables). The problem? Nuclear power generates $30/MWhr and will make between $60-$70MWhr producing hydrogen. Sounds like a win, but reactors are already at 90% capacity and supply ~20% of the US's energy and half of our zero emission energy. Variability isn't that much of an advantage. Excess energy can often be sold off as well, reducing other areas' reliance on fossil fuels. France, Norway (almost all hydro), and Sweden (also a major nuclear player) and the main energy exporters in Europe (also lowest energy based carbon emitters)[1,2]. We see a similar thing with Quebec (major nuclear). But it is concerning given that nuclear is the main source of zero emission energy in the American South East[3]. Gates probably isn't concerning himself with the variability since there's no shortage of regions where selling a zero emission source isn't going to help reduce its neighbors energy emissions. The only areas where there is a shortage is where regions already rely heavily on either nuclear or hydro (or a combination). There's no reason to not run at max load. You either sell the energy or your produce hydrogen. This is also a big reason that a carbon tax makes nuclear a viable option. Just for reference, here's an annual solar radiance map[4], wind (10m)[5], and hydro[6] as they might help explain the situation in the South East. [0] https://heatmap.news/economy/the-nuclear-hydrogen-conundrum https://heatmap.news/economy/the-nuclear-hydrogen-conundrum [1] https://www.enappsys.com/interconnectorreview/ https://www.enappsys.com/interconnectorreview/ [2] https://app.electricitymaps.com/zone/FR https://app.electricitymaps.com/zone/FR [3] 80% of TVA's zero carbon, 77% of SCS, 86% of Duke Carolinas, 81% of Duke Ease, 80% of PJM(looking at 12 months) [4] https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018-usa-scale-01.jpg https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018... [4.5] find other maps -- look at DNI -- for different months and energy sources here https://www.nrel.gov/gis/solar-resource-maps.html https://www.nrel.gov/gis/solar-resource-maps.html [5] https://www.nrel.gov/gis/assets/images/wtk-10m-2017-01.jpg https://www.nrel.gov/gis/assets/images/wtk-10m-2017-01.jpg [6] https://www.nrel.gov/gis/assets/images/map_hydrogen_kg_county.jpg https://www.nrel.gov/gis/assets/images/map_hydrogen_kg_count...