One thing I’ve never figured out about fusion - how do you get the heat out and turned into electricity?
(Presumably, water to steam then turbines, like everything, but how do you get the heat out from the reaction?)
(Presumably, water to steam then turbines, like everything, but how do you get the heat out from the reaction?)
There are other reactions one can pursue that produce charged particles instead of neutrons. With these reactions, there are alternative energy conversion pathways that turn the kinetic energy of these charged particles directly into voltage, and you can skip the turbine. Of the fusion startups, Helion is probably the most prominent pursuing this kind of approach, with a D-He3 reaction. See https://en.wikipedia.org/wiki/Direct_energy_conversion for more info on this general approach.
New-build coal isn’t economically competitive anywhere, even where you get the coal essentially for free.
This article from DW explains it doesn’t make economic sense there either:
https://www.dw.com/en/why-build-600-new-unprofitable-coal-pl...
Provide a source or your own analysis for this claim:
>If the plan for energy conversion is a steam turbine, it’s never going to be economically competitive.
The key point is that only roughly 20% of the capital cost of a coal plant is related to coal handling and pollution control.
https://esmap.org/sites/default/files/esmap-files/TR122-09_G...
So even if the fusion reactor reduces all of those costs to zero, the capital costs would only be 20% cheaper than new-build coal.
As I mentioned earlier, coal isn't economically competitive with renewables pretty much anywhere, even places with very cheap coal resources that can't be traded on the global market. There's heaps of lignite in Texas, for instance, but nobody's building new plants to burn it.
As such, it's hard to see how fusion reactors turning steam turbines are going to be economically competitive either.
Some have a secondary steam turbine as an exhaust energy recovery system but as I understand it that’s becoming uncommon on new builds because new gas turbines are expected to be used less now that there’s a lot of renewable energy on a lot of grids.
For comparison, fusion fuel is $0.00014/kWh, equivalent to coal at $0.27/ton. There's no where on Earth where coal is that cheap. You couldn't move it from the mine to the powerplant for that cheap even if they were next door to one another. Even if all the costs got subsidized away, you couldn't count on the fuel remaining cheap for the lifetime of a powerplant.
And of course there's that pesky CO2 issue that makes investment in coal unattractive even if it could be economically competitive.
There are places where there is abundant brown coal, which cannot be economically transported long distances and is therefore basically loaded on a conveyer belt directly into power stations.
New-build brown coal isn’t economically viable either.
The fraction of the energy that is retained as velocity of particles with a charge vs that is lost as the velocity of neutrons turns out to be conveniently just about where you'd want it to be. So, to capture the energy you need to surround your reactor with something that effectively converts fast neutrons to heat, such as a blanket of molten lithium, which you then use as a heat source. Lithium is proposed because it would also breed the necessary tritium.
That's an energy output of 7 x 10^7 Wh per gram [1], or alternatively, a 70MW reactor needs one gram per hour, or alternatively, a very large 3.5GW plant needs 500 grams per hour, roughly the equivalent of the water drunk by a single thirsty person.
[0] https://en.wikipedia.org/wiki/Deuterium%E2%80%93tritium_fusi...
[1] https://www.wolframalpha.com/input?i=17.6+MeV+divided+by+ato...
The world final energy consumption (2018) [0] is around 9717Toe or 9,717*11.63=113,009TWh
1g for 70MW = 1T for 70TWh
113,009 / 70 = 1614
1614 ton of lithium every hour seems huge to me, does my calculations are wrong ?
[0] https://en.m.wikipedia.org/wiki/World_energy_supply_and_cons...
The worldwide primary energy consumption is ~600EJ. 1g/70MWh * 600EJ ~= 2400t per year.
Cost of cryogens, cost of steel, cost of working nitronic, cost of Beryllium, and cost of superconductors are the dominant sources to track.
Your fuel costs are replaced by the reactor replacement cost. Spent nuclear rod fuel waste is replaced by the irradiated materials in the reactor.
Since it is a complicated engineering problem there is space to turn engineering effort into reduced cost.
Materials are being investigated that can withstand the heat and neutron bombardment to attach a steam turbine the old fashioned way.
But we ain't there yet, not without having to constantly change the 'walls'.
> Most of the energy produced inside a fusion reactor is emitted in the form of neutrons, which heat a material surrounding the fusing plasma, called a blanket. In a power-producing plant, that heated blanket would in turn be used to drive a generating turbine