There are a lot of unknowns around fusion plants (with the current big one being is it even feasible to build one). The last time I was looking at grid infrastructure questions the largest power plants on US grids stayed below 3GW because, as I was informed but cannot cite/verify, that was the limit on infrastructure carrying capacity of the western grid.
One of the unknowns is what is the minimum cost to build a plant capable of sustained nuclear fusion. Once you know that, you will also know what its net energy output is as well. Next you will want to know what is smallest practical increment of net energy output and what is the marginal cost of that increment.
Then, as we've been discussing here, what is the sweet spot with respect to total plant cost versus kW capacity (it's LCOE). I have chosen to use as a base estimate the cost of building a nuclear plant (the discussion of nuclear LCOE is here[1], here[2], and here[3]). I base that assumption that if we're going with heat conversion then the primary differences between fusion and fission plants will be reactor construction and fuel efficiency.
If we take it as a given that the LCOE for nuclear is approximately 10 cents per kWh, if our Fusion plants cost the same and can generate twice the power that is 5 cents per kWh. Given the difference in energy production between fusion and fission I'd like to believe it would be closer to 10x more power for the same cost or an LCOE for 1 cent per kWh.
The optimism here stems from an assumption that plant costs scale with size so smaller more powerful plants win in two ways, more power and less cost.
And yes, nobody knows if we can even build these things yet. So it really is all just speculation at this point.
You have it backwards. Fusion will have much lower volumetric power density than fission, for fundamental reasons (one can circulate coolant through the core of a fission reactor, but not a fusion reactor). Fusion reactors will likely be much larger, and therefore much more expensive, than fission reactors.
Look at the power density of ITER (0.05 MW/m^3), of ARC (0.5 MW/m^3), and a PWR reactor vessel (20 MW/m^3).
There are a lot of unknowns around fusion plants (with the current big one being is it even feasible to build one). The last time I was looking at grid infrastructure questions the largest power plants on US grids stayed below 3GW because, as I was informed but cannot cite/verify, that was the limit on infrastructure carrying capacity of the western grid.
One of the unknowns is what is the minimum cost to build a plant capable of sustained nuclear fusion. Once you know that, you will also know what its net energy output is as well. Next you will want to know what is smallest practical increment of net energy output and what is the marginal cost of that increment.
Then, as we've been discussing here, what is the sweet spot with respect to total plant cost versus kW capacity (it's LCOE). I have chosen to use as a base estimate the cost of building a nuclear plant (the discussion of nuclear LCOE is here[1], here[2], and here[3]). I base that assumption that if we're going with heat conversion then the primary differences between fusion and fission plants will be reactor construction and fuel efficiency.
If we take it as a given that the LCOE for nuclear is approximately 10 cents per kWh, if our Fusion plants cost the same and can generate twice the power that is 5 cents per kWh. Given the difference in energy production between fusion and fission I'd like to believe it would be closer to 10x more power for the same cost or an LCOE for 1 cent per kWh.
The optimism here stems from an assumption that plant costs scale with size so smaller more powerful plants win in two ways, more power and less cost.
And yes, nobody knows if we can even build these things yet. So it really is all just speculation at this point.
[1] https://www.britannica.com/technology/nuclear-power/Economic...
[2] https://world-nuclear.org/information-library/economic-aspec...
[3] https://www.energy.gov/sites/prod/files/2015/08/f25/LCOE.pdf