Closed cycle gas turbines still need heat exchangers (at least two).
One very interesting grid energy storage concept (currently being commercially developed by Babcock & Wilcox) involves heating sand using electric resistance heating to about 1200 C, storing then using that heat to drive a gas turbine (round trip efficiency > 50%). I mention this because you can transfer heat from sand to compressed air in a very compact and cheap device that mixes the two, then separates the air with cyclone separators.
(This concept would likely also need something to destroy thermal NOx in that air, though.)
Nuclear is going to have to compete with heat from cheap renewables stored in sand, then turned back to power using a machine like this with only the one really cheap heat exchanger.
One very interesting grid energy storage concept (currently being commercially developed by Babcock & Wilcox) involves heating sand using electric resistance heating to about 1200 C, storing then using that heat to drive a gas turbine (round trip efficiency > 50%). I mention this because you can transfer heat from sand to compressed air in a very compact and cheap device that mixes the two, then separates the air with cyclone separators.
(This concept would likely also need something to destroy thermal NOx in that air, though.)
Nuclear is going to have to compete with heat from cheap renewables stored in sand, then turned back to power using a machine like this with only the one really cheap heat exchanger.