Certainly interesting tech. While the energy-per-massflow is pretty crap for co2 compared to water, that doesn’t matter since in a sealed recirculating system it’s cheap to just increase mass flow. But co2 tranistions from liquid to SC-fluid at pressures equivalent to current LP steam turbines, but at a fraction of the temperature (31C at 7.3MPa). You would need the phase change for maximum heat movement/volume change of course.
But this does mean that if your initial charge was precise enough, you could very well drive one of these power cycles with a heat source that operated only a little higher than human body temperature with significantly cheaper engineering materials (albeit at a terrible efficiency). Pretty wild to think about from a thermodynamics perspective.
Supercritical C02 turbines are fuel agnostic, but the really interesting development here is using them in conjunction with concentrated solar power systems. Power cycles based on a sCO2 working fluid have the potential for higher thermal efficiencies and a lower capital cost when compared to state-of-the-art steam-based power cycles.
Concentrated solar power has long taken a back seat to photovoltaics as the dominant means of generating solar power, but maybe it’s about to have a renaissance. Australia’s National Science Agency CSIRO, says it has made a key breakthrough with concentrated solar thermal technology (CST) that could see it act as grid storage batteries.
More specifically, it behaves as a supercritical fluid above its critical temperature (304.128 K, 30.9780 °C, 87.7604 °F)[1] and critical pressure (7.3773 MPa, 72.808 atm, 1,070.0 psi, 73.773 bar),[1] expanding to fill its container like a gas but with a density like that of a liquid.
For perspective on that pressure: a US natural gas car fills at 3,600psi (240 Bar)
This article contains a turbine picture…
