I'm curious if this could be utilized with less pure fuels such as organic wastes rich with oils and waxes. Supercritical CO2 is often used to remove oils and waxes from organic matter and clothing. The high temperatures and pressures might even be sufficient for pyrolysis of the organic matter, allowing for further removal of combustable materials. Of course organic materials are highly variable and full of other volatiles that may harm the turbines (i.e. sulfur, fatty acids, etc.). Sadly the purity of the exhaust gases would likely be effected as Nitrogen from proteins, along with other elements are going to end up in the exhaust stream. These could all be distilled out, or scrubbed, but with higher energy costs.
Still there are lots of exciting developments that can be made to cogeneration power production using organic waste streams.
Agricultural waste seems like a better use case, but that's just my sensibilities. A fluidized bed of 700C supercritical CO2 would be able to thermally crack woody biomass quite effectively. The remaining biochar could be used for carbon sequestration (reverse mining) by adding it to soil as an amendment to improve it's nutrient holding capabilities, ion exchange and friability.
Still there are lots of exciting developments that can be made to cogeneration power production using organic waste streams.