>>64471297
Filters: Less PM and heavy metals (from power plants and blast furnaces). The minimum necessary to no kill your own people and environment but a lot of countries still don't use or turn off to reduce costs.
Ultra-supercritical just means heating steam at higher temperature and pressure (and it needs different materials for the turbine/boilers) it isn't a new invention but its commercialization is recent and a power plant using it releases 10-25% less CO2 per KWh of generated electricity. They worked alongside Japan and Germany besides basic research by themselves.