Power plant turbines might be getting smaller. The tech is still in its early stages but GE Global Research is developing a turbine that - though only the size of the average desk - could someday power entire towns. The principle behind it could have a big effect on the future of turbine power. Instead of being pushed by steam, like most power plant turbines, the "minirotor" as [steam turbine specialist at GE Global Research Doug] Hofer calls it is pushed by CO2. Not gaseous CO2, or liquid CO2, but CO2 so hot and pressurized that it forms what is called a supercritical fluid, a state of heat and pressure so extreme that the distinctions between liquid and gas basically cease to exist. The tiny turbine's design is intended to harness the power of this specific (and weird) state of matter which could make the turbines as much as 50 percent efficient at turning heat to electricity, a significant improvement over ~45 percent efficient steam turbines. On top of that, these turbines should be relatively easy to spin up or down as demand shifts allowing power plants to more accurately tweak supply on the fly. The prototype design is a 10 MW turbine, though GE hopes to be able to scale the tech to enough to power a city, somewhere in the 500 megawatt range. The first physical tests are scheduled for later this year.