Tiny turbine could power 10k homes with CO2

GE Global Research is testing a desk-size turbine that could power a small town of about 10k homes. The unit is driven by supercritical carbon dioxide, created by very high temperature and pressure where carbon dioxide is neither a liquid nor a gas. After the carbon dioxide passes through the turbine, it is cooled and then re-pressurised before returning for another pass. The unit’s compact size and ability to turn on and off rapidly could make it useful in grid storage. It’s about one-tenth the size of a steam turbine of comparable output, and has the potential to be 50% efficient at turning heat into electricity. The GE prototype is 10MW, but the company hopes to scale it to 33MW.

GRC's Hofer says his "minirotor" could power a small town. Image credit: GE Global Research

A picture may be worth 1,000 words. But this one is also worth 10,000 kilowatts.Though small in stature, the turbine in the photos could contribute to solving some of the world’s biggest energy challenges, not to mention powering an entire town, says Doug Hofer, a steam turbine specialist at GE Global Research.Full disclosure: The model in Hofer’s hand was 3D-printed from plastic. The real functional version of the turbine, made from high-strength metal, would make the scientist hold up about 150 pounds. But even that’s like lifting a feather. Machines generating this kind of power typically weigh several tons.“This compact machine will allow us to do amazing things,” Hofer says. “The world is seeking cleaner and more efficient ways to generate power. The concepts we are exploring with this machine are helping us address both.”Here’s how: The medium spinning this turbine isn’t steam but carbon dioxide, squeezed and heated so high that it forms a supercritical fluid. At that level, the difference between gas and liquid basically disappears and gives the CO2 marvelous properties that the turbine harnesses for superefficient power generation.GE Reports recently ran a piece showing how this turbine can help energy companies turn CO2 into cleaner power . But Hofer and other GE researchers believe it can do a lot more and address other big energy challenges. In addition to the CO2 program with the government’s Advanced Research Projects Agency-Energy (ARPA-E), GE is working on other programs with the U.S. Department of Energy.One is looking at using this technology to increase the efficiency of centralized power plants. Hofer and his team are gathering insights that could allow them to scale the technology to the 500 megawatt range — enough to power a large city. The research could lead to smaller “large” turbines that are more efficient in the future. “With energy demand expected to rise by 50 percent over the next two decades, we can’t afford to wait for new, cleaner energy solutions to power the planet,” Hofer says. “We have to innovate now and make energy generation as efficient as possible. Programs like those we are working on with the U.S. Department of Energy are helping us get there.”Hofer cautioned that the technology is in its early stages of development. But he and his team are planning to take it for a spin later this year.