When it comes to clean energy sources, size really matters. The trick is, depending on the detail you are looking at, small and big can be equally interesting. For example, the bigger the solar power plant or the wind energy farm, the more impressive. However the smaller the turbine, or the thinner the solar cell- the more desired, especially if they can pack up huge capacity.
So here comes the latest technology from GE. Their supercritical carbon dioxide turbine is currently under testing. It has the size of a desk, but it has a capacity to power as many as 10,000 homes, or a small town.
Carbon dioxide is “supercritical” when the temperature is up to 700°C, and the pressure is extremely high. At this state, carbon dioxide is neither liquid nor gas. Exactly this supercritical carbon dioxide state is needed to drive the GE’s turbine. The liquid/gas passes through the machine, where it gets cooled, and then it gets repressurized again, before it returns for a consecutive pass.
The guys behind the technology believe that the turbine can provide the ultimate solution to energy storage for the grid. When energy comes from solar, nuclear or wind, it can be stored as molten salt. The heat can then be used to drive the process at a later stage. The GE turbine needs only a minute to start operating, which makes it perfect for emergency situations such as unexpectedly high peak hour energy demand.
Because it can be turned on and off rapidly, it is highly efficient. Its compact size gives it a big advantage over other technologies. The turbine has much better heat-transfer properties than regular steam-based systems. In addition, it does not require as much system compression because it uses supercritical carbon dioxide and not steam.
For now, the prototype is 10 megawatts, but the plans are to grow it to 33 megawatts.
The system is picking up popularity very fast. Its emission cycle is near zero, it has much smaller footprint than traditional turbines with the same efficiency, it can use up sequestered carbon dioxide and replace carbon capture facilities. It is also easily integrated with any source of renewable energy (solar, wind, nuclear, geothermal). Last but not least, it is the prefect technology for ship propulsion or other means with limited volume.
Image (C) GE