GE sees its new supercritical carbon dioxide turbine as a strong rival to batteries for storing power from the grid. GE Global Research is testing a desk-size turbine that could power a small town of about 10,000 homes. The unit is driven by “supercritical carbon dioxide,” which is in a state that at very high pressure and up to 700 °C exists as neither a liquid nor a gas. After the carbon dioxide passes through the turbine, it’s cooled and then repressurized before returning for another pass.
It’s about one-tenth the size of a steam turbine of comparable output, and has the potential to be 50 percent efficient at turning heat into electricity. Steam-based systems are typically in the mid-40 percent range; the improvement is achieved because of the better heat-transfer properties and reduced need for compression in a system that uses supercritical carbon dioxide compared to one that uses steam. The GE prototype is 10 megawatts, but the company hopes to scale it to 33 megawatts.
Doug Hofer, a GE engineer in charge of the project, shows off a model of the turbine.
In addition to being more efficient, the technology could be more nimble—in a grid-storage scenario, heat from solar energy, nuclear power, or combustion could first be stored as molten salt and the heat later used to drive the process.
Doug Hofer, a GE engineer in charge of the project, shows off a model of the turbine
Nextbigfuture reviewed the supercritical CO2 turbine roadmap. The Toshiba work is executing to the dates on that roadmap.
* Sandia National Laboratories and Lawrence Berkeley National Laboratory are involved with Toshiba, Echogen, Dresser Rand, GE, Barber-Nichols in S-CO2 cycles.
* Toshiba, The Shaw Group and Exelon Corporation are engaged in a consortium agreement to develop Net Power’s gas-fired generation technology with zero emissions target. This approach uses an oxy-combustion, high pressure, S-CO2 cycle, named Allam Cycle. Toshiba will design, test and manufacture a combustor and turbine for a 25MW natural gas-fired plant. A 250MW full-scale plant is expected by 2017.
* Echogen Power Systems has been developing a power generation cycle for waste heat recovery, CHP, geothermal and hybrid as alternative to the internal combustion engine.
* Pratt and Whitney Rocketdyne is engaged with Argonne National Laboratories in a project with aim to integrate a 1000 MW nuclear plant with a S-CO2 cycle.
The reasons of growing interest toward this technology are manifold:
* simple cycle efficiency potentially above 50%;
* near zero – emissions cycle;
* footprints one hundredth of traditional turbomachinery for the same power output due to the high density of working fluid;
* extraction of “pipeline ready” CO2 for sequestration or enhanced oil recovery, without both CO2 capture facilities and compression systems;
* integration with concentrating solar power (CSP), waste heat, nuclear and geothermal, with high efficiency in energy conversion;
* applications with severe volume constraints such as ship propulsion