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.
Nextbigfuture has covered supercritical CO2 turbines several times.
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
There is a DOE project to a make a 10 MWe supercritical CO2 turbine that should be completed in 2015.