Felice Frankel/MIT
Researchers from Massachusetts Institute of Technology (MIT) & National Energy Laboratory (NREL) have just released information about a new type of heat engine with no moving parts. The heat engine has an efficiency of around 40% and could one day replace conventional steam turbines. in the future.
Their results have just been published in the journal Nature.
Called a thermophotovoltaic (TPV), the new engine shares some common features with traditional photovoltaic cells, but captures high-energy photons from a white-hot-source to generate electricity. This new engine can generate power from temperatures between 3,400 & 4,300 degrees Fahrenheit (1,900 to 2,400 degrees Celsius).
The future plan for the heat engine is to integrate the cells into a grid-scale thermal battery that could absorb excess heat-thermal energy from sources such as the sun & store that energy in heavily insulated banks of hot graphite. When energy is really needed, the TPV cells could then convert the heat into electricity & supply it to the grid to fill gaps in supply from renewables when they aren’t able to meet demand.
However, that is for the future. Now, the team successfully demonstrated the main components parts of such a system, but on a small scale. They are currently working on a way to put all parts together for a demo testbed of real things.
Once that is achieved, they hope to scale the things-up with the long-term goal of replacing fossil fuel driven power plants.
“Thermophotovoltaic cells were the last important step to-ward demontrating that thermal batteries are a viable concept,” explains Asegun Henry, Robert N. Noyce Career Development Professor in MIT’s Department of Mechanical Engineering. “This is an absolutely critical step on the road to proliferation renewable energies and achieve a fully decarbonized grid.
This could prove revolutionary for energy industry
At present, most of the world’s energy production comes from sources such as coal & natural gas, as well as some major renewable sources such as concentrated solar & nuclear power. At present, most of the world’s energy production comes from sources such as coal & natural gas, as well as some major renewable sources such as concentrated solar & nuclear power.
This has proven effective, but this technology has changed little for-over-a century. But it turns out they’re not that efficient.
Steam turbines can typically convert about 35% of the energy provided by their heat source into useful electricity, with some engines being as efficient as 60%. That’s great, but steam turbines have one major weakness: moving parts that can break over time.
Parts must also be able to withstand high temperatures over long periods of time. Parts will eventually wear-out over time.
To counter this, some researchers like those behind the new thermophotovoltaic engine have been looking for solid-state alternatives that could replace traditional steam engines.
“One of the advantages of solid-state energy converters is that they can operate at higher temperatures with lower maintenance costs because they have no moving parts,” Henry added. “They just sit there and reliably generate electricity.
TPV cells could be the ticket to such things. They could also be made of semiconductor materials with a specific band gap: the gap between a material’s valence band and its conduction band. Under such circumstances, If the material absorbs a photon of high enough energy, it can kick an electron across the band gap, where the electron can conduct and thus generate electricity. All this without moving rotors or blades.
A great potential help to reduce the dependency of global economies on this old technology and later on fossil fuels.
“There’s definitely a big net benefit here in terms of sustainability,” says Henry. “The technology is safe, environmentally benign in its lifecycle and can have a huge impact in reducing CO2 emissions from electricity production.
This research was supported, in part, by the U.S. Department of Energy.
