Beijing Unveils Supercritical CO2 Turbine That Could Upend Power Tech
- China has launched the world’s first carbon dioxide–based power generator, using supercritical CO2 instead of steam to produce electricity with over 50% efficiency.
- The system harnesses industrial waste heat—such as from steel plants—and needs no water or fuel, reducing maintenance and equipment complexity.
- Compact and versatile, the technology could revolutionize carbon capture by using CO2 for profitable energy generation, potentially lowering emissions and storage costs.
China has launched a first-of-its-kind power generator that works with carbon dioxide instead of steam, like traditional generators in power plants. Perhaps more importantly, however, the new generator works with waste heat and boasts a much higher efficiency than existing ones at doing that. According to the company that designed it, the generator is the start of a new era, the South China Morning Post reported.
Normally, thermal power generators work in one of two ways, both relying on heat to turn a turbine. In coal power plants, the burning of coal heats up water until it vaporizes, the vapor then being directed to the turbines that generate electricity. In gas-fired power plants, the turbines are activated by the heat, generated from the compression of gas and its subsequent heating.
Unlike them, the SCMP reported, the new generator uses carbon dioxide in a supercritical state, meaning the compound is subjected to a certain pressure and a certain temperature, which makes it behave simultaneously like a gas and a liquid. The state is called supercritical, hence the whole generator is called a supercritical one. Conveniently, waste heat from sintering in steelmaking plants could reach as much as 700 degrees Celsius—so the inventors of the new generator connected it to one steel works, and to the grid. Even more conveniently, the supercritical state of CO2 does not, in fact, require this high of a temperature.
According to one Chinese power systems major, Hanwha, carbon dioxide begins to behave like both gas and liquid at temperatures of over 31 degrees Celsius and a pressure of 74 bar. The hybrid behavior of the compound features properties such as low friction (like a gas) and high density (like a liquid). Among the advantages of the technology, Hanwha counts the fact that such generators do not need water or fuel, they require much less maintenance, and the equipment they use is much simpler than what other generators require. On top of all this, the supercritical carbon generator boasts an efficiency rate of over 50%, compared with 40% for traditional thermal power generation technology.
The South China Morning Post notes that the advantages of the supercritical carbon generator technology also make it more widely applicable: thanks to the fact that supercritical carbon dioxide is denser than steam, the generators do not need to be as large as they need to be in steam-powered plants, meaning they could be installed on, for instance, ships or spacecraft. They can also be installed in any confined space, too.
The technology could potentially give a major boost to carbon capture, providing a use for the captured carbon dioxide rather than simply dumping it underground, as the European Union plans to do, spending billions of no-return euros on transporting CO2 via a pipeline to a storage site in the North Sea. Utilizing the chemical for power generation certainly seems like a better idea—and an idea that could bring the cost of carbon capture down by adding a revenue-generating aspect.
Currently, the only viable form of carbon capture technology is the one that involves the captured gas being used for injection into oil wells for what the industry calls enhanced recovery. CO2 injection works by the CO2 molecules getting flushed into the well at high pressure, mixing with the oil molecules and forming a less viscous liquid that can then be extracted—and sold. A lot of oil companies have been using carbon dioxide for enhanced oil recovery for years, even without the pressure to cut emissions, in evidence of the sound economic basis of the technology. Power generation using supercritical carbon dioxide could develop into a similarly sound technology, utilizing a compound that is being considered a pollutant by some—at a profit.
By Charles Kennedy for Oilprice.com
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