North Carolina-based NET Power is pioneering a novel approach to capturing carbon dioxide in its reportedly zero-emissions natural-gas pilot power plant in Houston, Texas. The company is investing $150 million in its innovative design, which is centered around turbine technology that is mostly unchanged since its invention over 150 years ago. The key difference is that NET Power’s turbine uses carbon dioxide, rather than a mixture of hot gases, to transfer heat, which is then converted into mechanical energy and, ultimately, electricity. NET Power hopes that its plant design will prove efficient enough to be mass marketed and installed at natural gas power plants around the world.
The turbine technology used in NET Power’s demonstration plant is based on the Allam cycle, named after its creator Rodney Allam, who developed the system in collaboration with colleagues at 8 Rivers, an investment firm focused on innovative technology. “He did it old-school style—with just pen, paper, and a four-function calculator,” said Walker Dimmig, a principal at 8Rivers, according to Quartz. “We had to hire an engineering firm to redraw Rodney’s drawings on the computer, and verify whether what he claimed would be feasible.” The Allam cycle exploits the unusual qualities of carbon dioxide, which, under high pressure and temperature, becomes a “supercritical fluid,” a state of matter that shares characteristics of a liquid and a solid. In its supercritical fluid form, carbon dioxide has proven to be an efficient extractor of heat energy in a turbine.
In collaboration with Toshiba, NET Power modified turbines to be compatible with the Allam cycle. Because of their highly efficient design, NET Power’s turbines are one-tenth the size of normal turbines. After some final tests are conducted and minor problems are fixed, NET Power expects its plant to begin its operation in 2018. At full capacity, it will produce enough electricity to power 40,000 homes. NET Power plans to license its technology, rather than building its own plants, a practical move in response to a challenging market. However, if the natural gas boom is here to stay, NET Power hopes that its carbon capture technology may prove useful and popular as the world shifts towards a cleaner energy economy.