авг 17, 2018
Zero-Carbon Natural Gas
The world is probably stuck with natural gas as one of our primary sources of electricity for the foreseeable future. Cheap and readily available, it now accounts for more than 30 percent of US electricity and 22 percent of world electricity. And although it's cleaner than coal, it's still a massive source of carbon emissions.
A pilot power plant just outside Houston, in the heart of the US petroleum and refining industry, is testing a technology that could make clean energy from natural gas a reality. The company behind the 50-megawatt project, Net Power, believes it can generate power at least as cheaply as standard natural-gas plants and capture essentially all the carbon dioxide released in the process.
If so, it would mean the world has a way to produce carbon-free energy from a fossil fuel at a reasonable cost. Such natural-gas plants could be cranked up and down on demand, avoiding the high capital costs of nuclear power and sidestepping the unsteady supply that renewables generally provide.
Net Power is a collaboration between technology development firm 8 Rivers Capital, Exelon Generation, and energy construction firm CB&I. The company is in the process of commissioning the plant and has begun initial testing. It intends to release results from early evaluations in the months ahead.
The plant puts the carbon dioxide released from burning natural gas under high pressure and heat, using the resulting supercritical CO2 as the "working fluid" that drives a specially built turbine. Much of the carbon dioxide can be continuously recycled; the rest can be captured cheaply.
A key part of pushing down the costs depends on selling that carbon dioxide. Today the main use is in helping to extract oil from petroleum wells. That's a limited market, and not a particularly green one. Eventually, however, Net Power hopes to see growing demand for carbon dioxide in cement manufacturing and in making plastics and other carbon-based materials.
Net Power's technology won't solve all the problems with natural gas, particularly on the extraction side. But as long as we're using natural gas, we might as well use it as cleanly as possible. Of all the clean-energy technologies in development, Net Power's is one of the furthest along to promise more than a marginal advance in cutting carbon emissions.