The US energy startup, Net Power, has successfully fired up its natural-gas plant in La Porte, Texas. In the age of climate change, when reducing emissions should be our primary goal, it may sound odd to celebrate the launch of a fossil fuel-burning plant. But Net Power is unique. Its new facility is the first fossil-fuel power plant that promises to capture all its emissions effectively at zero extra cost. 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. This 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.