Net Power announced today that it successfully fired up a pilot plant near Houston that takes an entirely new approach to capturing carbon dioxide. The news marks a critical first test for a system that promises an economical path to cutting greenhouse-gas emissions.

What does that mean? The 50-megawatt natural-gas facility will put carbon dioxide to work, using heat and pressure to turn it into a “working fluid” that drives a specially designed turbine. That replaces the traditional steam cycle in power plants. Excess amounts of the gas can be siphoned off during the process, ready to ship and sell.

The “first fire” shows that the combustion process and integrated system works, a validation of the basic approach. But the company isn't using carbon dioxide to turn the turbine or actually producing power yet, which will represent the next major test.

What’s the big deal? To date, adding systems that can capture emissions from power plants has been complicated and expensive, jacking up the cost of producing electricity. Net Power expects that after it builds a few commercial-scale plants, it will be able to beat the costs of standard natural-gas plants.

That means the technology could provide a cheap, clean, and flexible source of power for the grid, capable of ramping up and down with demand more easily than standard solar and wind plants can. That promise is why energy researchers have been closely following the $140 million demonstration plant—and why MIT Technology Review placed the facility on its 2018 list of 10 Breakthrough Technologies.

What’s next? Once Net Power is able to demonstrate the full sytem works as hoped, it intends to license the technology. The company is already in talks with potential partners and customers, and it hopes to flip the switch on 300-megawatt commercial plants as early as 2021.

This post has been updated to clarify what the "first fire" accomplished.