Over a video call, Finnish start-up Soletair Power showed Ars Technica their Machine that converts office-air Carbon Dioxide into Fuel. Scott K. Johnson reports: The value proposition for the first part of the device is pretty straightforward. Carbon dioxide accumulates in buildings full of people, and higher CO2 concentrations may impact your ability to think clearly. The usual way to manage that is to introduce more outside air (which may need to be heated/cooled). Another could be to selectively filter out CO2. This device could do the latter for you. That CO2 could simply be vented outside or used to produce an unwieldy amount of seltzer. Instead, what makes Soletair's idea more interesting is that the rest of its device turns the CO2 into fuel. The configuration the company demonstrated makes methane but could be swapped for a liquid fuel process. Depending on the source of the energy running the machines, these fuels could be carbon-neutral since the carbon comes from the air. Whether it's economically viable is another question. The CO2 capture technique they're using is a scaled-down version of those designed for combustion power plants. Air goes through a chamber full of small granules that contain amines -- compounds that bind with CO2 molecules. Periodically, the granules are cycled through a heating step. The temperature only needs to rise to shy of 120C, Soletair's Petri Laakso and Cyril Bajamundi told Ars, so steam from the local heat system and/or an electric heating element is sufficient. This makes the amine granules release the CO2 they're holding, which accumulates in a storage tank. The granules are then ready to absorb more CO2. The other two-thirds of the machine, which measures about 2 meters tall, 5 meters long, and 1 meter wide, deal with turning that CO2 into a usable fuel. First, there's an electrolyzer that splits water to make hydrogen gas. Then hydrogen is combined with CO2 in a methanation reactor to produce pure methane gas.

Read more of this story at Slashdot.