Mon. Sep 26th, 2022
This is Soletair's demonstration unit.  Air goes in, fuel comes out.  (Espresso machine optional.)
enlarge This is Soletair’s demonstration unit. Air goes in, fuel comes out. (Espresso machine optional.)

At Ars we get a lot from pitches from start-ups who want to talk about their products. At least for this science reporter, the feeling is rarely mutual. But every now and then something arouses my curiosity. Something like… carbon capture for an office HVAC system.

During a video call, Finnish start-up Soletair Power recently showed a unit working in its office. It was built for the 2020 World Expo in Dubai, but you know what happened to exhibits. Instead of powering an expo booth, a gas-powered espresso machine was screwed onto the unit – as this machine turns CO22 in methane fuel.

The value proposition for the first part of the device is quite simple. Carbon dioxide accumulates in buildings full of people, and higher CO2 concentrations can affect your ability to think clearly. The usual way to manage that is to add more outside air (which may need to be heated/cooled). Another possibility is to use CO. selectively filter out2† This device can do the latter for you.

that CO2 can be easily vented outside or used to produce an impractical amount of seltzer. What makes the idea of ​​Soletair more interesting is that the rest of the device uses the CO2 in fuel. The configuration the company demonstrated makes methane, but can be swapped out for a liquid fuel process. Depending on the source of the energy that runs the machines, these fuels can be carbon neutral, as the carbon comes from the air. Whether it is economically feasible is another question.

Carbon makeover machine

the CO2 capture technology they use is a scaled down version of that designed for combustion plants. Air passes through a room full of tiny granules containing amines – compounds that bind with CO2 molecules. Periodically, the granules are cycled through a heating step. The temperature only needs to rise to 120°C, Soletair’s Petri Laakso and Cyril Bajamundi told Ars, so steam from the local heating system and/or an electric heating element will suffice. This gives the amine grains the CO . free2 they keep, which accumulates in a storage tank. The granules are then ready to accept more CO. to include2

The other two-thirds of the machine, which is about 2 meters high, 5 meters long and 1 meter wide, turns that CO2 to usable fuel. First, there is an electrolyser that splits water to make hydrogen gas. Then hydrogen is combined with CO2 in a methanation reactor to produce pure methane gas.

The Soletair had a Bunsen burner roar for this demonstration, and the company said it had previously run a cooking stove in the office. (And of course there’s that espresso machine…) The viability of this whole concept revolves around the fuel that delivers value somewhere.

as CO2 filter, this unit is built to handle a standard HVAC flow of approximately 3 cubic meters of air per second. That could serve an office building with a few hundred residents, says Soletair. In the company’s own, smaller office, the filter took in air at about 500 parts per million CO2 and halve that concentration.

However, generating fuel is not a common function in an office building. If you have a local use for it (heating? vehicles?), the prospect may be of interest to you. But Soletair also said that its local gas company is amenable to sending it to the public grid, such as net metering of solar electricity, but for gas. It doesn’t sound like that arrangement runs the risk of making a profit, but it can offset some costs.

The idea of ​​”air to fuels” is being pursued by companies such as Carbon Engineering that design facilities for capturing carbon on an industrial scale. It’s interesting to see that this has been attempted in a much smaller package, albeit with the focus shifted from fuel production to indoor air quality. As with all forms of carbon capture, imposing a cost on carbon emissions could improve the cost-effectiveness of spending that reduces emissions. But in this case Soletair mainly sells something other than the social climate benefit, although making your own fuel is a nice addition.

By akfire1

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