I think your comment describes something very similar to what Solar Foods is doing (https://solarfoods.fi).
There was a previous discussion with some more details about what they're doing: https://news.ycombinator.com/item?id=18344636
There was a previous discussion with some more details about what they're doing: https://news.ycombinator.com/item?id=18344636
Basically animal food that is made in a bioreactor from methane. Methane can be easily made from hydrogen and carbon dioxide via the sabatier reaction.