You could. There are several ways of taking CO2 out of the air or separating it. The ideal way of doing it is basically doing it on the same site where you merge the two components together to make natural gas, but there are simpler ways when you have limited resources. To give an example, in the Netherlands, for instance, in a high-rise with solar panels on the roof, all year round, whenever the sun makes hydrogen, when the heating season starts you just bring in a bottle of CO2 and mix it together at the time they use it to heat up the apartment building. It is a very simple process, if you want to keep it very simple, but ideally you have sources where you take the CO2 out of the air.
There's a company in Calgary right now. There are investors involved in it, like Bill Gates and Google. It's called Carbon Engineering, and they are looking at the cheapest way to extract CO2 out of the air. It's right now at a stage where they can extract it, but it is a liquid. To get it out of the liquid more cheaply is the next step. If they do that, they are the champion in separating the CO2 out of the air. You can set these things up wherever you want in the world with solar or wind power to power it, and it's the equivalent of thousands of trees, basically.