Well, anything that goes through methane isn't much of a solution in my books. Most will be captured by fossil methane. Anaerobic digestion is leaky and methane is a global warming problem, obviously. Methane pyrolysis has a limited market. I'd prefer that existing anthropogenic biomethane be diverted to things like the existing methanol problem. Not a fan of Hazer, in other words.

I'm a big fan of seaweed-derived feed supplements to avoid ungulate methane emissions from digestion. Not familiar with Sea Forest specifically, but thumbs up.

Given 20% of the earth's land surface is for crops, I don't think adding heat exchangers under it is much of a game changer. ;) Roots looks like a niche for high-value greenhouse crops, like the cannabis it mentions. Nothing wrong with that, just not that interesting as a big lever.