[dredmorbius]

But plants already convert solar energy to chemical storage at efficiencies of 1-3%. Up to 10% for algae (higher per-hectare yields are based on added energy). It turns out that existing artificial proceses might already get close to this via electrolysis, carbon separation from seawater,and Fischer-Tropsch synthesis. But for raw efficiency, it's really hard to beat plants.

The other problem is that humans are already appropriating 20-40% of all primary production. So while plants are good at what they do, we're already leaning on them really hard.

Unless humans can come up with methods which are 1) complimentary to existing plant activity (e.g., they don't compete for the same space, water, and/or minerals), and that's 2) roughly as efficient or better, we look kind of stuck.