[bumby]

This assumes humans could turn 100% of the feed into usable calories. Considering 1) the link defines feed to include grazing and 2) humans are 0% efficient at turning cellulose into calories, the quoted number probably doesn't mean what you think it means.

[Retric]

We have many ways of turning cellulose into useful calories. Fire being perhaps the oldest.

[bumby]

If we could eat fire to sustain ourselves, then that would be a cogent point.

[Retric]

Even if you’re just talking about biological calories rather than as a unit of energy, fire reduces energy expenditure to stay warm. Thus acting as a significant food supplement both historically and currently.

[bumby]

This is still a bit of a stretch to make a relevant point given the context of the discussion. I don’t think many are promoting getting rid of cattle to make room for biomass fuel.

[Retric]

I've seen that argument made several times. EV's are great on land, boats have several options, but for mid to long range air travel biofules have a lot going for them. Unfortunately they need a lot of land.

The underlying numbers seem reasonable with US airlines use ~10 billion gallons of fuel per year while the US produces ~15 billion gallons of ethanol being freed up by the rise in EV's.

Globally things aren't as rosy, but freeing even 1/5 of the land devoted to grazing, alfalfa, and feed corn would go a long way. Reducing US beef consumption would have positive health impacts. So from a policy standpoint shifting the specific subsides seems like a good idea.

Even if we can't get net zero the more we can cut quickly the longer we have to finish the job.

[bumby]

I don’t think that premise holds. With the exception of sugar beets, crops are largely net negative in terms of energy production. You don’t create a more efficient system by adding layers of inefficiency.