Considering agriculture and forestry combined produce about 5 billion tons of methane emissions a year, I don't think there's a shortage of availability.

It'll be a lot more work to capture and direct all that, but the biosphere spins off plenty of decomposition byproducts.

Is it more or less energy dense than oil?

    The consumption of oil has steadily increased over the last three decades, totaling 4.53 billion metric tons in 2023,

That's oil shipped and used, not methane drifting free from biowaste across the plant.

How much can we actually capture, how much energy is that, and how great is the conversion challenge to shift most cars to methane, etc?

It appears a little larger than a handwave problem IRL.

> Can we get that much methane from biomass?

I know that food waste generates a heck of a lot of methane in landfills, but I’d love if someone could add some rough napkin math on this!

Biomass availability in the US:

https://www.energy.gov/eere/bioenergy/2023-billion-ton-repor...

One would like to focus on existing streams before having to increase area used to grow biomass.

be afraid.

methane hydrates;

strip mining ocean floors could keep fossil fuel consumption going at current rates for millennia.

but before that we could get we stuff in the permafrost

all terrible ideas ... so probable.

https://duckduckgo.com/?q=methane+hydrates&t=lm&ia=web