[calmdownpeople]

Isn't the carbon already locked away in the coffee grounds? Why spend energy and hence more CO2 emissions on charring the grounds?

[mrguyorama]

Because coffee grounds would actually make terrible aggregate, as complex organic and formerly alive compounds, there's a lot of potential for weird chemical breakdown that could harm the concrete or anything else in the concrete.

Char is pretty chemically stable, because carbon is very chemically stable.

[tedivm]

The coffee grounds are biodegradable, and that process causes CO2 and methane to be released.

[soperj]

Just to clarify, methane is only released if it biodegraded by anaerobic bacteria, if it's biodegraded by aerobic bacteria it only produces CO2.

[jayd16]

We could carbonize the biomass then cram it in a landfill and... wait that's just reburying charcoal.

[thfuran]

My vote is for sequestering carbon as an ever-growing mountain range of diamonds.

[Eldt]

Where are the grounds going to be stored?