The article they link about pyrolysis is worth a read too. The main source of CO2 emissions from cement production is cooking down limestone into lime IIRC. I was curious how much energy is used to turn the biomass into the end product and what waste is generated. It's a bit too detailed for me to understand, but the process ends up with 15-25% biochar (the stuff they're promoting in this article), some potentially useful byproducts, and some regular combustion pollution.

I worked on some undergrad research examining the potential to use spent coffee grounds for biodiesel. SCG has residual oil that can be extracted and refined. I wonder if this could be combined with biochar, getting multiple commodities from a waste product.

I guess this means I'll need yet another, different colored wastebin just for coffee now. I mean I'll do it if it helps, but I can only fit so many receptacles in my kitchen. Meh, I'll just put the rest in the twins' room.