We have always year round composted our coffee grounds. It makes great dark, rich looking compost. I always thought it was holding the carbon, but maybe not? What do I have to do to activate the grounds?
By activate the grounds I have to suppose you mean getting microorganisms to start occupying them, yes?
One of the great things about SCG (spent coffee grounds) is that once they have been brewed, the bacteria, molds and fungi in the air will settle on the grounds and start feeding and multiplying.
Within a week those grounds will be home to many different microorganisms which means you could call them at that point "activated".
SCG don't really need any care to become bioactive, worms love them and will even seek them out from far away since they are a favored food for earthworms and compost worms (red wigglers).
Compost made with SCG additions is a very rich compost, full of many minerals both from SCG and other inputs.
I would advise against using SCG for making char, first off, the grounds are fine enough that they will turn to ash long before they would become char, they are far more valuable as compost additions or simply added to a garden bed as part of a mulch layer.
Bryant RedHawk wrote:first off, the grounds are fine enough that they will turn to ash long before they would become char, they are far more valuable as compost additions or simply added to a garden bed as part of a mulch layer.
This would the primary concern. There just isn't enough structure in a small fleck of coffee that would remain after it's been charred. It would simply turn to dust.
Biochar is a hotel for microbes. They move into the nooks and crannies and take up residence. With a chunk of wood, much of that structure remains after charring, and thus, many rooms are left in the hotel for the microbes to live.
Coffee grounds then serve as the food source for those microbes. There's not enough pore space in a tiny charred chunk of coffee to make a hotel for the microbes. It's better to just let them decompose the coffee and have a hearty meal.
"The rule of no realm is mine. But all worthy things that are in peril as the world now stands, these are my care. And for my part, I shall not wholly fail in my task if anything that passes through this night can still grow fairer or bear fruit and flower again in days to come. For I too am a steward. Did you not know?" Gandolf