Burning coffee logs in woodburner?

paperclap

Hi all,

I often use pallet wood (heat treated only) for kindling, and “real” wood (sourced for free), cut up and seasoned for the bulk of fuel.

But, been looking at coffee logs lately. I drink a fair amount of coffee, and it often goes either in the bin, or on the compost bin!

Does anyone here make their own coffee logs? I’ve watched a handful of videos, and I think the general mixture is coffee grounds, shredded paper and sawdust. I have sawdust (from cutting said “real” wood), but I don’t have shredded paper laying about. Plus, not sure I feel comfortable burning any ole paper in my woodburner anyhow.

Can these logs be made with just coffee grounds and sawdust? If so, what’s the best ratio? Do I need to add water (and then push it out)? How long do they take to dry out before they can be burned?

Thanks!

twopenny

This one uses coffee and sawdust
https://www.tinyecohomelife.com/coffee-logs-environmentally-friendly
Haven't got time to investigate but I'd be concerned about oil from the grounds sticking to the chimney.
Also - 20 cups to make 1 log?   

FreeBear

paperclap said: Can these logs be made with just coffee grounds and sawdust? If so, what’s the best ratio? Do I need to add water (and then push it out)? How long do they take to dry out before they can be burned?

You could probably make some logs with just sawdust & coffee grounds, but... In the commercial world, these things are made using very high pressure extrusion machines that cost £10K or more. You might be able to cobble something together using a bottle jack (or log splitter), but you'd only get pellet sized fuel for your efforts.

Without high pressure equipment, you will need a binder so that everything will stick together - This would be something like a weak wallpaper paste or PVA (have also heard of some people using cement). Using a binder, you'd then need a mold or use cardboard tubes (bog roll perhaps). Fill your mold with the sawdust/coffee grounds/binder. Tamp down well, and leave to dry a little. Then stack somewhere warm & dry.

I did something similar a while back using sawdust & PVA. Lined a briquette maker with newspaper, filled with the sawdust mix, and squeezed the hell out of it. Left them in the shed for ~6 months to bake over the summer. Yes, they burned in the stove. Didn't seem to kick out much heat, and not really worth the effort in my opinion. If I have sawdust to burn, I'll just put a mound in the bottom of the stove before lighting the fire.

daivid

I'm not sure how your 'fair amount of coffee' compares to mine - I probably average 3 cups a day with a stovetop press. This summer I collected all the coffee grounds (to experiment with making rooting compost) and the amount I ended up with would make no more than 1 or 2 logs (depending how much it is bulked up). As well as using industrial machines the way this works commercially is by collecting huge amounts of coffee grounds from coffee shops. Years ago I worked in a busy cafe; the 30l bin the coffee grounds went in needed emptying at least daily. With domestic amounts it might be an interesting experiment but I can’t see it being an effective method of fuel production.

JohnB47

Years ago, when I had an allotment, I decided to try mixing used coffee grounds and compost to make an ericaceous mix for blueberries. I asked my local coffee shop if I could have some of their throw-outs and they gave me a huge black bag of grounds. Since then I see Waitrose have started leaving a little bin of used grounds just outside their store where they let people take some for free. It's worth asking nearby coffee shops if you can have some of theirs.