Tried making tiny burnable biomass logs out of coffee. Didn't quite work, I'll keep trying.

@verretor I'm not sure I can generate that sort of power to do it tho.

@neauoire I bet this will smell so good!

Have that and some wood in the furnace for a smokey, roasty boat!

@neauoire I wonder what other binding agents would work for this 🤔
@neauoire if they need to be durable maybe a natural hard resin? I wonder if the molasses is even necessary? wax isn't too hard to come by.

@neauoire That's a really cool idea! I'd never imagined it could be done, and it's cool that they have some nicer properties than regular wood in how they burn hotter and longer. It's a shame that it's such a resource-intensive process to make them though.

We are churning through a lot of coffee beans these days. The grinds go on the garden and occasionally in the worm farm but I'd love to find a more creative use for them.

@dotpk we can compost our beans when at a marina, when the marina has bins, but otherwise this is just waste that we toss in the water. I think we'll experiment with making logs from it.

@neauoire It's interesting that the article maligns sending 6 million tons of coffee grounds a year to the landfill. But doesn't that remove carbon from the atmosphere? Whereas burning them releases the carbon back into the air.

I'm probably misunderstanding or missing something, though.

(I realize transporting stuff to a landfill has a non-zero cost.)

@cancel @neauoire Landfill is generally pretty bad because most rubbish is compressed as much as possible so it becomes anaerobic and produces greenhouse gasses.

Also, in Europe there's a lot of incineration of rubbish, so over here it gets burned anyway.

I'll always prefer to throw used coffee grounds outside in the garden, but I'd love to find an alternative use for them

@dotpk @neauoire That makes sense.

Does the compression thing still apply even for coffee grounds?

@cancel @neauoire For whether an anaerobic situation produces more greenhouse gasses when in the decomposition of used coffee grounds? My presumption is yes, but I really don't know for sure.

@dotpk @neauoire used coffee grounds are almost entirely carbon, right? How could it produce more when buried?


Coffee ground make excellent compost.

They are also really energy-dense, so are an excellent feedstock for bio-diesel.

Someone calculated if you turned the entire amount of coffee drunk in the UK, and used all of the grounds for making bio-diesel, the UK would be self-sufficient in fuel. :D

Still unsure whether it's a comment on the energy-density of the coffee bean, or a comment on how much coffee we drink... :D

@neauoire and that entire process is supposed to be energetically sensible? I hope it's just a joke.

@neauoire It sounded like a very nice idea, but… wax and molasses? it looks like about half of the brick is made of things that could be used for better things than just burning for heat.

OTOH, in smaller quantities that sounds like a good recipe for firelighters.

as cool as this sounds, you need 225 gram wax per block one big candle, and an oven to preheat. and it is only one log per week that you get depending on how much you can drink.

@zem @neauoire Possible to get tons of grounds from local coffee shops. And if you heat the space with a wood stove, can utilize that heat to dry/melt the ingredients on the top of the stove. Use a log, make a log.

My experience of 15 years van life is:

you try to collect (coffe) waste first...

you add a high risk of fires if you dry sth on your stove, and also add smells. usually drying produces less output than input.

Liquid wax can burn on its own if hot enough, which means don't put it on the oven and forget it there, you ship might sink after you did.

I am happy to hear the test reports as i have never tried coffee pads, but i will remain skeptical, due to my own experience.

@zem Yep, dangers of hot wax is a good point, tho I am not likely to leave it unattended (not a big boat).

@neauoire this and the discussion makes me remember my wish we had a safe way to burn things other than mains gas for heating here in winter.

I have so many wood shavings and sawdust that would at least make amazing kindling and could probably be compressed into "logs" like that pretty easily.

The ishitani furniture folks do the same with a little pot belly stove iirc

@neauoire (does make me wonder about emissions vs the grounds or shavings just degrading in a landfill with or without methane capture, no idea where I'd find that information)


Uhm… maybe some fresh pine resin would help to keep the coffee together.
And I guess in Canada you can find it for (almost) free at lumber yards.

@neauoire What was the failure mode? Was it failing to burn, or falling apart, both, something else?

@ColinTheMathmo both, but it wasn't a serious try, I have an idea that I'll try today. Will report tomorrow :>

@neauoire don't really understand why you'd like to burn it. how much coffee do you produce a week? an espresso is like 7g, a week is gonna be something like 150g/person. supposing it has the same energy density of wood (but it's much lower) you could get about 1 kWh/1kg, so that would be equivalent to 150Wh per person a WEEK. so, basically you get the same amount of heat a single person generates in an HOUR. each day you get roughly 150Wh/(7days*24h)=0.88Wh. your raspberry pi emits about 5-10 times more than that.

drop your grounds into the ocean, it's much more ecological :-)

oh, I didn't take into account the effort to dry it down or worse, adding other substances to it to create "logs".

@zabow you're saying we should carry more logs of wood basically.

@zabow (the drying of the grounds is currently done with passive heat btw)

@neauoire what I'm trying to say is that you'll end up decreasing the stove efficiency, more ashes, more CO2 in the air. if you try to optimize your combustion with dry logs and keeping your stove clean has a much greater effect.

@neauoire much greater as in orders of magnitudes. I remember some guys here in Sardinia, they had a startup for creating piezoelectric mats with people walking on them. I think they managed to sell some to the Louvre... they were able to light up some minuscule lights with that. each 1m2 mat would cost like 1k$. buying a photovoltaic panel for 10$ would have produced much more energy for maybe 30 years, no maintenance :-D sometimes back of the envelope calculations do help

@zabow yeah I'm trying to just that right now.. I can't quite figure out how buying extra wood that's less energy dense than coffee logs is more efficient. Gimme a minute.

(30 years for a photovoltaic panel?!)

@neauoire @zabow when i last looked into it, the lifetime of a solar panel is given as 10 years for warranty purposes. they do lose efficiency over time but recent research has foond that some cleaning and maintenance can recover at least some of that efficiency.

@neauoire @zabow that is, it serms, and i could be wrong, that it has been recently discovered that solar panels can potentially last a lot lot longer than 10. given they were introduced in the early/ mid 80s their actual lifetime is undetermined

@neauoire @zabow the confusion may be the efficiency difference expected by both of you being in opposite directions

From the article, "According to Bio-Bean, they burn up to 20% hotter and longer than kiln-dried wood!" - but obviously this would vary with the preparation, and doesn't say anything about the soot/co2 production differences or energy used for production.

Imo it's all good fun but I do feel like it's likely to have similar issues to other waste to energy methods

@maxc @neauoire bio-bean logs contain about one third of coffee grounds in weight: 25 cups (25 X 7g) = 0.175kg and each log weighs 0.5kg. I didn't find anything about the other components, but they explicitly say "Coffee Logs are not suitable for barbecues or other open fire cooking". so they may contain anything as far as I know. and I don't really like the fact that they don't publish anywhere scientific energy tests. any cheap pellet maker publishes the energy content these days...
and their price is incredibly high: ~7$ for a bag of 16 logs (8kg): here wood logs go by ~$8 for 100kg.

@zabow @neauoire completely agree re: cost trade-off not being there if you are buying them. It's just a citation for where the idea that the coffee "logs" may be higher energy density than wood came from.

For the waste conversion aspect as well - depending on where you're located, firewood is also often (in commercial terms) waste quality wood or off-cuts - hence being so cheap per unit mass.

@neauoire most panels are guaranteed at least for 80% after 25-30 years. this was known for decades. of course it may be much less in marine installations if the hardware is cheap. PV tech is absolutely mature and the last 20-25 years didn't see any relevant efficiency increase in the basic physics (~20-25%), they just improved module topology, and the cost plummeted.

@neauoire someone needs to do that with those environmentally-hostile plastic nespresso capsules.

@neauoire if its vaguely biological, and with substantial applied heat, the majourity of thing shall charcoal

@neauoire coffee grounds make fantastic compost and the world needs more soil.

i'm not certain this process is energy positive without industrialized optimization and identification of salvage binding agents.

"industrialized optimization" just means batch size and the correct machines--- it could be modeled on community bread baking at a centralized oven, for example.

@tehn obviously, this is for when we don't have access to local compost bins.

@neauoire this is actually quite an old method - after world war two (and probably already during) my uncle told me that the people made their own coal by mixing coal dust with water, pressing the resulting coglomerate down and drying the resulting pellets. we came upon this topic when i showed him pictures of devices for doing this with paper pulp that are sold today:

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