Hello. It’s been a while.

A year or two ago you subscribed to this newsletter in the hope I’d be sending you regular missives about composting. And then the long-Covid I’d been struggling with kicked into a higher gear and I was incapacitated, both mentally and physically – no more composting, no more writing about composting, no more anything at all really. I wrote about it back in March on my personal site, if you’re curious.

The good news is that while I’m not in any way “better” I’m figuring out how to work with this new body and mind, learning how to pace myself and respect the limits to my capacities. And as part of that I’m giving the Aerobic Digest another go, writing a paragraph here and there when I have the energy, until a newsletter is ready to send.

Of course just because I wasn’t personally able to do any composting doesn’t mean composting didn’t get done. The rabbits still produce a giant sack of poop and pissy hay each week and it has to go somewhere. So every month or so I’d get a friend to fill up the hexagon while I sat and pointed like some wise old fool.

And then at Christmas my sister and brother-in-law arrived in Birmingham. To cut a very irrelevant story short, having lived on the other side of the planet in New Zealand for 20 years they ended up moving in around the corner from us. Lucy’s a keen gardener with an interest in permaculture, so she’s taken on what was threatening to become a rather neglected allotment plot, with spectacular results!

Having someone actively working the plot means much more material to compost, and so we’re back to the three heap system, hot composting in the hexagon and then decanting to the right for mesophilic and again for final maturing. It was a bit slow during the drought but since the late summer storms hit last week it’s been cooking nicely. Which is good as there’s a lot more growing happening on the plot these days!

That’s enough about me. Here’s a bunch of things that caught my attention recently.

Before I was properly disabled by my chronic fatigue I did a bit of freelance work for Compost Culture in Birmingham, designing and, while I was able, building their three-bay composting structures. But I never got to see them fully in operation so when they released a video about the project in February it was my first chance to see how they were being used and what was coming out of them. Quite an emotional feeling, I have to say.

I wanted to talk about this at the time but it was always evolving and it never seemed the right moment. Since then I’ve been slowly working on the build documentation and want to write a bit more about the why as much as the how, so look out for that in a future issue.

In the meanwhile, enjoy the film, check out their website (look, there I am at the bottom of the page!) and get involved!

You might remember, way back in the last Aerobic Digest, I linked to an astronomy article that claimed our sun produces less energy than a compost heap. The number given is 276.5 watts per cubic metre, or about three 100 watt lightbulbs, which is nice to know. We’re all aware our heaps are giving off energy in the form of heat and capturing that otherwise wasted energy is something gardeners often ponder, be it for a seedlings hotbed or an off-grid shower.

So I was intrigued to stumble across Compost Computer, a project by the FutureEverything tech/art conference in Manchester, “an experimental project that will radically transform FutureEverything’s computational infrastructure by integrating more-than-human protocols”. A compost heap running a computer? That’s new.

Like most things that come from the intersection of art and technology you’ll probably be, at best, scratching your head and at worst screaming “what do you mean?” at the screen. I spent a while as a digital artist (I was on the FutureEverything website looking for talks from when I attended in the mid 2010s) and even I struggled to figure out what the hell is going on here. It’s a mini-masterclass in taking something interesting and smothering it in a find blend of academic jargon, art-speak and tech boosterism, but having dug a little deeper I can assure you there’s something interesting going on here.

This article goes into some actual detail of how it will work, and my reading is they’re not tapping the heat given out by the composting process. They’re utilising the chemical properties of the compost to build electric batteries.

An electric battery can very crudely be broken down into two different pieces of metal – the cathode and anode – which sit in a suitable chemical soup – the electrode. When connected to an electric circuit they react and generate a current. We commonly think of the electrode as “battery acid” – the gunk that you find when you leave an electric device in the drawer for years – but it can be a wide variety of media. An earth battery is literally metal rods plunged into damp soil, the chemistry of which can produce a current, and the earth itself conducts electricity, known as telluric current. Since soil is partially made of decomposing organic material it’s not a great leap to try doing to the same with a compost heap.

I assume the end result of this project will be a full-size compost heap with a cathode and anode inserted and kept moist enough to ensure a current can be generated between them, with the hope that this is enough to power a computer running their website. (Which isn’t actually as much as you might think - see the solar powered website running Low Tech magazine.)

Of course composting isn’t a process that’s easy to control. You’re at the mercy of your available inputs, the climate and the available resources to manage the heap, and this could have some interesting effect on the battery.

More critically, if this process is taking energy from the heap, what does that do to the resulting compost? This project is working with MUD, a community growing project, and doesn’t want to inadvertently reduce their crop yields. They expect the electrochemical potential of the heap to be depleted before this affects nutrients, but it’ll be interesting to see testing of this. As we know, compost is not just about nutritional load. It’s about how that nutrition is locked in and slowly released, and how the microbiome interacts with it. That electrochemical stuff might turn out to be important.

Will it work? I’m cautiously optimistic. Compost heaps are huge piles of energy potential which we turn into heat and plant food. Why not also electricity? And if the heap is powering essential infrastructure that means there’s an incentive to look after and maintain it. I very much doubt we’ll be connecting our heaps to the national grid but as a proof of concept it’s certainly an interesting one.

Having understood broadly what’s going on here I find myself with more questions and thoughts and may well return to this project in a future newsletter. I’m particularly interested in how this might manifest as an artwork and what that artwork might be saying. If you have thoughts, please send them my way.

And yes, pop-culture heads, this is basically the same as how Doc Brown powers the DeLorean at the end of Back to the Future.

Machynlleth is a town in central Wales which I jokingly call the home of the practical hippies. Up the hill is the Centre for Alternative Technology, established in the 1970s and acting as a gravity well for eco-minded folk. So it wasn’t a big surprise to learn they have a fairly impressive community composting scheme running in the town.

Like a lot of practical-focused enterprises the web presence for Criw Compostio is a little basic, with all efforts put into the composting itself, something made very clear in this great talk given by Ffin and Steph for the Social Food & Gardens online gathering.

What I really appreciated was the time given to making the composting setup fit the inputs available and the needs of the community, and how they use waste processing to, as they say, go “beyond community composting”. Next time we’re heading to the seaside from Birmingham I think a visit might be on the cards.

Add this to the list of things to do with woody material that won’t compost quickly. alongside Hügelkultur mounds and biochar. A dead hedge is probably better considered a temporary structure than a compost factory, although I guess you could harvest the remains once it’s done. Primarily though it’s a barrier constructed in a managed woodland, usually to mark out a path or protected area. The big advantage, as outlined in this lovely relaxing video, is how it’s made up of waste material, most of which would be hard to compost, creates a habitat for animals and fungi, and after a few years returns nutrients to the soil.

That’ll do for this issue. I don’t know when the next one will be out but if I had to guess I’d say in a couple of months? Maybe? I know I have plenty of things to write about so that’s not a problem.

If you have any questions about composting that I could answer in a future issue, please send them along. It's always good to have a writing prompt. And I'm always up for interesting links to share here.

Email to [email protected] or @ me on Mastodon or Bluesky where I keep tabs on the various #compost tags.

Your friend in rotting vegetable matter,

Pete Ashton
peteashton.com