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Small-Scale AD & On-site Composting in London

"Often the thing that is driving you is not the thing at all which is driving residents"


This episode corresponds to Lesson 3 and Lesson 6 (coming soon) of our course.

In this second episode we stopped in London to talk to Clare Brass from FoodLoop and Rokiah Yaman from LEAP. Eleen Murphy  asked them about their respective projects: A small-scale anaerobic digestion system and an organics recycling program for an inner-city housing estate!

Thank you to BiobiN for making  this episode possible.

BiobiN® is a mobile, on-site organic/wet material management solution that starts the composting process and effectively manages odour from putrescible waste. BiobiN® can be used in a variety of outlets, including food manufacturing, restaurants, shopping centres, supermarkets…it’s endless. Whereever organic or wet materials are generated, BiobiN® is THE solution



EM: So Rokiah, I’ll start with you. Maybe you can tell us a little bit about Community By Design and the project you’re working on?

RY: Okay. Community by Design is a social interest company – community interest company – and we are currently developing anaerobic digestion on a small scale. It’s looking to make the technology cost effective at that scale and user friendly. There’s not that much of it at the moment at the very small scale and what we’re doing is to see if we can spin out as many environmental, social and economic benefits as possible all in one go. So it’s a partnership project and we’re just one of the partners, and the other partners include Methanogen who is a supplier, a research engineer from a company called Alvan Blanch, there are other engineers involved, and also Leeds University.

EM: Right, and how are you funded?

RY: We’re funded by Camden Council, and they’ve been great because they’ve supported us through the initial two years and we couldn’t have done this without them. And their objective in funding us is to see if we can generate any employment and training opportunities. So the training side of things…we’ve had quite a lot of opportunity during the build and also at all kinds of different stages of the project. And by the end of this year we hope to do a bit of economic modeling and see where we can pull the income in from to take beyond the funding. But WRAP has also funding us: WRAP are Waste and Resources and Action Program, and they’ve given us funding for the next year to do the other sites, basically.

EM: Yeah that’s really cool. And I know that some of our listeners have not yet “graduated” from, or are beginners on the anaerobic digestion topic. Maybe you can re-detail the process so we have everyone on board here.

RY: Okay, so anaerobic digestion is a type of composting that happens without oxygen. It takes place in a sealed vessel and it can break down any organic material, except for wood: it’s the lignin in the wood that it can’t deal with. And we capture the gas that comes from it, which is about 60 percent methane, 40 percent Co2 and then some trace elements of other gasses. And the waste itself turns into a pretty liquid fertiliser: that’s what happens when we use food waste as the main feed stock. It’s a good compliment actually to compost that’s generated through an aerobic process, so they compliment each other pretty well in terms of nutrients.

EM: Brilliant stuff. And I was looking at how you use the biogas that you trap, maybe you can explain that a little bit?

RY: Oh right. So the biogas: the 60 percent of it which is methane is pretty much identical with what comes out of your mains gas, so that’s the bit that we can burn and generate heat and electricity with. It can also be used as a vehicle fuel. So we basically have got funding for the next year to set up three sites, and one of them has just been set up and been commissioned already. That one is going to be generating electricity and heat using something that looks like a boiler – it’s called a Combined Heat and Power Unit. It’s a micro-scale unit and the electricity and heat will be used for the building that we’re attached to.

At the other sites we’re going to just generate space heating, so use it as a normal space heater. And that will be in polytunnels and greenhouses. It’s quite nice because we don’t need to do anything to the gas before we do that. Some of the other sites, we’re cleaning the gas, taking out the Co2 and various other things. But the one with the polytunnles and greenhouses, you can just heat it up. The Co2 in the gas then comes out in the atmosphere and it helps plants to grow. So you get the heat, and the Co2. And then the third site is where we’re going to clean it really well, and compress it to about 200 bar or something like that and that will be used for vehicle fuel.

EM: And I was just wondering now as well, I was very curious to know how you go about collecting all the organic waste. I saw on the website that it’s bicycles that you use?

RY: Yes, that’s right, we’ve got a cargo bike. At the moment the digester that’s up and running is 2 cubic meters, it’s not massive, and it’s to demonstrate the technology can work, and we are collecting about 100 kilos a week at the moment, which is…depends on what size you are whether that’s big or small. But we’ll probably go up to about 250 kilos maximum, once we’re fully up and running. But you have to treat the digester as a stomach and keep it warm and stirred, and start to feed it slowly basically, so it doesn’t get shocked.

EM: Oh right. Okay, okay so it’s a very gentle process?

RY: Yes it is, exactly.

EM: And are businesses happy or is it businesses that you collect from, or where do you collect it?

RY: Yeah, mainly local businesses. Everything’s within a 1 mile radius area and we really want to demonstrate the benefits of doing it all very locally. And with bicycles and trailers it’s obviously zero carbon. If we had a bigger network, let’s say, we could maybe move to a small vehicle and that we could covert the engine to run on biomethane, which is the gas once it’s been scrubbed and compressed. So you then kind of would be demonstrating a closed circle within the local area with the vehicles that go out, and the signing on it.

EM: And have you got maybe an idea about how much biogas and fertiliser you can generate with a small system like this, how much it would be?

RY: Yes, yes we do. So, a 2 cubic meter system, running on food waste, you’re going to generate about twice that volume a day – that’s about 4 cubic meters of gas. And 60 percent of it being methane…that’s about 2.4 cubic meters of methane. So that’s the burnabile bit.

And I think I did some calculations a while back and it seemed to say that if you looked over a year, that system could produce enough energy for a household in terms of the gas and electricity production, using one of these CHP units. But when you look at your domestic usage of gas and electricity, it changes in the year because it’s colder in the winter obviously so you’re using more. But the digester itself would produce gas fairly constantly on a 24/7 basis, so one of the challenges is to how to manage that energy output, and how to use it when it’s summer or winter or whenever. So on each site we have slightly different solutions.

EM: That’s very cool. So where or in what context would it be beneficial do you think to roll out more of these anaerobic digestion systems, in schools maybe or? Where would be a good place to put them into?

RY: Well, we may have a school that’s interested so that’s one possibility. It would have to have space, and then it would have to have a use for the gas and you’d have to make sure that through the holidays and stuff…that there’s a use for it all through then.

We think that, having done a bit of research, the main market areas would be small businesses who produce waste. Because they have to pay for that organic waste to be taken away, it might make more sense for them to process it onsite and make use of the renewable energy and the fertiliser. Particularly if they grow things or have the chance to grow things on site. And one of our sites this year will be an organic wholefood manufacturer. So he’s got a factory with grounds, he’s a very keen permaculturalist. It’s Solara Wholefoods in Central London. And he’s already built a 50-meter forest garden, he’s got an orchard and he’s got a vineyard onsite. His digester is going to be 6 cubic meters, and that’s going to be big enough to produce enough vehicle food for his food delivery vehicle. So it’ll go around and deliver local food and run on the gas from his food waste.

So he produces enough waste…the factory produces enough waste to run that digester. And the fertiliser will be used onsite there, so it’s going to be pumped round in an irrigation system. So that will be a fantastic demonstration of closed-loop recycling.

EM: Yeah, it’s pretty perfect really.

RY: Yes it is, yeah.

EM: You said I remember, I was looking through some of your interviews on Youtube and stuff, and you mention that these very small anaerobic digestion systems are not very common here in the western world. But you would have known about…this would have been happening in other parts of the world?

RY: Yeah, so basically in the West we have quite a large number of industrial-sized digesters. And I think the incentives are mainly to do with the energy that’s produce, so there are green tariffs for the electricity or the heat that you produce using these systems.

In developing countries there are much more…many more micro-scale digesters. So they’re for maybe an individual smallholding or group of houses or something like that – similar to the scale we’re looking at. But because they tend to be in warmer climates, they need less technology, they don’t need to be heated generally. They’re often not stirred, whereas we have to keep it warm and keep it stirred and there’s other considerations in a cold climate.

So I think that what we’ve heard is that there’s more capacity in those micro-digesters in developing countries than there is in all the digesters combined in western countries. So there’s absolutely millions of digesters in China and India, for instance.

EM: That’s fascinating. And did you research about them to get started on your own or?

RY: We had a look at some of the designs, yeah. But they basically benefit because the labour there is a lot cheaper, whereas here it’s much more of the bill. And so in some cases…in China I believe they have somebody who’s trained to build these digesters and they build them into the ground – I’ve seen some built with bricks and cement, and they get the community involved in building it and that makes everything a lot cheaper.

So here, I mean it could happen in the same way here. I mean, we are developing a digester that is a lot lower cost than some of the others, just so that community groups can benefit from it. And one of the thoughts that we have is that we can troubleshoot the whole thing, get it to the point where it’s very robust and then have it is a kind of a kit that people can put together if they want so that would bring the cost right down again for them.

EM: Yeah that would be amazing.

RY: Mh-hm.

EM: So Clare, now on to you. I was very excited to read about your project Food Loop, a recycling project set up in Maiden Lane estates in London. I was especially taken by the idea of getting the community involved in the project itself. Maybe you could tell us a little more about that?

CB: Food Loop was born out of a DEFRA funded project. So DEFRA is the Department of Environment, Food and Rural Affairs. And the project was about looking into the barriers – what is it that makes it so difficult for people to separate their food waste and give it in a separated state? And we proposed to carry out this research project based on a principle that people don’t understand food waste as a resource. They look at food waste as a waste stream and they don’t see it as a resource, and if they were able to visualise that food waste is a biodegradable, natural, compostable product that turns into earth, then people would be able to associate that with the growth of new food and therefore, they would understand that it’s something precious.

We set out to explore, in very dense urban environments where food waste collection is actually very difficult, we set out to explore what the barriers were, and what might a community be able to do to in order to recycle their own food waste. This was together with Camden Council, the London borough of Camden. And the proposal was that we set up a machine to compost the residents’ own food waste, and we asked the residents to help us design a system which suited their needs. So we did that for two years: we set up the machine, a company was brought in to manage the actual collections…

We worked with the residents to design not only the communications but the whole system: how should it work, what do they thing the benefits might be…. And through talking to residents and working with them we kind of established that…we asked them what they thought would be a good idea to do with the compost. They said that they thought that it would be good to use it to – not only for growing food, we were thinking it would be about growing food – their idea was more about making the estate a more beautiful place to live.

So one of the things that came out of this project is that people who live in these, now this is quite a run-down estate, it’s quite a problematic estate and people have got more immediate problems than worrying about the environment in a wider sense. But the thing that they are very concerned about is: how they can improve their own local environment?

And now, two years down the line, it’s almost entirely run and managed by residents – volunteer residents. No one is paid, but we generate enough income. We get a little bit of money back through the North London Waste Authority, who reward community groups for biodegradable waste collection, and we sell a little bit of our product as a fertiliser and a slug repellant to urban food growers and urban gardeners.

EM: I’m just envisioning how it was when you started out and you went there for the first time and everything: how did you get the community involved – was there a lot of interest or?

CB: That’s a very good question. I think where the first issue is: how do you recruit people? Recruitment is still the most difficult thing with these projects and you need to get under the skin of the people, your primary stakeholders. Now, often the thing that is driving you, so in our case the environmental challenge of food waste, is not the thing at all which is maybe driving a resident of a housing estate.

The thing that works quite well, and I think this is a really good trick, is that we piggybacked on an event that was happening at the estate. Just when we started the project there was a barbeque event coming up on the estate. We went along to that event, and we set up a stall with a poster. All we did really was go along with a whole stall full of little tomato plants, a bucket of food waste and a bucket of compost, and just talked to people and say “did you know that your food waste can look like this one day, and then it turns into this?”. And most people were quite surprised, but it was an opportunity for us to start a conversation with them. And then we asked them if they’d like to be involved in some design work.

So lots of people actually said afterwards, you know, that they thought the design workshop was a cool thing (we were going to be designing the leaflets for the communication for this new project). So we had about 15…we had about 20 people sign up. Every time someone gave us their phone number or contact details, we gave them a tomato plant. And I think the key thing here is, if you’re recruiting, it’s to go to where people are already going to be going, and just give them a little, a little tiny reward. Just to have a first point of contact. After that we managed to get about 15 to come to our first workshop. So that was a really good way in.

We also had, which is not at all indifferent…because we were a funded research project; we also were able to give people a financial incentive. It wasn’t cash actually, but we were able to give them gardening related products when they spent a day with us in a workshop. So, it wasn’t really payment but it was again a little, little reward and that was quite lucky and I think, you know, it’s really nice to be able to give them something back.

EM: Yeah that’s a very clever point actually. That’s really cool. So Rokiah and Clare – I just asked you about your projects and now I’d like to ask the both of you: what barriers or roadblocks did you encounter when setting up? Clare you go first.

CB: Sometimes the bigger decisions take a long time, so even, for example, getting a memorandum of understanding which allowed SEED to run the project…well, we started running it anyway, but it took three months to have an actual piece of paper saying “Okay, you can run the project”.

RY: Yes, that definitely can happen. Our kind of barriers have been more in terms of legislative ones and the regulatory rules around animal byproducts in particular. So I know Clare, you’ve sort of sorted it out on your end, but we’re still a bit in limbo because the people who are deciding about anaerobic digestion at this small scale and whether or not it’s possible to distribute the digestate still haven’t really made up their minds.

So when we started the project they said, yes it’s fine to distribute, but we need an agreement with the people who are going to use it to say that they’re not going to put it near farmed animals. So we thought, okay that’s fine.  But now they’ve seemed to have changed their minds (laugh). So we’re in a slight quandary at the moment. iI’s something we hope we’re going to be able to work through, you know. It’s partly because it’s not really done that much at this scale, so everything’s a bit new.

CB: Yeah, we had similar issues, and actually we’ve only managed to have sign-off on distribution of the product (which is a critical part of the cycle, if you like)…. You can’t really make this work, this kind of project, unless you can close that loop by distributing the end product and (in theory) hopefully making some money out of it. And it’s taken us a good year and a half before we got that sorted and it’s partly as you say because the legislation is still slightly in flux and is still changing. We’ve managed to get away with quite a lot by being such a small scale that we fall under the radar.

So we, you have to…tick a certain amount of boxes, for example: you have to be producing less than a certain tonnage of compost per year, and you have to have a certain, less than a certain number of people working on the project, etc etc. And by slipping under that radar we actually have quite a degree of freedom – a much higher degree of freedom than a slightly bigger project might have like yours…

RY: Hmm…

CB: While you have the advantage of being a bigger project, in lots of ways that’s a good thing, but in lots of ways being small is an advantage too.

RY: It’s, I mean we are basically classified as the same scale as you guys, and it’s not so much to…we haven’t encountered the problems so much to do with scale, it’s more to do with the technology. So coming under the radar, we can also get the low-risk matrix position with the animal health, but because we’re not pasteurising, or we weren’t planning to, that’s the sticking point, basically. And they’re not happy for us to take it off-site at the moment. So that may change, but yeah…

And because your technology, the heat process is built in. And our process, the heat is built-in but it’s only to 40 degrees and to pasteurise it – to get it properly by animal bi-products regulations – you have to take it to 70 degrees for an hour and that kind of raises the energy costs, if you like, of the whole thing. So if we can prove we can kill off the pathogens we need to without doing that, we’re hoping that might be acceptable. But if we can’t, we might have to pasteurise, so that’s another cost on top of everything else.

EM: Right, and in a similar vein now, since this is going out to an international audience, maybe there’s some advice you might have for people who are started up something similar somewhere else? Or maybe there’s something you wish you’d known when you started out?

CB: When I started doing this stuff I really didn’t know anything about anything, and I had a hunch there was something in food waste but I didn’t really know any of the detail, or I didn’t really know where the clue was going to be. And it’s really important to do an initial phase of research. Research is really critical.

And another thing which I think is very important is not assuming that you know the answers and not being afraid to admit that you don’t have the answers, but to sort of state what you know and what you think the answers could be, and then use that as a starting point for a conversation with a whole host of experts who can set you straight.

So our project was kind of build on a vague notion: if you make the link between food waste and food-growing more evident, are people more likely to compost their food waste? That was the basic premise, and starting from there that was an idea that we visualised: our idea of getting people to collect and compost their food waste locally, and then grow things with the compost. And once we had done that we were able to use that basic visualisation as a kind of a starting point for a conversation with all kinds of different experts. Whether they were experts because they were people who lived on a housing estate, or they were experts within the local council, or whether they were from the waste management company that was sub-contracted by the council; we spoke to all these people and each of them added to our knowledge and slightly shifted our perception of what the solution needed to be. And that is a process that goes on I think continuously.

You need to continuously change and flex and adapt your thinking to accommodate your learning. But also, you know, things are in flux all the time and I think it’s about being very, very light footed and flexible and you know, keep going. You have to keep at it.

EM: Hm, that’s excellent advice.

RY: Yes, I would agree. I just probably add – and this is advice I probably don’t follow very well (laughs) but it’s really valid nonetheless: don’t try to take on too much. It’s easy to get over-complicated with things sometimes. And you’ll get a lot of positive feedback from people because it’s a concept (waste of energy, closed-loop cycles), it’s a concept that everybody intrinsically likes that, you know, makes sense to them. People don’t like waste and they don’t like waste going to waste.

I’d say…I think what the usual kind of thing, when you’re setting up a project is to look at things like how much waste you have, or how much waste can you get your hands on, and what are the logistics of that. And then what would you like to use the gas and the digestate for – and bear in mind that the digestate is as important, if not more important, than the energy when you’re talking about anaerobic digestion. So it’s not just like an add-on, it’s one of the primary outputs and it often gets a bit overlooked.

But with our kind of digester for instance, the logistics are…basically we’ve got a 2 cubic meter digester. Once we’re fully up and running we’ll be putting in roughly 40 to 50 kilos a day, and pretty much most of that will come out as digestate a day. That’s liquid digestate. So it’s a lot of stuff to use and you have to sure that you’ve got the channels to route this stuff to, otherwise you’ll end up with a lot of surplus that you might end up having to put down the drain.

So, just work on developing the networks for using it, unless you can use it on site, which is perfect. And then think about – in terms of anaerobic digestion again – think about the gas use through the seasons, so not just a one-off use. Unless it’s vehicle fuel, which you can use all the way round the year. But heating you will need less of in the summer, obviously. So you could use it instead to heat hot water for teas and coffees or cooking or something like that. It could be a different use then.

EM: Well yeah, that’s great…great advice too.

CB: Well just building on Rokiah’s point though, I do remember one funding application that we did, which was all about closed-loop recycling, and the thing that they said was…they had three things you absolutely had to have nailed down in order to get this funding: you had to know where your feed stock was coming from, you had to know and have understood how you were going to process it, and you had to know what you were going to do with the output afterwards. So I think that what Rokiah said is absolutely critical, you know, if you get stuck with a growing mountain of, or you know, a waterfall of liquid compost you’ve got a problem (laughs).

EM: (Laughs) Oh my god…

CB: And it’s quite a big problem! Yeah, but if anyone is interested in the project, I’m always very happy to take people round to see our project, so you’re very welcome to pass that message on.

EM: Yes, definitely, anyone in London or England, please go check them out!

CB: I had two ladies come from Czechoslovakia, and they have subsequently set up a composting project and they’re in touch with me, and it’s always very satisfying, you know, because they came and took notes and everything and…. We are putting together a manual now because we’re…in the end of our project the idea is that we replicate what we’re doing, so we keep on developing these small scale recycling projects on housing estates.

RY: I guess I’d like to add, the same thing again: anybody who is interested in visiting our demonstration sites near Kings Cross is really welcome, and they could tie it in with, well they could visit both sites at the same time because they’re practically within walking distance so that’s really good.

CB: Oh yeah, they’re very close to each other, I completely forgot…

EM: (laughs) Right, cool. Okay guys it’s been an absolute pleasure having you on the show!

CB: Yes thanks, thank you for your interest!

RY: Thank you!

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