Anaerobic digestion (AD) breaks down organic materials using microorganisms to minimise waste and generate useful biogas. Although not a new process, it is one that has not yet met its full potential. Human waste alone could generate enough electricity to power 138 million homes, if it were possible for it to be processed in a digester system. The equivalent amount of natural gas power would cost $9.5bn (£6.7bn).
To tap into this potential, British company QUBE Renewables has developed a ‘flat pack’ digester that uses a flexible, fabric bladder design that can be set up anywhere, from domestic kitchens to war zones. The QuickQube, as it’s called, can process a range of biodegradable waste and is already being used in the UK.
What are the advantages of implementing this Ikea-esque renewable energy generator? We spoke to founder Joanna Clayton to find out.
Molly Lempriere (ML): Could you tell me about the origins of QUBE Renewables?
Joanna Clayton (JC): QUBE started officially back in 2012 and came out of our sister company Aardvark, which is a technical environmental consultancy business that’s been going for about 21 years. As Aardvark, and as consultants, we were asked to perform a desktop feasibility study looking at available technologies for the UK MOD because they needed to find ways of dealing with sewage and food waste in their operating bases. What they were doing with it at the time was just burning it and the very high cost of diesel fuel at the meant they were looking for some alternatives.
So as Aardvark, we created a desktop study looking at all available technology around the world at the time, and came to the conclusion that there wasn’t anything that fitted their needs exactly. They then asked us whether we could design something that would fit their needs, which we did over the next few months. They liked it and to our surprise said ‘could you build it for us as a prototype to see if it works?’.
We built it and out of that we had a working model financed by them that we then thought would make a nice little company on its own. We split off from the consultancy side of things and formed QUBE Renewables as its own company.
ML: Was the first anaerobic digester that you developed the flat pack version you have now?
JC: No, the original mark-one version was for army purposes and the whole thing was in a 20ft shipping container. That was the digester, the gas treatment, the engine; the whole lot was all containerised. The remit from the MOD was that it needed to be able to be put down somewhere that had absolutely no grid connection whatsoever, be started up and then run on diesel, which obviously isn’t something that most people ask for.
From that has come a much more sophisticated design, if you like, of the BioQubes, either in 20ft or 40ft shipping containers. There are now various components which are outside of the digester that you can add and takeaway, depending on the client’s needs. Then from that came the QuickQube, which is the flat pack version.
ML: Could you tell me about the QuickQube?
JC: The QuickQube has all the functionality of the BioQube; it does exactly the same heating, stirring, creates exactly the same environment for the digester part as the BioQube. But instead of being inside an expensive steel box, it’s in a flexible fabric, specialised PVC. The bladder is almost like a tea cosy that folds down onto a pallet.
The digester is contained within a metal framework which will stand it up, that again can all be taken apart and packaged on a pallet. So in effect, you’ve got a 20ft shipping container’s worth of digestion space that can be flat packed down onto two pallets and transported.
It was trying to marry together the robustness, durability and functionality of what in the past has been much larger, reducing that down to a much smaller scale without losing that quality of the kit. And doing that without it becoming so costly that the whole thing became nonsensical.
ML: Where do you envisage the QuickQube being used?
JC: It has been used in the UK, but we think that hopefully the biggest market for it is in developing countries, particularly for things like aid camps and refugee camps where there is a sanitation issue. As well as it producing gas, what it will do is process the sewage waste and clean it, in effect, so that the gestate that comes out is a usable fertiliser rather than a risk to the people.
ML: Is AD something that’s often used in aid camps?
JC: No, this would be a real first. As far as we know it’s not being used in aid camps, not as a standalone digester, obviously there are lots of versions of composting loos and things. But as proper digestion, producing gas that could then be useable for something like cooking in the camp, which is why we think they’d probably like the energy as cooking gas rather than as electricity, then you’ve got useful resources at that end as well.
ML: What was your reaction to the new tariff for anaerobic digestion brought in by the UK Government as part of the renewable heat incentive?
JC: It’s affected our business model considerably. The drivers for QUBE projects are no longer energy-driven, the finances on the energy side are a nice added extra to a project, but what we view our kit as is now waste disposal.
I can truthfully say, at the moment we have very few projects coming online in the UK. We have projects in Canada, the Philippines, all over really, but only one new one in the pipeline for the UK. So it’s certainly affected where we market and where we’re selling at the moment.
ML: When thinking of AD, the sanitation side of things pops to mind. But what weird and wonderful fuel stuffs have you digested?
JC: We have digested in the past dog poo, lots of energy out of dog poo. The idea being that instead of it going to landfill, which is where the majority of it goes, or being incinerated, is that in the separate collection dog poo bins it would get separated off and fed into a digester. The trials on dog poo weren’t particularly pleasant.
We’ve done bath bombs, we’ve done knives, forks, spoons etc. that are biodegradable, so for festivals and things like that people could chuck their food waste plus the knife and fork in one bin, and that could all go into a digester.
Seaweed off a power station, that was quite nasty and smelly. All sorts of things, really, weird and wonderful things.
ML: Finally, what does QUBE have in the pipeline at the moment?
JC: In the last few weeks we have completed an installation in the Philippines. We have developed a new piece of technology that we are trialling there, working with rice farmers, taking dry rice straw as an incentive for farmers not to burn the rice straw out in the fields after harvest, which is theoretically banned in a lot of countries but still happens.
When farmers come in and bring their rice into the rice mill, they’ll also bring their rice straw. Then the innovative part is that, normally dry digestion takes big, huge-scale, expensive kit, but we’ve scaled it right down. At the moment we’re trialling 600m² little digesters that you can put the rice straw into and leave, and dry digest it. Then the farmers can have cooking gas or bottle gas for vehicle fuel in return for having brought in their straw.
We think it’s something that has not been done before and an application for digestion that hasn’t ever been done before.