Micro Anaerobic Digestion: how wee can it be?
Anaerobic Digestion (AD) technology has been present in Europe from the early nineteen hundreds. It was bought to Europe from India where the first anaerobic digester plant was built in a leper colony in Bombay in 1859.
Nowadays, the technology is commonly used in agriculture, municipal waste and brewing industries; converting the organic waste and residues into biogas which can be used to produce heat, electricity or vehicle fuel.
"Processing Scottish food waste through modern treatment plants has the potential to generate enough energy to power the city the size of Inverness and supply 10% of Scotland’s fertiliser needs’’ Zero Waste Scotland .
What’s not to like about the AD? It takes care of your waste whilst bringing you heat and fuel, what a great idea! Perfect for all remote, rural communities out there striving for sustainability.
However, when looking at the Scottish AD landscape we mostly see large merchant plants dealing with thousands of tonnes of organic waste or slurry, requiring expertise, land, permissions and big money. In other words, AD accessible only to a few.
SO….Is there a place for microAD in Scotland? AD that deals with 20, 100 or 400 kg of organic waste per day and produces enough biogas to satisfy the needs of a small bistro, fuel a delivery van or heat pollytunells.
At the recent event organised by the Scottish Biofuel Programme ‘’ Don’t waste money on food waste ’’ we heard a fantastic presentation from Community by Design project from London introducing us to LEAP – Urban MicroAD concept.
LEAP project has set out to prove that AD can be done on a micro scale. The Leap project brought together partnership of community, industry and academia all working together to challenge popular opinion that AD is only cost effective when you go large.
They created a closed-loop system with AD in the centre offering potential solutions for food waste producing businesses, schools, small farms, community gardens, and eventually, individual households. Watch a web cast of their presentation here.
So, how wee can it be? The smaller AD system design by Leap is only 1m3, allowing processing 20kg of food waste/per day, the system is heated by Photovoltaics (PV) and creates enough gas to heat pollytunels in the community gardens. The largest converts 400kg/day of food waste into biomethane for use in vehicles saving the business £17700 in fuel cost.
The 4 demonstration sites that the project is developing will show MicroAD in action in different settings, scales and using different business models. It will allow for better understanding of the challenges and opportunities, as well as offering excellent educational opportunities to help people better understand the benefits of recycling.