LEAP micro AD is a cross sector partnership developing micro
anaerobic digestion, a renewable technology that turns all organic
waste (except wood) into a clean fuel and fertiliser. The biogas
produced can be used for heating, cooking and lighting or be
cleaned and compressed for use as a vehicle fuel. The fertiliser is
a valuable product with excellent levels of nitrogen, good for food
growing and turf strengthening.
Just as a pearl forms from a tiny grain of irritation, so the
LEAP project evolved in response to a dissatisfaction. In 2011
Community by Design, the organisation who went on to found LEAP,
realised their latest 3-year project was not sustainable. It relied
on regular injections of funding to deliver its free health and
wellbeing services to the community.
Previous projects followed similar lines, with the excitement of
an initial concept leading to fundraising and subsequent
realisation of the idea. However, missing in their design was an
inbuilt ability to become economically sustainable, thus limiting
benefits and autonomy.
Another concern arose; providing something for free can
sometimes encourage reliance; how could we create something that
generates concrete opportunities for people so they can sustain
themselves? And while we’re at it, how can those benefits be
mirrored in the environment, particularly those largely
unsustainable arrangements we call cities?
These questions led to research into establishing a social
enterprise to generate biodiesel from waste oil. Several months in,
anaerobic digestion (AD) emerged as more promising technology
around which multiple social, environmental and economic benefits
could be woven.
Sending out roots
Networking played a large part in forming the LEAP partnership.
Later in 2011, a 3-year pilot project exploring micro AD was
reaching its culmination after having commissioned several reports
and demonstrated the technology with a 0.6m3 digester in
Led by Cath Kibbler from the Community Composting Network (CCN),
it had gathered substantial interest across the country, forming a
Micro AD (mAD) steering group with members spanning
engineering/manufacturing, public, academic and community
This blend of private, public and community interests informs
LEAP, which comprises Community by Design, the Community Composting
Network, several members of the mAD steering group including James
Murcott and Angie Bywater from Methanogen, Guy Blanch (Alvan Blanch
research engineer) and David Neylan PhD, plus a few new additions -
Mark Walker and Davide Poggio from Leeds University and Aleka
The partnership’s first funding application with Camden Council
was successful, giving us a solid 2-year foundation upon which to
build. Camden is known for its progressive approach to
sustainability, which led to their installation in 2008 of the
first biomethane refueling station in Europe, despite other
countries having larger AD industries e.g. Germany’s 7000-8000
plants compared with the UK’s 100 plants. Biomethane burns cleaner
and more quietly than petrol or diesel, significantly lowering
PM10s ((particulates) and NOx (nitrogen oxides), the most harmful
emissions for health.
Kicking off in April 2012, the project designing its first
system building on CCN’s experience. While AD plants in the West
are generally medium-high tech large-scale industrial affairs,
developing countries actually have more m3 of digester
capacity, with millions of low-tech micro plants in China, India,
Our challenge involved making micro AD cost effective in a
colder climate where heating and mixing are required, and
expectations of user friendliness, aesthetic design and regulatory
compliance are generally higher.
Our initial system design addressed changing gas use across the
seasons to include electricity and heat generation in winter and
cooking and water heating during summer. It also featured feeding
flexibility with a mill and pre-feed tank that could receive
feedstock (organic waste) and pump it ready macerated and mixed
into the digester at regular daily intervals.
Regularity is important, as the digester is essentially like a
stomach where microorganisms break down organic matter in the
absence of oxygen, releasing methane, carbon dioxide and traces of
hydrogen sulphide and moisture in the process.
This methane is largely identical to the mains gas we use to
cook with and heat our homes. It is also given off from landfill
sites when food waste is dumped there. Currently, around 50% of UK
landfill sites capture and clean up this gas for fuel use however,
the rest don’t, allowing it to escape into the atmosphere.
Methane is a greenhouse gas 20-30 times more potent than CO2.
Reducing methane emissions is a an effective way to combat climate
change. Scotland has taken the bold move of banning food waste to
landfill from 2014, while Wales has committed to zero waste by
2050. England remains on the fence and currently relies on raising
landfill tax to dissuade people from dumping waste there.
We applied for full planning permission for our pilot
2m3 AD system after having found a home at Camley Street
Natural Park – a London Wildlife Trust environmental education
centre set in a beautiful 2-acre nature reserve by the canal near
While waiting for consent to build, we were commissioned to
produce a report for the Technology Strategy Board’s Future Cities
Competition, where cities were encouraged to dream up ways of
integrating systems within a dense urban area to demonstrate
sustainability, efficiency and better quality of life.
Our proposal naturally focused on micro AD and how networks of
small-scale digesters ranging between 1-500m3 could help
reduce waste transport and emissions, save waste management costs,
generate local energy and employment and produce fertiliser to
support local food growing and greening projects. The report
quantified these outcomes and explored the business case for their
sustainable development post funding.
Meanwhile, with planning permission granted, we began building
the infrastructure for our pilot plant at Camley Street, a process
that would take us through the cold winter of 2012. It was
freezing! A welcome interruption in the spring of 2013 came with
another feasibility study, this time for WRAP – Waste &
Resources Action Programme – a government funded body focused on
waste prevention and recycling.
While the Future Cities report had a theoretical budget of £24
million to play with (which eventually went to Glasgow), WRAP’s
DIAD II fund was more modest and realistic, focusing specifically
on driving innovation in the AD sector. We scaled down our initial
AD network concept to three sites within a 1-mile radius. A
potential fourth self-funded site was 6 miles away.
WRAP liked the proposal. They felt it was both innovative and
achievable and granted us funding to demonstrate the network.
For a group of engineers, academics and community bods, this was
hugely exciting! A chance to show how decentralized, closed-loop,
integrated thinking can create sustainability and benefits on
multiple levels. Aside from environmental and economic gains, the
project has great potential to develop educational and community
engagement opportunities as the technology is easier to grasp at a
more human scale. People get to see the benefits close up and can
be inspired by it.
Site 1 Camley
Street Natural Park would be upgraded to include a micro CHP
(combined and power) unit. Its about the size of a boiler and
generates electricity and heat from the biogas, which will be
scrubbed (cleaned) to remove most of the hydrogen sulphide,
moisture and CO2, leaving largely methane. The design is
simple and if it works as well as we hope, will be a massive cost
reduction on the nearest scrubbing unit we can find. The site will
also host algae cultivation and low cost hydroponics to utilise
fertiliser and CO2 from the AD process. We plan to grow Spirulina
and Chlorella, two stains of algae with regenerative properties
used in cosmetics and soap making, and as a food supplement.
Site 2 The Calthorpe Project on
Grays Inn Road is a well-established community garden and centre.
The biogas there will be used raw to heat polytunnels and a
greenhouse - a fantastic use as the CO2 and sulphur
released during burning helps plant growth, so nothing is wasted.
The fertilizer will of course be extensively used on-site. The
Calthorpe’s 1m3 modular digester will be a low-cost, manually
operated system that will become affordable to community
Site 3 Alara
Wholefoods was established in 1975 with a factory and
successful wholefood shop, both close to Kings Cross. Their
commitment to becoming the most sustainable business ever, led them
to manufacture high quality organic wholefoods. They have also
created a 300m2 forest garden, vineyard and orchard on
their factory grounds - ample space to utilise the fertiliser from
a 6m3 digester. The biogas there will be scrubbed and compressed to
biomethane for use in their local food delivery van.
Site 4 Loop Management Services based
in Waltham Forest collect a wide range of recyclable waste
including half a tonne of food waste daily. They are keen to keep
on improving their sustainability both economically and
environmentally. We proposed a 20m3 system with the ability to
convert biogas to biomethane for their collection vehicles. We’re
still waiting to see if this might materialise but it is worth
mentioning as the economics of this size work out nicely with a 5-6
year payback period.
This may still seem a lot in today’s world but is worth it for a
technology that saves waste miles and makes use of what might
otherwise be a wasted resource, not to mention the benefits of
recycling nutrients and closing the urban waste-energy-food loop.
As the technology is more widely taken up, these costs will reduce.
This is what we are working towards.
We launched the pilot system at Camley Street Natural Park on
October 4th this year. Commissioning is still in
progress, which means some feedstock has been introduced into the
digester from established digesters as a starter culture complete
with microorganisms. The heating has just been turned on as the
organisms like to be around 38-42oC. Energy wise, this
along with power used for mixing and monitoring is considered a
parasitic load and must be carefully managed to ensure systems
produce a positive net energy total.
We use a cargo bike for collections and have so far collected
200kgs food waste from local businesses including Kier, a large
construction company championing our cause and supporting us with
timber, St Athans Hotel, whose manager Stefan Geyer is Chair of the
Permaculture Association, and London Contemporary Dance School,
whose CEO, Kenneth Tharp OBE personally made sure they were
involved with the project at the early stage.
The more businesses we talk to the more we are realising the
scale of available food waste and how many people there are wanting
to do something useful with it. One 2009 statistic described the
volume in Central London as 200 tonnes produced in a 2-mile radius
We are currently in early discussions with R-Urban a Hackney Wick-based
initiative and Cob in
the Community, both with exciting visions involving urban micro
digesters in closed loop demonstrations.
Cob in the Community’s proposal is evolving around a 20m3
digester insulated with cob and straw that would become a
beautiful, educational sculptural feature. Site expansion would
include a café and resulting food waste complete with Loowatt
waterless toilets providing AD ready feedstock.
R-Urban Wick aims to set up a citizen-led Re-Use Centre in
Hackney Wick & Fish Island (HWFI), a public facility supporting
and making public the culture of re-use, invention and
resourcefulness that is embedded in the area. Their proposed centre
would include a 20m3 digester, workshops, tool library, kitchen,
shop, archive, research space / artist residency space.
For both proposals, community engagement opportunities would be
maximised throughout the building and operational phases and the AD
systems could be modular, able to expand if more food waste became
LEAP’s previous research contributes a number of additions;
pre-processing biomethane collection vehicles operating locally
with parallel zero carbon cargo bikes collections to canalside drop
points; biomethane barges to transport this waste plus residential
barge food waste and sewage pump outs collected en route to the
digester; barges could also distribute fertiliser to users along
By utilising AD byproducts methane generated heat and
electricity, CO2, sulphur and fertiliser, a range of micro
enterprises could complete the closed loop demonstration;
- polytunnels with raised beds for food growing,
- micro algae cultivation to produce ingredients for soap and
- aquaponics (micro fish farming) and
- a micro brewery (thermal synergy with AD).
Waste products from these activities would be fed back to the
These projects would benefit temporary sites or brownfield sites
by the canal, which could be regenerated using digestate and
provide a training ground for young unemployed people learning to
grow food. Any potential site owners out there…?
Part of the groundswell
The future is a creative act we all participate in on a
day-to-day basis. We tap into rich seams of energy and inspiration
when we focus on the best we can be, the best we have to offer at
any given time. In this collective endeavor, every contribution
counts, be it local or global, corporate or community individual or
state. We hope these micro ADventures can contribute to the
emerging vision of sustainability and joined up thinking that may
just carry us through the 21st century.
To find out more about the LEAP project or
visit the pilot system:
To speak to Andreas about the R-Urban Wick Re-use Centre
To speak to Linda about the closed-loop, sculptural,
cob-insulated digester proposal: