From beer to biogas - and back

11th June 2011


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Becky Allen finds out how a chance meeting led to the UK's first gas-to-grid anaerobic digestor

October 2010 saw Adnams Bio Energy deliver its first biogas to the national grid. That first delivery was the culmination of a chance encounter at a Business in the Community May Day celebration in 2007, as Andy Wood, chief executive of Southwold-based brewery Adnams, explains. “I was a speaker at the event and we’d supplied some beer – Adnams East Green – which we produced to celebrate our eco-distribution centre and the new brewery,” Wood says.

“Steve Sharratt [chief executive at Bio Group] came up to me and we started to chat. He wanted to come and look at our facilities and when I asked him what he did, he said he turned waste into energy.

“I’d been thinking about waste streams from our business – food waste from our pubs and hotels, as well as waste from the brewery’s manufacturing process – so it seemed an idea we should explore. And that was the genesis of the thing, that chance meeting.”

Waste not, want not

Finding smarter ways to deal with Adnams’ waste streams was a logical extension of recent developments in the business. According to Wood: “Our investment in the new brewery and distribution centre was predicated on a business case that said fossil fuels will continue to rise in price and businesses and individuals who pollute will continue to pay for that pollution.

“The cost of that pollution will rise, which led me to think about what comes out of the back end of the business and whether we could do anything positive with it,” he explains. “I’d also been reading about industrial ecology and thought there was the potential for a closed-loop system here.”

Discussions with experts at the University of East Anglia, with whom Adnams has a long-standing relationship, suggested the most efficient use of the waste would be to convert it into gas, which in turn could be used to power both the brewery and, in time, its commercial vehicle fleet.

And so Adnams Bio Energy was born: a 50:50 joint venture between Bio Group, which contributed the know-how and intellectual property needed to build and operate the anaerobic digestor (AD), and Adnams, which contributed the land and their brand, as well as some of the waste.

With a name like Adnams Bio Energy, most people associate the AD with Adnams rather than Bio Group. “Everyone talks about it being an Adnams’ plant, even though it’s Bio Group’s,” says Sharratt. “We knew that would be an issue but it’s fine – we wanted to get the word out. The branding is deliberate. Having something called Adnams Bio Energy has raised its profile.”

Funding for the plant – some £2.7 million – was raised from bank borrowings (RBS) and three grants from the European Regional Development Fund, East of England Development Agency and DECC.

Plastic building

By July 2010, only three years after their first meeting, construction of the AD plant was complete. As well as being the UK’s first AD to turn food and brewery waste into biogas for the grid, the plant is innovative in other ways.

“Just because we’re making energy doesn’t mean we want to waste it,” Sharratt explains, which means lower-carbon buildings and simplifying the AD process.

Compared with the metal and concrete that has been common in the industry to date, Bio Group designed and built the Southwold plant a little differently to reduce its carbon footprint.

The main building – which receives the waste, removes the plastics and heats the resulting mixture to 70°C to kill pathogens – is made from a pre-tensile recyclable PVC fabric stretched over an aluminium frame.

It may not be the cheapest building, but took just four days to erect, compared with around six weeks for a steel shed, and brings other benefits. “It’s lighter so it needs less concrete and it lasts longer than steel given the acidic environment and the condensation,” says Sharratt.

“And the roof is opaque, which reduces its visual impact as well as letting in more light, which reduces the amount of internal lighting we need.”

Other buildings on-site come with a more modest price tag. The pump house, which contains the high-tech peristaltic pumps that move material round the system plus part of the plant’s control centre, began life as a pair of shipping containers. “We don’t need a fancy building for this, so we took two battered, rusting containers and repainted them,” Sharratt says.

More innovative is Bio Group’s approach to the AD tanks themselves, three of which are installed at the Adnams Bio Energy site. Instead of vertical steel tanks on a concrete base, the recyclable high-density polyethylene plastic tanks are horizontal, reducing the site’s visual impact.

“We’ve taken the tanks out of the sky by putting them on their sides and burying them. And we’ve made the tanks out of plastic because it’s a more robust, resilient and lower-carbon material,” explains Sharratt.

“Instead of spending 12 weeks casting in situ, they come on the back of a lorry and take a day to put together.”

Internally too, the tanks are innovative. Whereas other tanks keep their contents moving with paddles, using energy and requiring periodic cleaning (a confined-space operation that caused a fatality elsewhere in the industry last year), Bio Group has developed and patented a new process known as the orca valve system, so called because it “blows like a whale”.

“What we’ve always done is look at what else is available in the market and then decide how it might be improved upon or changed. A major use of energy in AD are the paddles that agitate the porridge, but our tanks have no moving parts,” says Sharratt. “They use the gas to push the mixture around, so instead of energy and moving parts it’s just gas and physics.”

Community sensitivity

As well as tackling technical issues, Adnams Bio Energy worked hard to communicate with the local community during the planning process. As a business that can trace brewing on its Southwold site to 1354, when Johanna de Corby and 17 other local “ale wives” were charged by the manorial court with breaking the assize (law) of ale, Adnams prides itself on being a good neighbour.

“We are sensitive to the community. It’s where we earn our living,” says Wood. “We have no interest in turning Southwold into an industrial wasteland. Whatever we do will be sensitive to the environment – both built and natural – and we care about the social environment as well.”

While Wood believes there was local concern about the AD, following a series of open days and conversations on-site with neighbours, the plans met no opposition. “From submitting planning to putting a spade in the ground took six weeks. It’s unbelievable how smooth it’s been but that’s because we were prepared to have a dialogue with people and share a vision of what we’re trying to achieve,” he says.

Adnams Bio Energy has also been very clear about being a local facility to handle local waste. “We explain that what we’re doing here is part of tackling climate change because the plant this year will take 69,000 tonnes of CO2 equivalent out of landfill,” says Sharratt.

“We also commit to putting a 35-mile ring round the project beyond which we won’t accept waste.”

When a visitors’ centre opens on-site later this year, residents and schools will have an open invitation to visit the plant.

As well as showcasing the plant’s green credentials and explaining how the process works – “we’ll have a perspex mini-AD so that kids can drop a sandwich in at one end and use the energy produced to boil a kettle at the other,” says Sharratt – the centre will host exhibits on a range of sustainability issues.

In liquid form

Nine months on from delivering its first biogas to the grid, Adnams Bio Energy is now preparing to take the first liquid waste from the brewery. “It’s been a slow build because these things are organic,” says Wood. “They are like a stomach and you need to get them used to their diet.”

During phase one of the project, Adnams is supplying 15%–18% of the AD’s 12,500 tonnes-a-year capacity, but this will almost halve when the plant expands to its full capacity of 25,000 tonnes.

Adnams Bio Energy currently takes waste from a range of businesses, including Waitrose, as well as some homes and schools via a contract with the local council-owned collections firm Waveney Norse. Gate fees vary depending on the type of waste, but will always be £20–£22 a tonne cheaper than landfill, and schools get a preferential rate.

Scaling up a plant of this nature from 5-metre AD tanks in a research and development environment to 70-metre tanks is never plain sailing, Sharratt admits.

“There are always niggles – that’s the nature of commissioning – and you don’t take an AD plant out of a box and turn it on. But there’s been nothing unexpected,” he says.

“We are adapting equipment from other industries – the mincing machine is just that, it comes from the food industry and will consume a cow – but there are certain things you have to adapt to work in our sector. We’re learning.”

One key lesson Bio Group has learned is how to separate plastics more effi ciently from the waste.

“Removing plastics is the bane of recycling. It clogs up the system and you can’t have it ending up back on the land,” says Sharratt. And more learning is taking place at the end of the process. The gas collected from the AD tanks is a 50:50 mixture of methane and CO2.

The latter is removed by freezing and the 98% biomethane – some 600,000m3 a year during phase one, enough to heat 235 family homes – injected, with a little added odour, into the national grid. Bio Group is experimenting with ways of fixing the CO2, returning the resultant biomass to the AD tanks and using the residual water for local irrigation.

As with other AD plants, the remaining digestate will be returned to the land, hopefully to fields producing barley for Adnams’ beer, says Wood: “It’s actually an organic fertiliser and it would be fantastic if we can give or sell that – at an appropriately discounted rate – back to the farmers who support us.

Let the sun shine

This summer £1 million-worth of photovoltaics will be installed on-site, making Adnams Bio Energy what Sharratt calls “an energy park with AD at its heart”, and by the end of the year work will start on the gas-filling station that will fuel Adnams’ commercial vehicles.

The first three vehicles capable of running on biomethane will join the fleet this year. The benefits to Adnams of AD are multiple. It takes the business a step closer to a closed-loop system, something that makes both economic and environmental sense.

“We are probably one of a handful of people doing this in such a holistic way, but it makes so much sense. We believe in man-made climate change and we think the business can and should take a leadership role. You can’t just rely on the consumer to make choices,” Wood explains.

“Whenever we’ve gone after reducing carbon emissions or waste we’ve saved money. And the more you see the price of diesel, electricity or gas going up, the more money we save.”

The move bolsters the brand’s environmental credentials too, something Adnams believes helps it address younger customers. “Businesses such as this traditionally have an older customer base, but we find that younger people absolutely understand what Adnams is doing and want to support businesses of this kind,” he says.

“Let’s face it, our generation has dropped the ball financially and environmentally, so for the next generation of consumers – generation Y – this is an important reputational and ethical matter.”

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