Biogas: from bad smells to big bucks

After years in the wilderness, biogas is set to play a major role in powering the future.

Andrew Needham, Operations Director of BIOGEN, is looking bullish. His anaerobic digestion (AD) plants in Ludlow (Shropshire) and the Bedfordshire village of Milton Ernest are among only a handful in Britain, but he has plans for 100 more. When he first looked into AD, it was to turn nutrient-rich waste into good fertiliser. He wasn’t expecting to become a leading player in the UK’s infant – but rapidly growing – biogas industry.

For farm-based businesses like BIOGEN, AD is a natural winner. Rather than being a problem to be disposed of, the slurry from cattle becomes a valuable ingredient. And the ‘digestate’ solids which are left over at the end of the process make good fertiliser for the fields.

But it won’t just be farms getting in on the act, says Entec consultant Dave Auty. Thanks to a number of key policy shifts, he is expecting to see many more ambitious minds turn to AD.

First, there’s the sheer amount of food which UK producers, retailers and households throw away each year. The food industry is under increasing pressure to meet waste reduction targets, and landfill tax – set to reach £72 per tonne by 2013 – should spur further cuts. The Department for Environment, Food and Rural Affairs (Defra) is keen to see AD become an established solution for municipal food waste, and local authorities also have recycling targets to meet. And with the rising cost of fuel and carbon, biogas could become an attractive alternative.

What Needham has also spotted is the potential for AD to tap various income streams. There’s the immediate gain of substantial ‘gate fees’ for every tonne of waste food taken out of the hands of local authorities. The digestate can be sold as fertiliser or for landscape restoration. And the methane produced by the AD has a number of buyers. It can be burned in domestic appliances, liquified to make vehicle fuel, or used in centralised heating and power (CHP) applications to generate ‘green’ electricity – as Ecotricity is doing [see below]. And power from AD wins double renewable energy certificates (ROCs) when sold on to providers to boost their portfolio.

National Grid is also advocating investment in distribution infrastructure, and forthcoming incentives for heat from renewable sources can only make it more attractive.

With such money-making potential, everyone’s looking to get involved. The water industry is already re-evaluating sewage sludge as a resource rather than a problem. More familiarity with the technology could make it a no-brainer for some large-scale food processors, who could recycle their organic waste and power the premises in a neat loop. Retail majors such as Sainsbury’s are sounding out possibilities, says Auty, and Marks and Spencer is offering to buy electricity from any farm-based AD plants.

But the biggest opportunities depend on a good tie-in with appropriate council waste collection routines. Modern AD requires significant capital, so investors will want secure waste contracts in place for the longer term. They’ll also want the right sort of organic waste. Experience argues for separating leftovers from kitchens and catering services, which are ideal for AD, from garden greenery, which is not.

If Britain’s AD industry grows to £5 billion in the next ten years, as Entec’s Terry Brownhill believes it can, its new trade association and best practice website (www.adbiogas.co.uk) will be busy indeed. Expertise will be at a premium not only in waste logistics, but in planning and environmental assessment: a proposed digester in the neighbourhood is likely to arouse (largely unfounded) local concern over everything from bad smells and vermin to lorry traffic, explosive gases and air pollution. And there’ll be a need for training to ensure the process is managed safely and successfully. Timing and temperature are critical, and digestate quality needs to be up to scratch with new product protocols in place.

Get all this right, Brownhill says, and you’ve got a winner. It’s really about “taking something bad and turning it into something good” – the perfect recipe for a green new deal.

–  Roger East

Entec UK is a Forum for the Future partner.

29 January 2010

Roger East and Tricia Holly Davis