Hosted by Philip Green, Chief Executive of United Utilities, and Mark Price, Managing Director of Waitrose, business leaders from the worlds of utilities, retail and agriculture last week visited some of the key sites in the North West already making use of anaerobic digestion.

The technology has been used in the water industry for decades to treat sewage sludge, but it can also be used to treat food waste, manures and biofuel crops. The potential is huge, set against a back drop of increasing fuel prices and tougher EU targets on waste recycling and agricultural pollution.

The visit followed Defra's announcement in June of a £10 million grant under its Anaerobic Digestion Demonstration Programme to assist the development of five new projects across the UK.

HRH The Prince of Wales, who champions investment in rural communities and the fight against climate change, sparked the visit through his Seeing is Believing programme, supported by Business in the Community (BITC). Anaerobic digestion is under-utilised across the UK at present and The Prince has challenged BITC member companies to explore how the uptake of the technology can be accelerated.

 Water industry experience can help break technological barriers

Philip Green, Chief Executive of United Utilities, said:

"The water industry has a wealth of experience in anaerobic digestion and we are well placed to offer leadership and help to break down technological barriers. Tackling climate change is an issue very close to my own heart and there is a golden opportunity here waiting to be exploited by farmers, food retailers and small rural communities. Of course, it has to be economically viable, so that's why I'm delighted to bring together leaders of such high calibre who have the power to make this happen."

The group toured United Utilities' Davyhulme wastewater treatment works where anaerobic digestion is used on an industrial scale to break down sewage sludge, power the works and where plans are in place to upgrade the biogas for injection into the local supply grid; APS Salads at Alderley Edge where the technology is used to break down tomato crop leaves and generate heat and carbon dioxide for the glasshouses; and Ashton Hayes village in Cheshire which aims to be the first carbon neutral community in England.

Mark Price, Managing Director of Waitrose, added: "We are constantly looking for ways to reduce our carbon footprint and were the first UK supermarket to use anaerobic digestion to turn food waste from our shops into renewable energy. However, we've experienced, first hand, the urgent need for more plants - capable of processing food waste - to allow us to extend this technology to more of our shops".

 Infrastructure among barriers to widescale development

Current barriers known to be hindering the widescale development of anaerobic digestion include the uncertainty surrounding issues such as:

. infrastructure eg. connection of renewable power into the supply grids;
. finance eg. attracting investors to back such projects and incentivising smaller developers
. technology eg. maximising the energy output from a variety of organic waste

The Davyhulme Wastewater Treatment works is one of Europe's most significant treatment facilities. In operation since 1894, the site remains United Utilities' largest treatment works, serving a population equivalent of 1.2 million in and around the city of Manchester.

It was announced this June that Davyhulme was one of five pilot projects to be awarded funding from Defra under its Anaerobic Digestion Demonstration Programme. The joint initiative between United Utilities and National Grid aims to deliver renewable gas direct to consumers for the first time, and supply gas for fuel use in the UU sludge transport fleet.

The upscaling of gas production at Davyhulme will remove the CO2 and trace elements from the biogas to leave biomethane. It will then condition the gas with propane and odorants before injecting it into the grid. The pilot project, which should be operational by early 2011, will produce enough biogas for around 500 homes and also provide enough fuel to power 23 of United Utilities' sludge tankers.