Pigs produce crackling of electricity

In the biggest project of its kind in Scotland, East Lothian landowner Jamie Wyllie will build a 1.5 million "anaerobic digester" to turn pig slurry into power for his farm, with any surplus being sold to the national grid.

An added bonus for nearby residents is that the process is expected to reduce the smells wafting across the countryside from pig-derived fertiliser.

The Scottish Government hopes the project, financed under its Rural Priorities grant scheme, will pave the way for other farms to transform animal waste into green energy as part of plans to combat global warming.

As there are 3,200 breeding sows, producing 70,000 pigs a year, on the 137-hectare farm – one of the biggest pig units in the country – there will be no shortage of muck to feed the digester.

Wyllie, the director of Ruchlaw Produce in Dunbar, learned about how to turn waste into electricity while at Reading University. After graduating last year, he decided to put what he had learned into action.

"Anaerobic digesters are very common in Europe but not at all common in Britain," said Wyllie."We used them to try to combat oil and gas shortages after the war, but they were really inefficient. Then we forgot about them. We have always had oil, so we have never needed them.

"Now we are in a good position because countries like Germany and Denmark have done all the hard work."

Methane and carbon dioxide will be created from the pig slurry fed into the digester.

The digester works by pouring the waste into an airtight unit containing bacteria, which partly breaks it down into methane gas. The methane is then pumped into a "biogas" plant, where it is burned to generate electricity and hot water for heating systems. The remaining material is a powerful fertiliser which can be spread on land as pig slurry is now. The benefit of the new process is that the smell is reduced.

The process produces 800kg of fertiliser and 200kg of biogas for every tonne of waste.

Wyllie said: "The anaerobic digester is a living process, using bacteria which feed on the pig manure and food waste to produce methane gas.

"This methane gas is then burnt in an internal combustion engine to drive a generator which provides electricity for direct farm use or which will be fed into the national grid."

Wyllie said it would be a win-win situation. "I want to help the community and the environment. I'm aware that we have to change the way we do things to do this.

"The construction of a digester will not only do that but also provide us with a better byproduct at the end of it."

As well as pig muck, it is hoped that approximately 2,000 tonnes of vegetable waste will be gathered by the local council and vegetable producers to be converted to energy at the Dunbar farm, reducing the waste going to landfill.

Wyllie believes many farmers in Scotland have a progressive attitude towards the environment. "People have this image of a farmer as a rough old man with only a sheepdog for company, but the fact is that the farming world is full of intelligent people whom people outside of farming wouldn't realise were farmers.

"People have this stereotype that farmers think, 'We did it like this ten years ago so that's how we will do it.' With changing climates and so on we have got to change too."

Environment minister Richard Lochhead said he hoped the project could lead to farms across the country being turned into mini-electricity stations, helping cut Scotland's carbon footprint.

He said: "Agriculture is well placed to help Scotland reduce harmful emissions and at the same time reap the benefits for farming businesses.

"Scotland has some of the most ambitious climate change legislation in the world."

The biogas project comes as the SNP government launches a five-point plan to reduce farm waste and improve energy efficiency. This will urge farmers to use energy and fuels efficiently, ensure that material used in farm businesses are put to the best possible use, develop renewable energy schemes, reduce carbon emissions and maximise the use of fertilisers and manure.