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Construction of the new mini 100kW AD plant, which is being installed on the University of Newcastle’s pig unit by Anaerobic Energy Ltd.
on July 28, 2010

Smaller-scale energy generation could be key for pig farmers

Less ambitious anaerobic digestion plants could be easier and simpler to adopt

A new, £1.85-million (US$ 2.88 million), project looking at innovative ways to convert farm waste into energy in England could provide some good news for the small to medium-sized pig farmers around the world who want to invest in anaerobic digestion (AD) to generate green power and deal with slurry in an environmentally friendly way.

Many smaller farmers have been put off by the high capital costs of the typical large-scale plants, and because most depend on large quantities of imported food waste and green waste, as well as slurries and silage to optimise gas production to operate on an economically sound basis.

Current obstacles  

The majority of pig farmers simply are not interested in having to import extra waste on to their farms to can generate sufficient biogas to produce electricity. Not only could it expose their herds to increased biosecurity risks, it would also mean a lot of additional paperwork to cope with the strict regulations most authorities impose on people handling food waste.

So researchers at the UK’s University of Newcastle are looking into how they can develop ways to make a small 100kW AD plant economically viable for farmers, using feedstock that is available on the farm to make these farms more sustainable, as well as to help the country reach its international renewable energy targets.

Jointly-funded by the university and the regional development authority One North East, the innovative project also enjoys support from the British Pig Executive (BPEX).

Small is beautiful 

BPEX environment expert Nigel Penlington says: “This is an important project and could benefit pig farmers in many different countries.

“While increasing numbers of producers are looking to see how they can invest in renewable energy to help them cut fuel bills and create another income stream, many are being put off AD by the sheer size of the conventional large-scale plants and huge upfront investments costs.

“They just want a small plant that will use their slurry and other farm waste to optimise biogas production and produce enough electricity for their on-farm needs, as well as provide enough heat from the generation of electricity to help keep their pigs warm during the winter.”

The leader of the Newcastle project, Dr Paul Bilsborrow, who is based at the university’s School of Agriculture and Rural Development, comments: “Anaerobic digestion offers huge potential in terms of using methane from animal waste and converting it into renewable energy, which can then be used to heat and power buildings on farms. By working together with the agricultural industry we hope to develop innovative ways of making this process a viable proposition for uptake by farms across the UK.”

Based on the university’s own Cockle Park Farm in Northumberland, his aim is to use the new, smaller AD plant to show how waste from pig, as well as dairy and beef units, can be used to produce heat, electricity and fertiliser.Tthe residual digestate from the AD process can be used as a soil conditioner and a nutrient source and offers considerable potential for farmers to reduce their fertiliser budget.

“We want to test different types of feedstock to see how the economies of a small plant like this stack up for farmers,” says Dr Bilsborrow. “We will be using a combination of pig slurry and straw-based litter from the university’s own pig unit, which caters for 320 finishers, as well as some manure from our dairy herd and vegetable waste from a local vegetable packer for feedstock.”

Kirsten Young, a senior specialist who is working closely with Dr Bilsborrow, believes that, while AD offers considerable potential for farms and rural businesses in the management of animal manures and other waste streams, its use to produce energy had been neglected.

It is an area that is waiting to be exploited, and the uptake of the right technology by a large number of small to medium-sized farmers would lead to a significant contribution of renewable energy to the UK market.

And UK pig farmers can look forward to being kept informed of progress on the project, because the university plans a series of Open Days for farmers after the plant has been commissioned and as it builds up to full power. The university is committed to keeping farmers informed of how the project develops and how they can use the results to help their own businesses.

This new project is one example of the growing interest in renewable energy, especially in what is called microgeneration, where individuals, or small groups of farmers, can get involved in producing their own power at less cost than needed for large-scale multi mega-watt plants.

This includes one or two wind turbines near the pig sheds, or solar panels on the roof of the piggery to generate heat, or electricity, as can already be seen on a number of pig farms in the Netherlands and Denmark, as well as the increasing number of anaerobic digestion plants near pig farms in Germany, where many use maize with pig slurry to optimise gas production.

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