AD benefits for farmers

Research from the universities of Southampton and Reading has found that anaerobic digestion (AD) take-up on farms would have financial benefits for farmers as well as environmental advantages.

The research, carried out by the UK research councils’ Rural Economy and Land Use Programme, says that a typical dairy farm could supply most of the electricity it needs to milk the cows, by converting their manure into energy.

The researchers say that relatively small digesters could be economically viable when fed with mixtures of animal slurries and imported wastes or energy crops. This has the potential to boost the profits of both arable and dairy farms.

Further benefits include reduction of CO2 emissions and could save farmers money on artificial fertilisers.

Digesting the slurry produced by one dairy cow has the potential to reduce methane emissions by 25 kg, and generate 1000 kWh of electricity per year – equivalent to three months’ electricity consumption for an average household.

The digestate left at the end of the process is a valuable fertiliser and could replace artificial fertliser.
This would reduce the amount of money farmers spend on artificial fertilisers, and also save the CO2 emissions involved in their production.

The team also researched public attitudes to the building of anaerobic digestion plants in rural areas.

Consumers tended to support the idea, particularly if cattle and pig manures were used to feed the digester, but most were also happy for food crops to be used.

They thought that the most important benefit was that the digesters provide an alternative to landfill for organic waste, including waste food.

Researchers concluded that the government needs to support agriculture further in the use of AD to encourage take-up of the technology.

University of Southampton professor and lead researcher, Charles Banks, said: “Other European countries have forged ahead with this technology. But although the UK Government has expressed its support, this has still not led to widespread adoption of the technology on farms.

“This research has shown that there is an economic incentive for farmers, but further encouragement may be necessary, and perhaps some financial support for demonstration projects.

“Widespread adoption could provide multiple benefits, not just for the farmer but also for the environment.”

Alison Brown

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