“...And on that farm he had an anaerobic digester”

CSE has a gas down on the farm

18 July 2012

The landscape of modern farms is changing. Many are quite a long way from the picture-book ideal of a few pigs, a cows, a few sheep, a horse and a duck pond and resemble medium-scale industrial sites.

And many are well-positioned to take advantage of renewable energy  technologies, such as wind, solar (on the barn roof) and, if they have a river running through the site, hydro.

A further technology which is particularly suited to dairy farms is anaerobic digestion, or AD. Although still relatively rare in this country, anaerobic digesters are commonplace in many countries on the continent, and farmers in the UK are now starting to become aware of the benefits.

So to acquaint ourselves with the growing number of such enterprises, staff from CSE's Local & Community Empowerment team recently spent an afternoon at Kemble Farms Ltd in Gloucestershire, to try and gain a better understanding of the least well-known of all renewable energy technologies.

“AD is a complicated technology that needs much more constant monitoring and maintenance than, for example, solar panels,” said CSE’s Low Carbon Localism Project Manager, Liz Beth. “But when it’s up and running in a farm environment, it has agricultural benefits as well as renewable energy and carbon reduction pluses, so it's well-suited to a farm environment."

Kemble Farms installed their 300kW system in September 2008, so has one of the oldest systems in the UK. The farm was supported with a grant from the Department of Energy and Climate Change.

You can find out more about the background to the installation here.

The system runs on slurry from a 750 herd of milking cows, with additional inputs of maize silage and glycerol to optimise the digestion process. Methane gas is then produced by the digestion process, which fuels the generation of electricity.

Output is around 90% of maximum capacity, and the farm estimates the system produces annually the electricity equivalent to 600 homes which is fed directly into the grid.

“The benefits are obvious, aside from capturing large quantities of methane (a gas more damaging than CO2), the system also produces digestate at the end of the process – which acts as a better fertilizer with potential commercial use off site as well as on the farm.” Liz explained. “They also estimate the system will have been paid back within seven years, so will then start providing another income stream for the business.”

Which goes to show how much the business of farming has changed since Old MacDonald’s day.


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