Biogas Featured Articles
Making a Profit from Waste?
Manures and slurries destined for anaerobic digestion treatment are now, as set out in the recent Environment Agency’s paper on the matter, considered ‘waste’. But, asks Katie Zabel, is there a profit to be made – for both your pocket and environment?
It seems everyone from Adam on the ‘Archers’ to Hilary Benn is talking AD – anaerobic digestion – at the moment. So what is it, how does it work and is it suitable for your farm? Owen Yeatman, who farms 400-head of dairy cattle and 1,200 acres of arable crops in Dorset, began investigating the opportunities presented by AD in 2004. He became interested as a result of his Nuffield Farming Scholarship, through which he investigated anaerobic digestion in Germany, where over 3,500 digesters provide local, renewable energy to homes and businesses. Gripped by the idea, and its potential to create a more profitable farming business, he returned to Dorset and secured planning permission and a grant from Defra’s bioenergy capital grant scheme to help with costs. Today he’s in the process of powering 400 local homes with biogas from crop and animal wastes. “Methane has a calorific value and is commercially viable, so we were able to convince our investors that it would be profitable as well as a renewable, non-fossil fuel. Three cows produce enough gas to provide electricity for one household” says Mr Yeatman, sharing his story with the Farming Futures project.
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| BIOGAS DEVELOPMENT: Two of the on-farm biogas plants on Meikle Laught farm and Knockri voch farm; part of the seven farm scale plants that Greenfinch built in South West Scotland. |
His digester currently returns at around 19% but he is confident that this will improve as the price for bioenergy continues to rise.
Owen Yeatman admits that planning permission and connection to the grid were challenging barriers to overcome, but he deliberately selected technology that fitted into the surrounding landscape, and regular talks with his local community ensured the planning application not only went through within eight weeks, but was also accompanied by letters of support.
As he says: “The technology is unobtrusive, creates jobs, keeps the farm profitable and doesn’t affect people negatively… And it provides opportunities for the agricultural community – reduction of methane emissions, saving of mineral fertiliser, reduced odour emissions, strengthened rural infrastructure, security and decentralisation of energy supply, and diversification of agricultural income”.
Potentially a win-win-win for the pocket, environment and community.
ANAEROBIC DIGESTION (AD) ESSENTIALS:
What is AD?
Anaerobic digestion (popularly known as AD or biogas) is the controlled breakdown of organic matter, crucially without air, to produce a combustible gas (methane) and a nutrient rich organic manure. Systems can be located on farm to deal with farm waste, or in larger centralised anaerobic digestion facilities which have the potential to divert tonnes of household waste from landfill.
How does it work?
Organic material (see below for a full list) is collected and stored in a closed container that acts as the ‘digester’. Oxygen supply is removed to stimulate feedstock breakdown into useful products. After 20-40 days (depending on the internal temperature of the digester and the feedstock choice), biogas and a nitrogen and phosphate rich solid ‘digestate’ is produced. The biogas can be burnt to produce heat and electricity, and the digestate can be applied as fertiliser back on the land.
What feedstock is needed?
Co-digestion – a combination of feedstock is likely to produce the best economic results, enabling the waste to attract a gate fee and can comprise of:
- Animal manures and slurries
- Energy crops, such as whole crop (silage) maize or grass leys
- Food waste
- Food by-products and crop residues
- Biodegradable domestic waste.
What's the cost?
Costs are obviously variable depending on location, size and feedstock, but with grants available from the regional development agencies and Defra’s bioenergy capital grant scheme, plus income from double ROCs (renewable obligation certificates) for electricity sales, this technology is increasingly financially viable.
The best option for farmers interested in AD is to contact the technology producers directly for a farm visit and quote. The Biomass Energy Centre provides a list of producers:
www.biomassenergycentre.org.uk or call 01420 526197.
Grid connection costs are also determined by the size of the unit and need to be considered before locations are selected. Again, contact technology producers for advice tailored to your farm.
Why should I think about it?
AD offers a new opportunity for dairy farmers to make a profit from their herd, and play their role in being part of the climate change solution. AD enables farmers to mitigate climate change by capturing methane emissions, and utilising them in a useful form to produce natural, renewable heat and power. Your farm business could be transformed by diversification into local energy production and waste processor.
Originally published in May's edition of British Farmer and GrowerMay 2008
