Duncan Worth, Chairman of QV Foods, medium scale, Lincolnshire
We operate a 1.4 MW plant developed and operated by Tamar Energy. It uses waste from our packing and processing operations, as well as vegetable food waste from other sources. We also have a contract to supply 8,000 tonnes of maize a year for the plant, which is grown on 170ha of land unsuitable for potato production. In the future, however, rye and energy beet could also be considered as feedstock for the plant.
As a relatively remote farm site with relatively weak infrastructure, having an on-site power plant makes us more robust and gives us a better platform for growth. With rising energy costs our AD plant has made our site between 90-95% self-sufficient in electricity.
The other factor in favour of AD is that we have out grade produce and peel waste which was being used as stock feed many miles away. We are, therefore, now keeping around 10,000 tonnes of potato out grades and peel on site, reducing costs and transport. The supply of liquid biofertiliser (digestate) saves us around £100,000 a year before application costs. In addition the solid soil conditioner will replace all of our current artificial sugar beet base fertiliser.
Making AD work:
The first stage is obviously to reduce the amount of waste generated, but ensuring that you use the right type of plant will ensure that you maximise the value of any out-grades or waste that you do generate.
In addition, we have increased our potato rotation from 1 in 6 to 1 in 8 years as part of efforts to reduce potato cyst nematode (PCN), helping us to incorporate more energy crops into the rotation. In addition, liquid and solid digestate from the plant provides valuable fertiliser for the farm.
Advice to farmers considering AD:
AD is hard work and not for the faint hearted. It has been said before that it is basically a concrete cow and so needs to be treated as such. In my view it only suits certain environments and applications, but where it does there is real benefit.