As a joint entry in this year’s UK AD & Biogas, hosted by Anaerobic Digestion & Bioresources Association (ADBA), Edina and Guy and Wright have been shortlisted for Best On-Farm AD Project. Tomato growing pioneers, Guy and Wright use enhanced photosynthesis through CO2 addition to their crop. However rather than the usual route of burning natural gas, the family’s unique approach was to develop their own AD plant which provides biogas for their heat, power and carbon source, with electricity export bringing in vital revenue to re-invest in the business.
They established the basis of the system approximately 15 years ago when energy costs rocketed and many other producers were going under. The family built their own digesters, fed largely from “spoilt” tomatoes and other green waste such as bananas and cereals, successfully collecting the gas and using all the heat from small gas turbines to drastically reduce their energy bills. This process also enabled them to apply for ROCs.
With the existing engines now superseded by much more efficient models, Guy and Wright considered an additional unit and finally opted for an MWM TCG 2016 V12 from Edina. This provides all the heat and electricity for the growing enterprise, the 6 glasshouses take up 3 ½ acres, and a high proportion of electricity is exported to the grid.
The gas is cleaned by the Codinox unit from Holland with a system of catalyst bricks which absorb harmful gases leaving the resulting CO2 which is piped into the glasshouses at perfectly safe levels for humans and animals. This then aids the photosynthesis of the tomatoes, resulting in more plentiful flowers/fruits. Guy and Wright also report that the heat has had a beneficial effect in reducing fungal type diseases such as petritis. The levels of CO2 and heat are controlled by computer which can operate vents and manage the system to perform at its optimum.
Two types of tomato are grown, Piccolo just for the farm gate (honesty box) and Encore, Guy and Wright’s “Eco-tom” which is supplied as the main crop for supermarkets. “Green” production is now possible 10 months of the year, the remaining 2 months being set aside for cleaning and re-planting. Bumble Bees are used as pollinators in conjunction with a careful programme of non-pesticidal management to control threats to the crop.
This fascinating enterprise is both lucrative and kind to the environment with plans underway for further storage and treatment of liquid waste to supplement the digestate used already as a land fertiliser locally.