Sophie Parker
BBC News, Wiltshire
Designscape Architects
The plans involve placing greenhouses for growing food on top of the landfill
Plans have been revealed to grow fruit and vegetables using “cleaned” carbon dioxide in greenhouses above a landfill in what it is claimed will be a “world first”.
The landfill in Wiltshire is run by Crapper & Sons Ltd, which is currently waiting to get planning permission for the project.
The company already captures methane coming off the waste to power its operations and send energy to the national grid, as well as producing CO2.
Having now started a community interest company called Sustain Wiltshire, it has said it wants to use the site to grow food for the local area all year round.
The site already uses gas from the rubbish on its site to power machinery
The plans involve using greenhouses on the site to take advantage of CO2 and heat to produce food such as avocados, which are not usually grown commercially in the UK.
The produce would then be sold to people living in the local area in towns and villages such as Royal Wootton Bassett, Malmesbury and Brinkworth.
The system to generate electricity from captured gas also produces CO2
Project Director Nick Ash said there are other similar projects across the world but the specific Wiltshire one is a world first.
“What comes out of the top of the gas engine [the one already generating energy] is quite clean CO2. In Europe, that’s already used in greenhouses, so we would get that into our greenhouses.
“So you’d grow them [vegetables and fruit] in a rich CO2 environment so they’d grow better than in normal air,” he explained.
“They [the plants] will be the using the heat, the light and the power, but they will have no contact with the ground at all.”
The system at the moment takes the gases from the landfill and extracts the methane for power and cleans the gases – for example, by removing hydrogen sulphide and using bacteria – with cleaner CO2 a by-product of the process.
Project Director Nick Ash said he wants locals to be able to buy fresh food to order
The project will involve flattening a large section of the landfill site to create pits – called “cells” – which will be lined with concrete and have waste put in them to produce gases.
The gas will then be captured and cleaned so it can be used to produce electricity and pump the CO2 into the greenhouses which will sit above the cells.
“We plan to totally change the way that we effectively landfill,” said Mr Ash.
“It [waste] would go into fast-reacting gas cells, which would produce gas very quickly, then have the rubbish taken out, then [go into] storage cells that would feed recycling.”
The company also plans to make the greenhouses portable which will allow the pits underneath to be emptied and have fresh waste put in.
Waste that cannot be recycled right away can have the organic matter rot and produce usable gas, and then that waste can also be processed again.
Mr Ash said that if granted planning permission, the project would change the appearance of the site, with more grass and trees added.
The extra power generated will enable a bigger recycling operation, the company said
The project overall is called the Super Midden, based on midden – a word mostly used by archaeologists to describe ancient rubbish dumps.
Crapper & Sons Ltd said the development could produce 80% of the fruit and vegetable needs of the surrounding area, reducing emissions, food miles and improving food security.
Mr Ash told the BBC he does not think it will fail technically and that the biggest challenge will be “introducing something new”.