High return for anaerobic digestion, operator claims

Greenfinch Ltd, which opened its plant in South Shropshire earlier this year (see letsrecycle.com story), said on Tuesday that plants processing 15,000 tonnes a year could cost in the region of 2.2 million to set up.

” There is a general misunderstanding in the waste industry over the cost, size and nature of anaerobic digestion. “
– Michael Chesshire
But the company's director, Michael Chesshire, revealed to an audience in London that every year a plant like his can command 300,000 for electricity generated from biogas as well as 675,000 in gate fees for taking in waste.

Mr Chesshire told delegates of the Composting Association seminar in Croydon: “There is a general misunderstanding in the waste industry over the cost, size and nature of anaerobic digestion.

“A 2.2 million plant, which takes 15,000 tonnes of waste a year, costs 350,000 a year to operate. It can raise 675,000 a year through its gate fee and generate 300,000 of renewable energy at current electricity prices, which is a strong economic return,” he said.

Diversion
Mr Chesshire said anaerobic digestion – in which waste breaks down without oxygen – was capable of a 100% diversion of material from landfill. But, he suggested the process worked best with food waste treated alone, rather than commingled with garden waste.

However, the 100% diversion rate would be reliant on finding an end-market for the end product, he said. As well as a methane-based bio-gas, which is used to generate electricity, anaerobic digestion also produces a solid digestate, which can be made into a soil improvement product.

Mr Chesshire said: “There is currently no equivalent to PAS 100 for digestion in the UK, and no standards in place yet, as it's a new technology in the waste sector. But it's part of our vision to see the material beneficially used in agriculture.”

In terms of climate change impact, the Greenfinch director said anaerobic digestion could “significantly” reduce the emissions of green-house gases compared to other forms of treatment.

As well as generating non-fossil fuel energy, Mr Chesshire said the process keeps carbon from entering the atmosphere. He said: “The process is &#39ca;rbon positive' rather than carbon neutral, which is where the process really starts to score.”