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The digestate dilemma

An excerpt from The Digestate Dilemma, an article in the Summer 2020 Edition of AD & Bioresources News…

Unless new markets are created for digestate it will become a barrier to growth. Jon Hughes assesses how this quality natural fertiliser, conservatively valued at being worth £200m a year, has become a headache for operators and what needs to be done to realise its potential.

A remarkable line in the sand was erased at the ADBA members meeting on 30th April 2020. Digestate was put on the BEIS agenda. During a presentation on the Green Gas Support Scheme (GGSS), the proposed successor to RHI, it was revealed that consultation would be asking
the question, ‘How can we improve air quality and increase the commercial
market for digestate?’

For BEIS watchers in the industry this was a landmark moment. Having previously always kept a laser-like focus on energy production from AD and energy alone this marks a significant step-change towards valorising the environmental services the industry delivers. It seems safe to assume that the future GGSS will to some degree have digestate factored in.
Defra is singing from the same song sheet, also asking how we can come up with innovative solutions to valorise digestate and secure end markets. The members meeting was told that ‘digestate is viewed more as a resource now’.
Simultaneously, the Environment Agency (EA) is reviewing the ADQP (AD Quality Protocol) governing digestate from AD plants that accept waste materials to digest such as food waste from households and abattoirs. The ADQP defines end of waste status, which must be achieved for digestate to become a product.
A revision of the QP, which is fully expected although later than scheduled, will have a bearing on a revised standard for digestate, PAS 110, and could be key to opening new markets for it. The current QP creates barriers, particularly to entry into the horticultural market.
When this review is concluded it is fully expected to include more stringent rules on contamination levels in digestate, particularly plastics. It is likely that England will as a minimum follow Scotland, which already demands much lower levels of plastic contamination than is allowed under PAS110. This is presented as 8% of PAS 110, as contamination levels are set by
nitrogen content, which determines how much digestate can be spread over a hectare.
There are clear drivers behind policy. The treasury has told ADBA it wants to see a tripling of biomethane production under GGSS, for which BEIS has delivered a favourable cost-benefit analysis. Defra wants to see all household food waste going through AD, describing it as the ‘the best environmental outcome for the treatment of unavoidable food waste’. All of which would result in a commensurate increase in the levels of digestate produced.
Unless new markets are developed this will become a barrier to growth….

Find out more about digestate in the Engine Room Theatre at The World Biogas Expo, 6-8 October, ONLINE. Register for free here.


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