- Overview of digestate drying technology, production, and markets
- Economic evaluation of digestate drying
- Assessment of value as an eligble use of renewable heat
- Comparison to other digestate processing technologies
- To inform policy makers about the value of supporting digestate drying
- To inform investors about various digestate processing technologies and the economics associated
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Digestate is an organic
fertiliser product, produced in anaerobic digesters, that is mostly spread to
land. Despite extensive work being done to stimulate markets for and improve
confidence in digestate, its value potential remains low and due to its bulky
nature, storage, transport and spreading costs can outweigh the inherent value
and it often becomes a cost burden to the operator.
There are a number of markets where drying may be an
essential step, to prolong storage periods, protect or enhance the quality of
the product, to produce higher value products for more specialist markets (e.g.
bagged fertiliser for horticulture, or for combustion), or where drying also
facilitates a secondary process, such as pasteurisation. This effectively
utilises ‘waste’ heat, reducing the cost and environmental burden elsewhere in
the supply chain.
However, digestate drying is also energy intensive and can
have a higher GHG footprint compared to spreading unprocessed digestate.
This report explores the pros and cons of digestate drying
as a practice and alternatives methods to handle digestate. It then assesses
the value of supporting digestate drying under the Renewable Heat Incentive,
providing key evidence for renewable energy policy making.
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