Ann Ballinger, Eunomia

1. DIGESTATE MANAGEMENT –
TECHNOLOGY AND INNOVATION
#UKADBiogas @adbioresources
CHAIR:
DR DAVID TOMPKINS, AQUA ENVIRO
PANEL:
ANN BALLINGER, EUNOMIA RESEARCH & CONSULTING
RAY LONG, CITADEL ENVIRONMENTAL SOLUTIONS
BURKHARD MEINERS, AGROENERGIEN GMBH & CO. KG
TONY CLUTTEN, HUBER TECHNOLOGY

2. Cost Benefit Analysis of Applying
Digestate to Agricultural Land in
Wales
UK AD & Biogas
Presenter
Ann Ballinger, Senior Consultant, Eunomia
1st July 2015

3. The project
• Started in May 2013, completed March 2014
• Funded by WRAP Cymru
• Project team
• Eunomia led the project and developed the cost benefit model
• Technical support from Aqua Enviro
• Option development
• Data on processes obtained from industry
• Peer review by Cranfield University
• Considered EIGHT options for digestate

4. Issues with using whole digestate
• Potentially up to three tonnes digestate produced per tonne of
food waste treated
• Limited time period each year when spreading the digestate to
land is possible
• = the potential for a SUBSTANTIAL
storage problem
• Transport costs may also be significant

5. Scenarios included in the CBA model

6. Cost Benefit Analysis (CBA)
• Calculation of financial costs
• Focus on comparative costs of the different options for managing
digestate
• Environmental analysis
• Uses life cycle assessment to develop inventory of pollution
• Greenhouse gases and air pollutants (e.g. NOx)
• Impacts monetised using standard data from DECC and HM Treasury
• Methodology recognised by UK Government

7. Whole fibre and liquor
Digestion
process
Production
of
digestate
Digestate
treatment
Product
transport
Water
treatment
Applying
products
to soil
Biogas
utilisation

8. Results – dilution to 20% dry solids
Comparative costs per tonne of feedstock; digestate transport 80 km (round trip)

9. Financial costs
• Transport costs are relatively significant
• But at dilution to 20% and where digestate is transported 80 km (round
trip), the costs of other the digestate treatment processes outweigh
transport costs
• General trend towards higher financial costs with additional
processing steps
• However the cost of discharge to sewer is relatively high
• Use of biochemical oxidation offsets the otherwise larger costs
associated with discharging liquor to sewer, through avoided Mogden
charges

10. Results – dilution to 10% dry solids
Comparative costs per tonne of feedstock; digestate transport 80 km (round trip)

11. Results – round trip transport 280 km
Comparative costs per tonne of feedstock; digestate transport 80 km (round trip)
Saving of
around £10 per
tonne feedstock
on baseline

12. Conclusions
• Best environmental outcome achieved through applying whole digestate to
land for all options - but financial costs dominate the CBA results
• Applying whole digestate to land is the best performing option overall
where feedstock diluted to 20%
• Biological oxidation with liquor discharged to watercourse is the best
performing option
• Where feedstock is diluted to 10%
• Where whole digestate needs to be transported long distances to market

13. www.eunomia.co.uk
@Eunomia_RandC
mail@eunomia.co.uk

14. DIGESTATE MANAGEMENT –
TECHNOLOGY AND INNOVATION
#UKADBiogas @adbioresources
CHAIR:
DR DAVID TOMPKINS, AQUA ENVIRO
PANEL:
ANN BALLINGER, EUNOMIA RESEARCH & CONSULTING
RAY LONG, CITADEL ENVIRONMENTAL SOLUTIONS
BURKHARD MEINERS, AGROENERGIEN GMBH & CO. KG
TONY CLUTTEN, HUBER TECHNOLOGY