John [email protected]
Determining the real value of on-farm Anaerobic Digestion
Penderfynu gwir werth Treuliad Anaerobig (Anaerobic Digestion) ar y fferm
Measure crop yield
Measure leachate levels
Above findings will provide the basic information to determine accurate economic values for AD, for government and farmer
Aims and Objectives Nodau ac Amcanion
Two soil types◦ Conventional ◦ Organic
Grass and grass/clover mix established
5 treatments◦ Control; NPK; N; Fresh
slurry; Liquid digestate ◦ Normalised for N
content (150 kg ha-1)◦ Applied via surface
spreading
5 reps, 70% field capacity
Managed for 15 weeks Three harvests
Analysed for◦ Yield (crop)◦ Leachate: amount of N
and P present (soil)◦ Bacterial and fungal
growth (soil)
Methods Dulliau
Crop Yield Fresh slurry (FS) produced half the yield of
liquid digestate (LD) in 3 out of 4 treatments No difference in yield between LD and NPK
21.8.11 in 3 out of 4 treatments
Leachate LD and FS statistically the same level of
leachate NPK had more leachate than LD in all
treatments
Results Canlyniadau
Crop Yield Cynnyrch Cnwd
Digestate had double the yield of fresh cow slurry in 3 out of the 4 treatments
NPK 21.8.11 cost £281/tonne At a rate of 150 kg N /ha, digestate saved
£103/ha on fertilizer expenditure
Simple valuation: introduction of AD doubles the value of a farmers organic fertilizer
Fertiliser Saving Arbed Gwrtaith
Treatment
OLDG ONPKG OLDC ONPKC HLDG HNPKG HLDC HNPKC
mg
/L
NO
3 -
0
20
40
60
80
100
Mg/L
NO
3-
Total Nitrate Cyfanswm Nitrad
Treatment
OLDG ONPKG OLDC ONPKC HLDG HNPKG HLDC HNPKC
mg
/L N
H4 +
0
2
4
6
8
10
12
14
16
18
Total Ammonium Cyfanswm Amoniwm
Treatment
OLDG ONPKG OLDC ONPKC HLDG HNPKG HLDC HNPKC
mg
/L
P2 O
5
0
1
2
3
4
5
6
mg/L
PO
4
Total Phosphate Cyfanswm Ffosffad
AD: 500 kW 11.5 (p/kWh) AD: 500 kW 9.0 (p/kWh)
Wind: 15 kW – 100 kW 24.1 (p/kWh) Wind: 100 kW – 500 kW 18.8 (p/kWh) Wind: 500 kW – 1.5 MW 9.4 (p/kWh)
Current FITs price doesn’t reflect all benefits of AD
Positive externalities of AD have not been valued
Feed-in Tariffs Tariffau I’w Cynnwys
Doubles the value of fertilizer produced on farm.
FIT’s and ROC’s under priced for AD
Double advantage of reducing fossil fuel usage and cutting down on current GHG emissions Only renewable energy source to do this
More nitrogen and phosphorus stays in the soil than inorganic fertilizers
Conclusions: AD Casgliadau: AD
My supervisors for guidance: Prysor Williams, Gareth Edwards-Jones, Davey Jones
Acknowledgements Diolchiadau