This document discusses the experience of a farmer who built an anaerobic digestion plant on his farm. Some key points: 1) The farmer had 700 hectares of arable land with livestock and wanted to generate electricity from manure and crops to increase farm income. 2) The initial plan was to use manure from pigs and chickens as well as crops but gas yield was lower than expected. Building costs were also higher than anticipated. 3) Running the plant requires near full-time labor and attention to maintenance. Feedstock quality and quantity directly impact electricity output and profits. Using waste heat is important to viability. 4) While returns have been OK, the business requires high reliability, efficiency

1. The reality of (self build) AD
James Hart
ad@farming.co.uk
Nextgen 2013

2. Why AD?
 We had 700Ha arable, chickens, pigs and cows.
 Make money from selling (green) electricity
 Increase arable returns (increase gross output /Ha, reduce
purchased fert, improve rotation)
 Digestate is better than neat slurries / manures
 Will have surplus heat
 Reduce cost of some electricity into the business
 Reduce livestock smells to our neighbours

3. Our initial plan
 Pig slurry from 400 sow unit (now gone)
 Chicken litter from 4 broiler houses
 FYM from 100 suckler cows
 = gas yield of about 130kW/hr (hoped for 200)
 2000t +Maize and grass silage
 electricity sales of £300k+ PA
 Plus a hot house + hot whatever else..
 Digestate = fert savings on arable

4. Deciding on how to build
 Price up turnkey vs self build
 Turnkey aprox £1.6M vs Self build aprox £1.2
Therefore
 Find a suitable person to design / source equipment
 Find people to build various different bits
 Convince bank that we can do it!
 Persuade planners that it will be good for all neighbours
 Get on and build

5. Plant components and design
 Had to build something that worked
 Lots of new ideas now but many weren’t proven in time for us
 Lots of trips to Germany to view / source
 Integration into UK standards very possible
 Engineering relatively well known but interfaces important.

6. Things that we forgot / got wrong
 Parasitic load / site use
 Electric sales / PPA’s / % sold vs made, non generation
periods
 Use of heat
 The time it takes…
 Figures to use for budgets; industry achieved vs “salesman
specials”…!

7. Reality of AD
 24 / 7 operation
 Needs <4hrs /day additional labour but reality is full time to
get the most out if it.
 Initial cost high.
 There is no certainty that it will work. Most do and alot really
well. But some don’t!
 Returns with ROC’s not great but better with FIT’s
 Need to use a lot of the elect and heat to make it pay

8. Homeleaze Farm

9. Issues at the start
 Electrical connection. (Export changed)
 Planning / EA. Every situation is different. Personnel
delightful, rules not!
 Feed Stocks
 Finance
 Choice of equipment / installer.
 Use of surplus heat / rest of site

10. Feed stocks
 The aim must be to be in control as much as possible.
 Animal manures (good / own supply) “free” (130kW/hr =
£175k PA electric)
 Energy crops (grass and maize silage) should be a good
return for arable, good for rotation. However a bad harvest
and cost of feedstock goes up. Post 2011 returns not good
with wheat at £200/t as the cost of maize into AD is
significantly increased
 Still good advantages for rotation / digestate.

21. Building issues
 Euro rate change. Benefitted us by £80k but could have
been horrible if the other way!
 Site electrics way over budget (unexpected)
 Elect board connection 3 months late (expected)
 Ground works done in summer / dry.
 If turnkey, check you are getting the right / best equipment
not the cheapest to suit quote. The same design input is
needed from you if Turnkey or self build!

22. Little things count.
 Layout is vital. You want bits that you have to manage alot to
be visible and accessible
 Turnkey not always as well thought out as you would expect.
Have someone else look at the design layout and equipment
choice.
 Running a plant is time consuming at best so getting the
design and layout right is vital

23. Plant maintenance
 Most kit even if German in origin has UK suppliers
 There are some very good / better UK items available
 The environment is harsh and equipment need to be fit for
purpose
 A good farming mentality is perfect for running an AD plant
 Getting Germans over is expensive so we are all working
together to develop the people / skills in the UK

24. Results to date
 Initial gas production / start up ok.
 Silages have to be sufficient in quantity and quality. If either
is lower than expected then the output will drop. That sounds
very obvious but we are talking “farming” here, not energy
production!!!
 CHP (touch wood) going well.
 Find the people who know what they are talking about not
those who think they know!
 Hard work getting it going well and harder still to keep things
going well. Always something “not quite right”

25. Results so far (cont)
 First year output is determined by when you start to build vs
maize / energy crop planting season.
 Harvest quality and quantity vital.
 Good staff. Attention to detail absolutely vital. It is like an
intensive livestock unit and needs constant effort.
 Digestate doesn’t smell and is a great fertiliser.

26. Problems to date
 Poor grass yield yr 1. Weather!
 Poor maize yield yr 2. Weather!
 Mixer failures resulted in 3 months of below budget output
and above budget costs in yr 2. Avoidable if designed right
 Hours required. Definitely more than we expected.
 Costs in are too high, returns are capped so 100% output
vital

27. Good things to date
 Gas. Good quality and hence CHP ok thus far. Gas cleaning
a very good expense that many questioned.
 Heat to house 100% success.
 Separator. No crust in lagoons now and adds income if you
don’t need the P & K.
 Crops do look very good on digestate.

28. External influences..
 RHI’s. Needs careful planning
 Even with a closed nutrient loop it is still food vs fuel using
energy crops
 HMG not 100% convincing in their support; they are just
politicians!
 Food waste recycling via AD is great but secure the source!

29. Our future…
 Increase efficiency of our system, of biogas yield / tonne of
feedstock.
 Reduce our electric parasitic load
 Increase reliability of equipment to reduce labour
requirement.
 Find a use for heat and elect by developing the whole site.
Future is not so bright without an income from heat.
 Spend less and make more elect. More difficult than it
appears.

30. Thoughts on AD as a whole
 AD is a “busy” 24/7 business
 The returns are OK in our farm system.
 As an addition to a pig / poultry / dairy + arable unit it can be
a good fit.
 If you have a large electricity need it is much better.
 You MUST use heat to make it long term viable.

31. James Hart
ad@farming.co.uk