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Recycling with AD,
Feedstock, Operator and Digestate Issues
By Dr Les Gornall
Recycling with AD
Biogas
Digestate
Fertiliser to
Agriculture
Feedstock
Food
Wastes
Energy
Crops
Farm
Manure
Operations/
Regulations
• CHP
• Gas to Grid
• Industrial
Boiler
• Drying Plant
• Vehicle fuel
CNG
£FIT
£RHI
Food, Fuel & Fibre crops
Recycling with AD
Reference: Waste Management World - Local Generation AD Plant, 2011
Feedstock Availability
CostStoragePreparation
Operating RegulationsTrainingRetention
Digestate Management
Feedstock - Available and Valuable
• 90-100 million tonnes of agricultural by-products like manure and slurry
• 16-18 million tonnes of food waste (from households and industry)
• 1.7 million tonnes of sewage sludge dry matter.
• Each £10/T in added value or saved cost = £1,000,000,000 per
year to the country – enough money to buy 2,000 primary
schools a year.
www.biogas-info.co.uk/faqs.html
Feedstock - Available and Valuable
Feedstock availability because:
Feedstock defines Regulations applied
Feedstock controls Acidosis/Alkosis
Feedstock controls Reaction Rate
Feedstock produces Biogas
Feedstock produces Compost Fibre
Feedstock produces Liquid Fertiliser
Feedstock determines Trucking costs
Feedstock determines Pre-treatment
Feedstock determines Digester selection
Feedstock determines Gate fees
Feedstock determines Landfill costs
Feedstock Availability = Access to Finance
• Feedstock Contract Duration = Term of the
Bank Loan
• A one year feedstock contract = a one year
bank loan and pro rata
• The availability of feedstock controls
access to finance for AD Plant Capital
Expenditure
“Are you getting enough feedstock?”
Surveyed some plants PROjEN had been involved in[May 2015]:
• “There’s no more available” (SS food waste, England)
• “Food waste includes wellington boots, lots of wellington
boots” (there is a quality issue as well as an availability issue- LKG)
• “Every council that collects food is only receiving 50% of the
food waste generated” (England, Food waste plant)
• (Recycling?) “the people that do, do and the people that
don’t, don’t” ( More education is required – LKG)
• “Use of special starch bags is a barrier… that has the
potential to be removed.”
• “There is not enough food waste to run at full output”
(England, manure and food waste plant)
“Are you getting enough feedstock?”Replies May 2015:
• “We cannot get enough feedstock locally – we are now
importing some from Scotland where there is a surplus
since the ban on landfilling food waste came into being”.
• “The plant (in Scotland) is being expanded to cope with the
large amount of surplus food waste since the landfill ban.”
• “The problem is access to food waste”
It would help AD Plants in England if there was a similar ban on
sending organic matter to landfill as there is in Scotland and
(Beginning in) Northern Ireland
(see NNfCC anaerobic digestion deployment in the UK – 2nd annual report)
Feedstock COST - Waste
• Feedstock used to come with big gate fees offset against
the landfill tax (currently Landfill Tax = £82.60/T)
• Split the difference with the source of the waste and the
AD plant developer had an income from gate fees of £20-
40/T
• On a 30kTPA plant = £1.2 Million per year
• Now, food wastes producing good gas are in short supply
and gate fees are falling towards zero
• New commercial operations have started to convert waste
into digester feedstock for purchase by AD plants for £30/T
• That is a shift of -£60/T on front end value
Feedstock COST – Energy Crops
• The issue FOOD VS FUEL
• All of the AD plants in development in the UK will only require
1% of UK arable crop land while Generating 1TWh electricity,
enough to supply around a quarter of a million UK homes;
• Feedstock cost is highly regional – Maize does not grow well in
the West and an agronomist is required to evaluate success in
crops on a field by field basis.
• See ‘Biogas from Crop Digestion’ Task 37 IEA Bioenergy’
Feedstock COST – Energy Crops
AD Can help the agricultural sector• Poor prices for agricultural produce
• £20 a tonne for potatoes just sold (below production
cost)
• Large scale dairies offering 19p a litre for milk (below
cost of production) - Grassland is becoming idle or
under-used
• Loss of the dairy industry in the UK accelerating under
global competition
• Bad years for farmers = good years for AD feedstock?
• The AD industry cannot plan on a prediction of bad years
ahead for farmers
There are good examples of AD-farm co-operation
Feedstock COST – Energy Crops
The relationship between agriculture and AD
Barkip – photo credit Luddon Construction Ltd.
Feedstock COST?
“ [The local Scottish farmer] had virtually stopped traditional mixed
farming due to the cost of fertilisers making cereals production
impossible. SEPA was asking for bunding on all slurry tanks - no
money to pay for the civils work required therefore no food
production from the farm and he had opened a farm shop as a retail
operation to stay on the land.
I offered to take his slurries, store them in big stores in bunded
enclosures and give him back nitrogen enhanced fertiliser . The
predicted NPK looked very attractive, so much so that the farmer was
able to design a new farming enterprise to grow cereals on marginal
land in the west of Scotland and return to mixed farming. ”
It’s not just marginal land in the UK: In the USA….
Digestate
fertiliser
CHP
Desert land $10 per
acre reclaimed for
Growing maize
Desert $10 per acre
Growing soya -
fixes nitrogen
Husbandry 2 people /1000 head
Milk
To the
nation,
Butter
and
cheese
to the
world
Bedding fibre
No power bills
manure
Maize
Feedstock Cost includes depacking, screening,
making “soup” from difficult waste
Magherafelt IVC
UK Gate fees currently
only cover the cost of the
processing of the organic
waste into a digester
feedstock
Much organic waste is
only addressable with
composting techniques
resulting in a loss of
available organics to AD
Cost of storage
Current cost of a
silage clamp for
10,000 tonnes of
silage is about
£250,000 or £25/T
Spread over 5 years
the cost of storing a
year’s feed is £5/T
Plus machinery,
operators and diesel
for handling.
Making soup means grinding contaminants
May 2015:
• “The food waste stopped my separator/ screening machine when it
was fed a wishbone”
Car suspension wishbone
Preparing Feedstock – Ligno-Cellulose?
Long Straw (over 5cm long) forms ‘ships ropes’ inside the digester
Large proportions of untreated garden/wood waste (in wet digesters)
BUT one problem is another opportunity – research efforts are
working towards conversion of this into chemical feedstock or
digester soup – there is a lot of this material available
Preparing means excluding from feedstock:
• Tri-butyl tin (wood preservative)
• Large amounts of disinfectants
• Potentially Toxic Elements (PTE’s) e.g. copper in
pig feed
• Oil and petrol products
• Glass and Sharps
• Plastic
• Iron bars and chains
Destroy Bacteria
Contaminate Digestate
Recycling with AD
Reference: Waste Management World - Local Generation AD Plant, 2011
Feedstock AvailabilityCostStoragePreparation
Operating Regulations
TrainingRetention
Digestate Management
DSEAR 2002
Responsibility for safety is with the owner
Assess and quantify risks
Reduce risks ALARPDefine Maintenance
and inspection requirements
ATEX
Run and Maintain plant in line with
design requirements
Planning
Planning consent requirement – AD plants
Design of plant will have constraints after acquiring consent
Important to check conditions e.g. height restrictions, lightening
protection, and noise and traffic during operation.
Gelliargwellt Farm in Gelligaer near Nelson
(South Wales) , Barton Willmore, 2013Biogas holder with lightning protection rods -
Wikipedia Article (Anaerobic Digestion), 2015
Odour Control – EA and Planning requirements
Active Odour control on storage tanks and waste storage areas is
considered to be the best technique by the Environment Agency.
The requirements should be assessed and if required the tanks and
buildings should have odour control measures.
The type of odour control unit will be dependent on the odorous
compounds within the air to be treated:
• VOC’s (aldehydes, ketones, organic acids)
• Sulphur compounds (Hydrogen sulphide, R – SH)
• Nitrogen compounds (NH3, R-NH2)
Bunds and Confined Spaces
Ref. CIRIA publications on Containment and Bunds
‘Google’ Confined Space Training for details of your local training facilities.
Feedstock and Regulations
Manure + Crops + farm spread digestate and ‘digestate not a waste’
ADD food waste and regulations for waste processing apply -‘digestate is a waste’.
You can avoid the worst of the legal waste handling processes by converting waste to a product. In this case the ‘product’ (digestate) needs to Meet PAS110/ADQP
Kemira, Digestate Treatment ,2015
• Energy Crops / Farm Manure
• Source Separated kitchen food waste
• Catering waste
• Abattoir waste
• Cooking Oil
• Glycerol
Acceptable Feedstock List - : Appendix B ADQP
<0.5% plastic in digestate
(after biosolids reduction to gas)
= <0.05% plastic in feedstock?
EN 13432 bio-degradable bags are allowed
PAS110 achievable ref. Plastic Contamination
Animal by-products (ABP's) = products of animal origin that are
not intended for human consumption.
Hides and skins Fallen stock Pet animals Zoo and circus
animals Hunt trophies Manure Ova Embryos and semen
Catering waste
Used cooking oil
Former foodstuffs
Butcher and slaughterhouse waste
Blood
Feathers
Wool
ABPR – Animal by-products regulations
Training and Retention• The number of operators required for a plant is determined by the
loading rate of the digester (see appendix)
• There are about 100 biogas plants a year being built, two a week requiring a minimum of 2 trained operators per week.
• “once you train an operator someone will offer more money”
• Rural areas seem to have more family loyalty and have a higher success rate in retaining good operators
• “Best operators I have trained – one was an industrial painter, one a truck driver.”
Recycling with AD
Reference: Waste Management World - Local Generation AD Plant, 2011
Feedstock AvailabilityCostStoragePreparation
Operating RegulationsTrainingRetention
Digestate Management
Digestate IssuesDigestate storage – restriction in deployment to land such as Nitrate Vulnerable Zones and Soil Phosphorus limits.
Digestate should meet standards set out in “Quality Protocol” and “PAS 110” which ensures the digestate can be sold as a high nutrient rich fertiliser.
The storage required is for a minimum of 5 months but for security more than 6 months is often built.
These are big tanks, 6 times bigger than the digesters.
“ the whole business case for AD hinges around digestate”
(large digester operator UK)
NVZ Zones – 12th February 2013
Digestate Issues – storage, cost, land banks
6 Months Storage of digestate
Digestate storage and spreading
May represent 50% of the operating
budget
of the plant
• Quality Meat Scotland recently
accepted PAS110 for cattle ground
• Northern Ireland is still evaluating
• England has more experience and
is positive about digestate.
Summary
• 185 AD plants built plus about 350 being built in the UK mainland and 150 in NI have only claimed access to about a tenth of organic waste & <1% of the arable crops.
• Access to organic wastes is the major policy issue – Scotland is leading the way but finance may demand at least temporary security from energy crops.
• We need more than two newly trained operators a week, but there are some great examples in the UK
• The industry is learning from design and operating errors – the regulations are evolving rapidly. Most are simply the existing UK industrial regulations for health, safety, build quality and operator responsibility.
• The pressure on feedstock prices, FIT and RHI digression is putting increasing financial pressure on AD plants with the smallest units the first casualty. The industry is still embryonic and still lobbying for continued support in a noble endeavour to convert waste to electricity and remove landfill and GHG.
• There is a need to improve financial yields and this conference may provide some measure of how the value of the outputs can be improved through new and innovative processes and novel products.
Appendices – Useful Tables
• The current Feed in Tariff and RHI for Biogas plants with useful hot
water (Note: pasteurisation heat is eligible for RHI)
• Northern Ireland rules for Landfilling organic waste April 2015
• Highlights of the NNfCC second report on AD deployment in the UK
• The Operating Regime required to manage a biogas plant at different
loading rates
• Catagories of treatment required for ABPR materials
Thank You!
Dr Les Gornall BSc.(Hons),D.Phil, C.Biol. FRSB
Process Consultant
PROjEN Ltd
Part of CAPITA
DD: 01928 752 568
Mob: 07921 388 422
Email: les.gornall@capita.co.uk
Version 2.1.1
Waste Management – Edinburgh AD Plant , 2015
Appendices – Useful Tables
• The current Feed in Tariff and RHI for Biogas plants with useful hot
water (Note: pasteurisation heat is eligible for RHI)
• Northern Ireland rules for Landfilling organic waste April 2015
• Are you getting enough feedstock? Highlights of the NNfCC second
report on AD deployment in the UK
• The Operating Regime required to manage a biogas plant at different
loading rates
• Catagories of treatment required for ABPR materials
April 2015 FIT
• Note this is the value of methane put to chp units and rhi
for the hot water from the engines. For biogas value
multiply by the fraction of methane in the biogas
<250kw <500 >500 Yield
Income p/kwh S M L kWhe S M L
FIT on generation 10.13 9.36 8.68 4 0.40 0.37 0.35
Export electricity G'tee 4.77 4.77 4.77 3 0.14 0.14 0.14
RHI sale 0 0 0 2 0.00 0.00 0.00
april 2015 RHI 7.62 5.99 2.24 Total 0.55 0.52 0.49
Income £/ m3 methane
“Are you getting enough feedstock?”
Northern Ireland
The Department of Environment (DOE) implemented a ban on
Landfilling SS Food Waste from 1st April 2015
• By 1 April 2016 food businesses that produce more than
50kg of food waste per week are to present that food waste for
separate collection.
• By 1 April 2017 food businesses that produce between
5kg and 50kg of food waste per week to present that food waste
for separate collection, and food businesses to ensure that food
waste is not deposited in a lateral drain or sewer.
• Hospitals will also be required to present food waste for
separate collection from 1 April 2017.
“Are you getting enough feedstock?”
The REA reports the key points from the NNfCC Anaerobic digestion deployment in the UK second annual report :
• There are currently 185 operational AD plants in the United Kingdom, 102 of which are farm-fed and 83 of which are waste-fed;
• AD plants currently operational in the United Kingdom require almost 2 million tonnes of food waste, 636,000 tonnes of manure or slurry, 1.2 million tonnes of crops, 229,000 tonnes of crop waste and 1.2 million tonnes of other waste each year;
• The estimated cropping area required by operational AD plants in the United Kingdom is 27,800 hectares; equivalent to around 0.5% of UK arable crop land;
• There are 500 AD projects under development in the United Kingdom; 343 of which are farm-fed and 157 of which are waste-fed;
• AD plants currently under development in the United Kingdom require over 4 million tonnes of food waste, 2 million tonnes of manure or slurry, 3 million tonnes of crops, 200,000 tonnes of crop waste and over 2 million tonnes of other waste each year.
“Are you getting enough feedstock?”• The estimated cropping area required by AD plants in development in the United
Kingdom is just over 60,000 hectares; equivalent to around 1% of UK arable crop land,
much of which could feasibly be used in rotation with crops destined for food
markets. This contribution would result in the generation of just over 1TWh electricity,
enough to supply around a quarter of a million UK homes;
• Small and medium scale developments (500kWe and below) have faced severe tariff
cuts over the past 12-months, as a result of the FIT cost control mechanism;
• Biomethane injection plants have increased more than fourfold over the past year as a
result of RHI support;
• The pipeline for biomethane injection facilities remains strong, but following the recent
tariff structure change and as a result of the RHI cost-control mechanism, activity is
expected to slow.
- See more at: http://www.nnfcc.co.uk/news/anaerobic-digestion-deployment-in-the-united-
kingdom-second-annual-report-published#sthash.diXkdTnX.dpuf
Full Report from:
- Lucy Hopwood
Lead Consultant – Bioenergy & Anaerobic Digestion
Tel:+44 (0)1904 435182 l.hopwood@nnfcc.co.uk
“Are you getting enough feedstock?”
• The UK produces over 100 million tonnes of organic material
that is suitable for treatment by AD. This includes:
• 90-100 million tonnes of agricultural by-products like manure
and slurry
• 16-18 million tonnes of food waste (from households and
industry)
• 1.7 million tonnes of dry sewage sludge.
www.biogas-info.co.uk/faqs.html
Electrical output at 85% VSR
Daily Organic
Loading Rate
kg-VS/m3
Digester VOLUME (m3)
6,000 4,000
MWe MWe
3.3 1.2 0.8
4 1.5 1.0
5 1.8 1.2
6+ 2.2 1.5
KEY – OPEX AND
MANAGEMENT
Simple Lab TVFA/NH4
Daily Lab TVFA/NH4
Intensive lab checks
Foam+NH4 issues
24 hour active
management with on
site chromatography
OPERATING REGIME VS LOADING RATE
ABPR CategoriesCat 1 – Highest risk (BSE) plus ‘international catering waste (from
ships etc.), zoo and circus animals’. Not for AD – Incinerate or
Render
Cat 2 – High risk. AD feedstock allowed if pressure cooked to the
EU Standard (133°C/3 bar/20 minutes).
EXCEPTIONS: Manure, Digestive Tract Content, Milk and
Colostrum can be digested with pasteurisation but without
pressure cooking.
ABPR CategoriesCat 3 – Low risk – intended for human consumption and can be
treated via AD.
• Raw meat intended for human consumption
• Waste from food manufacturers and retailers
• Eggs, and other by products that do not show signs of
transmissible disease
• All UK derived catering waste (i.e. from domestic and
commercial kitchens)
• PASTEURISATION FOR MAX 12mm Particle size is 1 hour at
70 Deg. C
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