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Role of Anaerobic Digestion in a Role of Anaerobic Digestion in a Role of Anaerobic Digestion in a Role of Anaerobic Digestion in a Sustainable WalesSustainable Wales
Anaerobic Digestion and the Planning Process Worksh op, Llandrindod Wells – 25 th June 2009
Dr. Sandra EstevesDr. Sandra EstevesUniversity of Glamorgan
sesteves@glam.ac.uk
Overview of the Presentation
1. Background to the Wales Centre of Excellence for Anaerobic Digestion
2. UK Commitments and Targets
3. Policy, Regulatory and Fiscal Developments
4. Aims and Challenges for Implementation of AD in Wales
5. The AD process – benefits, end-products and uses
6. Example of AD plants
7. Quick comparison of AD with IVC Systems
8. Site and Planning Considerations/ Mitigations
9. Information for Planning Application9. Information for Planning Application
• To ensure that sufficient, appropriate and technically accurate information regarding
Role of the Wales Centre of Excellence for Anaerobic Digestion
technically accurate information regarding AD is available to all stakeholders with an interest in the technology
• To provide specific technical assistance to those who are considering AD as a waste treatment option, or are in the process of developing, constructing or process of developing, constructing or operating an AD plant
http://www.walesadcentre.org.uk/
The AD Centre project is delivered by academics and researchers of the Sustainable Environment Research
Centre (SERC) at the University of Glamorgan
Information and Dissemination Activities
• Awareness raising and seminars • Developing guidance for AD plant
developers developers • Developing best practice for AD operators • Dissemination of best practice in AD • Collation of information on AD technology
suppliers / contractors for dissemination• Advice on organic waste collection• Life Cycle Assessment of AD technologies • Life Cycle Assessment of AD technologies
and biogas utilisation• Web Portal – One stop shop for AD related
information• Bespoke training
Technical and Analytical ServicesLaboratory Testing • Organic waste analysis and characterisation • Laboratory testing of biodegradability of kitchen waste
collection bags • Digestate analysis
Pilot Scale • Assessment of digester inhibition• Biogas yield / biodegradability studies (laboratory and pilot
scale) • Biogas analysis and biogas utilisation options • Digestate analysis and quality assessment
Design and Commissioning • Advice on reactor design and pre and post-treatment
stages integration for optimised performance stages integration for optimised performance • Independent design reviews • Independent support for tender preparation/assessment • Plant start-up and commissioning
Monitoring and Management Support• Process monitoring, optimisation and management • Digester ‘Health Checks’
Anaerobic Digestion
Waste Treatment
Bio Hydrogen
Bio Energy
MonitoringWastewater Treatment
Research Unit
WWTRU
Hydrogen Energy
Microbial Fuel Cells
SERC and Anaerobic Digestion
• 40 years of R&D related to Anaerobic Digestion
• Agricultural, municipal and industrial wastes and • Agricultural, municipal and industrial wastes and wastewaters
• Reactor design
• Monitoring, modelling and control systems
IWA Specialist Group on Anaerobic Digestion – Wester n Europe Representative
UK Representative on the IWA-AD Task Group on Harmo nisation of Anaerobic Biodegradability/ Activity/ Inhibition Test Methods
• EPSRC AD Research Facility(1986-94)
History of SERC and AD
(1986-94)• Ice-cream effluent
(Bird’s Eye Wall’s)• Instant coffee
effluent (Nestle)
EU FP4 R&D ProjectsDevelopment of an integrated process control system for a multi-stage wastewater treatment plant - Bakers Yeast Wastewater (1991-1994)
Integrated water recycling and emission abatement in the textile industry (1996-1999)
• Anaerobic Digestion of High Solid Content
History of SERC and AD
High Solid Content Waste (1994-1996)– Novel reactor design
tested on market waste
– Collaboration with ENEA-Italy
• Review published in May 2007• Partly funded by WAG and
RCT• Includes a Summary of AD Site
AD of BMW - Review
• Includes a Summary of AD Site Visits
• AD Technology Status and Trends
• 20 European case studies– BMW + other wastes – 9
plants– OFMSW + other wastes - 8 – OFMSW + other wastes - 8
plants– industrial and agricultural
organic wastes – 3 plants• Lessons learnt
World-leading R&D scaling up to pilot scale• Industrial systems• Energy balance
Current SERC’s R&D in Anaerobic Processes
• Energy balance• System control & optimisation
Pilot scale 2-stage biohydrogen and biogas plant at Barry using wheatfeed (above) and at Treforest using Sewage sludge (below)
Pilot scale 2-stage biohydrogen and biogas plant at IBERS Aberystwyth using rotated crops
CO2 Emissions, Renewable Energy and Landfill Diversion for UK
• Climate Change Act 2008– 26% reduction in CO2 emissions from 1990 level by 2020
Legally Binding Targets!!!
– 26% reduction in CO2 emissions from 1990 level by 2020– 80% reduction in all GHG emissions by 2050
• EU Renewable Energy Directive– 20% renewable energy in EU by 2020– UK is required to go from ~1.8% now to 15% by 2020– 10% of energy used in transport is required to be renewable by 2020– GHG emissions from road transport fuels will reduce by at least 6%
(from 2010 levels) by 2020
• EU Landfill Directive 1999– Reduction in biodegradable municipal waste sent to landfill from 1995
level of• 25% by 2010• 50% by 2013• 65% by 2020
AD Technology is Able to…..
• Divert municipal biowastes from landfill
Co-digest these wastes with other organic wastes• Co-digest these wastes with other organic wastes– sewage sludge, manures, slaughterhouse wastes, industrial
organic wastes and spoilt crops
• Produce a beneficial soil conditioner/fertiliser– quality dependant
• Produce CO neutral renewable energy
Reducing GHG emissionsReducing GHG emissions
• Produce CO 2 neutral renewable energy– Electricity, heat and transport fuel
UK Policy, Regulation and Fiscal Developments (1)
• Revised waste exemptions from environmental permitting– Digestate from manures/slurries are not classified as wastes
• Development of Standard Environmental Permits for AD • Development of Standard Environmental Permits for AD plants and storage of digestate– Reduce assessment timescales and costs
• Ability of AD plants to treat ABPs
• Development of the quality protocol and the PAS 110 for digestates (currently at draft stage)digestates (currently at draft stage)
• Willingness to change UK policy and regulation in relation to biomethane injection to the gas grid– Flexibility of uses; allows improved environmental performance and
contributes to security of energy supply
UK Policy, Regulation and Fiscal Developments (2)
• 2 ROCs/MWh for electricity generated through AD (except for sewage sludge digestion) from April 09 –(except for sewage sludge digestion) from April 09 –although a revision may take place in 2013
• Extension of the RO from 2027 to 2037
• Energy Act 2008 enables the Government to introduce feed in tariffs for the generation of electricity in projects up to 5 MW and the Secretary of State to establish a financial support mechanism for renewable heat including financial support mechanism for renewable heat including support for biomethane injected into the gas grid– Full implementation expected by 2011
– More bankable projects and diversification of biogas markets
Policy and Support for AD in Wales (1)
• WAG has accepted AD the best environmental option for treatment of food wastes and suitable organic C&I wastes
• Revised Waste Strategy currently at consultation stage • Revised Waste Strategy currently at consultation stage ‘Towards Zero Waste’ aspires at 70% recycling and 30% Energy from Waste by 2024/25– AD making a significant contribution to organics recycling
• WAG Bioenergy Strategy and Bioenergy Action Plan have considered a contribution from AD to renewable electricity and heatand heat
• Producing awareness/educational materials on AD that will support the reassurance regarding waste facilities to local communities
Policy and Support for AD in Wales (2)
• Financial support– Public sector - separate food waste collection and capital and – Public sector - separate food waste collection and capital and
revenue support for AD systems– Business sector - AD facilities that can treat at least 60% C&I
wastes
• Established a Planning Task Force to work with Planning Authorities to help accelerate the Planning Application process
• WAG has funded partially the Wales Centre of Excellence for Anaerobic Digestion (from April 2008)
AD Implementation in Wales
• Challenges– Accommodate wastes
• Aims
– Accommodate wastes generation distribution in Wales
– Ensure a close market for digestates
– Ensure a market for energy output
– Achieve a minimum scale AD – Achieve a minimum scale AD plant for economic viability
– Build partnerships for co-digestion of waste
Food Waste Treatment Hubs in Wales(potentially via AD)
Hubs Participating Authorities
Indicative BMW treatment capacity required to meet
2012 landfill diversion targets
North East Conwy, Denbighshire and Flintshire circa 20 ktpa
Central Powys and Ceredigion circa 20 ktpa
South WestBridgend, Carmarthenshire, Neath Port Talbot, Swansea, Pembrokeshire, [Vale of Glamorgan]
circa 75 ktpa[circa 10 ktpa]
Valleys West Rhondda Cynon Taff, Merthyr Tydfil circa 30 ktpa
Valleys East Blaenau Gwent, Caerphilly and Torfaen circa 30 ktpa
Total Circa 185 ktpaNewport may be procuring capacity in the futureOther wastes such as C&I wastes may be co-treated at these planned facilitiesMBT plant(s) are also being assessed for treatment of the residual waste stream
Anaerobic DigestionA ‘living process’
Degradation of complex organic matter to its simpler chemical constituents, and ultimately to CH4 (55 – 65%) and CO2 (34 – 44%) by a consortium of bacteria in the
absence of oxygen
Acid-forming Bacteria
Food chain in Anaerobic Digestion
Acetigenic Bacteria
Methanogenic Bacteria Lithotrophic Bacteria
AD Process Requirements
• Co-ordinated participation of the required groups of bacteria
• Biodegradability of the waste input• Biodegradability of the waste input
• Adequate mass transfer – mixing and retention time
• Appropriate loading organic rates and solids
• Monitor and control performance
– e.g. pH, C:N:P, alkalinity, temperature, volatile fatty acids
• Avoid toxic and inhibitory substances and other contaminants
– good quality source separation will help
– e.g. heavy metals, salts and biocides
Feedstocks for AD Systems
• Some industrial wastewaters• Agriculture manures and slurries and crop • Agriculture manures and slurries and crop
residues• Sewage Sludge• Municipal and C&I organic wastes• Energy Crops• Energy Crops
Co-digestion is possible
Matrix for Co-digestion Feedstocks
Types of wastesMethane Potential
Gate Fee Potential
Negative Impact on Digestate Quality
Local Availability
(urban, rural, industrial)
Nutrient Content of Digestate
Level of Pre-treatment Required
Source separated kitchen waste
high high none everywhere, especially urban
medium/high medium - high
kitchen waste especially urban
OFMSW of residual waste
medium high highly negative everywhere, especially urban
medium/high very high
Commercial organic wastes
high(depending on waste)
high none everywhere, especially urban
variable medium
Industrial organic wastes
low – very high (depending on waste)
high depending on waste
industrial areas low low
Agricultural wastes
low none none rural areas high low
Abattoir wastes high high none rural areas high lowAbattoir wastes high high none rural areas high low
Sewage sludge low none Possibly negative *
everywhere, especially urban
high low
Energy crops (depending on crop) negative none rural areas low low
* depending on heavy metal content
Co-digestion should in general be maximised wherepossible to achieve the benefits of economy of scale
Types of Industrial Wastewaters Being Treated using AD
Parmaceutical 2%
Pulp and paper9% Sludge liquor
Chemical13%
2%
Starch8%
Fermentation (yeast)10%
Vegetable 5%
Distillery1%
Soft drinks and Juices
Brewery21%
Sludge liquor1%
High rate 5%
Sugar8% Potato
processing waste10%
Diary5%
Other food4%
Juices3%
High rate digester granule
Courtesy of van Lier 2004
British Sugar Wissington (UK)
Thames Water Biosolid Digesters (Reading, UK)
Example of Anaerobic Digesters
COD Load: 42 t d -1
Flow: 320 m 3 h-1
Types of AD Systems for Solid Municipal Wastes
• Single step or multi-step digestion• Single step or multi-step digestion• Batch or continuous feeding • Wet or dry digestion• Mesophilic or thermophilic operation
Optimum configuration and integration with Optimum configuration and integration with other technologies is case specific
Reception/Storage
Fee
dsto
ck B
(ton
nes)
Feedstock A(tonnes)
Exhaust gases
Used in the plant (MWh)
Storage, compression and other additions
(% efficiency)
Biogas Upgrading(% efficiency)
e.g. PSA, water scrubbing, etc.
Biomethane for transport or gas grid injection (GJ)
Weight bridge
Example of Flowdiagram(s) for AD Plant(s) Treating BMW and OFMSW (and co-digestion with other feedstocks)
Cleaning and storage
CHP(% efficiency)
Engines, gas turbines or fuel cells
Reception/Storage
Pre-treatmente.g. sorting; shredding,
pulping, hydrolysis (percolation, biological, chemical and thermal)
Bio
gas
(GJ)
Electricity (MWh)
Heat (MWh)
Used in the plant (MWh)
Electricity Market (MWh)
Heat Market (MWh)
Water, chemicals(tonnes) Water, chemicals and
other materials (tonnes)
Hygienisation
Tanks/enclosed buildings
Equalisation and Digestion vessel(s)
Feedstock C(tonnes)
Dig
esta
te(t
onne
s) Dewatering, composting,maturation,
Storage, and on-site
WWT
End Market: High quality digestate
whole, liquor, fibreor compost (tonnes)
% rejects
disposal or market
(tonnes)
Hygienisationor
pasteurisation for ABPR
compliance(can be after
digestion)
Further Treatment:
e.g. sewerage systemFlow
Alternative Flow
Disposal:Low quality digestates
/composts (tonnes)
Not to scale
Plant optimum configuration is case specific
• Amount and characteristics of wastes
• Aims of the projectTechnical, environmental and economic assessments for the various plant configurations are
• Local circumstances
Ultimately, the plant needs to be able to:
Access feedstocks
various plant configurations are required
Find markets for the digestate and biogas
Obtain planning permission, environmental permit (from EA) and when treating ABPs approval from Animal Health Agency (responsible to WAG for approval and inspection of premises under the ABPR) for which plant location, stages, layout and flows, equipment size and specification and operation are key
AD and IVC Systems Comparisons
• Volume reduction of 60% and weight reduction of 50-60% for both systems
• AD does not require structure materials for treating BMW• AD does not require structure materials for treating BMW
• Improved fertilising characteristics for digestate
• AD has generally lower retention times
– Smaller space required
• LCA studies concluded ‘treatment of biowastes by AD is by
far the most environmentally sound option’– Mostly related to AD energy positive balance
– Electricity balance (in favour of AD) is 125 – 235 kWh/t of waste during operation, reducing 54 -102 kg CO2/tonne of waste treated
Economic ComparisonsAD and IVC Systems
• AD systems’ capital costs are in general higher• Operating costs of AD systems are lower• Operating costs of AD systems are lower
– due to income from biogas and less energy use– become more favourable with increased plant scale
• Costs minimised if AD projects are sited close to:– existing infrastructure e.g. landfills, WWTPs or thermal
treatment plantstreatment plants
• AD systems will have shorter payback periods– Even more with market support to promote renewable
energy and carbon emission savings
AD of Municipal Biowastes in Europe
• European countries are leaders• Late 1980s: 1st full scale plants (OFMSW) • Late 1980s: 1 full scale plants (OFMSW)
Amiens – France; Vaasa – Finland• Still operating successfully
• At least 168 industrial scale AD plants treat BMW or OFMSW (2006)– 120 treat BMW; 48 treat OFMSW
• Total AD capacity of over 6 million tpa (2006)• Total AD capacity of over 6 million tpa (2006)(including non-municipal wastes that are co-digested)
• Average capacities of digesters treating– BMW ~ 30,000 tpa; OFMSW ~ 56,000 tpa
Anaerobic Digestion Plants Visited (2006)
Treating various substrates
• BMW + other • BMW + other wastes – 9 plants
• OFMSW + other wastes - 8 plants
• Industrial and agricultural organic agricultural organic wastes – 3 plants
BMW – Source separated biodegradable municipal wastes
OFMSW – Organic fraction of municipal solid waste(as part of a Mechanical Biological Treatment plant)
Example of AD Plants Treating BMWPlant, Location Wastes Treated Capacity
(tpa)AD Supplier
Brecht II, Belgium SSKW, garden waste 50,000 OWS Dranco
Salzburg, Austria SSKW, garden & industrial organic waste 20,000 OWS Dranco
Niederuzwil, Switz. SSKW, garden & industrial food waste 20,000 Kompogas
Otelfingen, Switz. SSKW, garden & industrial food waste 12,500 Kompogas
Oetwil Am See, Switz. SSKW, garden & industrial food waste 10,000 Kompogas
Grindsted, Denmark SSKW, sewage sludge & industrial organic waste 52,600 Krüger
Ludlow, UK SSKW, garden waste 5,000 Greenfinch
Jonkoping, Sweden SSKW 30,000 JonkopingsKommun
Västerås, Sweden SSKW, grease trap sludge, ley crop 23,000 Ros Roca
Note: Source Separated Kitchen Waste (SSKW)
Example of AD Plants Treating OFMSW
Plant and Location Wastes Treated Capacity(tpa)
AD Supplier
Buchen, Germany Residual MSW 151,000 ISKA
Heilbronn, Germany Residual MSW 88,000 ISKA
Heerenveen, Netherlands Residual MSW, commercial wastes 300,000 Grontmij
Mons, Belgium Residual MSW 80,000 Valorga
Saschenhagen, Germany Residual MSW, commercial wastes 85,000 Horstmann
Pohlsche Heide, Germany Residual MSW, commercialwastes, sewage sludge
92,500 OWS Dranco
ZAK Ringsheim, Germany Residual MSW 100,000 WehrleWerkZAK Ringsheim, Germany Residual MSW 100,000 WehrleWerk
Vaasa, Finland ‘Kitchen’ waste 42,000 CiTec
Example of AD Plants Treating Other Biodegradable Wastes
Plant and Location
Wastes Treated Capacity(tpa)
AD Supplier
Lintrup,Denmark
Agricultural, commercial abattoir and hospital food wastes
200,000 Krüger
Linkoping,Sweden
Commercial, agricultural and abattoir wastes
22,000 SvenskBiogas
Holsworthy,UK
Agricultural and commercial wastes (currently changed
150,000 Farmatic
operation)
• 95 – 99% if quality of source separation is maintained
Landfill Diversion of Municipal Biowastes
– Improves with familiarity and continuous public education
– Digestate suitable for land application
• 60 - 90% for MBT-AD plants– assuming sufficient thermal capacity for
RDF and depends on the end use of CLO
Source separated kitchen and garden waste at Brecht Plant (IGEAN, 2007)
– highest diversion with potential income if CLO is converted to SRF
Source separated kitchen wastes in paper bags at Grindsted Plant,
Denmark (Bro, 2006)
Digestate as a Soil Conditioner/Fertiliser
• Output: Whole digestate, separated liquor and
De-watered digestate at Grindsted Plant,
Denmark
Solid digestate at Västerås
Plant, Sweden
• Output: Whole digestate, separated liquor and separated fibre
• Containing organic matter and nutrients (e.g. N, P, K, Ca, Mg, S)
• Success of source separation is crucial to the quality of digestate
• Suitability for spreading on land – agriculture, horticulture, land reclamation and forestry markets
Spreading the liquid digestate (Pettersson, 2006)
horticulture, land reclamation and forestry markets
• A sustainable income from digestate?
• Digestate may go through an aerobic stage and a CLO is produced
Greenhouse at Otelfingen Plant, showing crops growing on
digestate
Biogas Production from Organic Wastes Waste Biogas (m3/tonne)
OFMSW 50 - 137
SSKW 100 - 140
Food waste (from canteen) 108
Food processing waste 40 - 48
Waste Biogas (m3/tonne)
Abattoir gastro-intestinal waste
40 - 60
Abattoir fatty waste <100
Animal by-products 225 (CH4)
Slaughterhouse waste mixture 160 (CH)Food processing waste 40 - 48
Cattle slurry 7.5 - 31
Dairy cattle slurry 20
Fattening cattle slurry 34
Pig slurry 5 - 32
Poultry manure 25 – 150
Slaughterhouse waste mixture 160 (CH4)
Vegetable residues 35
Rape seed cake 612
Whole crop silage 195
Grass silage 183
Ley (clover) 80
Sewage Sludge (2 – 5% VS) 15 - 56Biodegradability testing programme should always be carried out
Biogas yield varies with:
• reactor systems; loading regimes; total solid content %; mixing efficiencies; operating temperatures; retention times…
should always be carried out
Biogas for Renewable Electricity and Heat
• AD of BMW produce net electricity and heat (60-80% is typical)typical)
• AD within MBT plants– Biogas mostly used on-site
• Remove H2S (and water)– for use in gas engines, turbines
and fuel cells
CHP and boiler at Ludlow plant, UK
and fuel cells
• 2 ROCs/MWh of electricity from April 2009
Gas engine at Oetwil Am See Plant, Switzerland
Upgrading Biogas to Biomethane
• Removal of gases such as H2S and ammonia, drying, and separation of carbon dioxide, nitrogen and oxygen and separation of carbon dioxide, nitrogen and oxygen are currently being used at full-scale
• Commercial systems are available at competitive costs for medium and large biogas flows, low energy consumption and reduced fugitive methane emissions
• Processes for CO2 separation are typically pressure-swing adsorption, temperature-swing adsorption, water swing adsorption, temperature-swing adsorption, water scrubbing, amine scrubbing, membranes and cryogenic separation
Biomethane as a Transport Fuel• Biogas upgraded to ~97-98% CH4 and
compressed• Biomethane as a transport fuel is proven and
developed• Comparing it to other renewable transport fuels• Comparing it to other renewable transport fuels
– Lower emissions (CO, NOx and particulates), noise reduction and local availability
• Enhanced income for transport fuel (by replacing diesel/petrol use) as compared to CHP but higher capital costs and need for fuelling infrastructure (possibility for grants)
• Biomethane from waste treatment AD plants should receive more RTFCs – that requires
Biomethane storage at fuelling station in Switzerland
should receive more RTFCs – that requires addressing soon
• A series of vehicles from a number of manufacturers are available in the UK market Biomethane fuelling station in
Austria
Biomethane as a Transport Fuel
1 tonne (kitchen waste) = 1000 km (car) (Kompogas, 2006)
1 tonne (OFMSW) = 740 km (Volvo V70) (Murphy, 2004)
Biomethane fuel pumps atVästerås Bus Depot, Sweden
Public biogas filling stationat Jonkoping, Sweden
Biomethane for Injection into the Gas Grid
• Biogas must be upgraded to biomethane and potentially add ~ 4% propane to meet CV of UK gas grid
• Biomethane requires appropriate compression depending on the pressure of the gas network injecting to; it may require also pressure of the gas network injecting to; it may require also odorisation for safety reasons
• The biomethane will need to be monitored in terms of flow and quality
• Gas grid regulations and incentives need to be in place in the UK; relaxation of %O2 allowed is required within safety
• United Utilities have been approved funding for a biogas upgrading facility for gas grid injectionfacility for gas grid injection
• Scenario very welcomed by the National Grid and also favored by gas distribution networks
• Recent impetus in the UK for injecting biomethane into the gas grid– The UK will rely on imported gas to meet up to 80% demand by 2020 as
well as the recent gas supply row Russia-Ukraine
Advantages of Biomethane in the Gas Grid
• Increase security of gas supply reducing external dependence
• Decarbonisation of the UK gas network• Decarbonisation of the UK gas network• Flexibility for its use i.e. direct combustion for heating,
transport fuel and electricity generation– resulting in an improved energy supply and demand response
• Improve energy conversion promoting reduction of carbon emissions– direct burning for direct heating - in high efficient boilers using – direct burning for direct heating - in high efficient boilers using
existing infrastructure/appliances– Improve energy efficiency using CCGT electricity generation as
compared to CHP if heat is not used
• Support local economy
CO2 Emission Saving Potential of Anaerobic Digestion in
Comparison to the Installation of Cavity Wall Insulation in Cavity Wall Insulation in
HouseholdsExample - Cardiff County Council
Over 25 years
Source: Energy Saving Trust, 2009
Assumptions for the AssessmentCavity Wall Insulation:Number of households with residents 123,580 (Census, 2001)
Installation costs of cavity wall per property £500 (Energy Saving Trust, 2009)
CO2 saving per year per property 0.8 tonnes (Energy Saving Trust, 2009)
Savings off-gas bill £160/year (Energy Saving Trust, 2009)
Population of Cardiff 305,353 (Census, 2001)
Biodegradable waste yield per person per week 2.2 kg
Biogas yield per tonne of wastes 110 m3
Biogas methane concentration 60%
Electrical conversion efficiency 35%
Anaerobic Digestion and CHP Systems for Treatment o f BMW:
Electrical parasitic load 20%
Heat conversion efficiency 50%
Heat parasitic load 50%
CAPEX (40 ktpa AD plant) £6.5M
OPEX 10% of CAPEX per annum
Assumptions for the Assessment
Energy use in an IVC per tonne of waste 75 kWh
Additional structural material (garden waste) 2x food wastes
IVC for the Treatment of BMW:
Others:Others:
CO2 emission factor from electricity generation 430 kg/MWh (DEFRA, 2007)
CO2 emission factor from combusting natural gas 190 kg/MWh (Carbon Trust, 2009)
Conversion factors for methane 21 x CO2 potential (DEFRA, 2007)
UK annual average gas consumption per household ~18 MWh
UK annual average electricity consumption per household ~4.8 MWhUK annual average electricity consumption per household ~4.8 MWh
CO2 emissions per capita in Cardiff (2005-2006) 7.2 tonnes (Defra, 2008 - report by AEA)
Landfill methane capture 70%
Landfill Tax £40/tonne
Results of the AssessmentIf Cardiff was to implement an AD plant for treatin g BMW
CO2 Emissions avoided by diverting the waste from landfill to an AD plant over 25 years
718,982 tonnes
Total CO2emission reduction: 815,486 tonnes ,
CO2 emissions displaced from renewable electricity and heat exported by the AD plant over 25 years
96,504 tonnes
Equivalent number of homes that could be heated using the output from the AD plant
319 homes
Equivalent number of homes that could be supplied with electricity from the AD plant
1341 homes
Reduction of CO2 emissions over 25 years when using AD Tech. as opposed to IVC
152,832 tonnes
tonnes , equivalent to 4531 people
CO2 emissions for 25 years ~
1.5 % of Cardiff’s
population
Benefit to the Local Authority
CAPEX and OPEX related costs per tonne of CO2 saved £28/tonne of CO2saved over 25 years
Cost per tonne of CO2 saved, including no payment of landfill tax, heat and electricity sales and 1 ROC
-£33/ tonne of CO2saved over 25 years
Cost per tonne of CO2 saved, including no payment of landfill tax, heat and electricity sales and 2 ROCs
-£61/ tonne of CO2saved over 25 years
Results of the AssessmentComparison of the AD scenario with the one of insta lling cavity wall insulation
~
Equivalent of installing cavity wall insulations in 40,774 households in Cardiff (33% of total number of houses) (over £20M CAPEX) with an equivalent
CAPEX of £25/tonne of CO2 saved. Cost per tonne of CO2 saved including household saving in gas bill -£175/tonnes of CO2 saved over 25 years
To the benefit of the resident…..
~
If the AD plant was instead an IVC plant, there would be a need to install further cavity wall insulation in 7642 households (over 7%) in addition to the
40,774 households.
Initial Assessment of Transport Energy and Costs Transport Energy and Costs Related to Centralised AD
Facilities
Collection and Transport Energy for BMW and Digesta tes Compared to Net Energy (Electricity) from AD BMW + CHP
• 7.5 tonne vehicle carrying 4 tonne waste (same for digestate)• Diesel consumption for collection (2 km/l) for 20 km; Diesel consumption for transport (15 km/l) to plant • 1 tonne of BMW generates 110 m3 of biogas (60% methane)• Electricity generation efficiency (35%) and 20% parasitic load• No export of heat (only 50% of the heat generated is consumed within the plant)
Assuming:
Transport Costs for BMW and Digestates Compared to Revenues from Electricity and Heat (incl. incentive) Generated fr om AD of BMW via CHP
• 7.5 tonne vehicle carrying 4 tonne waste (same for digestate)• Service charge for collection and transportation - £0.57/km for the 4 tonnes of waste/digestate• 1 tonne of BMW generates 110 m3 of biogas (60% methane)• Electricity generation efficiency (35%); 20% parasitic load; sale + 1 ROC = £0.08/kWh; sale + 2 ROC =
£0.12/kWh• Heat generation efficiency (50%) and 50% parasitic load; potential heat tariff = £0.04/kWh + 0.04/kWh for heat
sale only
Assuming:
Site and Planning Considerations/ Mitigations (1)
• Carefully located, where possible should be away from sensitive receptors
• Avoid locations close to natural and historic interest• Avoid locations close to natural and historic interest
• For the 17 plants visited location varied from rural to industrial areas
• Area requirements depend on many factors– AD plant able to treat 2 to 4 tonnes BMW/m2 per annum
– MBT plant able to treat 1 to 12 tonnes of OFMSW/m2 per annum
• AD plants should be sited near:– waste origin, market for the digestate and if possible market for CO2
– existing sites for sharing of infrastructure (e.g. landfill sites, WWTPs, electricity
Indicative only
– existing sites for sharing of infrastructure (e.g. landfill sites, WWTPs, electricity grid)
– close to grid connection and heat user (industrial or residential) if CHP is used
– good transport infrastructure (free from restrictions for HGVs)
• Controls to avoid pathogen transfer – fencing and vehicle wheel wash
Site and Planning Considerations/ Mitigations (2)
• Minimise traffic impact (e.g. a 30 ktpa waste capacity AD plant (taking wastes 265 days per year) corresponds to a daily traffic of approximately 11 vehicles of 10 tonnes each, in addition to digestate for which a maximum would double the traffic movements); schedule deliveries to avoid traffic rush periods, rail transport?
• Minimise air emissions, dusts and odours impact– Good house keeping
– Keep building doors closed
– Exhaust gases (from waste reception area, mechanical pre-treatment and post AD maturation areas or digestate storage) require treatment before being released to atmospherereleased to atmosphere
• Keep buildings under negative pressure and ventilation fitted with biofilters, chemical scrubbers, ozone treatment or even regenerative thermal oxidation systems
– Appropriate digestion – so that digestate will not emit bad odours
Site and Planning Considerations/ Mitigations (3)
• Minimise visual impact (digesters are normally the highest structures, typically 5 to 30 m high (some biogas upgrading systems are even higher)
– Locating the plant near existing buildings of similar scale
– Use to the best advantage the natural landscape
– Tanks including digester built partially underground - however more expensive and equipment should be easily accessible for cleaning and maintenance
– Planting around the site
– Consider even changing the shape to tanks including digester – however not always easy
– Laying electricity connections underground
– Use less intrusive colours for buildings and tanks
• Minimise noise– Appropriate location of certain operations
– Appropriate use of acoustic enclosures, attenuation features and physical barriers
• Minimise pollution of water resources– All tanks and digester(s) may need to be surrounded by containment bunding
Information for Planning Application (1)
• Submit a comprehensive application even if an EIA is not formally required
• Information and descriptions• Information and descriptions
1. Detailed site plan – showing the development site, applicant’s control area and neighbouring dwellings and other sensitive buildings
2. Plans, elevations and sections of the development
3. A full description of the processes to be employed e.g. waste reception, processing, digestion and energy generation
4. Description of the feedstocks, its origins, transport routes, delivery vehicles used etc.
5. Description of the solid and liquid digestate and end use or disposal
Information for Planning Application (2)
6. Energy output and utilisation
7. Environmental advantages of AD including carbon emissions offset
8. Economic/social advantages for the region – employment etc.
9. Potential emissions and related mitigation measures for – Odours and air pollution
– Noise and visual impact
– Ground and water courses pollution
10. Safety regime and strategy to avoid explosion
11. Requirements for off-site equipment e.g. electricity lines and substation, 11. Requirements for off-site equipment e.g. electricity lines and substation, gas pipelines, gas storage/refuelling station
ConclusionsAD Technology
• Technically established – 15 years experience and a lot longer for other substrates
• Versatile and unique• Versatile and unique
• Sustainable, helping achieve
– landfill diversion and recycling targets
– security of energy supply
– renewable energy targets and carbon emission reduction
• Centralised systems can provide environmental /cost effective solutions– even with the burden of some additional waste/digestate mileage
• Financially viable• Financially viable– AD technology has a reasonable CAPEX compared to other CO2 abatement technologies and in
addition treats wastes!
• Current and future policy, regulatory, market and fiscal developments will further support an effective implementation of the technology with improved digestate and biogas markets
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