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

History of SERC and AD

Anaerobic Treatment of Textile Wastewater

Improving the Digestibility and Dewaterability of Sewage Sludge

• 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

Biological Fuel Cell Development

UK Commitments and Targets

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

Examples of Digesters for BMW and OFMSW

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

http://www.walesadcentre.org.uk/

Thank you

Dr. Sandra EstevesDr. Sandra EstevesUniversity of Glamorgan

sesteves@glam.ac.ukTel. 01443 654130