developing on-site anaerobic digestion for smaller ...development of anaerobic digestion (ad) in the...

Reference Article1st published in June 2017doi: 10.1049/etr.2016.0128

ISSN 2056-4007www.ietdl.org

Developing On-site Anaerobic Digestionfor Smaller Businesses in the Foodand Drink Sector

Mr Richard Gueterbock Director, Clearfleau Ltd, Lily Hill Court, Lily Hill Rd, Bracknell, UKMs Bunmi Sangosanya Process Manager, Clearfleau Ltd, Lily Hill Court, Lily Hill Rd, Bracknell, UK

AbstractDevelopment of Anaerobic Digestion (AD) in the UK has lagged behind other European member states. Focus onlarger footprint plants has restricted the smaller scale (sub 250 kW electrical output) on-site AD sector,where energy can be generated from bio-residues at or close to the location where they are produced.Britain’s food and beverage sector, as part of the transition to a more circular economy, must make betteruse of its raw materials by extracting value from unwanted residues (or co-products). Development of thebio-economy and on-site generation of decentralised energy should be part of the UK’s industrial strategyprior to Brexit.There is considerable potential for bio-energy generation in the food and drink sector, including on smaller

sites that proliferate across the food industry. More deployment of bio-energy needs less indifference frompolicy makers and more imagination from regulators. Also, the British bio-engineering sector needs to makethe case for more proactive policy framework. The authors, based on their experience with on-site bio-digestionin the food and beverage sector, including plants for several multinational companies, explore how this ap-proach could be deployed more widely, as part of the bio-economy, in the food and drink sector in Britainand across Europe.

Definitions
The Bio-economy encompasses the production of renewable biological resources and their conversion into
food, bio-based products and bio-energy using innovative technologies. It offers new opportunities and sol-utions to a number of social, environmental and economic challenges, including climate change mitigation,energy and food security and enhanced resource efficiency.On-site AD: smaller scale deployment of the process used to generate bio-energy in a biological degradation

process whereby micro-organisms that thrive without oxygen convert bio-degradable (volatile) process residuesinto renewable energy. Clearfleau’s industrial AD plants convert liquid effluents and production residues intovaluable bio-energy.Digestion Plant Scale – small, medium and large scale AD plants: A classification for AD was developed by the

Renewable Energy Association (REA) and other partners for dealings with policy makers:

† small: on-site AD plants generating under 100 Nm3 of biogas or 200 kW thermal output,† medium: plants generating >200 kW thermal but <2 MW thermal output,† large: plants generating over 2 MW thermal (increasingly using gas to grid technology).

Eng. Technol. Ref., pp. 1–16doi: 10.1049/etr.2016.0128

1& The Institution of Engineering and Technology 2017

IET Engineering & Technology Reference R. Gueterbock and B. Sangosanya

Nomenclature

Aerobic

2& The Institution of Engine

a natural organism that thrives or aprocess that can occur in air or freeoxygen

Anaerobic
an organism that thrives or aprocess that occurs in the absenceof air or free oxygen
Biogas
gas produced from the biologicaldegradation of bio-residues in theabsence or air or free oxygencomprising of mainly methane andcarbon dioxide
BiologicalOxygen Demand

measurement of dissolved oxygenused by aerobic microorganisms inthe degradation of organic material

Biomethane
enriched biogas achieved bypurification/removal of carbondioxide
Bio-residues
biodegradable materials producedas part of a manufacturing process(also co-products)
Bio-energy
renewable (non-fossil fuel) energyderived from organic biomass,including bio-residues
Bio-solids
residual solid material(containing nutrients) produced asresult of a bio-degradation process
Chemical OxygenDemand

measurement of degradableorganic compounds in effluent andresults of COD test can be used toindicate the presenceof decomposing pollutantsthat absorb oxygen from water

Digestate Liquor
residual liquid after AD containingnon-biodegradable materials
Merchant AD
commercial, centralised AD plantsthat are designed to handle a rangeof biodegradable materials fromhousehold or high street collection,operated for municipal authorities
Symbiotic
linked processes where one processcannot proceed for very longwithout the other process
IntroductionThe British market for Anaerobic Digestion (AD) can bedivided into three sectors (municipal, on-farm and in-dustrial). Clearfleau is a leading technology providerspecialising in on-site industrial plants, treating bio-degradable residues. On-site AD also has a role onfarms (for manure, slurry and other residues) and inrural communities (converting food waste to energyfor local use).

Amongst a range of smaller scale renewable energytechnologies, on-site digestion has a value for indus-trial sites because demand for heat or power can bemet at the point where bio-degradable residues are

ering and Technology 2017

produced. On-site bio-energy cuts fossil fuel use,while reducing emissions that would be releasedfrom biodegradable residues and cutting disposalcosts.

There needs to be a greater synergy between Britain’sindustrial and energy policies within the Departmentof Business, Energy and Industry Strategy (BEIS),if we are to do more to encourage the transitionto a more circular bio-economy. The previousGovernment’s Policy Green Paper ‘Building ourIndustrial Strategy’ [1] highlights the value of sustain-ability and clean technologies but does not indicatehow the bio-engineering and renewables sectors willbe supported after Brexit.

Existing on-site bio-energy plants are illustratingthe benefits of decentralised generation. For instance,at one of the UK’s largest cheese creameries (seeFig. 1 – plant built for the farmer owned dairycompany, First Milk), an on-site AD plant is convertingcheese residues into biogas, while dischargingcleansed water to the nearby river Ellen. It suppliesupgraded biomethane to the creamery and otherusers on the gas grid and is an example of innovativebio-engineering.

Clearfleau’s approach to on-site digestion is based ontailoring each facility to the specific requirements ofthe site where the plant is located. Also, by developinga more modular approach to plant design we aimto facilitate export opportunities and help makeplants affordable on smaller SME (small or mediumenterprise) industrial sites, with a comparable returnon investment (ROI) to larger projects. From 2017,Clearfleau will be installing on-site bio-energy facilitieson smaller industrial sites and we hope to boost de-ployment in the SME sector in future.

On-site AD technologyAD is a bio-chemical process, where bacteriabreakdown organic material in the absence ofoxygen to produce biogas which is predominantlymethane (CH4) and carbon dioxide (CO2). Thetechnology has existed for many years. However,applications that treat residues other than thoseoriginating from municipal sources are a more recentdevelopment. The digestion process relies pre-dominantly on two types of organism in a symbioticrelationship – acid forming and methane forming bac-teria [2]. The process occurs in the stages shown inFig. 2 [3].


Fig. 1 Arial photo of Lake District Biogas on-site AD plant

Fig. 2 Metabolic pathways and microbial groups

IET Engineering & Technology Reference Developing on-site anaerobic digestion for smaller businesses inthe food and drink sector

The main phases of the anaerobic process are outlinedbelow:

† Hydrolysis: Complex compounds are convertedinto simpler substances by fermentative bacteriaand some fungi. These compounds are carbohydrates,fats and proteins which are converted intosimple sugars, fatty acids and amino acids, respectively.† This stage is followed by Acidogenesis, where fer-mentative bacteria again convert the simpler


substances produced in the hydrolysis phase toorganic acids and alcohols.† The next stage, Acetogenesis sometimes cannot bedistinguished from Acidogenesis. Here organic acidsand alcohols are converted to acetates prior tomethane production.† The final stage, Methanogenesis is carried out byMethanogenic Bacteria that form the methane, plusCO2 and Hydrogen gas (H2), from acetates createdin the previous stage.

In the industrial sector, the substrate (or feedstock)fed to the AD plant is measured in terms of itsorganic strength – commonly called Chemical OxygenDemand (COD). Although digestion is a highly effectiveway of treating biodegradable residues on industrialsites, most AD plants built in the past decade are pro-cessing municipal bio-waste feedstocks or purposegrown crops. However, there is increasing interest indeployment of on-site AD in the agri-food sector.

Technology innovationClearfleau’s liquid digestion plants utilise theContinuously Stirred Reactor system, adapted tooptimise COD removal and hence gas output. Themain innovation is breaking the link between theliquid retention time to minimise the size of the digest-er tank) and extended bio-solids retention period(to about 50 days to optimise COD removal and gasoutput) (see Fig. 3).

In optimising the effectiveness of the bio-degradationprocess two key operating parameters are:

† Temperature: Microorganisms can be mesophilic –meaning they grow best in a range between 20 and


Fig. 3 Basic process schematic


40°C (although operating experience shows theoptimum to be from 35 to 38°C). They can also bethermophilic (operating range 50 and 60°C, with anoptimum of 55°C). Operating under mesophilic condi-tions generally means less energy is required to main-tain temperature, which can be beneficial for runningcosts.† Alkalinity or pH: The pH of the digester is importantas microorganisms in the digester, in particular meth-anogenic bacteria, can be sensitive to pH outside arange of between 6.8 and 7.2. With pH valuesoutside this range, a reactor will still degrade the sub-strate, however, the level of COD removal and biogasproduction will be severely compromised.

To optimise performance and hence payback,process management is crucial. Unlike, municipalsludge digestion systems or dry fermentation pro-cesses, where the incoming waste compositionis fixed and each tonne of material is equated to a spe-cific gas and sludge output, Clearfleau’s mass balanceis correlated to the organic strength of the feed (COD)and level of degradability.

COD values can vary greatly, suitable biodegradablefood or drink residues can include wash waters andeffluents, plus co-products from production processes,plus product discards and other processing residues.Even as sites become more efficient and ableto recycle water for other site operations, there isoften a liquid residue with a related disposal cost.Harnessing the available energy from such materialscuts costs and supplies energy to substitute fossilfuels (see Fig. 4).

Clearfleau’s process is better suited than other systemsfor handling both fatty and non-fatty food residues,dairy and bio-fuel sectors, due to the ability to break


the link between solids and liquid retention time,reducing cost and tank capacity, while facilitatingmore cost effective operation. Also, by achievingover 95% degradability, these plants maximise asso-ciated biogas output.

The proprietary method of solids retention maintainsan elevated biomass content within the reactor, todeliver efficient COD reduction and quality effluentfor discharge. The system produces gas with optimalmethane content, due to effective mixing of liquorsin the anaerobic reactor and sustained exposure ofactive biomass to incoming COD load. Post digestion,aerobic treatment will remove any residual COD andnutrients before discharge to river or re-use as greywater.

Industrial on-site digestionThe AD market is subdivided into three sectors: mer-chant sites (predominantly handling municipal bio-wastes) farm plants (digesting manures or crop residues– plus less appropriate purpose grown crops) and plantson industrial sites (treating bio-effluents and residues).On-site digestion can process biodegradable residuesgenerated by the site where a plant is located.

On-site industrial digestion systems have only threeoutputs: biogas, clean water and bio-solids. The bio-solids produced from the digestion process are richin nutrients, in particular nitrogen and phosphorous.The bio-solids often undergo a dewatering processto remove the liquid fraction and create a spreadablematerial that can be spread to land as a fertiliser or soilimprover.

Regardless of the source of feedstock, biogas producedcan be combusted in a boiler to supply hot water orsteam, or a Combined Heat and Power (CHP) plant


Fig. 4 Outputs from on-site digestion


to generate electricity and heat. Gas can also beupgraded to produce biomethane (and fed into thenatural gas grid or pressurised to produce compressedbiomethane for use as fuel). Options for biogasuse mean that digestion offers a flexible alternative torenewable technologies that just supply electricity.

The food and beverage industry is devoting greaterattention on its environmental impact. For instance,the Scotch Whisky Association (SWA) sustainabilitystrategy is setting tougher targets but also encour-aging members to access sources of renewableenergy. A range of feedstocks from whisky distillationand brewing processes are suited to digestion includ-ing Pot Ale (residue from initial distillation) and SpentLees/Wash (also from distillation), plus residual washwaters.

On-site AD of such energy rich residues offers severalbenefits:

† Energy – on-site bio-energy cuts fossil fuel use,helping meet energy reduction targets,† Emissions – replacing fossil fuel with bio-energy, willreduce food sector emissions,


† Water use – after digestion, cleansed water fit forriver discharge can be re-used on site,† Land fertility – residual bio-solids provide nutrientsfor crops (e.g. grain for distilleries),† Efficiency – extracting value from residues offers amore circular (zero-waste) approach.

Most industrial sites are coming under pressure tocurtail their wider environmental impact and on-sitedigestion offers a cost effective treatment optionwith an attractive return on investment. Also anumber of national agencies (for instance, theScottish Environment Protection Agency – SEPA) arepromoting a more circular approach to resourceuse – while encouraging lower carbon emissions,better use of materials and a reduction in fossil fueluse. This approach could eventually be extended tothe imposition of penalties on sites that are more prof-ligate or do not take measures to cut energy use ordeploy renewables.

Despite the benefits for industrial sites, AD develop-ment across the UK has been slanted towards largermunicipal plants, often using imported technology.While this is an effective use of AD technology,



there have been issues with process efficiency andresidual digestate disposal, plus impacts on nearbycommunities (transport, noise or odour). This ispartly due to the involvement of major utility com-panies that tend to favour larger scale projects. Afterrapid expansion but with uncertain investmentreturns from a number of plants, this sector appearsto have stalled.

Also, there are concerns about use of purpose growncrops for farm AD plants and Government will belimited support for this sector from 2017, in partdue to concerns about the land use impact andcarbon efficiency. Despite potential for greater useof AD to treat manures or crop residues, it is a devel-opment of the on-site industrial AD sector (fed withmaterials at or close to the place where they arecreated) that has the most potential for furthergrowth and is the focus of this paper.

Harnessing the potential for on-sitebio-energyWith the food industry becoming increasinglyconcerned about its impact on the environment,there is an opportunity to replace the energy intensiveaerobic disposal of energy rich process residueswith on-site anaerobic plants. Growing interest inthe benefits of the circular economy, will transformbusiness models created when the level of resourceuse was of less concern.

Improved resource use should be part of Britain’s busi-ness strategy prior to Brexit – in part to ensure the UKcan meet sustainability requirements in other markets.The 2017 Green Paper ‘Building our IndustrialStrategy’ [1] places the switch to the low carboneconomy within the ten pillars of this new strategybut is less explicit than it could be on future supportfor industrial transition. Moreover, the Brexit WhitePaper [4] published in February 2017 underlines theGovernment’s aspiration for a cleaner environment,with the UK a ‘leading actor’ on climate change,without being specific on how it will support deliveryfor industry and specifically in the agri-food sector.

Decentralised energy supplyInvestment in decentralised (on-site) bio-energy willenable the British food and beverage industry toreduce its environmental footprint and overcome aperceived ambivalence about resource use and levelsof waste in the food chain. Such investment can bejustified as follows:


(i) A processing residue is no longer a waste but aresource used to generate energy on site, while mini-mising off-site disposal of unwanted bio-materials andliquid effluents.(ii) Disposal costs associated with such residues are

converted into a source of revenue. These costs notonly include energy used for aerobic treatment butalso transport off site for approved treatment or dis-posal – not only costly but a significant use of fossilfuel.(iii) Alternative solutions (often aerobic treatment)use more energy to achieve the same goal withoutgenerating renewable energy that can be harnessedby the industrial user.(iv) Importantly (and something we have experiencedrecently) on-site AD can help improve the position ofsites facing competition pressure or the impactof rising fuel and disposal costs. AD enables a site toprovide more sustainable treatment as well as secureenergy supplies that can offer a variable proportion(10–30%) of site energy needs.

With a number of multinational businesses likeUnilever, Nestle and Arla already investing in on-siteAD in the UK, there is scope to build the marketfor industrial solutions, also for the smaller SMEbusinesses that proliferate across the European foodand drink industry.

In addition to the potential to export modular plants toother markets, we are developing plants on smallersites – e.g. the plant being installed on a craft distilleryin southern Scotland (see Fig. 5).

Expected increases in costs of energy and the handlingof process residues will support the business case foron-site bio-energy. However, to encourage investmentin renewables (AD plants can take over a year to fund,design, install and commission) businesses need to beable to predict their return on investment. While thereare still incentives available, ultimately future on-sitebio-energy plants must be viable without currentrenewable generation support.

In the shorter term, to deliver more widespreaddeployment of such bio-energy systems on industrialsites, we need for a more creative approach fromGovernment, including support for industrial lowcarbon demonstration sites. While it is helpful thatthe recently published Brexit White Paper andthe Industrial Strategy Green Paper make passingreferences to carbon reduction and clean technolo-gies, greater clarity on what is expected from the


Fig. 5 3D image of Craft Distillery with planned AD plant in the background


business community would be helpful. All too often,actions of Ministers and key Government departmentsdo not necessarily match up to the fine words in policydocuments.

To prepare for a future without renewable incentives,the industry needs a period of policy stability to enablebio-energy to fulfil its potential in delivering decentra-lised bio-energy and to boost carbon savings. Also, thepriorities of policy makers must switch from further in-vestment in larger centralised plants towards multiplesmaller on-site units that treat biodegradable feed-stocks where they are produced.

Developing a more circular economyThere is considerable potential for on-site re-use ofprocessing residues, as part of the transition to amore circular resource use and enhanced industrialsustainability. To stimulate industrial investmentin smaller scale renewables, policy makers mustrecognise that on-site digestion of process residuessaves costs and helps meet carbon reduction targets.Bio-energy generation can help protect sites fromfuture energy cost increases and enhance overallsustainability.

Despite the failure of past Governments to recognisethe value of smaller scale bio-energy, an increasing pro-portion of our energy could come from decentralisedinstallations at the point where energy is used. In amore circular economy, as part of a more integrated in-dustrial and renewables policy, investing in smallerscale, on-site renewables should help boost industrial


competitiveness. Interrelated drivers for increased in-dustrial investment in bio-energy, include

† Increased Focus on Resource Use – There is growingpressure to embrace a more circular approach to pro-duction but much of this is superficial commentary bypoliticians, academics and consultants. On-site gener-ation allows businesses to address concerns overresource use and levels of water loss and energydemand in the food chain.† Energy Costs and Carbon Emissions – The foodindustry is aware of the need to address futureenergy cost rises, as well as greater price instability.Some degree of on-site generation is a partial solution.Also, energy from biodegradable residues supportsde-carbonisation of the food chain, reducing thecarbon footprint of individual sites.† Handling Biodegradable Residues – Disposalcosts for process residues continue to rise, driven byregulatory factors and practices that deny accessto the available energy. Rather than disposal ofbio-residues to sewer or landfill, businesses needeffective, low-risk solutions that do not require exces-sive space or undermine production processes.† On-site Renewable Energy – Pressure to developlower cost renewable energy will increase with stake-holder (retail and regulator) pressure for low carbonmanufacture. On-site AD and biomass solutions willallow sites to generate base load power (or heat),while exporting electricity when on-site demand islower (or times of peak demand).

Greater awareness is encouraging British manu-facturers to evaluate bio-energy or develop better



resource use practises, looking for robust solutionsthat do not impact on manufacturing processes.However, for bio-energy to fully contribute to thetransition to a more circular economy, SME businessesalso require reassurance from policy makers that it willbe cost effective to access the energy value of theirresidues.

Targeting the food and drink sectorAfter the 2015 Paris COP21 Climate ChangeConvention, a group of leading food and beveragesector multi-nationals made commitments to changetheir practices. CEO’s of global companies likeUnilever and Nestle signed a statement of intent:‘We want the facilities where we make our productsto be powered by renewable energy, with nothinggoing to waste, as corporate leaders, we have beenworking hard toward these ends, but we can andmust do more.’

With global food companies setting ambitious targetsfor reducing their GHG emissions and developing thecircular economy, what should British firms, large andsmall, be doing to match this? Those UK companiesthat have installed on-site bio-energy plants are ben-efiting from incentive revenue and cost savings whileboosting their CSR profile.

Industrial deployment of bio-energyProgressive improvement in AD technology(e.g. process control, biogas yields, COD removalefficiency, ability to recycle grey water and plant foot-print) has enhanced payback. In the past decadeabout 30 AD plants have been built on UK factorysites – cutting emissions and producing a decentreturn on investment.

AD is now more attractive for off-balance sheetfinance providers, with an increasing appetite amongthe investor community for on-site plants that canprovide a better return than is available from merchantplants. In any case, the ROI for industrial investmentin renewables needs to be higher than the circa15% targeted by municipal projects.

Clearfleau has taken a lead in developing the on-siteliquid AD sector but other technology suppliers(of higher and ultra-low solids systems) are active inthe UK market. Some higher solids systems can befound in the food sector (mainly on vegetable pro-cessing sites) but they require more space (for multipledigestion tanks). More effective residue managementsolutions will help companies to recognise the calorific


value of their bio-residues and the carbon impact ofother disposal systems. Enabling smaller sites to usesuch residues rather than exporting potential energyvalue should be part of progress to a more circulareconomy.

Despite reduced incentive support for renewables,businesses will consider on-site alternatives to fossilfuel derived energy, not just biomass systems and bio-digestion but also fuel cells and hydrogen energy, ifthere is an adequate return. Benefits also includeimproved bio-security and less handling on site, asresidues are fed to the AD plant as they arise and donot have to be stored or transported. Fossil fuel substi-tution (with biomethane, biodiesel and hydrogen)brings a commercial advantage, by adding value todiscarded materials and reducing production costs.

The beneficial impact of on-site bio-energy is clearbut how do we make it easier for SME firms toinvest, given the challenges that arise with smallersites? Choices must be made regarding the bestmatch for a site based on space available, energyneeds, grid access and fluctuations in energydemand. There are specific issues to be addressedon smaller sites.

Fitting plants on a confined footprint: When fittingplants on clients’ sites, the footprint available is oftenless than ideal. On some sites containerised units forancillary equipment can be part of the solution. Theconsiderations that should be taken into account inthe preliminary design and evaluation phases include:

† Space saving and whether equipment can be housedin existing buildings. For instance, for the craft distilleryproject, to create space for the digester, all the relatedequipment is housed in a 2-storey building, thereforemaximising use of the limited area available.† Is there potential for shared technical services?Consideration is given to a shared laboratory andother facilities, although the boiler or CHP unit mustbiogas dedicated.† Integration with production is a key consideration –manufacturing processes cannot be compromised bythe AD plant. Production needs to always takeprecedence.

It may also be possible for smaller sites to combineand share the energy produced as well as to developcentralised plants for locations where there are anumber of smaller businesses.


Fig. 6 Micro Trials Plant for the EU funded Ambigas Project


Matching biogas output to thermal demand: Onindustrial AD plants with thermal output below1 MW, a common concern is finding the best way tomatch output with clients’ energy demand. Whenmore energy is generated than can be used inproduction, can it be exported as power? On somesites there may be a need to find other uses for thesurplus biogas – there are three main options forutilisation of biogas on-site:

† Combustion in a boiler (biogas dedicated to qualifyfor incentives) to produce hot water or steam. On siteswhere there are no incentives biogas and natural gascan be co-fired.† Combustion in a CHP engine to produce power forthe site. Power can be exported if not required butgrid access can be an issue on some sites.† Upgrade to biomethane for injection into the localgrid or compression for use as vehicle fuel. Gas gridinjection is not really viable for sub 1 MW (thermal)plants due to upgrade costs but vehicle fuel con-version could be an attractive option for producttransport.

The two Case Studies 1 and 2 (see Figs. 9 and 10)illustrate how decisions have been made at differentsites.

The effective use of energy is often key to the viabilityof individual projects but this is affected by incentiverates and the changes in incentive rules. However, abiogas boiler will tend to be the simplest solution onsmaller sites. As well as optimising the use of (andrevenue from) energy produced, there is a need tocurtail capital costs for smaller plants. For SME sites(plus potential export projects) we are developingsolutions based on modular units, to reduce con-struction costs and improve ease of deploymenton the site.

There are a range of technical options that if com-bined can provide cost-effective solutions for smallerSME sites. We have developed a micro test plant foruse in EU funded research into low temperature AD(the Ambigas project), as well as an earlier contain-erised unit for on-site trials. This modular approachshould allow on-site AD to be deployed on a widerrange of industrial sectors:

† Modular design for the ancillary equipmentmounted on skids or containers.† Lower temperature operation of the digester to runit at ambient temperature.


† Inclusion of grey water recycling, enabling sites toimprove use of water resources.† Pre-treatment of higher solids feedstock to extractfurther value from site residues Fig. 6.

Making the business caseIn addition to addressing technical and engineeringissues for smaller more compact sites, there is also aneed to make the business case for on-site bio-energygeneration and demonstrate an attractive return oninvestment. Despite the successful experience withexisting plants, concerns remain about impact on thecore business, access to funding (either internalcapital sanction or from third party funders) and the un-expectedly rapid degression of incentive rates. Hence,bio-energy technology providers must develop solutionsthat fit with individual requirements of the site but alsooffer an attractive investment proposition.

The plant built for Nestle on their Fawdon site (treatingconfectionery residues) included containerisation ofthe main process elements to allow off-site assemblyand reduced construction time on site. This approachcould also be applied for export projects (see Fig. 7).Other design configurations can also be used on con-fined sites such as the craft distillery and the rural dis-tillery site in Speyside (see Fig. 8).

While companies like Unilever or Nestle will considerinvesting in sustainable manufacturing, as part oflonger term strategy, the reality for smaller businessesis that internal funds are allocated to core productionactivity. Thus, external funders are needed to supporton-site renewables.


Fig. 7 On-site AD Plant on Nestle’s Fawdon Confectionery Site

Fig. 8 3D image of Smaller AD plant serving a Distillery to beoperational in early 2018


If on-site AD is to be deployed more widely on SMEsites, some key issues must be addressed:

† Access to Funding: Smaller companies are less ableto devote scarce resources to sustainability and requireexternal funding, from specialist funders that under-stand AD and recognise the better returns that canbe available from on-site projects.† On-site Solutions: Traditional practices (like aerobictreatment) or access to off-site solutions, combinedwith limited financial resources, tend to make SMEmanagers to be less open to novel technology andwe need to raise the profile of on-site options.† Carbon Savings: To date pressure from stakeholdersand regulators has had limited impact. But, as landfillcosts rise (and Scotland and Wales banning disposal


of biodegradable residues to landfill) less carbon inten-sive solutions will come to the fore.† Internal Resources: Many SME sites have limitedstaff time available for activities that are not directlyrelated to core production activity. Hence reliancecan be placed on external consultants who mayprefer to stick to established technologies, that donot offer access to on-site energy for the factory orthe extent of carbon and cost savings.† Incentives Rates: Despite pressure to reduceemissions SMEs and family companies are beingdeterred by declining incentives. Also, there is per-ceived lack of Government interest in addressingclimate change, the circular economy or supportingbio-energy (support for nuclear plants is beingcontrasted with falling renewables incentives).† Political Support: It is in the wider interests of theBritish economy (post Brexit) that Government helpssuccessful British bio-energy companies to competein the EU and globally. This should include supportinghe market for industrial on-site renewables.

There is greater recognition of the need for industryto invest in the circular economy and decentralisedenergy generation. However, there must also be aclear benefit from investment in on-site renewables,in terms of cost saving and manufacturing efficiency.However, to help keep the UK economy competitivepost Brexit, access to bio-energy solutions must beextended beyond the larger food sector businesses.

Delivering bio-energy in the SME sectorInterest in more sustainable manufacturing models isbeing led by food multinationals, as indicated by



their support for investment in on-site bio-energy afterthe Paris Climate change summit. However, extendingthis approach more widely in the British food sectorwill require a more supportive policy and regulatoryframework focused on changing existing practises.

Decentralised micro-generation from productionresidues and by-products can reinforce efforts toreduce reliance on fossil fuels and cut industrialcarbon emissions. Policy makers still need to be per-suaded of the value of the bio-economy and smallerscale on-site generation of renewable energy. In thepast decades, incentive support has been focused onlarger centralised merchant and crop based plants,not all of which are delivering cost effective, lowcarbon energy.

Developing the bio-economyDecentralised bio-energy can support the transitionto a more circular bio-economy, helping more UKindustrial sites to limit their environmental impactwith low carbon solutions. Adapting bio-energypolicy to help promote smaller on-site plants thatgenerate value from bio-residues will boost emissionsreduction. The installation of multiple bio-energyplants should be encouraged alongside the develop-ment of novel technologies and the supply of rawmaterials for more resource efficient bio-refinerytechnologies.

The bio-economy (which includes forestry and theagri-food sector) already contributes £36 billion ingross value added (GVA) to the UK economy, ofwhich over 80% is from food and farming. In 2012,industrial biotechnology and bio-energy contributed3% to the sectors’ GVA, accounting for at least 1%(6,000 jobs) of sector employment [5]. With growththat has taken place since 2012, this should be sig-nificantly higher (perhaps 10% of employment inthe renewables sector currently which exceeds100,000). Policy makers should value the number ofengineering and related jobs being created in thebio-energy supply chain.

However, development of Britain’s bio-economyrequires industry confidence in available technologiesplus a stable, supportive regulatory framework.Future growth in bio-engineering and the bio-energysector also depends on the policy framework andGovernment investment in research. With supportfor companies investing in collaborative or on-siteprojects, the bio-economy could a key growth sectorfor the post Brexit economy. While the UK may


be leading research in this field it is commercialexploitation that drives economic growth. Hencemore attention needs to be paid to motivation of busi-nesses to invest in this sector.

Enhancing resource efficiencyAssessment of site potential for investment inbio-energy should be a first step in the evaluation ofhow to boost resource efficiency. Companies shouldstart by looking at issues such as site energy require-ments or feedstock suitability. This includes specificsite criteria (such as seasonality, discharge require-ments or energy demand) and access to the spaceto build on-site AD plants, alongside the evaluationof biogas potential and degradability of availableresidual materials and their suitability for a particulardigestion system (higher or lower solids).

Investing in better resource use and bio-energy shouldprovide a competitive advantage while supportingcommercial goals, such as cost reduction, sustainabil-ity and plans for expansion or brand development.Other factors influencing decision making includeaccess to in-house skills to support and championa project, plus access to funding or credibility for anexternal investor. Also, whether a site is facing regu-latory pressures (e.g. due to a failing aerobic plant)and the planning landscape, particularly for urbansites.

Commercial interest in resource use and accessto bio-energy will increase but more political engage-ment is required if bio-engineering is to play a moreprominent role in development of the economy.Also, if technology providers are to capitalise onopportunities for wider deployment of on-site renew-ables, we must overcome reservations about investingin non-core activities like energy generation andcarbon reduction.

Commercial and political driversIn addition, as suppliers, we need to continue todevelop the technology to provide solutions that willminimise capex cost while limiting operating costs tohelp keep rates of return close to 20%. We alsoseek to keep core technology as simple as possiblewith limited operator input but also to minimise therisk of interruption to manufacturing processes.For smaller businesses with restricted funds, improvedaccess is required to external funding for more innova-tive on-site energy solutions, on a build and operatebasis but this also requires a stable incentive regime.



As energy prices start to rise again, we can demon-strate how reduced energy costs and other operatingexpenditure (OPEX) savings can boost on-siteefficiency and cost recovery. However, there is stilla need for more demonstration sites, other than onfactories run by the large multinational companiesand Clearfleau hopes to have several such referencesites in operation in the next 12 months.

Wider adoption of bio-energy generation on food andbeverage manufacturing sites (the sector is one of thelargest consumers of energy in the UK) requires amore strategic support to help smaller businessesfollow the lead from the multinationals. It is perhapsnot surprising that most of our current projects arein Scotland, where the devolved administration isenthusiastic about renewables. Government shoulddo more to engage with industry and facilitate moresustainable industrial development.

Regulators could do more to support smaller com-panies that are keen to invest in renewables.Perhaps assisting companies to access the most appro-priate technologies and showcasing novel solutionsthat are contributing to the bio-economy. Also, foodsector trade bodies should work with Governmentand the industry to promote the benefits of a more cir-cular economy and low carbon solutions, including:

† Challenging industry to find ways of cuttingemissions and fossil fuel demand.† Promoting the economic and wider benefits ofon-site decentralised generation.† Developing a more coordinated approach acrossthe food and beverage supply chain.† Encouraging more collaboration betweenbusinesses, particularly on adjacent sites.† Developing drivers and incentives based on carbon(GHG) emissions reduction.

Hopefully, in time, commercial interest in betterresource use within the circular economy will seegreater use of bio-feedstocks not only for energygeneration but also alternative industrial raw materialsin the emerging bio-economy. Improving resourceuse across industry could also include the ‘mining’ oflandfill to extract discarded materials and addingvalue to a wider range of residues.

However, the future of the bio-energy sector(and wider bio-engineering solutions) requires a funda-mental change of approach within Government, inrelation to energy and resource use priorities. BIES


should follow Scotland’s example and look at settingtargets for decentralised energy generation, whileadjusting the imbalance between levels of taxpayersupport for the nuclear sector and for renewables. Aswitch of 5% of funding from nuclear will stimulatesgrowth, support engineering jobs and boost technol-ogy innovation.

Moreover, future taxpayer support should focus onBritish technology as Britain risks handing a majorshare of its renewables market to EU suppliers. Weneed to see more overt support for developingthe Circular Economy by deploying British technology.On-site bio-energy will not just help the UK curbagri-food sector emissions and meet renewableenergy targets, as it is also able to provide baseloadpower and peak lopping capabilities, unlike solar orwind energy.

Conclusion – technical and policy driversThe UK has the technical solutions, engineering skillsand pioneering instincts to challenge the traditionalapproaches to resource use and commercial energysupplies but we need to find technical and fundingsolutions to help smaller businesses embrace lowercarbon manufacturing and on-site bio-energy.

In the run up to Brexit, the UK’s food and beverageindustry needs to be more competitive in Europeand develop new markets elsewhere. Also, withglobal food sector leaders pushing for more invest-ment in on-site renewables, the British supply chainneeds to match action by EU companies on emissions,resource efficiency and decentralised energy supply.However, to be technically viable on smaller sites inthe food and drink sector in Britain and acrossEurope, the on-site digestion sector needs to be:

† Innovative – reducing costs and increasingoperational efficiency, such as by limiting the liquidretention time and extending bio-solids retention tooptimise COD removal and biogas output.† Flexible – recognising that energy requirementsvary on each site and being able to meet this witha combination of options for use of biogas, whilematching peaks and troughs of site demand.† Reliable – acknowledging that the site’s productioncapacity cannot be compromised by a plant that is notavailable all the time or not able to handle expectedvariation in flows and loads.† Commercial – delivering a credible return on invest-ment that in line with industry expectations, and well



in excess of the 8–10 years payback that is the normfor other renewable technologies.

The on-site bio-energy sector can also generatebase load energy on factory sites where it is requiredbut wider adoption needs a more sustained com-mitment from policy makers. If Minsters are keen topromote a cleaner, more circular economy, includinglow carbon manufacturing, can they do more toback the deployment of decentralised energy gen-eration from process residues on industrial sites?

Government should collaborate with industrystakeholders on the delivery of a low carbon industrialstrategy. The actions of large multinationals may bedetermined by different drivers to those of smallerfirms but all businesses should be contributing to theimproved management of our natural resources.

Modest support for smaller on-site bio-energy plantsover the next five years will increase decentralisedenergy production. More efficient management ofresidues and carbon emissions will provide a boostto the circular economy. British technology and engin-eering skills can embed the circular economy in ourmanufacturing strategy and we should be challengingcompanies to embrace this.

The UK has the engineering skills to deliver technicalsolutions. But, if British industry is to match thelead being taken by global business leaders, it willrequire technology providers, trade associations

Fig. 9 Case Study 1. Glendullan Bio-energy Plant


and bodies concerned with our industrial com-petitiveness to challenge politicians to help with thetransition.

REFERENCES

[1] Building Our Industrial Strategy – Government Green PaperJanuary 2017, www.gov.uk/government/uploads/system/uploads/attachment_data/file/586626/building-our-industrial-strategy-green-paper.pdf, accessed May 2017

[2] Cheremisinoff, N.P.: ‘Biotechnology for waste and wastewatertreatment – 3.5.9 anaerobic digestion (treatment)’ (WilliamAndrew Publishing/Noyes, 1996), p. 136. Available at: http://app.knovel.com/hotlink/pdf/id:kt003VLSU1/biotechnology-waste-wastewater/anaerobic-digestion-treatment

[3] Adapted from Carlos Augusto de Lemos Chernicharo:‘Biological wastewater treatment series’ (AnaerobicReactors, IWA Publishing, 2007, 1st edn.), vol. 4, p. 6

[4] The United Kingdom’s exit from and new partnership withthe European Union – Government White Paper February2017, www.gov.uk/government/uploads/system/uploads/attachment_data/file/589191/The_United_Kingdoms_exit_from_and_partnership_with_the_EU_Web.pdf, accessed May2017

[5] Glyn Chambers, Alexandra Dreisin and Mark Pragnell: ‘TheBritish Bio-economy - an assessment of the impact of thebioeconomy on the United Kingdom economy’ CapitalEconomics Ltd, 11 June 2015, http://www.bbsrc.ac.uk/documents/capital-economics-british-bioeconomy-report-11-june-2015, accessed June 2017

Case Study 1. Glendullan Bio-energy PlantThe AD plant (commissioned in 2014) converts 1000m3 of distillery co-products per day into 1 MW of heat,feeding biogas to a dedicated biogas boiler that sup-plies renewable energy to the distillery, reducing its


http://www.gov.uk/government/uploads/system/uploads/attachment_data/file/586626/building-our-industrial-strategy-green-paper.pdf






http://app.knovel.com/hotlink/pdf/id:kt003VLSU1/biotechnology-waste-wastewater/anaerobic-digestion-treatment







http://www.gov.uk/government/uploads/system/uploads/attachment_data/file/589191/The_United_Kingdoms_exit_from_and_partnership_with_the_EU_Web.pdf






http://www.bbsrc.ac.uk/documents/capital-economics-british-bioeconomy-report-11-june-2015









carbon footprint. Following completion of an initialdigestion facility at the Dailuaine malt distillery (in2013, also in Speyside) Diageo requested Clearfleauto build a second facility. The on-site plants optimiseenergy output from distillery co-products and involvedclose collaboration between Clearfleau’s in-housedesign, installation and commissioning engineers,their Diageo counterparts and an extended supplychain (Fig. 9).

The Glendullan plant also receives feedstock fromother distilleries in the Dufftown area, fed via a recent-ly completed pipeline, reducing local truck move-ments. The bio-energy facility is generating 2 millioncubic metres of biogas per year – producing about8000 MW hours of thermal energy for the distillery.Diageo has set an example to British food and bever-age companies (plus other distillery sites). Engineeringchallenges involved developing a plant able to handlehigher strength materials such as pot ale, and vari-ability in strength and volume of feedstocks beingfed to it. They also included the location of the planton a sensitive location in a valley adjacent to theriver Fiddich and achieving the complex water coursedischarge standards.

Case Study 2. Lake District Biogas PlantThe innovative bio-energy plant built and operatedby Clearfleau for Lake District Biogas converts over1000 m3 per day of cheese whey into biomethane,generating 5 MW hours of thermal energy for thesite and local community. Located on First Milk’s

Fig. 10 Case Study 2. Lake District Biogas Plant


Aspatria creamery in Cumbria (one of the UK’slargest cheese creameries) the plant demonstrateshow the circular economy can be applied to food pro-cessing sites. The main project objective was to replacea failing and costly aerobic treatment plant (seen onthe right of the image) with AD to reduce carbonemissions, generate energy and make the site moresustainable (Fig. 10).

The largest on-site digestion plant in Europe’s dairyprocessing sector and the only creamery site thatis producing biomethane generated entirely from itsprocessing residues, without inclusion of additionalnon-dairy feedstocks. Biomethane, supplied to thenearby gas grid, is supplied to the creamery’s boilers,and to households or local businesses. In addition,power is generated from a 500 kW CHP unit run onbiogas generated from the AD process and cleansedwater is discharged to the nearby river. By treatingprocess residues from the creamery, it is reducingits use of fossil fuels by over 25% and provides along-term sustainable solution for process residuesfrom cheese making that can be deployed on compar-able large scale food and beverage sites. This ap-proach is now being replicated on other dairy sitesin the UK.

Case Study 3. Urban Craft DistilleryIn the case of a craft distillery being built in lowlandScotland, the most significant energy demand will bein the form of steam, with less demand for electricity.Hence, a biogas fired boiler producing steam has been



designed to produce a proportion of distillery heatrequirements. The distillery will be able use itsmodest output of co-product to produce about 20%of its energy needs and the biogas can provide a guar-anteed price per kWh for a proportion of steam sup-plied to the distillery (Fig. 11).

However, there were issues with fluctuating demandfor heat at certain times of the week and this hasbeen a major feature of the initial design phase. Inaddition, with the distillery being located on a derelictindustrial site in an urban location, it was essential thatthe client and plant provider work closely with plan-ners and other local stakeholders. The new distillerythat will help regenerate the area and will have aminimal impact on the environment, with zero

Fig. 11 Case Study 3. Urban Craft Distillery

Fig. 12 Case Study 4. Cheese Dairy


off-site waste disposal and effective re-use of all itsprocess residues (all the residual bio-solids will besent for composting). This site will combine optimalon-site energy generation combined with zerooff-site disposal of residues. It is hoped that this ap-proach will be replicated on other smaller maltdistilleries.

Case Study 4. Cheese DairyOn smaller sites the power output from the biogascan be sufficient to meet the dairy’s electricitydemand, avoiding the need for an export connection.However, a significant fluctuation in site energydemand during the day and over weekends,can result in periods where no energy is requiredfor the production process. Dealing with periods of



significant peak demand can be an issue when the ADplant is producing biogas at constant output (Fig. 12).

Options for optimal gas use can include storing biogasand combusting it when required in a CHP if thereis no ability to export power. Running a secondCHP unit on an adjacent site with its own powerdemand is an alternative, with the biogas beingexported in a private pipeline or upgrading to bio-methane, compressed for use as vehicle fuel in


the milk collection fleet for the creamery. Smallerscale technologies are available and engines can beadapted for biogas offering demand for a proportionof the gas on some sites.

On the smaller sites energy use has a major bearing onviability and in most cases a comparison will be madeon cost and revenue implications. For some sitesviability will be enhanced where there is scope touse bio-fuel, heat and power in the creamery.


developing on-site anaerobic digestion for smaller ...development of anaerobic digestion (ad) in the...

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