Northern Rural Network · 26 Nov. 2008

Gunter Woltron · SRG Energy Parks

The Biogas Business

Opportunities for the North East

Anaerobic Digestion

Anaerobic digestion (AD) is a natural biological process whereby various types of bacteria metabolize (‘digest’) the carbon of organic materials in an oxygen free (‘anaerobic’) environment.

The bacteria in manure, for example, behave as in a cow’s stomach, but in the controlled and enhanced environment of an AD plant. The outcomes of this process are biogas and a nutrient-rich digestate.

History

• Mumbai, 1859: start of modern industrialisation of AD• Cumbria, 1871: biogas combustion from animal fats• Exeter, 1895: biogas extraction from sewageCurrently: • A few millions of ‘village’ ADPs in China, India, • A few 1000s of high tech ADPs in Germany,

Denmark, Austria, Switzerland• Installed capacity ranges from 15kW (India) to 2MW

(Germany)

Some AD Benefits

An AD plant (ADP) delivers on:• Corporate carbon management strategy• Sustainable development and CSR• Legislative need for renewable energy• Waste diversion from landfill or incineration• Benefits to agricultural sector (fertilizer, pathogen)• Additional business: Coops, ESCOs, supply chain

Primary Products

Biogas consists of ca 60% methane (CH4), ca 40% carbon dioxide (CO2) and traces of hydrogen sulphide (H2S), moisture and ammonia. It is also known as sewage gas, syngas, marsh or mine gas.

The digestate has a neutral pH-value and no caustic action when applied to plants. Nitrogen can be assimilated directly by the plant as it is mainly in the form of ammonia (NH4) and not organically bound. The odour of digested slurry is significantly reduced compared to the original material.

Decide on yourBusiness Model

• Gate fees• R&D• Electricity sales (grid, private wire, ESCO)• Heat sales (industrial estate, eco town, ESCO)• Digestate (fibre, liquids)• Biofuel (= cleaned, compressed biogas)• Water, steam• Add-ons (grain drying, glasshouses, hydroponics)

Input Material

• Any manure, straw muck, slurry• Grass silage, green cuttings, energy crops, • Any diary products and by-products• Any CAT 2 or 3 waste (with adequate pre-treatment)• Vegetable waste, potato starch, brewer’s grain• Any industrial food waste• BMT waste (with adequate pre-treatment)

Note: yield hierarchy: carbohydrates –> fats –> proteins

Design Issues

• Digestion stages: single, double, multiple phased• Procedure: continuous or batch system• Tanks: vertical or horizontal; steel or concrete• Location: under or over ground • Input feeding system Stirring system• Pipe & pumping system Heating system• CHP unit • Scalability: upfront or later

Operating Parameters

• Operating temperature– Thermophilic (ca 50˚-55˚C): faster digestion, less storage,

more volatile, more management intensive, higher gas output

– Mesophilic (ca 30˚-45˚C): longer retention time, larger tanks, more stable, more solids in digestate, lower output

• Moisture content (wet – dry: >15%DM)• Acidity: ph-value (ideal 6.8 – 8,0) • Retention time• Carbon nitrogen ratio balance (30:1)

Improving Yield

• Combination of thermo- and mesophilic digestion• Retention time calculations• Gas collection at every phase/stage• Identify maintenance intensive components (pumps)• Intelligent agitators, stirrers• Cleaning and scrubbing (H2S) technology • Constant, but little supply, only gradual changes• CHP philosophy• Icing on the cake: straw, glycerol

Input Material Risks

• Inorganic bedding materials (sand) – removal?• Inert waste (glass, stone, plastics, metal) – removal?• Feed additives, cleaning agents, vaccines – inhibits

and kills bacteria• Chicken litter – in measure, or it ruins biology• Dirt, soil – removal?• Bones, feathers – removal issue or extra bacteria

Note: the main risk factor is the operator

AD Plant Types

• By input material:– agricultural (FYM, silage, vegetable waste)– ABP, food waste (domestic, commercial, industrial)– wastewater sludge treatment

• By energy user (incl. private wire or district heating):– agri businesses– industrial estates, eco towns, hospitals, villages

• By structure:– Agri’ based: Farm vs CAD (Centralised or Cooperative AD)– Waste centre based (MSW, sewage)

Planning Considerations

Prepare a mitigation strategy for the key impacts:• Noise – CHP unit, vehicle movements• Odour – delivery, storage• Transport – on-site, off-site• Fire/Explosion – ExZones, H&S• Visual impact – (partially) below ground• Spillage risk – bunding etc.• Contamination (water, disease) – H&S

Considerations for CAD

Centralised/Cooperative AD faces unique challenges:• Complex legal structures• Increased Transport• Supply chain control• Additional administrative staff and staff facilities• Tight digestate distribution management • Strict biosecurity measurements• Longer opening hours

Challenges for ADusing ABP/CAT 3

• Plant layout: clean and dirty zones, traffic scheme• Weighing bridge, bunding zones, vehicle cleaning• Additional space: reception, pasteurisation, storage • Pre-treatments: shredding/mashing, blending,

pasteurisation• Regulations: Animal Health, H&S, Water • Odour retention (biofilter), on-site laboratory• Hazard Analysis Critical Control Points (HACCP)• Skilled staff

Financial Support Mechanisms

• Renewable Obligation• Climate Change Levy• Renewable Transport Fuel Obligation and Excise

Duty for biofuels• Landfill Tax• Landfill Allowance Trading Scheme• Energy Crop Scheme• Nitrates Directive

Supply Chain Opportunities

• Planning and permitting consultant• CDM coordinator, HACCP consultant• Food waste collection and processing• Design, construction, M&E, O&M • R&D, IT solutions (SCADA), ROC agent• Skills provider, certification provider• Biological-chemical support and testing• Manufacturing: CHP, hardware• Fertilizer, pellets production and distribution

A bit ofMyth Busting

Things you hear on conferences and some believe it: • AD is not economical • AD is smelly • Large tanks don’t work• Small tanks don’t work• AD based on grass silage only does not work• XY cannot be digested• Farmer is better off with sheep than supplying AD

And the North East?

On the upside: • Waste streams: food at Teesside, crops in rural fringe• O&M and process engineering skills in the area• Renewables R&D: CPI, CREEL, NaREC, Universities

On the downside:• Little planning and no permitting experience so far• Grid constraints and no DNO renewables support • Delay of the digestate accreditation (PAS110)

Biogas-Hochreiter– the Company

• Leading technology provider with 800+ installations• 25 years of AD-experience (food waste and FYM)• Design, manufacturing, sales and maintenance of a

variety of AD equipment (biogas-CHP, stirrers, etc.)• AD range from 35kW - 2MW of installed capacity • Pioneering the concentric ring-in-ring design in 1999• Partners in Europe, India, South America• Total flexibility with owners/investors

Biogas-Hochreiter – the Technology

Core Technology Characteristics:• CSTR - continuous stirred tank reactor• Integrated thermophilic and mesophilic digestion• Maintenance-friendly ring-in-ring built below ground• Only 5% of parasitic energy use compared to 20%• 99% of technical availability of process run-time has

been achieved• Robust acceptance of varied input streams• Remote control by Siemens and Hochreiter

Below Ground Level

150kW biogas plant (digester and secondary digester) entirely below ground, mitigating visual impact

Recommended Reading• The Nitrate Pollution Prevention Regulations 2008• PAS110 (draft) for digestate accreditation, 2008• Biogas from manure and waste products, Swedish case studies, 2008• Economic Assessment of AD Technology, Andersons Centre, 2008• Environmental Permitting (England and Wales) Regulations 2007 • UK Biomass Strategy, 2007• The Animals By-Products Regulations 2005• PPS 7: Sustainable Development in Rural Areas, 2004• PPS 22: Renewable Energy, 2004• An Introduction to AD of Organic Wastes, Remade Scotland, 2003• Waste and Emissions Trading Act (2003)• The Landfill (England and Wales) Regulations 2002 (as amended)• The Water Code, 1998• BS 5502-50:1993 Buildings and structures for agriculture

Contact Details

SRG Energy Parks (UK) LtdCorrespondence: 58 Beach Road, Tynemouth, Tyne & Wear, NE30 2QT

Dr Mike Rule, T: 07902 315220, E: srgenergyparks@yahoo.com

Gunter Woltron, T: 07739 456547, E: biogas@anaerobic-digestion.net

www.biogas-hochreiter.de