“To encourage and empower small rural communities to take ownership of and develop community led renewable energy solutions for the benefit of their own locality”

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Biogas / Anaerobic Digestion for the Community

Noel GaviganTechnical ExecutiveIrish BioEnergy AssociationNoelgavigan [at] irbea.ie

• Recycles organic material

• Recovers the energy and converts it into usable gas

• Recovers the nutrients and allows them be used back on farmland

BIOGAS DIGESTER

Animal slurries, Energy Crops

Food Waste, Food processing Waste

Electricity Heat Vehicle Fuel

Digestate Fertiliser

What is Biogas / Anaerobic digestion??

https://www.youtube.com/watch?t=3&v=KgUwdepePF4

What is Biogas? - What Happens?

• Bacteria digest organic matter in a very similar manner to rumenants (cows / sheep). The Energy is converted intoMethane gas.

• The gas can readily be used to produce heat, electricity or be used as vehicle fuel afterpurification.

Industrial Scale Biogas

• 250kwe – 5MWe scale

• Capital Expenditure of €4-5m / MW

• Feedstocks: Energy Crops

• Feedstocks: Waste Materials

• Feedstocks: 10,000 tonnes to 200kt

Developing World Biogas Plants

Biogas Composition

• Heating

• Electricity

• Upgrading to gas grid

• Vehicle Fuel

Uses of Biogas

Digestate – High Value Fertiliser

• Liquid slurry – spreadable with normal farm machinery

• Retains all the original nutrients from the feed material

• Nutrients are more available to the plant, as much as double the amount of available Nitrogen

• Digestate can be separated into liquid and solid portions• Solids are high in Phosphate and

Potassium• Liquid is high in Nitrogen

What Materials can be used in a biogas plant?

• Agricultural waste & Products• Animal slurries

• Harvest residues

• Grass / Maize / Cereals

What Materials can be used in a biogas plant?

• Food processing waste• Meat/fish processing waste

• Dairy waste

• Brewery spent grains

• Vegetable waste

• Waste from prepared food factories

Offal

Food left over

Fruits and vegetables

• Food Waste• Household collected food waste

• Catering Waste

What Materials can be used in a biogas plant?

Gas Yield from Various Materials

Substrate Dry matter BiogasMethane Content

Net EnergyHeating value Electricity Electric value

90% efficient 35% efficient 19c/kwh

[%]m3/ton fresh

weight% kWH / Tonne @8c/kwh [kWh el./ton]

(not including heat

value)

Cattle Manure8 25 60 162 € 11.70 57 € 10.80

Pig manure 6 20 60 130 € 9.36 45 € 8.64

Milk whey 8 58 53 333 € 23.97 117 € 22.14

Brewers yeast (pressed, cooked)

25 152 62 1021 € 73.48 357 € 67.87

Potato pulp 19 108 50 585 € 42.11 205 € 38.89

Slaughterhouse waste (rumen)

15 60 55 357 € 25.73 125 € 23.77

Bread and baking residues

77 570 53 3272 € 235.57 1145 € 217.57

Corn silage 35 216 52 1216 € 87.58 426 € 80.89

Example 1: Gießen Dairy Farm (Germany)

Small-scale biogas plant (installed capacity 75 kW).Feedstocks: cattle slurry (10.950 m3/year)Energy use: heat for self-consumption, electrical energy is fed into local power grid.Digester: 600 m3 concrete tankBiogas valorisation unit: 75 kW boiler.Energy production : 630 Mwhel/a; 740 MWhth/aInvestment: 500,000€

Estimated payback period = 6 years

Example 2: Fahringer farm, Rettenschöss (Austria)

Small-scale biogas plant (self-built, low-cost).Feedstocks: cattle slurry, whey, pig slurryEnergy use: heat for the housing and the cheese plant.Digester: 150m3 concrete tankBiogas valorisation unit: 50kW boiler.Gas production : 150-180m3 biogas/dayInvestment: 35,000€Annual Maintenance cost (estimate 5% CapEx €1750)Gas value €6570/yrPayback 7 years

Data obtained from a report of the BIOREGIONS project (www.bioregions.eu)compiled by Patrick Daly

Example 3: Methanogen: Waterford, Ireland

• Built 1992 – running ever since• 2 x 70m3 insulated concrete tanks, Fibreglass top• €35,000 Initial investment• 50kw Heat output

Planning a Community Digester – Farmer Aspects

Farm Operation

• Facility to treat waste materials

• Access to enhanced fertilisers

• Reduction in pathogens and weed seeds

• Greening agricultural practice

Community Aspects

• Positive benefits of reduction of farm odours

• Lowering carbon footprint

• Who will provide a site for the digester?

• Ownership• Green Community• Potential for district heating

Planning a Community Digester – Non Farmer

Residents

• Greening the Commmunity

• Ownership sharing?

• Positive benefits of reduction of farm odours

• Outlet for food and garden waste

• Access to excellent fertiliser for DIY gardener

• Potential for district heating

Local Food Companies

• Outlet for food processing waste and surplus stock

• Reduction of carbon footprint

• Embedding company to the community

• Potential for heating and/or electricity

What must be done?

• Survey of available feedstocks (Community Meetings)

• Identify a suitable site

• Identify suitable uses for the gas in terms of heat, electricity or gas upgrading

• Community Meetings!

• Financial feasibility

• Regulatory aspects (planning, waste licencing etc..)

• Community Meetings!!

• Financing the project and ownership

• Community Meetings!!!

Ss

Biogas / Anaerobic Digestion for the Community

Noel GaviganTechnical ExecutiveIrish BioEnergy Associationnoelgavigan@irbea.ie