1. 1. APPROPRIATE FARM & ON-SITE ANAEROBICANAEROBIC DIGESTION Organic nutrient recycling & Pollution mitigation
2. 2. Context What is AD? AD Viability Dos and Donts Case study Topics Considerations for putting a project together
3. 3. Context www.methanogen.co.uk info@methanogen.co.uk The earth is what we all have in common (Wendell Berry)
4. 4. Long-lived digester design 450 years combined operation Many running > 20 yrs Low parasitic energy Simple, user-friendly
5. 5. Context & Drivers - Its time to act! Climate change: Last year, we reached 400ppm CO2 in the atmosphere The era of cheap energy is over global energy transition. Energy is NOT just your lights and heat. It is food. Population growth: 2050 9BN? 11BN? Population growth: 2050 9BN? 11BN? Increasing urbanisation: 1.4M people/week (Bham) Population age. 2000 2BN children Prediction for 2100? Legal CO2 reduction targets
6. 6. Energy Food So what can I do? Reduce (Efficiencies) Re- THINK!Reuse Recycle Water THINK! (resilience)
7. 7. UK Storms: We have no heating, no power, no hot food www.methanogen.co.uk info@methanogen.co.uk
8. 8. What is Anaerobic www.methanogen.co.uk info@methanogen.co.uk Anaerobic Digestion? AD is
9. 9. . a cow, not a tractor!
10. 10. What is Anaerobic Digestion? Organic material* Heat ANAEROBIC DIGESTER @ 40C Biogas H2S & other gases To CHP to create renewable electricity OR To boiler, Aga, Rayburn, gas ring(s) Digestate (Biofertiliser) Optional separation intoOptional separation into soil conditioner & liquid fertiliser OR Spread to land An enclosed vessel: heated, stirred (either by 60% CH4 & 40% CO2 An enclosed vessel: heated, stirred (either by gas mixing or mechanical agitation) www.methanogen.co.uk info@methanogen.co.uk Natures own biological decomposition by micro-organisms in the absence of oxygen (anaerobic) It is a natural process that breaks down organic material in an airless, heated and mixed tank
11. 11. Anaerobic Digestion Composting Degradation of organic matter in the absence of oxygen (bacteria, archaea, protozoa that do not need oxygen to grow anaerobes) Degradation of organic matter in the presence of oxygen in air (bacteria/fungi need oxygen to grow aerobes) Best way to treat all non-woody organic wastes Best way to treat all woody organic wastes Requires heat (ideally) Generates its own heat (exothermic) www.methanogen.co.uk info@methanogen.co.uk Creates CO2 Creates CO2 Creates fertiliser whose nutrients are more available to plants, as well as a soil conditioner Creates a soil conditioner / fertiliser Creates biogas which can be used to create electricity, heat or vehicle fuel
12. 12. Biogas 60% CH4 40% CO2 Boiler CHP Heat Losses Heat Losses Electricity 75%-85% 25%-15% 60%-45% 30%-40% 40% CO2 Upgrade Losses Biomethane CO2, H2S, H2O www.methanogen.co.uk info@methanogen.co.uk 15% (rem)
13. 13. SimpleAD plant running on slurry Cow slurry in Gas for cooking or heating farm house Liquid used on grass Fibre ploughed in Thermal solar heated digester Biofertiliser Digester 40C An enclosed vessel: heated, stirred (case studies used gas mixing) Biogas 60% CH4 40% CO2 Feedstock: Gravity or auger fed Gas Holder Liquid Fibre Storage Direct Use Heat/hot water Boiler: (digester heating) Aga/Rayburn
14. 14. AD plant with Combined Heat & Power (CHP) Digester 40C Biogas Gas Holder CHP -Tends to need a lot more feedstock -More complicated to run Electricity 60% CH4 40% CO2 Liquid Fibre Storage Biofertiliser Heat Heat Anaerobic Digester Feedstock
15. 15. Using the biogas fromAnaerobic Digestion
16. 16. Case study Bus Bristol-Bath Courtesy of University of Southampton: Dhivya, Alba & Leo-Paul
17. 17. Why AD? www.methanogen.co.uk info@methanogen.co.uk
18. 18. Farm Abattoir Food Processing The Food Production Process Currently, there is waste at every stage of the process AD closes the loop Nutrients must go back to land in a beneficial way Fertiliser(nutrients)backtoland* Retail Restaurant & Home Anaerobic DigesterEnergy from Biogas *Recycle NPK & micronutrients as fertiliser *Pathogen/weed seed kill *Sequester carbon *Improve soil structure Fertiliser(nutrients)backtoland*
19. 19. Why AD of slurries/manures? 1989 Clive Pughs Slurry System 1990 With Displacement of fossil fuels (both fertiliser and energy) Reduction in carbon dioxide, ammonia, nitrous oxide and methane losses to atmosphere greatly reduced GHG potential www.methanogen.co.uk info@methanogen.co.uk 1989 Clive Pughs Slurry System WRI (Murcott) Digester
20. 20. Environmental Benefits of AD Returns micronutrients, water, carbon, nitrogen to soil Reduction in carbon dioxide, nitrous oxide and methane losses to atmosphere greatly reduce GHG potential Offensive odours eliminated/reduced Kills many weed seeds/pathogens Kills many weed seeds/pathogens Addition of humus improves the physical properties of soil water holding capacity, aeration, water soluble aggregates and increased crop production up to 20-30% Reduction in BOD (80-95%) www.methanogen.co.uk info@methanogen.co.uk
21. 21. Improved slurry handling Less water use Fertiliser benefit is not just NPK, but significant and essential trace elements Fertiliser performance is superior; nutrients are more readily available, particularly Nitrogen Digestate does not hinder clover Farming Benefits of AD Digestate does not hinder clover growth like synthetic fertilisers. Faster re-grazing healthier animals Increased ley life Production of energy and fertiliser reduces costs of food production, improves profitability and adds an income stream to the farm www.methanogen.co.uk info@methanogen.co.uk
22. 22. Digester Economics www.methanogen.co.uk info@methanogen.co.uk Economics
23. 23. What is Small Scale? German definition (