ANAEROBIC DIGESTION Marco Poliafico WINACC 18.09.14
List of Contents Short Presentation AD Technology principles AD Technology Q&A
Short Presentation M Eng in Environmental Engineering (Italy) Academic Research - AD development in Ireland Energy Consultancy
AD Biochemical Process
AD Technology Process Electricity Feedstock Organic fraction of MSW, manure, wastewater, green waste, organic industrial waste, Energy crops Gas Formation Digester Biogas Digestate (semisolid) CHP Heat Leachate (liquid) Separator Compost (solid)
Energy Plant Layout Feedstock shredding and screening Feedstock collection and storage Digestate storage and dewatering DIGESTER Gas filter, condenser, H 2 S scrubber, storage CHP
Energy from AD Biogas 60% Methane (CH 4 ) 40% Carbon Dioxide (CO 2 ) Boiler CHP Upgrading 85%η Heat 38%η 47%η Heat Power Biomethane Gas grid Transport fuel
Energy from AD Feedstock Livestock feedstock Dairy cow slurry - Horse manure Energy Crops Grass silage - Barley straw MSW and others Food leftovers - Old bread Vegetable waste - Mixed Grain Whole cows milk (fresh) - Glycerine Food leftovers - cheese waste Biogas Yield (m 3 /tonne) 20-60 170-312 100-482 57-577 115-846 100-674 For each m 3 of biogas a CHP would produce: 1.7 kwh e + 2 kwh t
Digestate What is the residual waste from the process and how is it managed? can it be used as "manure"? High nutrient properties nitrogen: 2.3 4.2 kg/tonne, phosphorous: 0.2 1.5 kg/tonne, Potassium: 1.3 5.2 kg/tonne Processes & techniques link Produce concentrated or balanced bio-fertilisers, no one single solution but a range of options (thermal, chemical, biological, physical ) UK market not mature yet
Digestate WRAP quality protocol link quality depends mostly on the type of waste used and AD process (agriculture, forestry, soil/field-grown horticulture, land restoration) WRAP PAS 110 link
Environmental Performance How does it compare in terms of CO2 with other means of dealing with organic waste such as landfill, composting and incineration? Double contribution to GHG reduction (C content in the waste + fossil fuels energy sourced replacement) Not easy to calculate LCA approach needed and comparison between options should be carried out WRATE (Waste and Resource Assessment Tool for the Environment) Model has been criticised for high ranking of incineration (link)
Environmental Performance Evaluation of food waste disposal options in Korea (International Journal of Energy and Environmental Engineering) 342 259 211-178 33 Anaerobic Digestion 0 Co-Digestion (food+sewage) Dry-Inceneration -315 kg CO2-eq (LCA) kg CO2-eq avoided (energy) Net -657
Environmental Performance Comparative Life Cycle Assessment (carried by Eunomia for a private client) 1.31 Tonnes CO2-eq 0.06-0.03 0.03 0.05 0.03-0.47 0.12-0.09-0.16
Environmental Performance LCA studies for Composting and Anaerobic Digestion units (EU study applied to Greece) Metric Tons of CO2-eq / metric ton organic waste 0.63 0.22 0.29-0.06-0.07 0.02 0.05-0.06-0.25-0.24-0.74-0.76 AD Composting Incineration WTE -0.69 Home Composting landfill+flaring
Cost of Waste Management How does it compare in terms of cost with other means of dealing of organic waste? -- 2011 ARUP report for DECC (link) Capital Costs, '000/MW, 2010 8915 7134 6985 6260 5062 4463 3941 4000 2396 2147 6915 6711 5241 3740 3906 1673 6300 2825 6272 5473 2525 1403 Incin CHP 5-50 MW AD <1 MW AD 1-6 MW AD Food AD Farm ACT <10 MW ACT 10-30 MW Landf Gas <2 MW
Cost of Waste Management 2011 ARUP report for DECC (link) 2156 Operating Costs, '000/MW, 2010 482 368 900 335 630 263 98 728 481 219 1006 839 394 632 441 466 367 389 212 125 Incin CHP 5-50 MW AD <1 MW AD 1-6 MW AD Food AD Farm ACT <10 MW ACT 10-30 MW Landf Gas <2 MW
Small scale AD what scale does it need to take place on to become financially viable? Are there small scale examples? Example 1 (Gloucestershire dairy farmer) installed 1993 feedstock from 110 cows (140 acre land) Digester 125 m3 Capital costs - 60K payback 10-12 years Energy use heat for two farmhouses
Small scale AD Example 2 (Norfolk) installed before 2009 feedstock from 100 cows (500 acre land) Digester? m3 Capital costs - 750K payback 8 years Energy use heat + electricity production (surplus to the grid) Many other case studies link 1, link 2
AD & Heat utilisation Does the process produce waste heat? Are there example of the AD being utilised for heating? Heat is indeed one of the main products of AD (CHP) AD & district heating
AD economics Is there data available on costs in other countries who pioneered this? Already answered in other slides
AD for Waste Management Different types of Anaerobic digestion, the advantages and disadvantages of the different approaches and what is coming up Dry vs wet (co-digestion) Mesophilic vs thermophilic Single-stage vs multi-stage Further reading: link1, link2
Thank you for your attention marco.poliafico@gmail.com uk.linkedin.com/in/marcopoliafico