Reduction of Fossil fuel Dependency through the utilization of Anaerobic Digestion (Waste to Energy)

1. Reduction of Fossil fuel
Dependency through the
utilization of Anaerobic Digestion
(Waste to Energy)
Dr Gabriel Kelly Group EHS Manager
21/05/2015

2. 2
Need Anaerobic Digestion Project
• Need and Pathway
• Long term strategic development
• Quotas would be abolished in 2015 meant there was a pressing business need:
• Increased milk processing
• Increase energy demands
• Increased treatment requirements for waste
• Technology solution was and integrated Anaerobic Digestion system
• Alternatives
• Do Nothing
• Use existing treatment model – aerobic large tanks highly energy intensive, larger
footprint more manpower more waste increased carbon footprint of the facility
• Other alternatives
• AFC unproven (thermophilic)
• ATAD not particularly successful and possibly not a suitable application
• Process Steps
• Planning permission in 2006 involving EIS
• EPA licence boundary change 2010 and license change approval
• Vendor choice
• Construction and commissioning 2011 /12

3. 3
What is AD? Anaerobic Digestion Project
Anaerobic Digestion:
• Anaerobic digestion of organic materials by microorganisms under controlled conditions
with the production of biogas – Natural Waste to Energy Process
• Scale 45,000 m3 – “probably” the largest industrial Digester in Dairy industry
• Treatment of 27,000 kg/d COD current 50 to 60 % utilisation in peak
• €8 Million Investment in Waste to Energy – provides for future expansion
• BAT compliant

4. 4
• Low energy electrical energy
requirements
• Un manned automated system
• Mesophilic operation <50oC
• Generates high quality gas stream
typically 85% methane on our
waste (normally 55% +)
• Self heating in low loading
conditions
• Free useful energy
• Reduced Carbon footprint for the
Society
Technology of choice Anaerobic Digestion Project

5. 5
• Treatment of medium strength process
wastewaters from milk powder production
• Ability to reuse existing boiler to generate
steam
• Removal rates of 90%+
• Stable self sustaining process – can deal with
shock loading if required
• Temperature is important in the process
• Heat exchangers used to heat incoming
waste water to maintain temperature in
reactor
• Heat is generated by burning gas from the
process
Process Inputs / Outputs Anaerobic Digestion Project

6. 6
• Low biomass yield when compared with aerobic
treatment
• Provides increased COD treatment capacity and
treats more than the conventional aerobic system
• Small footprint and energy efficient when
compared with alternative technologies
• Energy efficient process and generates energy
unlike conventional aerobic systems
Inputs / Outputs Anaerobic Digestion Project

7. 7
• Generated excess energy of 9.1 million KWh of Thermal energy in
2013
• (externally verified)
• This is Waste to Energy and one of the best applications of concept
• The Free Energy represents:
• 107 therms of natural gas or 3135 KWh per 1000 kg of COD
treated
and
• 70% of gas produced is sent to second boiler for reuse
• All this currently represents 6% of Castlefarm’s steam requirements
during peak production
• Low Energy Cost for Treatment with AD versus Aerobic
• Aerobic is ~1.03 KWh per kg COD treated for 2013
• Anaerobic Digester is ~0.07 KWh per kg COD treated for 2013
• Novel approach by Dairygold in this project - normally small scale
reactors used to produce electricity for grid for schemes such as refit
etc
Energy Benefits 2013 Anaerobic Digestion Project

8. 8
• Waste sludge production is typically 10% of an aerobic process
• This means lower disposal costs and in particular
transport cost
• There is also and additional environmental benefit in the
reduction in carbon dioxide generation due to transport of
sludge versus aerobic plant
• Biogas generation is saving in excess of 1900 t/year of CO2
emissions in 2013
Energy Benefits 2013 Anaerobic Digestion Project

9. 9
• The Anaerobic Digestion project has the
potential to treat wastes from other Dairygold
facilities such as WWTP sludge thus reducing
dependence on land spread further reducing
environmental impact and carbon footprint
• Irish Dairy Board (IDB) are centralising
production of Kerrygold © at the facility as a
direct result of this investment
• Current Mallow expansion will consider this
technology –possibly during the installation of
the third dryer
• Expected that the benefits of this waste to energy
project will become more significant
contribution after 2015 as throughput increase
is realised
Future Anaerobic Digestion Project