Integrating Anaerobic Digestion with Composting

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Integrating Anaerobic Digestion with
Composting by James Lloyd
In partnership with
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What to expect

• A General Look
• Integrating anaerobic technology into an
  in-vessel composting technology sales business.
• A Closer Look
• Combining composting with anaerobic digestion
  and the reasons for doing it.

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Finding a new technology (1)

• Why bother?
• The Wind of Change
• English Waste Strategy
• WRAP food waste report
• Dont think of it as losing potential sales
• think of it as gaining a whole new market!
• A change in company direction and philosophy

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Finding a new technology (2)

• What did we look for?
• Quality and excellence in delivery
• Robust/ workable technology
• Track record and availability
• Price
• Ease of operation
• Compatibility with existing technology
• Suitability to UK waste and operations

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What did we find?

• 3 types of technology (broadly speaking)
• Lots of WET systems (lt10 DS)
• Few Intermediate Systems (10 -20 DS)
• Very few really DRY systems (gt20 DS)
• High Capex Opex
• Higher process performance risk
• Economics reliant on energy sales

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Why continue?

• EWS, WRAP report, market forces, Renewable
  Obligations, energy prices, etc.
• Some deliverable technologies
• High levels of return for Green Energy
• Advent of the DOUBLE ROC
• One imagination grabbing technology!

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What is BEKON?

• Dry digestion i.e. gt20 DS
• Ideal for solid wastes
• Able to process combined kitchen/ garden
• Batch process F.E.L. operated
• Idiot proof
• Robust and easy to fix
• Static relies on percolate recirculation
• No internal moving parts
• Very low parasitic energy use and opex

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Quick picture
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The result?

• Very positive high levels of interest from all
  sectors (WM Co. ? LAs ? Businesses)
• Wider company appeal development of new
  contacts
• Wider company appeal tailor-made solutions
• Problems with
• Re-branding the company
• Company identity

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More specifically
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Integrating the two ?on site?

• Only relevant for dewatered digestate or
  digestate from DRY digestion plants
• Digestate is still very active
• AD is good for quick release of energy but unable
  to cope with ligneous material
• Use of PAS 100 or PAS110
• ?Finished? product for end markets

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Benefits of Integration

• Flexibility ABP can be achieved in either
  composting OR anaerobic phase
• No need to shred, macerate, or pump solid waste
  and associated mechanical problems
• Higher resistance to feed variations and
  contamination
• Lower product contamination

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Benefits of Integration (2)

• Long term emission control strategy (Germany,
  Italy, UK to follow)
• Move towards enclosing ALL composting
• ABP composting already enclosed
• Recovery of higher capex through energy recovery
  (ROCs, e-kWh and t-kWh)
• Proven processes and markets (PAS100)

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Examples
Existing 80,000 tpa windrow composting operation
Existing Herhof composting operation
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Examples (2)
Previously a 10,000 tpa windrow composting
operation
Combined with a new Tunnel Composting plant
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Examples (3)
Combined with a new windrow Composting plant
Combined with a new Tunnel Composting plant
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How the economics work

• In simple terms
• ?to compete on a gate fee basis with traditional
  IVC the AD portion of the project must stack up
  on electrical savings or revenues alone?
• While the enclosed maturation is reduced, it is
  of comparable size and therefore cost to an IVC
  on its own.

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How the economics work (2)

• Depends on gas yield from feedstock (e.g.)
• Biowaste (6040 gardenkitchen)
• 85 110m3 biogas / tonne
• Household food waste (2080 gardenkitchen)
• 115 175m3 biogas / tonne
• Commercial biowastes
• Up to 195m3 biogas / tonne
• Fuel crops/ glycerin/ etc
• Up to 250m3 biogas / tonne

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How the economics work (3)

• For example 20,000 tpa
• Food processing waste, bakery waste, household
  biowaste
• 4,200,000 investment in AD technology
• 150m3 biogas / tonne processed
• 6,500,000 kWh per annum
• _at_ 11p/kWh 715,000
• _at_ 15p/kWh 975,000
• _at_ 18p/kWh 1,170,000
• Plus 4,550,000 thermal kWh available for use/ sale

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Conclusion

• Energy prices only going to increase
• Ongoing pressure for greener energy
• Ongoing waste problems in UK
• Secure source of fuel
• PAS100 products
• The right place, the right time
• The right technology!