Organic waste: Denmark

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Organic waste Denmark

• Thomas H. Christensen
• Technical University of Denmark
• - on behalf of many contributors

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Outline

• Danish preconditions / assumptions Boundary
  conditions
• Listing of many conducted projects
• Orware Simulation of Danish EPA scenarios
• Easewaste 2004 City of Aarhus Full scale source
  separation of organic waste anaerobic digestion
  use on agricultural land

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Danish preconditions / assumptions 1

• No landfilling of organic waste since 2000?
• Most residential as well as non-residential
  waste incinerated in modern incinerators with
  electricity production and heat utilization
  (district heating). Incineration capacity
  available.
• Energy is high priority Kyoto- demands high,
  since most power is coal- or oil- based. Energy
  prices are high and tax is added
• Waste incineration is a significant contributor
  to renewable energy.
• Garden yard waste very seasonal and collected
  mostly via recycling stations and composted
  (usually not mixed with kitchen waste) (mixing
  will induce requirements for hyginization, limits
  on heavy metal content and declaration)

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Danish preconditions / assumptions 2

• Waste hierarchy induced source separation of
  organic waste from households Many tests and
  trials done since late 1980s Composting and
  anaerobic digestion
• Danish EPA suggested introduction of mandatory
  source separation
• Several full-scale systems and plants established
• Danish EPA ranked anaerobic digestion above
  composting Energy and nutrients
• Many anaerobic digesters exist for manure and
  industrial organic waste (combined)
• Danish agriculture is rich in animals and
  nutrients hard to find space
• No significant market for urban organic waste on
  land Erosion is no problem, drought issues
  insignifcant, supplementary fertilizer (K, N)
  always needed

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Danish EPA reports 2000-2003
Most of them in Danish!

• Basic documentation of biogas potential in
  organic household waste, Technical University of
  Denmark
• Data report about composition and
  biogaspotential of organic household waste,
  Technical University of Denmark
• Should food waste from households be burned or
  recycled? A welfare economic analysis of
  increased recycling of organic household waste,
  Danish EPA
• Relating sorting, pre-treatment and quality of
  organic biomass, PlanEnergi Lund University
• Collection of organic waste from households,
  small industry kitchens and food stores in
  Aalborg Municipality, PlanEnergi
• Full scale experiment in the Greater Copenhagen
  area, Rambøll
• Full scale experiment in Kolding, Cowi
• Experiences about collection and treatment of
  biowaste in Aarhus Municipality, Technological
  Institute

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.continued

• Methane oxidation from storage of anaerobic
  digestion residue from organic household waste,
  Technical University of Denmark
• Pre-sorting of organic waste by Dewaster,
  PlanEnergi, Jysk Biogas International Aalborg
  Municipality (2002)
• Pre-treatment of organic household waste by
  hydraulic pressure device, AFAV (2003)
• System analysis of organic waste management in
  Denmark, Swedish Institute of Agricultural
  Engeneering Royal Institute of Technology
  (2003)
• Disposal of anaerobic digestion residue
  originating from urban waste, Hedeselskabet
  the Agricultural University of Denmark (2003)
• Central sorting of household waste, NLM (2004)
• Overview of Danish projects concerning
  biogasification of organic household waste
  2000-2002, Lunds University Technical
  University of Denmark

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Specific biogas generation
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City of Aarhus, DenmarkWaste system evaluation

• 282 000 inhabitants (household waste)
• Waste system paper recycling, glass recycling
  (bottles and cullets), organic waste in green
  bags and residual waste in black bags for optical
  sorting.
• Organic waste to anaerobic digestion and use on
  land (gas to electricity and heat)
• Residual waste to incineration with electricity
  and heat production
• EASEWASTE 2004 2 main alternatives were
  evaluated (81 000 tons)
• EASEWASTE 2004 8 sensitivity scenarios (What
  if?) for 17000 of organic waste

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City of Aarhus, DenmarkLCI studies

• LCI on waste collection Several routes monitored
  for fuel consumption
• LCI on incineration plant, including test on 1200
  tons household waste to determine heavy metal
  content and plant performance
• LCI on organic MRF, including dewaster test
• LCI on biogas plant and digestion test on
  pre-treated organic waste
• LCI on bottom ash treatment
• LCI on glass MRF

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City of Aarhus, DenmarkEASEWASTE 2004

• Life-cycle-based model including upstream and
  downstream activities
• Input and / or process-specific emissions
• Material fraction and substance related
• EDIP-impact assessment method
• Specifically involving- plastic bag production
  and incineration- fertilizer production and use
  (metals, N2O, N-leaching)- organic waste use on
  land (metals, N2O, NH3, N-leaching)- methane
  losses from digest storage and gas engine

Agricultural model, Daisy used to generate
transfer coefficients
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Mass flows Scenario BIO

Scenario INC
0
0
0
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Potential Environmental Impacts (Sc. BIO)
25.000.000
20.000.000
15.000.000
10.000.000
mPe
5.000.000
0
Collection and transport
-5.000.000
Bottle reuse
Glass remanufacturing
-10.000.000
Glass MRF
Recycling of paper
Paper MRF
-15.000.000
Iron remanufacturing
Landfilling
Eco tox, water, acutet
Eco tox, water, chronical
Reuse of bottom ash
Acidfication
Photochemical ozone
Eutrofication
, Eco tox,soil
Human tox,air
Human tox,soil
Ozon nedbrydning
Global warming
Bottom ash treatment
Human tox, water
Incineration
Use of organics on land
Anaerobic digester
Organic MRF
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Potential environmental impacts
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Ressource consumption
Primary energy normalised to Danish avarage of
38.000 MJ/PE (electricty and heat)
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Sensitivity scenarios/ What-ifs?(17 000 of
organic waste)

• Scenario C1 Biogas scenario, where the methane
  potential is increased to 500 Nm3 per ton VS
• Scenario C2 Biogas scenario, excluding the extra
  consumption of plastic bags (green and black bags
  delivered to the households)
• Scenario C3 Biogas scenario, reducing the energy
  consumption for optical sorting and dewasting
  to half.
• Scenario C4 Biogas scenario, increasing the
  energy effciency to 88 (41 for electricity and
  47 for heat production).
• Scenario C5 Biogas scenario, reducing methane
  emission from 3 to 1 .
• Scenario C6 Biogas scenario, reducing the heavy
  metal content of the digested biomass to half
  (As, Cd, Cr, Cu, Hg og Mo).
• Scenario C7 Biogas scenario, improving the
  energy efficiency at the incinerator.
• Scenario D1 Incineration scenario, increasing
  the electricity production according to existing
  plans (to 85).

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Potentiale environmental impacts Sensitivity
scenarios
800.000
600.000
400.000
200.000
0
mPe
-200.000
-400.000
-600.000
-800.000
-1.000.000
Eco tox,water, chronical
Photochemical ozone
Human tox, water
Acidifcation
Hum.tox, soil
Eutrophication
Human tox, air
Eco toc, water, acute
Global warming
Sc.C
Sc.C1
Sc.C2
Sc.C3
Sc.C4
Sc.C5
Sc.C6
Sc.C7
Sc.D
Sc.D1
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Conclusions

• Reuse of glass and paper saves resources and
  potential environmental impacts
• The energy effciencies are the most significant
  factors, in particular the electricity efficiency
  and its substitional value
• The use of special plastic bags increased
  resource consumption and potential environmental
  impacts
• Use of digested organic waste on land has a
  potential impact on humans, apparently primarily
  related to As
• The major potential impact from incineration was
  related to human toxicity caused by Hg emissions.
• The biogas scenario and the incineration scenario
  were close to identical as to potential
  environmental impacts

The City of Arhus closed the organic MRF, since
the costs were too high (2.5 million Euro per
year) considering that there was no significant
environmental benefit