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Recycling of paper: accounting of greenhouse gases and global warming contributions
Department of Environmental Engineering, Technical University of Denmark
* To whom correspondence should be addressed. E-mail: hkl{at}env.dtu.dk.
Greenhouse gas (GHG) emissions have been established for recycling of paper waste with focus on a material recovery facility (MRF). The MRF upgrades the paper and cardboard waste before it is delivered to other industries where new paper or board products are produced. The accounting showed that the GHG contributions from the upstream activities and operational activities, with global warming factors (GWFs) of respectively 1 to 29 and 3 to 9 kg CO2-eq. tonne–1 paper waste, were small in comparison wih the downstream activities. The GHG contributions from the downstream reprocessing of the paper waste ranged from approximately 490 to 1460 kg CO2-eq. tonne–1 of paper waste. The system may be expanded to include crediting of avoided virgin paper production which would result in GHG contributions from –1270 to 390 kg CO2-eq. tonne–1 paper waste. It may also be assumed that the wood not used for virgin paper production instead is used for production of energy that in turn is assumed to substitute for fossil fuel energy. This would result in GHG contributions from –1850 to –4400 kg CO2-eq. tonne–1 of paper waste. These system expansions reveal very large GHG savings, suggesting that the indirect upstream and operational GHG contributions are negligible in comparison with the indirect downstream emissions. However, the data for reprocessing of paper waste and the data for virgin paper production are highly variable. These differences are mainly related to different energy sources for the mills, both in regards to energy form (heat or electricity) and fuel (biomass or fossil fuels).
First published on October 23, 2009 |
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