49 research outputs found
Material Cycles and Chemicals: Dynamic Material Flow Analysis of Contaminants in Paper Recycling
This study provides
a systematic approach for assessment of contaminants
in materials for recycling. Paper recycling is used as an illustrative
example. Three selected chemicals, bisphenol A (BPA), diethylhexyl
phthalate (DEHP) and mineral oil hydrocarbons (MOHs), are evaluated
within the paper cycle. The approach combines static material flow
analysis (MFA) with dynamic material and substance flow modeling.
The results indicate that phasing out of chemicals is the most effective
measure for reducing chemical contamination. However, this scenario
was also associated with a considerable lag phase (between approximately
one and three decades) before the presence of chemicals in paper products
could be considered insignificant. While improved decontamination
may appear to be an effective way of minimizing chemicals in products,
this may also result in lower production yields. Optimized waste material
source-segregation and collection was the least effective strategy
for reducing chemical contamination, if the overall recycling rates
should be maintained at the current level (approximately 70% for Europe).
The study provides a consistent approach for evaluating contaminant
levels in material cycles. The results clearly indicate that mass-based
recycling targets are not sufficient to ensure high quality material
recycling
Setting priorities for land management to mitigate climate change
<p>Abstract</p> <p>Background</p> <p>No consensus has been reached how to measure the effectiveness of climate change mitigation in the land-use sector and how to prioritize land use accordingly. We used the long-term cumulative and average sectorial C stocks in biomass, soil and products, C stock changes, the substitution of fossil energy and of energy-intensive products, and net present value (NPV) as evaluation criteria for the effectiveness of a hectare of productive land to mitigate climate change and produce economic returns. We evaluated land management options using real-life data of Thuringia, a region representative for central-western European conditions, and input from life cycle assessment, with a carbon-tracking model. We focused on solid biomass use for energy production.</p> <p>Results</p> <p>In forestry, the traditional timber production was most economically viable and most climate-friendly due to an assumed recycling rate of 80% of wood products for bioenergy. Intensification towards "pure bioenergy production" would reduce the average sectorial C stocks and the C substitution and would turn NPV negative. In the forest conservation (non-use) option, the sectorial C stocks increased by 52% against timber production, which was not compensated by foregone wood products and C substitution. Among the cropland options wheat for food with straw use for energy, whole cereals for energy, and short rotation coppice for bioenergy the latter was most climate-friendly. However, specific subsidies or incentives for perennials would be needed to favour this option.</p> <p>Conclusions</p> <p>When using the harvested products as materials prior to energy use there is no climate argument to support intensification by switching from sawn-wood timber production towards energy-wood in forestry systems. A legal framework would be needed to ensure that harvested products are first used for raw materials prior to energy use. Only an effective recycling of biomaterials frees land for long-term sustained C sequestration by conservation. Reuse cascades avoid additional emissions from shifting production or intensification.</p