Page 275 - Materials Chemistry, Second Edition

LIFE CYCLE ASSESSMENT AND END OF LIFE 263

• Many waste items are not suitable for recycling because of their
quality and/or their degree of contamination with other mate-
rials. In cases where materials are not suitable for recycling, the
generally preferred management option is WTE.
• Solid waste management scenarios including both recycling and
WTE may be the most cost-effective and environmentally pre-
ferred option.
• Recycling performs better environmentally when it is assumed that
recycled material replaces an equivalent amount of virgin material.
• Recycling performs better in scenarios with source separation of
recyclables. When mixed waste or lower recycling separation effi-
ciencies were considered, WTE compared similarly to recycling.
• The difference in environmental impacts between WTE and recy-
cling decreases when WTE replaces electricity and heat generated
from fossil fuels instead of non-fossil fuels.
• Electricity brings more benefits than heat as a product of WTE
facilities. Combined heat and power (CHP) WTE facilities will
have lower electricity generation and associated benefits, but also
the addition of heat-related offsets (typically natural gas).
• The calorific value of the feedstock material as well as the energy
recovery efficiency of the WTE process has a significant impact on
its environmental performance. The higher the calorific value of
the feedstock and the energy recovery efficiency the better WTE
performs compared to other processes.
• As newer technologies (e.g., gasification and feedstock recycling)
develop to commercial scale and their cost decreases, they may
become more attractive as solid waste management options, in
particular for non-recyclable wastes.

These studies in the open literature suggests that recycling is the most favor-
able waste management option available, but other alternatives are needed to
manage waste materials that are not suitable for recycling. For waste that can-
not be recycled due to cost, technical feasibility or treatment facility capacity,
WTE is preferable to landfill. For example, many plastics are not [currently]
suitable for recycling because of their quality and/or degree of contamination
with other materials. Therefore, management scenarios where both recycling
and WTE are utilized become the preferable option and materials such as plas-
tics with a high calorific value (i.e., high energy generation potential) should
preferentially be sent to WTE. In addition,

• The efficiency of materials recovery limits the recycling benefits.
Heavily contaminated mixed recyclables are usually not cost-
effective for recycling. Therefore, recycling was shown to perform
better in scenarios assuming high recovery efficiencies. When
mixed waste or lower recovery efficiencies were considered, the
benefits from WTE were similar to recycling.