Plastic waste as a fuel – CO2-neutral or not?

Ola Eriksson*a and G€oran Finnvedenb
Received 23rd April 2009, Accepted 24th June 2009
First published as an Advance Article on the web 28th July 2009
DOI: 10.1039/b908135f

Municipal solid waste (MSW) is not only a societal problem addressed with environmental impact, it is
also a resource that can be used for energy supply. In Northern Europe combustion of MSW
(incineration with energy recovery) in combination with district heating systems is quite common. In
Sweden, about 47% of the household waste is treated by incineration with energy recovery. Most
incineration plants are CHP, summing up to 0.3% of the total electricity generation. MSW is to a high
extent a renewable fuel, but plastic, rubber etc. can amount to 50% of the carbon content in the waste.
Recycling of plastic is in general environmentally favourable in comparison to landfill disposal or
incineration. However, some plastic types are not possible to recycle and some plastic is of such low
quality that it is not suitable for recycling. This paper focuses on the non-renewable and non-recyclable
plastic in MSW. A CO2 assessment has been made for non-recyclable plastic where incineration
with energy recovery has been compared to landfill disposal. In the assessment, consideration has been
taken of alternative fuel in the incinerator, emissions from waste treatment and avoided emissions from
heat and power supply. For landfill disposal of plastic the emissions of CO2 amounts to 253 g kg1
plastic. For incineration, depending on different discrete choices, the results vary from 673 g kg1 to
4605 g kg1. Results indicate that for typical Swedish and European conditions, incineration of plastics
has net emissions of greenhouse gases. These emissions are also in general higher for incineration
than for landfill disposal. However in situations where plastics are incinerated with high efficiency and
high electricity to heat ratios, and the heat and the electricity from incineration of plastics are replacing
heat and electricity in non-combined heat and power plants based on fossil fuels, incineration of plastics
can give a net negative contribution of greenhouse gases. The results suggest that efforts should be
made to increase recycling of plastics, direct incineration of plastics in places where it can be combusted
with high efficiency and high electricity-to-heat ratios where it is replacing fossil fuels, and reconsider
the present policies of avoiding landfill disposal of plastics.

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