The mayor's office has published a report entitled “Greenhouse gas balances of waste management scenarios” which compares 24 waste treatment methods in terms of their impact on climate change, using life cycle analysis.
Some of these technologies have a very chequered record in terms of performance and there clearly needs to be a proven track record.
Paul Frith, Be Environmental
Written by consultants Eunomia and EnviroCentre, the report claims that new waste treatment technologies can deliver “far lower” greenhouse gas emissions than conventional incineration or landfill.
In particular, it ranks mechanical biological treatment followed by anaerobic digestion and gasification following by autoclaving, coupled with hydrogen fuel cell technology, above other technologies.
The findings were unveiled at the ACR+ international conference on waste and climate change last week by the GLA's head of environment Shirley Rodrigues, in support of London mayor Ken Livingstone's long-established support for new technologies and objection to mass-burn incineration.
Ms Rodrigues explained that the study would be used to inform the mayor's revised Municipal Waste Management Strategy.
She said: “The key findings are that we need to move away from outdated waste disposal methods….gasifiaction and anaerobic digestion are much better options that incineration and landfill.”
She added: “In our view the mayor's preference for new technologies are confirmed by this report. The lessons of this report provide a compelling argument in how we review our waste strategy.”
However, Paul Frith, director of consultants Be Environmental, questioned whether the technologies in question were necessarily proven.
He said: “Some of these technologies have a very chequered record in terms of performance and there clearly needs to be a proven track record where a substantial amount of public money will be invested.”
Mr Frith claimed that problems included some gasification and pyrolysis technology having efficiency rates as low as 10% and that some digestate from anaerobic digestion was not beneficial for spreading on land.
Proven
In the report itself, Eunomia and EnviroCentre stressed that their work did not take into account the full context of waste treatment scenarios, but focused wholly on climate change. The authors also acknowledged that technologies such as waste autolaves and hydrogen fuel cell technology was not fully proven and developed in the UK.
The report said: “This report does not seek to analyse financial viability, but it should be noted in this context that scenarious coupling MBT (AD with maturation) with gas engines (in CHP mode) or with biogas-fuelled vehicles, are the highest ranking configurations which might currently by affordable to local authorities.”
It added: “Currently an under-exploited approach across the UK, the GLA could bring together and integrate related research into specific planning and cost analysis to bring upon the results of this study and promote the development of best-of-breed MBT (AD with maturation)m facilities across the city.”
However, the greenhouse gas balance study stressed that recycling materials such as plastics made a “considerable” difference to greenhouse gas balances by avoiding emissions from virgin manufacturing processes -providing an argument against incineration.
It said: “Incineration with CHP reaches a high of only 15th place in the scenario rankings. The other two incineration scenarios fare worse still, and no not emerge until the bottom six positions. This poor performance is largely the result of wholesale combustion of plastics, which results in significant CO2 emissions. On this basis, unless couples with both significant kerbside recycling programmes and clear provisions for good quality CHP, the GLA position regarding mass-burn incineration within London receives some qualified support.”
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