Burning Auckland’s waste to generate electricity using a waste-to-energy plant is fantasy, according to Warkworth energy analyst Steve Goldthorpe.
I do not like the idea of all of Auckland’s waste being put in my backyard. However, the waste must go somewhere. Waste Management have selected Wayby Valley as the location for the next Auckland Regional Landfill. Auckland Council cannot forbid a lawful activity, they can only prescribe expensive conditions of consent.
Kevin Smith, who represents waste-to-energy company USGIS in New Zealand, suggested in Mahurangi Matters (MM May 20) that landfilling would be unnecessary if waste is instead considered a source of energy. Unfortunately, that idealistic dream is not a practical prospect.
He estimated that the energy content of the 5000 tonnes per day of Auckland’s waste could be used to generate up to 250 megawatts of electricity. That would require all recyclable paper, cardboard, and plastic to remain in the mixed waste stream to provide a viable fuel. Also there would be a large quantity of residual ash for disposal, containing heavy metals and other contaminants.
A key problem with burning mixed waste is avoiding the formation of carcinogenic dioxins, which are created from chlorine and partly burned plastic as the products of combustion cool. That reaction is minimised by rapidly quenching the hot flue gas with water. However, quenching sacrifices high temperature heat that could make electricity, so only low temperature heat is produced. Successful waste-to-energy plants in northern Europe produce low temperature heat as hot water for district heating in built-up city areas. Auckland has neither the infrastructure nor the need for district heating.
A practical way of generating electricity from urban waste is using the methane gas produced in a landfill. A 12 megawatt power plant for this purpose is part of the Waste Management proposal.
Modern engineered landfill designs use a belt-and-braces approach to leachate management so that all liquid run-off is captured and processed on site. This approach is proposed by Waste Management. The commissioners at the resource consent hearings must ensure that stringent conditions and severe penalties are included in the resource consent conditions so that avoiding leachate leaks is top priority for Waste Management.
In my view, the most unacceptable adverse effect of the Waste Management proposal is trucking waste on State Highway 1 through the Dome Valley. This will cause hazardous road conditions, delays, road damage, truck driver shortages and 20,000 tonnes per year of carbon dioxide emissions (CO2). Moving waste by electrified rail, with the construction of a spur line direct to the landfill, is a no-brainer. That option would reduce the CO2 emissions by 95 per cent, avoid road traffic problems and would be cheaper than transporting the waste by road.
Meanwhile, the local community must require the hearing commissioners to impose strict consent conditions on Waste Management to ensure that all potential adverse environmental effects are avoided, remedied, or mitigated, as required by the Resource Management Act.
Steve Goldthorpe is a specialist in CO2 emission reduction technologies. He is the convenor of the Sustainable Energy Forum of Aotearoa.
By Steve Goldthorpe
Independent energy analyst
Still a chance for late landfill submissions
Nearly 1000 submissions have been lodged on plans by Waste Management NZ to develop a massive new regional landfill in the Dome Valley.
Auckland Council received 776 submissions on the resource consent application and 191 submissions on a plan change request to rezone 1000 hectares of farm and forestry land from rural production to a special landfill precinct. Late submissions can still be lodged until the end of July, providing people give a reason for the lateness.
Submissions will be reviewed and summarised, and all information collated into hearing reports, and commissioners appointed to run the resource consent and private plan change hearings, which are separate legal processes.