An advanced waste treatment system could see 90 per cent of rubbish destined for landfill turned into gas.

14 May 2014 — The City of Sydney is planning to convert non-recyclable household waste into gas suitable for the supply network, a new draft waste management master plan will reveal on Thursday.

The strategy, which involves the construction of an advanced waste treatment plant, would see more than 90 per cent of waste destined for landfill converted to gas.

Currently, the City recycles 68 per cent of household waste, with the rest going to landfill at a large cost to consumers and the environment. Waste levies are now more $100 a tonne, and landfill gate fees are $270 to $300 a tonne, expected to rise to $400 a tonne by 2030.

Landfill is also a large source of methane, a greenhouse gas with 25 times the global warming potential of carbon dioxide. Adding to the emissions toll, trucks must currently drive 250 kilometres to dump at the nearest landfill.

Speaking to The Fifth Estate ahead of the plan’s release, City of Sydney manager sustainability Chris Derksema said the proposal would take non-recyclable solid waste destined for landfill, turn it into gas using a gasification process then upgrade it to create substitute natural gases for the city’s buildings, a move that could integrate with trigeneration plants to provide local electricity, heating and cooling.

Typically with gasification plants, solids are converted into a gas that is then combusted onsite to generate electricity.

“We’re suggesting instead of combusting gas we upgrade it into gas suitable for pipelines,” Mr Derksema said.

Chris Derksema

Multiple scales being investigated

A number of scales were being investigated, Mr Derksema said, which would be dependent on stakeholder feedback. If only the City’s residential waste were to be used, 0.38 petajoules of energy could be produced through the waste treatment plant. This would be around nine per cent of household gas demand in 2030. At this scale, all council’s operations could be powered by the gas.

However, if commercial and industrial waste were included – which includes a lot of composite building materials currently unable to be recycled – the amount of energy produced could rise to 1.62PJ a year.

Another ambitious option would be to include the Southern Sydney Regional Organisation of Councils in the plan. These 16 councils, servicing 1.2 million people, could bolster the gas energy up to 3.1PJ a year, which would almost cover the City’s entire domestic gas demand in 2030.

Mr Derksema said the City had conferred with the SSROC as part of a regional waste strategy being developed with the Environmental Protection Authority, and discussions were continuing.

The cost of the plan would depend on the scale decided, however, Mr Derksema said that financial analysis showed it could be done at around the same cost as current waste treatment programs, but with better environmental outcomes.

The financial case continues to improve, Mr Derksema said, as waste levies increase and the price of wholesale gas rockets, which would mean a larger income stream going to the City from gas that could be sold into the wholesale market or even straight to large users, such as buildings with trigen systems in the CBD.

The City of Sydney’s annual waste generation by source

Move would save ratepayers money

Lord Mayor Clover Moore said the technology would save ratepayers around $3.9 million a year by avoiding waste levy costs, and – at the residential waste scale – prevent 190,000 tonnes of greenhouse gas emissions.

“Our residents have done a terrific job of recycling and we’ve already met our target to divert two-thirds of household waste from landfill,” Ms Moore said.

“Currently over 40,000 tonnes of household rubbish a year is processed to remove recyclables and produce low-grade compost but one-third of waste still goes to landfill. The advanced waste treatment plant could reduce this amount to virtually nothing.

“If we don’t try to reduce our waste, by 2030 the household waste of city residents is predicted to grow to 80,000 tonnes. This means after recycling and treatment, 27,000 tonnes of non-recyclable household waste would end up in landfill – equivalent to the weight of a cruise ship.”

At current rates, all current landfills are expected to reach capacity by 2021. Under the plan, around 90 per cent of non-recyclable waste currently heading to landfill would instead be turned into gas.

Ms Moore said that an advanced waste treatment plant was a “viable solution” already used in other cities around the world, including Ottawa in Canada, Lahti in Finland and Chiba City in Japan.

The council would not be the owner/operator of the plant, with the City having to go to the marketplace to procure the needed services, Mr Derksema said.

The plant would be located in an industrial area that also had access to a pipeline able to handle the amount of gas produced, however no site had yet been chosen.

Air quality

There was little concern the plant would cause air quality issues, with Mr Derksema telling The Fifth Estate that similar plants internationally adhered to the EU directive on air quality, and exceeded standards in many instances.

The City hasn’t put a timeline on the project, however Mr Derksema said that history dictated that a best-case scenario would have the project up and running in three years, though five years was a more likely timeframe.

The plan will be revealed on Thursday at a stakeholder briefing and put on display for public comment from 15 May to 25 June. It will be available for viewing and feedback at www.sydneyyoursay.com.au