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Sydney’s household waste to be converted to gas in ambitious plan

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.

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.

Continue reading here on how the move could save ratepayers money.

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