The Nature Conservation Council of NSW has opposed a planned $400 million gas-fired power station near Newcastle, arguing it will emit up to half a million cars' worth of greenhouse gas emissions a year.
The Department of Planning, Industry and Environment is assessing the proposed AGL plant at Tomago, which would offset the closure of its coal-fired Liddell power station in 2022-23.
The power giant says it is investing heavily in renewable energy but needs the 250-megawatt Newcastle Power Station to provide rapidly dispatchable electricity in times of peak demand.
AGL says it intends to run the power station, under a "base-case" scenario, as a "peaking plant" to be turned on only in times of need.
Its environmental impact statement says the plant is designed to operate continuously under a "worst-case" scenario if "requisite circumstances arise in the National Electricity Market".
The EIS says that, under the base case, the plant would run for five hours a day in summer, eight hours a day in winter and not at all in spring and autumn. It estimates the plant will emit 220,000 tonnes of greenhouse gas emissions as a peaking plant and seven times that amount if it runs continuously.
The Nature Conservation Council, a peak body representing green groups, has called on the DPIE to establish how the plant will operate "so the full impact of the proposal can be assessed".
"Estimated emissions from the plant range between 220,000 tonnes (equivalent to 70,740 cars) and 1.6 million tonnes (equivalent to 514,469 cars) of greenhouse gas emissions a year, depending on whether it operates as a peaking plant or continuously," the council's chief executive, Chris Gambian, says in a written submission on the proposal.
"[DPIE] should recognise the role gas and diesel play in contributing to climate change and reject this proposal."
AGL says in a response to public submissions on the EIS that it is focused on developing flexible supply from new technology sources to support the transition to a low-emissions energy.
"AGL are the largest private investor in renewable energy ... having committed to a $1.9 billion development pipeline which includes wind, solar, hydro, gas, battery storage and improvements to the efficiency of their existing thermal generation," it says.
Newcastle Airport says in its submission that it supports the proposal but is concerned the exhaust plume from the power station will disrupt airspace "at a dangerous vertical velocity".
"The potential to impact on airspace adjacent to an aerodrome is a significant matter in respect of public safety and therefore should be mitigated as far as is reasonably practical," it says.
It has asked AGL to choose reciprocating engines as its preferred power-generating technology as these will have the least impact on aviation.
AGL hopes to start construction of the power station in early 2021 and have it operating in 2022.