The Coalition's need to close an energy supply gap triggered by Peter Dutton's plan for a late 2030s transition to nuclear power and curbs on future renewables would require a $70 billion gas expansion equivalent to five times current annual domestic and export production.

Fresh analysis to be released by the federal government on Thursday calculates the opposition's plan — which Mr Dutton said this week would ensure gas becomes a major feature of the energy grid — would boost emissions by 325 million tonnes through to 2035.

Labor's figures come as the Coalition has repeatedly delayed the release of modelling for its nuclear and energy policy.

Having previously signalled it would publish details during the mid-winter parliamentary break, and then in the lead-up to Christmas, Mr Dutton this week said it would be published "in due course, at a time of our choosing".

The Coalition promises to build seven nuclear reactors on decommissioned coal power sites, that are expected to open for business during the second half of the 2030s.

Mr Dutton argues that would then enable him to scrap Labor's commitment to erect 28,000 kilometres of new transmission lines, which he said on Monday would "rip up agricultural land and national parks".

In turn, the dearth of new transmission capacity would result in fewer solar and wind projects, expanding a forecast shortfall in electricity production as aging coal assets close.

Labor says gas supply gap will widen under Coalition plan

According to the government's Future Gas Strategy, Australia currently has a projected gas supply shortfall between 2027 and 2035 of 3,302 petajoules (PJ). For context, annual production for both domestic use and offshore shipments is expected to be about 1,977 PJs this year.

Under the Coalition's plan, Labor said, Australia's cumulative gas supply gap would widen to 9,383 PJs.

Between now and 2035 — during which time the Australian Energy Market Operator (AEMO) forecasts a 50 per cent increase in energy demand and a series of coal closures — the Coalition's freeze on utility-level renewables and halts on transmission infrastructure will create an east coast energy supply shortfall of 860 terrawatt hours (TWh). 

Annual electricity use across the National Electricity Market (NEM) last financial year was 188 TWh.

Energy Minister Chris Bowen said gas has a significant role to play in the future energy grid, but at nowhere near the scale the Coalition is proposing.

"Under our plan, [gas-fired power plants] will be there in reserve and be turned on increasingly less frequently," he told the ABC.

"Under their plan, with much less renewables in the system, they would have to rely on that gas a lot, lot more.

"That's bad for emissions, bad for costs and bad for reliability."

Shadow energy spokesman Ted O'Brien said the nation's energy grid was in "deep trouble".

"He's using government resources to attack a policy of the opposition which hasn't been released," Mr O'Brien said. 

"Meanwhile, prices are soaring, there's a threat of blackouts and emissions are rising."

Mr O'Brien reiterated that his plan remains for the Coalition to release the economics of his plan before Christmas.

Coalition to expand gas usage

Shadow resources minister Susan McDonald confirmed last week there would be a significant expansion in gas usage under a future Coalition government, which would seek to incentivise more exploration and production.

In exchange for the green light, the opposition says it will insist gas giants put aside enough gas for expanded domestic use.

"The Coalition sees a clear future for the gas sector and we are determined to bring more of our abundant gas reserves into the market," she told a conference in Darwin.

Labor has seized on the lack of detail in the Coalition's nuclear policy to work up its own analysis of the consequences using regulatory and departmental figures.

Meeting energy demand via an extra 6,081PJs of gas would cost $14.4 billion for new power plants, $2.3 billion in other costs and $53 billion in gas bills, according to the analysis. Those figures do not include the cost of additional pipelines that would be required.

Former chair of the Australian Competition and Consumer Commission, Rod Sims, said there was little doubt increasing reliance on gas would push up prices.

"If you replace aging coal-fired power stations with gas to do the sort of job that coal-fired power stations have been doing, then unquestionably, you're going to see power prices increase," he said.