Malcolm Turnbull has used Tony Abbott's own words to explain why the government won't back the former prime minister's call to drop the renewable energy target.
Mr Turnbull noted the RET was cut from 27 per cent to 23 per cent when it was "restructured" under Mr Abbott's leadership just 18 months ago.
"As he said at the time, it created certainty for investment in the renewable energy space," the prime minister told reporters in Canberra on Monday.
"It was very important that that certainty be maintained.
"We're committed to the renewable energy target as restructured at the time and it will not be changed."
Mr Abbott told a Young Liberals conference at the weekend the government's first big fight of the year should be stopping further mandatory use of renewable power.
Building on remarks he made earlier in January, Mr Abbott said the past year had shown what happens when mainstream parties lose touch with their supporters.
"The public are not mugs. We can't credibly attack Labor merely for being worse than us," he was reported as saying.
Mr Abbott claimed Labor's aspirational target of 50 per cent would cost households $5000 against the $1000 impost from coalition policies.
Opposition energy spokesman Mark Butler says Mr Abbott's sniping showed a revenge obsession with Mr Turnbull, while the Greens said the prime minister had to put his predecessor in his place.
"The best thing the prime minister could do to put Tony Abbott back in his box is expand the RET, not cut it," Greens energy spokesman Adam Bandt said.
The sniping over the RET comes as new research finds upgrading Australia's coal-fired power stations to cut emissions would cost up to $38 billion more than making the same reductions with renewable energy.
Ministers in recent weeks have been extolling the benefits of ultra supercritical coal-fired power stations.
But Dylan McConnell, from Melbourne University's Climate and Energy College, says their price tag is astronomical compared with renewables.
Federal government figures estimate switching Australia's coal power generators to the new, cleaner technology could cut emissions from the electricity sector by 27 per cent.
Mr McConnell calculates this would require 20 gigawatts worth of ultra supercritical coal power stations, costing $62 billion.
Achieving the same cut in emissions using new renewable energy generators would cost between $24 billion and $34 billion.
"Replacing Australia's current ageing coal fleet with newer models to cut emissions is possible, but the question is why anyone would choose to do so given the lack of cost-competitiveness," Mr McConnell said.
