Bill Shorten insists a plan to force commonwealth agencies to run on 50 per cent renewable energy will have no net cost.
But the opposition leader won't say if the policy has been costed, relying on a government-commissioned report that found renewable energy puts downward pressure on power prices.
He's also banking on technology getting cheaper before 2030.
"There'll be no net cost," Mr Shorten told reporters in Sydney on Thursday.
"I know if you want an economic plan you've got to have a plan for climate change."
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Mr Shorten repeatedly side-stepped questions on whether Labor had costed the plan to sign 10 to 15 year power purchase agreements with energy companies to buy renewables.
"It's called leadership," he said.
The agreements would equal half the volume of commonwealth agency power bills by 2030.
Mr Shorten referenced an Abbott-government initiated review into the Renewable Energy Target - which recommended the policy be pared back - as proof there would be no net cost.
The RET was subsequently slashed from 41,000 gigawatt hours to 33,500 by 2020, after a lengthy stand-off between the coalition and Labor.
Investment in the sector fell 88 per cent last year as a result.
Labor wants half of all Australian energy to come from renewables by 2030, while the coalition is yet to reveal a goal past 2020.
Many commonwealth services were in the ACT, which was already sourcing renewable energy, Mr Shorten said.
