The proposal was discussed by Australia’s federal and state energy ministers in Sydney on 10 August.
According to local media reports, the NEG policy received "broad support" from the state level ministers but changes need to be made in order for it to be fully backed.
Following the negotiations, CEC chief executive Kane Thornton said the policy had potential if the emissions target was increased and other concerns were addressed.
Thornton had previously said the proposed emissions objective would be met by the Renewable Energy Target (RET) — Australia’s existing energy policy — and that therefore the NEG would be "essentially useless".
"The NEG is a complex reform that requires careful consideration and design," Thornton said.
"Many of the conditions proposed… are reasonable and are supported by the clean energy industry, including the call for more frequent reviews and the inclusion of a mechanism that prevents the emissions reduction target being cut in the future.
"We call on the federal government and all state and territories to keep cool heads and negotiate in good faith to find a compromise that will provide the long-term investment certainty needed to deliver new clean energy generation," he added.
The NEG was unveiled by Malcolm Turnbull’s government in October 2017, instead of backing the clean energy target, put forward by the nation’s chief scientist Alan Finkel.
The guarantee is a technology neutral system that removes support or tax "creating a level playing field for all energy sources", according to the government.
It consists of two parts: a reliability guarantee that requires utilities to ensure the correct level of dispatchable energy; and an emissions guarantee to contribute towards the country’s international commitments.
Among the CEC’s recommendations to reform the NEG, it suggested including a "backstop" to prevent moves to decrease the emissions reduction target in the future.
The CEC also suggests omitting storage projects from the reliability obligation "given the significant role energy storage plays in supporting reliability".