Speaking at the National Press Club on Wednesday, King said keeping gas affordable for households and businesses was a critical part of the scheme's primary focus.
"The truth is, it's hard to establish a date because we don't yet have the replacement for some of the industries that will need it," she said. "Right now, there is no replacement for gas. I am totally supportive of any kind of research or development that finds a replacement, whether it's just in lower emissions or alternative. But right now, and for the foreseeable future, that does not exist."
The national gas reservation scheme, expected to take effect from January 2028, will force gas companies to set aside 20% of exports for domestic use. It gives the Australian Energy Regulator the power to force companies to meet a target of 110% of projected demand each year, limits ministerial discretion and replaces the Turnbull-era domestic gas security mechanism.
King said the modest oversupply created by the reservation would put downward pressure on prices. "We expect the oversupply part of the reservation to put that modest oversupply into the system, which will push down those prices," she said.
The minister argued gas was central to heating homes, keeping manufacturing industries running, processing critical minerals and rare earths domestically, and supporting the rollout of renewables.
However, she did not put a price tag on the cost of gas under the proposal, as the former opposition leader Peter Dutton once did, nor predict when households and businesses would start to see that financial relief.