Pledges by Victoria’s conservative opposition parties to review or roll back major energy policies of the present state Labor government would likely push up electricity prices by billions of dollars and require years to reset, renewable energy advocates say.

Stephanie Bashir, chief executive of Nexa Advisory, said household and businesses would pay significantly more for electricity if the government’s major transmission projects – VNI-West and the Western Renewables Link – were torn up as part of retreat from renewables.

“If we do rely on gas and expensive generation as a backup because we’ve cancelled or are delaying renewables, we will end up with a $33 billion additional cost in wholesale [power prices] for Victoria alone,” Bashir told journalists in a Monday seminar organised by the Smart Energy Council and the Climate Media Centre.

“So staying the course is really critical in Victoria,” said Bashir, formerly a senior director, public policy, at AGL.

Tennant Reed, director for climate change and energy at the Australian Industry Group, said developing alternative supplies of energy for the state would not be easy, particularly as power demand was rising rapidly.