The WA government has pledged to slash its emissions by 80 per cent by 2030, while announcing details for the state's third desalination plant.
The target, which will be based on 2020 levels, applies to emissions from all government agencies across the state, including transport, health and education, as well as those generated by government trading enterprises.
Speaking at the announcement of a new desalination plant, Premier Mark McGowan confirmed the government would be investing $3.8 billion over the next decade in renewable energy.
"That will be both public and private to ensure that we can phase out of coal and head towards stored renewable energy, whether that's batteries, or pumped hydro or wind or solar," he said.
When asked why 2020 was chosen as the baseline measure, instead of an earlier date like other states have done, the WA Minister for Environment and Climate Action, Reece Whitby, said Western Australia's emissions had fallen since then.
"We've actually in fact set a harder, higher hurdle for ourselves as a government by (committing to) an 80 per cent reduction of 2020 [levels]," Mr Whitby said.
The government says the move provides a clear message that Western Australia is open for investment in renewable energy.
New desalination plant to be built in Alkimos
Mr McGowan also laid out details for the state's third seawater desalination plant, which is set to be built on land owned by the Water Corporation in Alkimos, a coastal area in Perth's northern suburbs.
To be built near an existing waste management plant, it will have a capacity of 100 billion litres a year and is expected to open in 2028, with $1.4 billion dollars already set aside for the project.
Admitting that desalination plants use a lot of energy, Mr McGowan said the new plant would be powered by wind.
Minister for Water Dave Kelly said this would help the Water Corporation go from being one of the largest emitters of greenhouse gases to reaching net zero by 2035.
The proponent to supply the 400 megawatts of wind power needed to run the plant has yet to be contracted.
Conservation Council of WA executive director Maggie Wood welcomed the announcement to cut emissions, saying it set a "solid foundation upon which action can be taken to address WA's emissions crisis".
But she pointed out the United Nations Intergovernmental Panel on Climate Change (IPCC) said there can be no new fossil fuel proposals or expansions "which does not sit well with the state government's support of new gas plants, including the highly controversial Woodside Scarborough development".
The government said the Energy Protection Agency (EPA) in WA was unique in requiring the big emitters to reach emissions reductions by 2030.
Mr Whitby said Woodside had already committed to reducing its emissions by 30 per cent by 2030, while the top five highest polluters were going through a process with the government and EPA now to work out a course to reduce their emissions.
"We're an energy intensive state, we have these industries, we can't simply flick a switch and make our emissions disappear, so it's a complex and difficult challenge but we are making great inroads," Mr Whitby said.
Last week the WA government announced it would shut down two coal-fired power stations in the south-west of the state by the end of 2029.
On Thursday, Mr McGowan said keeping coal-fired facilities going beyond this date would cost somewhere between $700 million and $1 billion and increase energy bills for users by around 1200 dollars a year.