As Australians across the eastern seaboard grapple with rising energy costs, unexpected outages at a handful of Queensland's coal-fired power stations have been cited as part of the problem.
Queensland Energy Minister Mick de Brenni this week told ABC Radio Brisbane that while there was no shortage of energy supply, the market cost was the real issue.
"We do have here in Queensland those prevailing global circumstances impacting on electricity prices," Mr de Brenni said.
How many coal-fired power stations are in Queensland?
Queensland's eight coal-fired power stations are dotted across the southern corner of the state, from Rockhampton to west of Toowoomba.
They are supplemented by a host of renewable energy projects, and gas power stations including Swanbank E, which is currently offline.
State-owned Stanwell Power Station is at Rockhampton. The 1,460-megawatt subcritical station is fed by Curragh Mine, and is scheduled to close between 2043-2046.
Queensland also owns the two Tarong Power Stations in the South Burnett. Both the sub-critical 1,400-megawatt Tarong Power Station and the supercritical Tarong North, a single 443-megawatt unit, are expected to close in 2036-37.
Queensland's oldest and largest coal-fired power station is the subcritical Gladstone Power Station, commissioned in 1976 and owned by NRG Gladstone Operating Services.
The 1,680-megawatt Gladstone Power Station has six units, fed from Rolleston coal mine, 200 kilometres west of Rockhampton. It is scheduled to close in 2035.
Callide B and C subcritical power stations, close to Biloela, are owned by CS Energy – also fully owned by the state government. Callide B was commissioned in 1988, and Callide C in 2001.
The 740-megawatt Callide B is scheduled to close in 2028, but a closure date for the 840-megawatt Callide C has not yet been submitted. Both stations are fed by the nearby Callide Mine.
CS Energy also owns Kogan Creek supercritical power station, a 750-megawatt station near Chinchilla. It is also one of Queensland's youngest, commissioned in 2007.
Kogan Creek has Australia's largest single generating unit and, CS Energy says, has the lowest environmental impacts of coal power stations nationally. Kogan Creek is fed by the nearby Kogan Creek mine, and is slated to close in 2042.
West of Toowoomba, supercritical Millmerran Power Station has operated since 2003 and has an 852-megawatt capacity. It's owned by global power company InterGen.
Millmerran is scheduled to close in 2051.
How many are currently operating?
Last year, unit 4 at the Callide C power station exploded, triggering mass power outages across Queensland.
That unit won't be back online until April next year, operator CS Energy says.
Mr de Brenni said there had also been "minor" outages at Stanwell Power Station, compounded by gas station Swanbank E's outages.
Stanwell is also slated for major maintenance between June 26 and August 22 this year.
Tarong Power Station is then due for major maintenance between September 9 and October 21.
In 2020, the Australia Institute's Climate and Energy program released a study showing Queensland's gas and coal-fired power stations had 93 unplanned breakdowns between December 2017 and December 2019, out of 227 total breakdowns nationally.
Are we building new coal power stations?
Two proposals for new coal-fired power stations in Queensland still have significant question marks over them.
Clive Palmer's Waratah Coal wants to build a new $3.5 billion, 1,400-megawatt power station in the Galilee Basin. The proposal was called in by Deputy Premier Steven Miles last year.
Another proposed 1,000-megawatt power station in Collinsville, west of Airlie Beach, was awarded several million by the former Coalition federal government for feasibility studies.
The Collinsville plan was put forward by Shine Energy, a company owned by local traditional owners.
The new federal Labor government has not yet made any indications whether it will offer any further support to the project.
How much pollution do they emit?
The Clean Energy Regulator releases annual data on electricity sector emissions.
Queensland reported the highest amount of scope 1 emissions of all the states and territories in 2020-21, clocking up 29.1 per cent of emissions nationally – and also the highest net energy consumption.
Greenhouse gases are calculated through a single unit – "t CO2-e". This means a metric tonne (t) of carbon-dioxide equivalent (CO2-e) and covers all greenhouse gases.
Across 2021-22, Gladstone Power Station produced 6,324,885 tonnes of carbon dioxide equivalent gasses across the year, while producing 6,420,666 megawatt hours of electricity.
Millmerran Power Station produced 5,261,560 tonnes of CO2e and 6,341,418.775 megawatt hours of electricity.
Stanwell Power Station emitted 6,921,944 tonnes of CO2e, and 8,144,139.93 megawatt hours.
The two Tarong Power Stations produced 10,686,422 tonnes of CO2e, and 11,983,433 megawatt hours, while Kogan Creek emitted 4,370,999 tonnes of CO2e and generated 5,119,046.04 megawatt hours.
Callide B emitted 3,017,832 tonnes of CO2e, and Callide C 4,578,614 tonnes.
Over the year, Callide B produced 3,143,613.08 megawatt hours, while Callide C produced 5,057,212.701 megawatt hours.
What's the future for Queensland's energy?
A few years ago, new coal mines were being touted throughout Queensland's Galilee Basin.
Now, both governments and corporations are actively moving toward hydro, battery storage, wind, solar and other renewable energies - even as coal prices reach record highs and exports boom.
The Queensland government has set a target of 50 per cent renewables by 2030, and a net zero target by 2050.
As of January this year, 20.4 per cent of the state's electricity was produced by renewable energy sources.
But Energy Minister Mick de Brenni said no coal-fired power stations would be closed as part of the state's yet to be released 10-year energy transition plan.
On Friday, Premier Annastacia Palaszczuk announced another $35 million to find a second pumped hydro location.
And this week, for the first time after the federal election, the nation's energy ministers met to discuss the energy industry's skyrocketing prices.
The communique published after the meeting directly referenced a "new era of cooperation and collaboration" and noted the Ministers decided it was time to work on a new agreement "to set the vision for Australia's energy sector transition to net zero".
