EMISSIONS from Latrobe Valley brown coal power stations have fallen in the past year, continuing the trend of the past five and 10 years, the latest release of data from the National Pollutant Inventory (NPI) has found.

Mercury emissions from the Valley’s power stations fell by 20 per cent from 2021-22 to 2022-23, NPI showed.

In the past year, noxious oxide emissions were down by 1.8 per cent, while fine particulates – particles 2.5 micros or less in diameter (PM2.5) – fell by 8.4 per cent. Human hair is about 100 microns, so 40 fine particles could be placed on its width.

Similarly, PM10 – particulates 10 microns or less in diameter – were down by 4.2 per cent, while sulphur dioxide emissions fell by 11.3 per cent.

These results continued a long-term decline in Victorian emissions. The five and 10-year trends for the various categories were respectively: mercury minus 17.2 per cent and minus 42.2 per cent, noxious oxides minus 13 per cent and Minus 47.9 per cent, PM10 zero and minus 26.5 per cent, Pm2.5 minus 10.5 per cent and minus 58.1 per cent, and sulphur dioxide down 4.1 per cent and down 23.3 per cent.

Nationally, the NPI data showed a fall in fine particulate emissions from coal-fired power stations, while all other emissions also decreased when compared with the 2021-22 data.

The PM2.5 emissions fell 3.7 per cent and have fallen 20.1 per cent over the last five years and by nearly 38.3 per cent over the past decade. PM10 emissions decreased by almost 5 per cent (4.9 per cent) when compared to last year and were down almost 15 per cent (14.9 per cent) and 19 per cent (19.1 per cent) over the past five and 10 years respectively.

In other results, NOx emissions reduced by almost six per cent (5.9 per cent), the fifth consecutive year of reported reductions. SO2 dropped by more than seven per cent (7.3 per cent) after a slight increase last year. All emissions have decreased significantly over the past decade.

The most notable decline was in mercury emissions, which were 9.3 per cent lower year-on-year. This follows an unexpected increase last year of almost 11 per cent after four consecutive years of decreases. Mercury emissions are now down more than 10 per cent over the past five years and down 25 per cent in the last decade.

An Australian Energy Council spokesperson said this year’s results were positive.

“We should expect to see overall levels continue to fall over the next few years. A range of factors can result in noticeable shifts in emissions, particularly year-on-year, such as demand and availability of plant,” they said.

“Plant performance will also depend on how often they are dispatched by the market operator, changes in the operations of the plant, and the quality of the coal used.”

Some individual plants have shown abnormal year-to-year variations as a result of variability in individual plant performances, however the critical data remains the overall sector trend, which continues to be positive.

Last year, coal-fired plants across Australia accounted for 63.4 per cent of generation, a decrease of more than 0.6 per cent on 2021-22.

“It’s important to note that for many of the important emissions, electricity is not the main contributor,” the NPI found.

“The latest annual NSW Air Quality Statement showed that the state saw a decline in its air quality last year, with PM2.5 and PM10 levels increasing on 2022 levels in most locations.”

While large industrial emissions, including power plants, are often cited as the key source of air pollution, this latest NSW report shows the principal factor in the air quality results was variations in natural sources as a result of weather patterns.

“The most common causes of particulate matters in NSW are natural sources, which are not included in the National Pollutant Inventory Data. The 2022 Sydney Air Quality study found 52 per cent of PM2.5 particles came from natural sources, such as windblown dust and bushfires,” the NPI report continued.

“Of the 48 per cent of man-made emissions, 42 per cent came from wood heaters, 21 per cent from industry, 17 per cent from road transport and seven per cent from power stations, which is a decrease of 10 per cent on 2020 levels.

“Importantly, the NPI data and the NSW Air Quality Study shows, coal-fired emissions continue to trend downwards year-on-year, and this can be expected to continue as more renewable energy is added to the grid’s generation mix.

The Australian Energy Council is the peak industry body for electricity and downstream natural gas businesses operating in the competitive wholesale and retail energy markets.

AEC members generate and sell energy to 10 million homes and businesses and are major investors in renewable energy generation.

The AEC supports reaching net-zero by 2050 as well as a 55 per cent emissions reduction target.