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Everything you wanted to know about coal but were too afraid to ask
In an interview with the ABC 7:30 program, Australian Prime Minister Anthony Albanese claimed if Australia stopped producing and exporting coal, “what you would see is a replacement with coal from other countries that’s likely to produce higher emissions because of the quality of our product”.
It’s a line that’s been spruiked before by Australian leaders like former Prime Minister Malcolm Turnbull in 2015 and Scott Morrison in 2021.
What is coal anyway?
Coal is a type of sedimentary rock formed when plants and organic matter are put under heat and pressure over millions of years. Hence why we call it a “fossil fuel.”
Australia’s black coal resources date from up to 299 million years ago, while some brown coals are a recent as 23 million years ago.
Coal calling the kettle black
Forget fifty shades of grey, engineers and geologists have come up with almost as many names and ways of classifying this browny, black rock.
Let’s sort first by colour and carbon.
Geoscience Australia says coal ranges in colour from yellow through to pitch black. The level of shade and gloss corresponds carbon content ranging from 60 – 86%.
Peat – at under 60% carbon content, is an “almost-coal,” an organic sediment that looks like a clod of earth.
Brown coal (aka lignite) is 60 – 70% carbon and ranges from yellow to brown with a woody appearance.
Coal comes in three types of black.
The first, ‘sub-bituminous’ (aka black lignite) is dark brown to black (carbon content: 70 – 76%). The second ‘bituminous’ (aka soft coal, aka steam coal, aka rock coal) is around 76 – 86% carbon.
The third, blackest, and highest in carbon (more than 86%) is anthracite.
But wait, just when you’ve got your head around those categories there’s a whole other way of sorting things.
Coal calling
Another way of naming coal relates to how it’s used.
Any coal used in power stations is referred to as “thermal coal” and can be black or brown. . Despite progress on renewable energy, coal still fuels the majority of Australia’s electricity (59%).
Coal used in steel making is usually referred to as “coking coal.” It’s usually made from certain types of bituminous black coal which is then processed into a new type called ‘coke’ which has a higher share of carbon.
And just by-the-by “jet” is the fancy name for brown coal when its used as ornamental stone, while graphite is the type used in pencils.
Here’s a riddle: what can be washed, but is never really clean?
Pollution from burning coal can include carbon dioxide and other greenhouse gases, heavy metals (like mercury), particulates (like ash), nitrogen oxides (which are both greenhouse gases and components of photochemical smog) and sulphur dioxide (which can lead to acid rain).
So, does the quality or source of coal make a difference?
In terms of climate change, according to the International Energy Agency, coal is the largest source of greenhouse gas pollution.
Brown and black coal power stations produce different amounts of greenhouse gas pollution per unit of electricity. For example the Finkel Review found, a brown coal power station produces between 0.96 – 1.14 tonnes carbon dioxide and a black coal power station between 0.7 – 0.9 tonnes for each megawatt hour of electricity generated. Multiply this by a power station’s size and electricity output, and this results in a large amount of pollution. Loy Yang A power station for example emits around 19 million tonnes of carbon dioxide annually.
While burning lower quality coal (with higher ash or moisture content) could in theory reduce power station efficiency, resulting in more greenhouse gas pollution due to wasted energy, power station technology and age has a significant effect on emissions.
While some studies suggest Australian thermal coals may contain lower levels of certain elements, there is limited evidence to assess Albanese’s claim. Air pollution from coal power is also affected by many different factors including coal quality and composition, how it is mined, processed and transported, along with power station regulations and technologies (like filters).
Does Australia’s coal count?
Australia’s coal is a significant source of domestic and global emissions.
The IEA says Australia is the second largest exporter of coal globally, after Indonesia.
When Australia exports coal and other fossil fuels like oil and gas overseas, those fuels are ultimately burned and the resulting emissions are more than double Australia’s annual emissions.
In this context, discussing the relative merits of one type of polluting coal over another, is kind of missing the point. Particularly given the alternatives to coal – like renewable energy – produce power without these kinds of pollution.
That’s why the International Energy Agency says reaching ‘net zero’ emissions means: no new coal mines and no extensions from 2020, a global phase out of coal power by 2040 (and by 2030 in advanced economies like Australia), a 90 per cent decline in the total use of coal by 2050.
This article was originally published on Cosmos Magazine and was written by Petra Stock. Petra Stock has a degree in environmental engineering and a Masters in Journalism from University of Melbourne. She has previously worked as a climate and energy analyst.
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