‘Clean coal’ is like a unicorn. It’s nothing but a pretty fantasy.
In a desperate effort to be able to proceed with massive coal mining developments in the face of climate change, fossil fuel companies are developing a series of experimental technologies that they claim will produce ‘clean coal’.
Brown Coal Drying
Victorian coal deposits are made up primarily of brown coal, which is significantly less efficient to burn than black coal. It has a high water content, is expensive to transport and is prone to spontaneously explode. It also emits 37 % more carbon dioxide than black coal.
So-called ‘clean coal’ involves drying the brown coal, which make it as ‘efficient’ as black coal and enables it to be exported. However the drying process is incredibly carbon intensive, so despite there being fewer emissions when burnt overseas, it makes no real difference overall. Also, there is no evidence anywhere that this technology has been scientifically tested or independently verified. Most importantly, the term ‘clean coal’ is an almighty oxymoron, given that the emissions, pollution and health impacts from black coal are still incredibly damaging.
Other clean coal techniques involve converting it to other fuel forms, or by trying to catch the pollution out of the air after the coal has been burnt.
Underground coal gasification
Underground coal gasification was first developed to cheaply collect coal that is too expensive to mine, either because it is too deep, too low grade, or simply because there is not enough coal in the coal seam.
The basic model involves two shafts. The first one pumps air into the seam, which causes the coal to oxidise, which is essentially the same process as rusting. There is a reaction which creates heat, causing the coal seam to burn at an extremely high temperature, which then turns into syngas. The gas flows up the second pipe where it is collected and used as a fuel or for various industrial processes.
The process releases a mass of toxic and carcinogenic tars, and has potential to contaminate as well as drastically reduce any nearby water sources. The most recent underground coal gasification plant was in El Tremedal, Spain, which resulted in an underground explosion and a mass of toxic waste being plastered across the area.
Although industry claims it has a small carbon footprint, syngas is still a fossil fuel and still contributes to global warming an unacceptably large amount. A lot of gas escapes the seam without going up the pipe and can be found in waterways and leaking into the atmosphere. Some estimates actually put coal gasification plants as 67% more carbon-intensive than a brown coal plant.
Carbon Capture and sequestration
Carbon capture and sequestration or CCS basically involves collecting the carbon dioxide exhausts from fossil fuel power stations, and storing it underground. This technology does not yet exist in any well-rounded way. There are a number of experimental CCS plants in the USA, Canada, Norway and one in Algeria. However industry groups are already holding it up as a ready-made solution to climate change.
CCS technology is doomed to fail. Storing gas underground is incredibly difficult, and extremely prone to leakage. It doesn’t matter how much carbon we sequester if it can all come rushing back out into the atmosphere at any time. Industry suggests we start pumping carbon dioxide into the oceans – a process that will lead to ocean acidification, resulting in the loss of more species and an increased rate of sea level rise. It is also likely that CCS will be economically unviable as capture and storage is estimated to increase electricity consumption of power stations by 20 – 40%.