by Pat Lane, 2019
I have worked on the IT side of coal generation and mining in Victoria’s Latrobe Valley for many years.
The first time I visited a black-coal-fired power station, I looked around and asked “Where is everything?”
Brown coal stations are huge compared to their black coal cousins. There are two main reasons:
- Brown coal has very low energy content. Latrobe Valley brown coal has a Net Wet Specific Energy of between 5.8 and 11.5 MJ/Kg. By comparison, Bowen Basin black thermal coal has an energy content of around 25 MJ/Kg., two to four times more.
- The biggest difference between brown and black coal is moisture content. Brown coal can have as much as 70% moisture compared with black coal’s 8-10%.
I’ve heard brown coal described by station operators as “wet dirt”.
Before brown coal can be burnt, it has to undergo a fair amount of care and nurture. Here’s an abbreviated description of what goes on:
- Furnace flue gasses pass through a huge rotary air heater to pre-heat the air going into the coal drying shafts. The pre-heated air has to be hot enough to dry the coal, but not so hot as to set it on fire. That comes later.
- Brown coal is transported to the upper levels of the power station by conveyor to be fed into vertical drying shafts.
- The coal is dropped down the drying shafts and mixed with the pre-heated air to dry the coal.
- The dried coal hits big beater wheels in the coal mills at the bottoms of the drying shafts and it blown up into the furnace in the form of tiny particles of coal, called ‘p.f.’ for ‘particulate fuel’.
- The coal burns, radiating heat into boiler tubes embedded in the walls of the boiler, turning the water in the tubes into steam, the steam into rotary motion in the turbines and the rotary motion into electricity in the generators.
There is much more to this process, of course, but that’s general idea. In a black coal power station, most of the coal handling is much, much less complex and, hence, much, much smaller.
There are other complications, of course. I remember when the East Field Mine at Yallourn was first opened, mine employees found that there were seams of black sand running through the coal. A mining manager explained that “separating black sand from brown coal is like separating fly poop from pepper; it’s possible, but very labour intensive.”
So why go to all the trouble of mining brown coal? Again, there are two main reasons:
- It’s cheap. When I worked at Yallourn, the short-run marginal cost of generating one megawatt of electricity was $2.00. That’s cost of winning enough coal to make one megawatt. This doesn’t include capital costs of plant and equipment; just the operational costs. Latrobe Valley brown coal is relatively cheap to win because it’s near the surface. Very little overburden (surface dirt) needs to be removed before the coal is exposed. Once uncovered, there’s little contamination, bits of black sand notwithstanding.Two bucks is cheap. That’s why in the 1999 financial year, the average annual wholesale price of one MW of electricity in Victoria was among the cheapest in the world at just $24.51.
So far, for the 2019 financial year, it’s among the world’s most expensive at $111.30.
It’s not going to get cheaper anytime soon. The table below, compiled from information supplied by the Australian Energy Market Operator, compares usage, total and average price paid for New South Wales, Victoria and South Australia for the first 28 days of January 2019.
State Electricity usage (MWh) Total price paid Average price paid $/MWh New South Wales 11,936 million $687 million $57.34 Victoria 6,771 million $1,272 million $187.83 South Australia 2,002 million $385 million $192.26 Totals for 3 states 20,709 million $2,344 million
Analysis by The Australian on 30/1/2019 reveals that South Australia and Victoria together spent the nearly half of this total of this, $1.1 billion dollars, on just two days, the 24th and 29th of January.
No points for guessing which two of the three are the ‘greenest’ states.
In any case, a state like Victoria could make a nice down-payment on a new power station with the nearly $1.3 billion paid for wholesale generation so far this month.
I remember when Yallourn Energy was sold in April, 1996, it went for $2.4 billion, near enough to the monthly bill for just these three states.
- The other reason brown coal is a good fuel for generating electricity? There’s heaps of it. Geoscience Australia estimates 43 Giga-tonnes (Gt) of ‘Economic’ reserves of brown coal in Victoria. In 2013-2014, the Victorian electricity industry used approximately 57.8 Mt. At that rate of usage, there’s enough for another 754 years.
Victorian brown coal is an amazing asset for the State of Victoria and for Australia generally. It’s cheap, plentiful and provides the 24×7 reliable electricity that consumers and businesses have enjoyed since the 1920s.
Unfortunately, brown coal is being vilified by activists with a range of agendas, none of which are favourable to either business or to ordinary Australians. Even more unfortunately, our politicians are too weak to even question the propaganda and have jumped on the bandwagon.
Coal royalties collected by the Victorian State government were tripled in January 2017 and undoubtedly had an influence on the decision to close Hazelwood Power station by the owners.
Along with bans on gas exploration, subsidies for so called ‘renewable’ energy sources and accelerating costs for energy, governments at both the state and federal level appear determined to shut down Australian industry, make electricity unaffordable to consumers and to make the once reliable supply subject to the whims of wind and weather.
All of this pain produces no measurable economic or environmental gain.
Meanwhile Yallourn, Loy Yang ‘A’ and Loy Yang ‘B’ will continue to provide reliable baseload supply for Victoria and Eastern Australia.
When they reach the end of their useful lives and are replaced with more windmills and solar gizmos, we’ll step outside on a windless night and ask the same question I posed earlier: “Where is everything?”