Flames rise from the Pike River mine shaft. Photo / Mark Mitchell
In the wake of the Pike River tragedy, PhD student Jesse Dykstra blogs on the mining industry and the associated risks.
An Important Fossil Fuel
Coal is a rock that forms under intense pressure and high temperatures when plant material is buried under younger sediments over periods of millions of years. The resulting mineral has a very high concentration of carbon, and therefore is an important source of energy.
Coal is the most abundant fossil fuel on earth, with an estimated 900 billion tons of recoverable reserves. In fact, even with recent advancements of clean energy technologies (such as solar and wind), coal is still the single most important source of electricity on earth. Coal is abundant and relatively easy to extract because it tends to be concentrated in the earth.
However, using coal to generate electricity is a very dirty business. Coal mining releases greenhouse gases such as methane, and it is estimated that the burning of coal has produced nearly half of the carbon dioxide in our atmosphere.
Burning coal also produces nitrogen and sulphur dioxides which contribute to acid rain. Waste ash from burning coal contains high concentrations of toxic heavy metals such as mercury, lead, cadmium and arsenic, not to mention uranium and other radioactive nasties.
The United States has the largest coal reserves of any country, and is the largest consumer of electricity, both per capita, and in total consumption. The US generates nearly 50 per cent of its electricity from coal. Therefore it should not surprise anyone that the U.S., (also the largest emitter of greenhouse gases) has refused to commit to the emission reduction targets of the Kyoto protocol.
Source: OECD/IEA 2006
Carbon Capture and Storage
CCS has been touted as the answer to cleaning up coal, with the potential to reduce atmospheric CO2 emissions by up to 90 per cent. But CCS isn't actually working on a large scale-power plant anywhere, at least not yet. This is partly due to the added cost of post-combustion CCS. Compressing, transporting and storing CO2 is an energy intensive process, so up to 40% more coal would need to be burned to produce the same net energy. The additional infrastructure required for CCS also raises power plant costs, and uses more raw materials and energy in manufacture.
And the really big unknown is still the storage part. Scientific studies are currently underway on various options, including underground storage in suitable geological formations, storage in the deep oceans, or reacting CO2 with naturally abundant minerals such as Calcium to produce stable carbonates that stay out of the atmosphere. There are many ideas for pre-combustion and post-combustion CCS that are currently being investigated or trialled, and it will likely be years before practical cost-effective solutions become a reality, if ever.
Coal in New Zealand
At present, coal is mined in New Zealand primarily for overseas export. Coal from the West Coast (such as Pike River Coal) is some of the highest quality (most energy-dense) coal in the world, and is used in the steel industry, both in New Zealand, and overseas in places such as India and Japan. In New Zealand we are blessed with arguably "renewable" energy sources such as hydro and geothermal, and only 10 per cent of electricity currently comes from burning coal, compared to over 40 per cent worldwide.
Is Coal Mining Safe?
Coal mining involves unearthing some very volatile substances, and has therefore never been a particularly safe occupation. Miners must contend with deadly poisonous gases such as hydrogen sulphide, in addition to highly explosive gases such as methane that accompany coal underground. In 1896, 65 coal miners were killed by a methane explosion in the Bruner mine on the West Coast.
Modern technology and mining techniques certainly mitigate many of the risks, but coal mining continues to claim thousands of lives every year. China accounts for nearly 80% of the world's coal mining fatalities, including a 2005 methane explosion that killed a reported 210 people in Fuxin, Liaoning province. China has recently begun to focus on capturing coal bed methane prior to mining, using new drilling technology from Australia. In the meantime, an average of 15 workers die every day in Chinese coal mines.
Following the Pike River mining disaster, New Zealand must reconsider the cost, in human lives, of extracting our coal resources. When we look at data from the U.S. Mining Safety and Health Administration, it becomes apparent that mining has become much safer in recent decades, and that the number of fatalities amongst coal miners is around 20 per 100,000 workers. This is comparable to industries like fishing and logging.
What about in New Zealand? The latest work-related injury statistics that I could find were from a 1999 report that used data from 1985-1994 (citation). Hardly up to date information. Nonetheless, we can make a comparison to data from Australia and the US during similar time periods. The following chart is based on a 2001 article in the journal
Injury Prevention:
Based on that rather dated data, it appears that working in the mining industry in New Zealand is indeed a risky business. Over 50 fatalities per 100,000 workers, which is more than double the US rate. Of course, the actual number of people working in the mining industry in New Zealand at any given time is relatively small, and tragedies like Pike River grasp the attention of the nation.
Mining is an important industry in New Zealand, particularly on the West Coast, where mining holds its own against the mighty tourism and dairy industries. Mining is "in the blood" of many coasters. But do the economic rewards justify the bloodshed? Perhaps now is a good time for New Zealand to take a hard look at the long-term future of coal mining.
This country is blessed with an abundance of alternative energy sources, such as hydro, and geothermal, and while coal is an important export product, it isn't a major component of our current energy use. As a long-term alternative to coal (and gas), New Zealand has great potential to develop clean, renewable energy options, such as harnessing solar, wind and wave energy.
The high quality coal on the west coast is a valuable economic resource. There will always be an industry keen to extract it. And there are large deposits of
in Southland that Solid Energy would like to extract.
But in New Zealand today, I doubt that we want huge open pit mines plastered all over the West Coast, or the rolling farms of Southland. We prefer the idea of "precision" or "surgical" mining, that operates mostly underground, with minimal impact on the surrounding environment. We want the type of mining hyped by Energy and Resources Minister Gerry Brownlee, back when National thought that mining the Coromandel might be an idea palatable to New Zealanders. Sadly, the Pike River tragedy suggests that the technology required for precision mining in New Zealand doesn't exist yet.
Jesse Dykstra is a PhD student in the Natural Hazards Research Centre at Canterbury University. View his work and that of 30 other scientists and science writers at Sciblogs, New Zealand's largest science blogging network.
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