Coal is seen today as the ugly sister of power sources: it is old-fashioned, dirty, costly to mine, and the most easily accessible supplies are close to exhaustion. But a research project could change that by offering a mining prospect that is safe, based on abundant resources, and promises clean fossil fuel energy for generations. And it would do that by igniting a coal seam deep underground.
© Euracoal, 2012
The project, Hydrogen-oriented Underground Coal Gasification for Europe (HUGE) and its follow-up programme is backed by nearly €3 million in European Union funding from the Research Fund for Coal & Steel. HUGE has brought together institutes, universities and mining companies from seven EU member states to study underground coal gasification (UCG), a technology that exploits coal seams up to half a kilometre underground - far too difficult to mine, and probably too expensive and dangerous as well.
UCG involves pumping oxygen and steam down a shaft to the seam where they react with the coal to form a mix of carbon dioxide, carbon monoxide, methane and hydrogen, known as syngas. The syngas is then brought to the surface where it is either burned to produce electricity, or turned into liquid fuel such as diesel. Meanwhile, ways to capture and store the CO2 emissions from the underground blaze are being investigated. Extracting energy in this way means fewer pollutants like carbon monoxide, soot and sulphur compared to burning coal in power plants and practically all the dust and dirt remains under the ground.
UCG is not new: the Soviet Union pioneered it in the 1920s, and a plant in Uzbekistan is still in use. What is new is cutting out the coal mining stage and doing the gasification underground. And thanks to new technologies like extraordinarily precise sideways drilling that can be kilometres long, it is now much easier and cheaper to reach deep coal seams. Combined, these innovations could make hard-to-reach coal deposits across the world available for the first time - including those beneath the sea - thus dramatically increasing Europe's exploitable coal reserves.
"UCG could add economical value to the mining process, and the pits themselves," says HUGE project coordinator Krzysztof Stanczyk, who works in the Polish Central Mining Institute (GIG), a government research centre. "Less coal would be wasted, energy output would increase and it would be produced in a more environmentally friendly way."
The first HUGE tests were held in Liège, in Belgium's mining heartland, where researchers simulated the interior of a coal mine, and tested how pressure and heat changes affected the outcome. This was followed by a trial 25 metres underground at the Barbara mining site, near Mikolów in Poland: around 22 tonnes of coal were gasified during the experiment at a rate of 50 kilograms per hour, while 269 gigajoules were generated by burning the syngas collected on the surface. "The idea seems simple but there are many challenges. Underground gasification cannot be controlled to the same extent as a surface process," says Stanczyk. "The trials helped us learn how to control the process safely and how to influence the quality of the gas."
Although HUGE initially ran until 2010, a three-year follow-up project, HUGE2, is running until 2014, with a focus on ironing out safety and environmental issues like toxic gas leakage and underground water contamination. Indeed, safety has been paramount in both projects: many dangerous and explosive gases are produced in UCG, and researchers have used a variety of technologies to check for leaks in the air and in the ground. The project is also looking at innovative applications of the hydrogen-rich syngas including as fuel for next generation electric cars.
Annual world consumption of coal today is more than 6.5 billion tonnes, but there are an estimated 5 trillion tonnes of otherwise inaccessible coal around the world. If HUGE succeeds, it could mean not only a new, clean form of energy, but also a new lease of life for Europe's struggling coal regions.