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A SOUTH African gold mining firm trying to cut carbon emissions and costs and improve the health of its workers could be the first globally to fuel trains with biogenic gas formed over millennia deep beneath the ground.

Molopo South Africa which holds the country’s first and so far only onshore petroleum production licence said on Tuesday it was partnering with Sibanye Gold to start underground testing next year on a locomotive that has been converted from diesel to run on compressed natural gas.

Biogenic gas, produced by bacteria interacting with ancient decomposing plants to release methane, has been found in South Africa’s Free State province close to the mining operations of Harmony Gold, Sibanye Gold, and Petra Diamonds.

Although there has been research into its use in powering trains it has never gone beyond the prototype stage, experts say.

But the compressed natural gas (CNG) locomotive was recently tested above ground and it managed to pull eight wagons carrying a 30t load, the equivalent of those pulled by diesel engines, Stefano Marani a director at Molopo, said.

“Which is a very big milestone to move to the next phase of what we believe is a world first,” Marani told Reuters. There was also a massive reduction in diesel emissions with big health benefits for mine workers.

If safety and gas distribution systems are successfully tested the South African gold producer may start replacing part of its fleet of 570 diesel engines within two years, cutting down miners’ exposure to potentially harmful emissions and saving fuel costs by around 25 percent.

This would potentially help meet demands by the South African government which intends introducing carbon taxes and has warned companies of penalties in an effort to force industry to switch to cleaner energy and reduce emissions for the good of the environment and mine workers.

Studies show that switching to natural gas from diesel could cut emissions overally by a third. Molopo, which sent its results to an independent laboratory for confirmation, expects to match or better this given the purity of the zero sulphur biogenic gas.

Molopo South Africa said it has measured amounts of recoverable biogenic gas at the Free State gas fields of just over 100-billion cubic feet with an upside potential of one trillion cubic feet which was enough to power the country’s gas-to-liquid Mossel Bay refinery for more than a decade. — Reuters