Monday, 13 June 2011

Coal Seam Gas as an Interim Fuel?

The gas mining industry is promoting gas as the interim fuel for power generation as Australia moves to a renewable energy future, claiming it is 60% cleaner than current coal-fired electricity, a 'line' which has been easy to sell to various Australian governments addicted to lucrative royalties.

It is widely acknowledged that the burning of gas for electricity produces far fewer emissions than coal. What gas mining companies are not promoting is the amount of polluting emissions that are created through the exploration, mining, transport and refining processes, not to mention methane released into the atmosphere from leaking pipes

Until now, this has not been accurately quantified, but in March 2011, scientists from the Cornell University in the USA released the results of a comprehensive assessment of the total emissions of various electricity generating fuels, including, coal, shale gas (referred to locally as coal seam gas), traditional gas, and diesel.

The collateral emissions from machinery used in coal seam operations are enormous. It requires trucking in millions of litres of water, tonnes of sand, and a 10,000 horsepower engine to drive the 'fracking' operation (fracturing of underground rock strata) for each well.

The scientists are at pains to explain that their calculations, based on US Mining Department statistics, are conservative, and show that when the emissions of all aspects of production are considered, coal seam gas burning causes by far the greatest amount of pollution than all other fuels.

One interesting statistic was that, over the life of the project, between 3.6% and 7.9% of all gas mined becomes “fugitive methane”, either 'vented' or flared directly into the atmosphere. Venting is the release of methane that unavoidably leaks or overflows into the atmosphere during the process, much of it during drilling, where it accompanies 'flowback' waste or 'produced water'. Flaring is the deliberate burning of surplus gas, a process that is banned in some countries.

The study's conclusion was, that rather than reducing greenhouse impacts, “developing gas from shale formations is likely to aggravate global warming”.

This is a powerful argument to place a permanent hold on all gas mining, particularly coal seam gas, and move directly to renewable energy.

- J Edwards