Capturing fugitive emissions

Rio Tinto is working to reduce coal bed methane gas at its Mount Thorley Warkworth site in New South Wales, with the hope of doing the same for other coal mines right across the Hunter Valley. Paul Hayes writes.

Given carbon emissions from coal mining are among the worst in the resources sector, the indus try is attempting to curb the problem.

Rio Tinto Coal Australia’s (RTCA) Coal and Allied Mount Thorley Warkworth in New South Wales’ Hunter Valley has worked with CRC Mining and AGL trialling a coal bed methane project designed to capture the greenhouse gases released during mining.

The $5.5 million project was designed to reduce Wark worth’s carbon footprint, with a view to helping other Hunter Valley coal mines.

According to RTCA’s man ager of new developments Chris Lauritzen, the ‘fugitive’ methane gas produced during coal mining is up to 21 times more potent than carbon dioxide.

“More than 60% of our total greenhouse gas emissions on site are fugitive emissions,” he told Australian Mining.

“If we can reduce that by capturing some of the methane gas prior to mining, we will substantially reduce our impact on the environment.”

Initially, the project was de signed to burn off methane gas as it was produced, but Coal and Allied has bigger plans.

“During the trial we will be flaring off the gas, which con verts the methane into less harmful carbon dioxide,” Lau ritzen said.

“But if the coal bed methane gas is available in sufficient quantities and flows freely, it could open up a new source of fuel to generate electricity.”

Equipment and technology

The project required the use of experimental equipment.

After drilling four vertical wells under reaming coal seams, Coal and Allied employed new technology from its research partners.

“The principal experimen tal technology used has been a trial of tight radius drilling me thod (TRD) developed in part nership with CRC Mining and AGL Limited,” Lauritzen said.

“RTCA allowed CRC Min ing to test the technology in one of our wells to support further research because their type of simulation has the potential to be a useful tool in extracting gas from multiple coal seams.”

The new technology can drill horizontally up to 200 metres from the initial wall.

According to Coal and Allied, scientists hope the horizontal drilling will open more pathways in which the gas can flow, which will in turn reduce the number of wells required to extract coal seam methane.

Project success

One of RTCA’s key hopes for the project is that it will not only prove a success for Wark worth, but also other mines in the Hunter Valley and Australia.

“If the pilot project is suc cessful it could trigger similar developments at the other Hunter Valley sites,” Lauritzen said.

“And perhaps also Queens land,” he said.

According to Lauritzen, success will depend on the poten tial financial benefits and burdens of capturing and limiting fugi tive emissions.

“Overall success will depend on the ability to extract the gas in a commercially viable way,” he said.

“This will depend on issues such us the cost, the quantity of gas extracted before mining and the potential liability of the greenhouse remaining gas.”

Project status

Drilling for the coal bed methane project was expected to be com pleted at the end of March, but according to Lauritzen there is still much work to be done.

“We are now preparing for construction of the surface facil ities, which is forecast to be completed by the end of July,” he said.

“The trial programme will then involve 12 months of well dewatering and gas production to assess gas flow potential, including comparing results from the TRD stimulated well with results from the other three wells that used traditional tech nologies.”

Regardless of any down turns in commodities, coal is a vital resource that is necessary for the growth of Australia and the world.

“Coal remains the biggest of Australia’s exports,” Laurit zen said.

“The world needs energy and coal is the most abundant form of energy.”

Lauritzen said while coal is mined, Government and mining companies must be aware of environmental implications and act accordingly.

“Mainstream Australian political parties have recognised that coal is an essential part of the energy mix of the world,” he said.

“The coal industry and par ticularly Rio Tinto have taken a very strong lead in research ing clean coal, carbon capture and sequestration.”

Coal & Allied

Chris Lauritzen

Manager of New Developments

07 3361 4200

info@rtca.riotinto.com.au

www.coalandallied.com.au

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