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Gas turbines proposed for mine ventilation

March 1, 2011
by Norm Tollinsky
In: Research with 0 Comments

 

 

 

 

 

 

 

 

 

 

 

Ultimately, Dean Millar, MIRARCO research chair of energy in mining and mining engineering professor at Laurentian University in Sudbury, hopes to revolutionize ventilation and energy management in the coal industry. However, there’s some basic research he needs to do first and Sudbury, he figures, is an ideal place to do it.Formerly program director, renewable energy and senior lecturer at the University of Exeter’s Camborne School of Mines, Millar is intrigued by the fact that “something like eight per cent of all anthropomorphic greenhouse gas emissions are attributable to coal mining underground” and that the culprit, for the most part, is methane in the ventilating air “upcast and discharged” to the atmosphere.

Not only is all that methane wasted energy, it’s also a significant contributor to climate change.
Millar, who joined MIRARCO last year, developed an interest in coal mining ventilation because “ultimately, we need to look at methods to mitigate that methane.”Separating it from the air, he thinks, would be impractical. Instead, Millar would like to add more methane, increasing the concentration to a level that will allow for sustainable combustion in a gas turbine that would produce heat and power, displacing electricity.

“Sudbury is a very good place to look at ventilating systems,” said Millar. “We could be exemplars for a global rollout of a new type of energy management strategy for the mining industry.”

The idea is to use gas turbines to power the giant fans that pump air underground and to use the heat produced by the combustion to condition the air.

Cooling

“Here in Sudbury, you have extreme low temperatures in winter and you have to burn propane or another hydrocarbon to heat the air that goes underground because it could be minus 30 degrees Centigrade on surface. In summer, you have to cool the air because it might be 30 degrees Centigrade on surface and by the time it gets 2,000 metres underground, you add another 20 degrees to that, which would make for very, very difficult working conditions.”

Exhaust heat from a gas turbine can cool the air through the use of absorption refrigeration technologies, “so you could produce power, heating and cooling all from the same co-generation plant,” said Millar.

Currently, electricity is used to cool the air in Northern Ontario mines at the same time that everyone else in the province is cranking up their air conditioning units and putting a strain on the grid, so using an alternate source of fuel would be good for the grid and free industry from having to purchase expensive, peak-time electricity.

“Engaging in research that looks at mine ventilation as an energy management system is clearly of relevance to my longer-term aim of looking at coalmine methane,” said Millar. “If I was somewhere in the U.S. at a university in Virginia, I think I’d have a much harder time convincing people to connect a source of combustion to a source of combustible gas.”

Using gas turbines to power ventilation systems would be a radical departure from current practice.

“I don’t know of a single mine fan that isn’t driven by electrical power anywhere in the world,” said Millar. “If any of your readers know, please tell me because I want to go visit it.”

Permafrost

Millar’s interest in methane has also drawn his attention to the permafrost in Northern Ontario’s James Bay Lowlands, which is a substantial source of dilute methane from decaying organic material. There’s also methane locked up in the ice and possibly stored in solid form, but no one knows how much.

The problem is that in 40 years, when temperatures in the James Bay Lowlands are six degrees warmer than now, the ice is going to melt and the methane that has been locked up in the permafrost will be released to the environment.

“Methane,” said Millar, “is 21 times worse that carbon dioxide as a greenhouse gas… You don’t want all that methane belching out from the Hudson Bay Lowlands…so the objective would be to capture it before it’s released to the atmosphere.”
The first step is to come to some understanding of how much methane is locked up in the permafrost.

To do that, Millar is working with the Ontario Geological Survey on a research proposal that would see a hockey rink-size, inflatable transparent canopy placed over a section of permafrost on the shores of Hudson Bay.

Over one summer season, Millar hopes to melt the permafrost to a depth of 10 metres using solar energy and maintaining a temperature of 28 degrees Centigrade.

“At the same time we’re doing this melting, we’ll meter the methane concentrations and transmit the data to Sudbury in real time. At the end of the summer, we’ll remove the inflatable building and monitor the ground to see how it refreezes.
“Forty years down the line with the methane out, it won’t matter if the permafrost thaws,” said Millar. “I have some concepts in mind about how we can turn that into some kind of production process, but I don’t want to get anyone excited about that at this stage. The first problem is to measure the methane.

“I know I have some mad and crazy ideas,” said Millar. “I recognize that, but at the same time, that’s the nature of research.”

 

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