Can mining slow global warming?

🕔Sep 22, 2005

Less than a year ago, global warming was identified by a Pentagon-commissioned report as a U.S. national security concern which eclipses even terrorism Now, a team of UBC researchers working in northern B.C. is looking at a surprising tool to address it: a weathering process associated with waste rock from mining.

“We want to know if we can design a mining process that offsets mining’s environmental impacts by helping to solve the greenhouse gas problem,” says Greg Dipple, a UBC geochemist who heads up research projects underway at decommissioned chrysotile mines at Cassiar and at Clinton Creek, in the Yukon. (Chrysotile is a serpentine mineral and a source of asbestos.)

It’s long been known that forests help remove carbon dioxide (CO2), a greenhouse gas which contributes to global warming, from the air. But Dipple and others now say that a natural process associated with some types of mining byproducts—such as the serpentine mine tailings at Cassiar—may do this even better.

It’s called mineral carbonation: CO2 from rainwater reacts with silicate minerals on the surface of crushed rock produced by mines. That reaction fixes, or sequesters, the CO2 into a solid mineral form. And if radiocarbon dating of similar mineral deposits at the village of Atlin is any indication, it’s not unrealistic to expect CO2 to be held by these “carbon sinks” for 10,000 years or more—much longer than do forests.

In other words, waste rock and tailings from mining could help slow global warming—by sucking this greenhouse gas out of the atmosphere and fixing it permanently into an innocuous form.

If this takes place on a significant scale, says Dipple, mining operations could help Canada earn CO2 credits towards its commitments to the Kyoto Protocol.

And removing greenhouse gases from the atmosphere isn’t the only possible benefit.

Currently, CO2 sequestration futures trade for about US$1 per tonne at the Chicago Climate Exchange. But long-term forecasts of CO2 value span the range of US$8 to US$80 per tonne. At these rates, active trading in CO2 credits and futures could provide a revenue stream to fund both remediation and acceleration of CO2 up-take on mining sites.

It’s not the first time people have thought of fixing carbon: several methods, including storage in coal seams, oil and gas reservoirs, the ocean and saline aquifers have been considered. But mineral carbonation is seen as the most stable and environmentally benign method.

“Canada already is a world leader in CO2 sequestration research, and this puts us well and truly at the front,” Dipple says. “No one else is doing this.”

The political and economic implications of this have set B.C.’s mining industry abuzz. Several major international mining companies have expressed interest in Dipple’s research, and company sponsorships for research are being sought now.

Dennis MacKay, MLA for the minerals-rich Bulkley-Stikine riding, sung Dipple’s praises after hearing about his research at a mining industry conference this spring in Smithers.

“We’re now starting to find out, through people like Dr. Dipple and listening to the mining industry, that mining does not hurt the environment,” MacKay told the B.C. legislature April 26. “All the news that’s coming from the mining industry is good news.”

But the jury’s still out on whether net environmental and economic benefits can be realized from mineral carbonation.

First of all, nature typically takes about a million years to sequester atmospherically-derived carbon dioxide into a solid mineral form. American scientists have already figured out how to speed up mineral carbonation of waste rock to 28 minutes in a lab—and some envision large treatment plants to do this, and new mines whose sole purpose is to provide feedstock for CO2 sequestration. But this expensive, energy-hungry process contributes more CO2 to the atmosphere than it stores.

“People are starting to lose faith in that view of mineral carbonation, because it’s still proving very difficult,” says Dipple.

By studying how a naturally occurring process draws CO2 directly from the air, Dipple says he’s taking a “slightly less radical approach.”

“This is one route that hasn’t been looked at. If we can get there, it’s sort of the holy grail of carbon sequestration.”

Although economically speeding up the manner remains a challenge, Dipple has observed the process happening much faster than expected in waste rock.

“We have measured significant dissolution in hours,” Dipple said by e-mail. “Scaling these results up, our calculations suggest that large active mining operations might be able to sequester hundreds of thousands to perhaps a million of tonnes of CO2annually.”

But Bill Price, a Smithers-based scientist with Natural Resources Canada and one of Canada’s foremost experts on metal leaching and acid rock drainage, offers other considerations.

“The mechanism that Dipple describes is there,” he says. “But when doing a CO2 budget for mine sites, one needs to consider all of mining’s CO2 sinks and sources.”

Mining generates significant CO2: through the production of lime (used to address acid rock drainage), dissolution of carbonate minerals in rocks due to faster oxidation of naturally occurring sulphide minerals, oxidization of rocks containing organic carbon (such as mined coal) and of course the energy expended to drive the mining process.

Meanwhile, Price estimates the sequestration process described by Dipple would likely occur at fewer than four per cent of closed and presently operating mines in B.C.—and less than one per cent of the rock they’ve disturbed.

A full accounting of CO2 generating/fixing activities of mines remains to be done, says Price. “But my gut take is that with such a small portion of mine waste capable of being sinks, versus those that are likely to be sources, mines would be a net source of CO2.”

His conclusion?

“It’s the early days for this research. People should move cautiously before jumping to any conclusions about net benefits of the mining industry with regards to CO2 budgets.”

It might be tempting to view CO2 sequestration as an easy way out of our addiction to fossil fuels, which account for 85 per cent of global energy use and are the primary source of greenhouse gases.

According to a July 2004 report on Dipple’s Clinton Creek project:

“Although alternative energy sources such as nuclear fission, wind, and solar power are available, it is unlikely that increased reliability on these methods of energy production will significantly reduce greenhouse gas emissions in Canada. As national dependence on fossil fuels is unlikely to diminish in the near future, the sequestration of [human-produced] CO2 may be required to meet Canada’s commitment to the Kyoto Protocols.”

Statements like these rile Glenda Ferris, who became the first downstream resident of Placer Dome’s Equity Silver Mine near Houston more than 20 years ago.

“That’s how you set an agenda: first you discount or discredit the opportunities represented by alternative technologies,” she says. “Then you say, ‘We’re going to keep using everything we’re using, so now to meet Kyoto we’ll find ways, like reforestation, to get credits to keep polluting everything and pumping out greenhouse gases.’”

Ferris, who insists she is not anti-mining but a promoter of dialogue and solutions, has worked on mining-related environmental issues since 1981—when she learned that Equity had just spilled enough concentrated sulphuric acid to decimate fish stocks in the Buck Creek watershed where she lives.

Her constructive approach to environmental activism has attracted prestigious awards from government.

and the mining industry alike. Ferris helped found the Environmental Mining Council of B.C., represented First Nations in land use planning, and has been appointed to federal government committees and international working groups on mining and sustainability.

“One of the main things we talked about … was where research dollars should go,” she relates. “It drives me nuts that the federal government’s agenda now includes spending research money to see if mines can act as CO2 sinks, when we have about 50 other far more important things to research.”

To Ferris, these include alternatives to fossil-fuel burning technology, economic incentives to reduce high-grading and underutilization of ore bodies, and technologies to control and manage impacts from acid rock drainage and metal leaching, which remain a concern for at least 60 mines in B.C. today.

Claims that mining is environmentally benign produce a strong reaction from Ferris: “They make me physically ill.”

“Impacts to the environment can be huge,” she continues, citing a second devastating hit to fish stocks in her watershed after a flood-related malfunction of Equity’s treatment plant in 2002, eight years after the mine had closed. Placer Dome spent millions upgrading its equipment, and today spends more than $1.2 million annually on environmental maintenance activities at Equity.

She’s particularly skeptical of the idea that mining, with all its CO2-generating processes, might actually be contributing positively to the greenhouse gas equation.

“Do the balance sheets. Provide the proof,” she urges. “But don’t turn [preliminary research on two chrysotile mines] into, ‘See, we told you that mining doesn’t adversely affect the environment.’”

Ferris believes Canada could meet its Kyoto commitments with expanded use of alternative technologies, but says politicians aren’t embracing these.

“What you have now are institutional economic engines based on the fossil-fuel formula,” she explains. “They have vested interests in maintaining the status quo. As long as they’re lobbying, driving the political machine… I don’t think there will be a lot of changes. But the opportunities are there.”

As Dipple prepares to submit a proposal to the National Science & Engineering Research Council for $250,000 in funding to ramp up research at Clinton Creek and a new diamond mine in northern Canada, he, too, reflects on Kyoto.

“It’s a huge thing, requiring massive effort,” he says. “Increased energy efficiency, reduced energy consumption, cleaner energy sources are all important, but so is making fossil fuel use more carbon friendly. That’s where CO2 sequestration comes in.

“Many say that in 100 years, the world economy will have moved on to where production of greenhouse gases is not an issue. In the big picture, we’re talking about a short-term fix.”

Although Dipple is hopeful, he doesn’t fully endorse MacKay’s view.

“Our research shows that there are some environmental benefits to mining but we do not yet know if they can be accelerated to the point of offsetting the detrimental environmental impacts,” he said by e-mail. “Clearly this is where we would like to be, but we’re not there yet.”

CO2 TRADING PRIMER Canada is among the many countries who’ve ratified the Kyoto Protocol. When it comes into force in 2005, ratifying nations will be obliged to cut greenhouse gas (GHG) emissions by up to 5 per cent below 1990 levels by 2008.

This won’t be easy: researchers at the U.S.-based Global Resources Institute say GHG emissions have actually jumped worldwide by 11 per cent in the past decade, and will rise 50 per cent rise by 2020.

Expecting stringent new rules, corporations and some public institutions in the U.S. (which withdrew from the protocol under President George W. Bush) established the Chicago Climate Exchange in 2003. Like a stock exchange, the CCX uses an electronic trading system to allow buyers to purchase rights to emit specific quantities of GHGs from sellers whose activities—such as planting new forests—contribute to their reduction. As with shares, prices are set when buyers and sellers reach agreement on value.

Corporations which depend heavily on GHG-causing fossil fuels view this new “environmental currency” as a critical means to comply with Kyoto-based rules, without jeopardizing profits. International carbon credits traders hope market forces will determine realistic prices for CO2 emissions—and quantify the importance that society places on the environment.

©Larissa Ardis