Trapping carbon works, but high cost will limit its use to essential processes: Don Pittis

Feeling guilty about all that carbon you produced to fly to the climate conference or maybe on your winter holiday? A whole business has grown up to help wash that guilt away by planting trees as a carbon offset.

The debate over whether it is possible to take carbon out of the atmosphere is now pretty well over. It can be done.

But whether storing that carbon in biological systems such asforests or putting it deep underground, the dream of solvingour climate change problem with carbon sequestrationis hopelessly flawed.

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A rising price for carbon will help. Buteven asa group of top business leaders throw their support behind carbon taxes, the cost of carbon capture technology means it will be limited to a small range of uses.

But within that range of uses the places where producing carbon is a necessary part of a necessary process carbon capture will be an essential tool.

Capture and release

Besides its high cost, the appealingidea of trees sipping up the carbon inholiday jet fuel has its own special problem it doesn't last.

"It's beautiful," says UBC carbon sequestration researcher Andrew Black."Wesee our trees actually sucking ... up CO2. It's amazing."

With delicate instruments installedinBritish Columbiaforests, Black and his team canprecisely measure the amount of carbon dioxide that an organic system produces andabsorbs.

"They're taking that carbon up and they're distributingthat carbon through the trees and into the soil and they are sequestering that carbon," Black says.

Black is a passionate advocate for sequestering carbon in old growth forests, partly because he says it stays there for the long term. But he knows that in most cases, carbon trapped in organic systems gets back into the atmosphere within as littleas ahundred years.

But whether in biological systems or in undergroundgeological storage, the biggest barrier to carbon sequestration issimply the huge volume of carbon humans release by burning fossil fuels, estimated at 36 billion tonnes in 2016.

There aren't enough old growth forests to make a dent in a number like that.

Problem of economic viability

The tens of thousands of megatonnesof carbon we've released over the last mere century or sohad been sucked up over millions of years andsequestered over geological time.

Researchers in Alberta and Saskatchewan have been finding ways to put the carbon dioxide back underground, injecting it into exhaustedoil formations or dissolving the gasin deep saline aquifers.

"I think it is fair to say that from a technical point of view [carbon capture] has been proven," says Rick Chalaturnyk an expert on the geological storage of greenhouse gases at the University of Alberta.

Whilein some cases CO2 has managed to escape back into the atmosphere, scientists have largely learned what works and what doesn't.

The problem, says Chalaturnyk, is that it's just not economically viable. He estimatescarbon taxes would have to rise to between $50 and $100 a tonne to change that.

Scientists around the world includingAbdelSayari from the University of Ottawaare working to try to bring those costs down.

Sayari, who will be presenting his technique in Edmontonthis week at the InnoTech Alberta Distinguished Lecture,uses what he calls "temperature swing adsorption," to capture carbon dioxide as it reacts on the surface of a solid substance something like an air filter.

"It reacts at a low temperature and releases at a slightly higher temperature," he says, making it much more efficient than previous techniques that trapped the CO2 in water, requiring the energy to heat all that water as well.

DuncanKenyon, resident expert on carbon capture and storage at thepro-environment PembinaInstitute, says carbon capture technologywillbe "essential and significant in de-carbonizing our world."

He is thrilled byrecent leaps in the technology. Buthe disdains what he callspolitically motivated spending on carbon captureas an excuse to keep on burning coal. He calls that spending a"boondoggle."

"We have already way more cost-effective options for producing [low carbon]electricity," says Kenyon.

Indispensable carbon

Although rising carbon prices will make wind and solar increasingly competitive, and technology such as electric or hydrogen cars will allow us to cut back on our use of oil, there are some processes where so far, fossil fuels are indispensable.

Heating rock to make concrete is estimated to produce about fiveper cent of all the carbon dioxide humans release. So far we have no practical alternative, says Kenyon. Fertilizer production to feed the hungry is also a place where carbon capture and storage will be essential, he says.

As technology brings costs down, and carbon taxes push the cost of greenhouse gases up, the research by governments and fossil fuel companies on carbon capture and storage could begin to pay off. But it's hard to imagine it will everbe cheap enough to allow us to keep producingthe amounts of carbon we are generating today.

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