Businesses pushing the technology's development such as oil firm Royal Dutch Shell PLC are also pragmatic about how much of a dent capturing carbon can make in global emissions.
Even if the technology works, and it is widely deployed around the world for coal and natural-gas power generation, carbon-dioxide emissions would be cut by just 20 per cent by 2050 from what they would have been otherwise, Shell has forecast.
Equally important, according to Shell, is developing renewable power such as wind and solar so that by 2050 fossil fuels like coal and oil account for a minority of the planet's energy use.
"There's still a huge gap between where we are today and realizing the full potential of [carbon capture and storage]," Peter Voser, chief executive officer of Shell, told a conference of executives in Calgary this month.
The tempered outlook by the companies whose operations emit carbon dioxide contrasts sharply with the optimism of governments such as Alberta, which have pinned multibillion-dollar bets on the technology. Alberta plans to spend $2-billion to help industry develop carbon capture and storage and is in the process of signing deals involving three projects, including one led by Shell at its oil-sands upgrader facility near Edmonton.
Carbon capture and storage technology is deployed at a only few projects around the world, including an EnCana Corp., venture in Saskatchewan and North Dakota. It is expensive, untested and technically challenging, from capturing the carbon to storing it below the surface.
In the ideal situation, the technology captures a large portion of the carbon dioxide emitted from a facility, capturing the gas from a pure stream. The gas is then compressed for transport by pipeline to a location where it can be injected into underground storage, such as a saline reservoir or a depleted oil field.
Carbon dioxide is easiest to capture when it is emitted in a pure stream. However, in many cases involving the oil sands, carbon dioxide is mixed in with other gases, making it much harder and more expensive to catch.
Because of this, costs right now are severe in the oil business. ConocoPhillips Co. looked at capture and storage for its oil sands where it drills wells and injects steam to recover the raw resource. The cost would have been $200 per tonne of carbon dioxide, which is about 10 times more than the current market price of about $22 per tonne for credit on nascent exchanges like Europe's Emissions Trading System.
The ConocoPhillips estimate would add roughly $10 to the production of a barrel of oil. The price of a barrel was $71.65 on September 24.
Companies producing electricity from coal feel much more pressure.
In Ontario, where Ontario Power Generation runs two of Canada's 10 biggest emitters, the plan is to stop using coal to generate electricity by 2014.
In Alberta, operators such as Capital Power Corp. are working on carbon capture with the provincial and federal governments. Capital Power has a project in development that would capture about 86 per cent - 1.2-million tonnes per year - from a new facility. But it is power plants like Capital Power's Genesee, which emits 9.5-million tonnes per year, that need to be retrofitted for capture. Technology to do that is not proven but could capture 80 per cent or so of the emissions most scientists link to global warming.
A small project, costing $100-million, is being tested by American Electric Power in West Virginia and would capture and store 100,000 tonnes a year.
The coal industry has to figure out a way to make carbon capture work.
"It's critical. Without being able to capture CO2 and store it, it's going to be very difficult in the future to continue using coal to generate electricity," said David Lewin, a senior vice-president at Edmonton-based Capital Power.
Oil industry leaders like Murray Edwards of Canadian Natural Resources Ltd., which has just opened a new oil-sands mine, has said government backing of the technology's development is essential, comparing it with the railway.
And while the widespread use of the technology is likely more than a decade away - and many issues as yet unsettled - top researchers such as David Keith at the University of Calgary have concluded the technology is among the best options to make "large cuts" in global greenhouse-gas emissions in "reasonable costs and time frames."