The science of carbon busting


Car and tar sands emissions combined generate nearly one-fifth of Canada’s greenhouse gas emissions, and the oil sands’ contribution will nearly triple this decade if production rises as forecast. Both carmakers and those developing Alberta’s oil sands claim new technologies will make their industries greener.

But examining the top proposed fixes shows how difficult any transformation would be. Improvements must be substantial, or dramatic increases in the number of cars and in oil sands output will overwhelm any gains in carbon reduction.

Most discussion about greener cars focuses on engine improvements. But advances are happening in other areas. Weight loss through materials such as aluminum and carbon fibre; aerodynamic designs; accessories powered by electronics instead of belts and pulleys; and continuously variable transmissions are available now and are relatively inexpensive.

These developments and modifications to conventional engines—such as direct injection and variable valve timing—each produce small fuel-economy gains that add up and are the main route for carmakers to reach the tougher emission standards taking effect in 2016.

A new technology may be a bigger leap. Homogeneous charge compression ignition, or hcci, might come through with up to 15 per cent less fuel consumption. It’s a cleaner, more complete burn that doesn’t use spark plugs. As with conventional engines, hcci mixes gasoline and air before injecting the mixture into the combustion chamber. The difference with hcci is that that the piston compresses the fuel as it rises up the cylinder, raising the fuel’s temperature until it’s hot enough to ignite.

As a result, hcci is much harder to control than spark ignition, and requires extremely precise valve timing and control of the air/gasoline mix and its temperature— not yet accomplished.

It also functions poorly at low speeds and under heavy load. Some suggest a dual system, with spark ignition part of the time, but that would add complexity and cost.

With the number of cars soaring worldwide, these changes, or even widespread adoption of conventional hybrids, won’t solve the greenhouse gas problem.

Plug-in hybrids could be better. Various manufacturers are unveiling models said to go 15 to 60 kilometres after an overnight recharge—enough mileage for most routine driving on battery power alone. Actual fuel consumption and emissions, though, will depend on how many trips stay within that range.

All-electric cars could be game-changers. Cost is a major impediment, as are current lithium ion batteries, since most are limited to less than 200 kilometres between charges.

Researchers are exploring lithium air, which employs air instead of a heavy metal to create the reaction that generates electricity. Theoretically, the result is a much lighter, more efficient battery with a range of up to 800 kilometres. Again, cost and degree of technical difficulty remain high— particularly since lithium can explode when exposed to air—and it’s at least a decade or two from commercial use.

Battery-powered cars will only reduce climate change if their electricity comes from renewable sources. On the other hand, computer-controlled systems are being devised to let utilities use plugged-in cars as electricity storage facilities, drawing power from them at times of peak demand. However, that process is slow and shortens battery life, so it’s likely “to be the exception rather than the rule,” says Dan Guatto of Burlington Hydro, which is testing a battery-powered Ford Escape converted by Vancouver-based Rapid Electric Vehicles.

Although the oil sands projects have environmental impacts beyond greenhouse gas emissions, shrinking their carbon footprint is crucial.

Most of tar sands’ heavy primary oil, or bitumen, now originates in open-pit mines, but an increasing proportion is extracted in situ—forced up through wells from underground. A report from the Calgarybased Canadian Energy Research Institute (ceri), to be published this fall, concludes each mining process requires a different solution.

Per barrel of oil recovered, mining emits much less greenhouse gas than in situ, but its vast scale makes the total amount huge. As with cars, a series of small improvements has reduced its impact, but major change is required.

That change, says the ceri report Green Bitumen 2010 to 2060, is carbon capture and storage (CCS), which is receiving billions of dollars from the federal and Alberta governments. CCS would grab carbon emissions from smokestacks and pipe them to underground sites where, in theory, they’d be locked away forever.

While it’s still at the experimental stage, with only a couple of pilot projects based at coal-fired power plants elsewhere in North America, “the technology is there,” says ceri’s research director, David McColl. The main trick is convincing all the oil sands miners to contribute to a pipeline to northwestern Alberta, where there’s plenty of storage capacity.

The estimated cost of ccs is $70 to $120 per tonne, and there’s no return on investment for the companies involved. ceri says the Alberta government would have to cover some of the cost, but by doing so might kick-start a valuable export business in technology and know-how.

The in situ process requires that the oil be loosened from the sand and made less viscous before it’s brought to the surface. Currently it’s heated with steam, produced by burning natural gas to boil water.

Some advocate shifting the heat source to nuclear power. But putting aside environment and health concerns, the ceri report says that while it may be technically feasible, it’s too costly, especially when alternatives are available.

Most promising, the report concludes, is injecting solvents into the sand to loosen the oil. Every major company with an in situ project is experimenting with the technique, says McColl, each with its own chemicals and capacity to replace natural gas. Cenovus, a spin-off of Calgary’s Encana Corp., is farthest ahead, with a technique that would cut greenhouse emissions in half. At that rate, he says, it would have a smaller carbon footprint than conventional oil.

It’s not guaranteed to work, says McColl. “No one has done a large-scale process,” but solvents have the best chance of being an environmental game-changer for in situ production.

Others suggest moving to geothermal energy, which involves tapping into the natural heat several kilometres deep under Earth’s surface. Water would be pumped down into the hot rocks through one well and, after warming, would be brought up through another. But that idea is in its infancy and faces difficult technical impediments. Some industry people doubt it can produce sufficient energy.

Suncor was leading the way on this technology, but a spokesperson from the Canadian Geothermal Energy Association says interest among oil sands companies has diminished.

Calgary’s ATCO Ltd. is investigating using microwaves to heat the sands. But this is decades away, and only likely if hydroelectric generation is installed on the Slave River and other Northern Alberta waterways.

As with cars, the only sure thing we know about reducing carbon in the tar sands is that the solutions will be complex and very expensive.

Cost shouldn’t be an issue. Whatever it takes to protect the environment should be included in oil sands’ prices, says Simon Dyer, with the Calgary-based Pembina Institute.

The bottom line, though, is that it’s too soon to count anything. We’re still a long way from understanding how green either industry can become.

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