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health and pollution > features > tar sands will increase canada's pollution

Tar sands will increase Canada's pollution

Posted: 10 Oct 2002

When Canada signs the Kyoto Protocol on climate change, it will hardly affect the sales of conventional oil and natural gas from Alberta, which will increasinly rely on huge deposits of oil sands for future energy needs.

In fact, the demand for Alberta's natural gas will increase - it will be used as a transition fuel for reducing greenhouse gas emissions as it replaces coal and heavy oil sources.

Unfortunately, in Alberta's rush to sell conventional oil, it is running out. Now Alberta has to turn to the low-quality, low-BTU, tar from its tar sands and attempt to upgrade it to synthetic oil with the same or less pollution. The problem is that it takes 5 to 10 times the energy, area and water, to mine, process and upgrade the tar sands oil, than it does to process conventional oil.

Huge deposits

Alberta has huge deposits of oil sands that underlie about 77,000 square kilometres (30,000 sq. miles ) of the province. The tar (oil) sands contain about 1.7 trillion barrels of oil, of which approximately 300 billion barrels are ultimately recoverable.

The Government of Alberta has played a major role in encouraging and promoting the development of the tar sands. The two most common methods of extracting bitumen from the oil sands are surface mining and in situ ("in place") extraction.

The reserves that are economically mineable from the surface lie under less than 75 metres of overburden: a layer of sand, gravel, and shale covering the underlying oil sand. This layer must be removed before oil sands can be mined by surface extraction methods.

Most of the remaining reserves lie below 200 metres, and the recovery of bitumen at this depth is typically economical only by using in situ extraction technologies, without removing the overburden or the sand itself.

To decrease the viscosity of the bitumen so that the oil it contains can be extracted, a dilutent such as natural gas condensate can be added, or the extracted bitumen can be upgraded into synthetic crude oil on the project site.
Nearly two tonnes of oil sands must be mined to produce one barrel of light, sweet synthetic crude oil.

The mining operation involves stripping off the overburden, separating the bitumen with steam, hot water and caustic soda, and then diluting it with naphtha. After centrifuging, liquid bitumen at 80 degrees C is produced, which is then upgraded in a coking process and subjected to other treatments, eventually yielding a light gravity, low sulphur, synthetic oil.

Big investment

Production from tar sands now accounts for about 19 per cent of Canada's crude oil supply, and investment in 1996 was over $3 billion. Over the next 25 years, Western Canada's oil industry hopes to increase synthetic crude oil production sharply, to 1.2 million billion barrels a day at a cost of up to $20 billion.

The problem is that it takes almost as much energy to produce tar sands as it generates. Indeed, it almost takes as much energy to mine, process, refine, and upgrade the bitumen oil out of tar sands as the oil-energy that would be produced from the tar sands.

In the process much more carbon dioxide emissions are generated getting the tar sands oil out than would be the case with conventional oil. There are estimates that 5 to 10 times the amount of greenhouse gas emissions come from processing tar sands as it does processing conventional oil.

All this will make it more difficult for Canada to meet its commitment to lower greenhouse gas emissions by more than 23 megatonnes by 2010. Canada relies heavily on energy intensive industries, but draws relatively lightly on carbon-intensive coal sources and has greater dependence on hydro-electricity, nuclear power and natural gas.

Source: The Gallon Environmental Letter, 8 October 2002.

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