Tar Sands and Energy Returned on Energy Invested

The No. 1 oil exporter to the United Sates is Canada, sending us close to 3 million barrels of oil per day, just under 15 percent of our total imports of oil. This is more than twice as much oil as we get from Saudi Arabia. Much of Canadian oil production, 47 percent, comes from tar sands. Tar sand formations contain a heavy crude oil called bitumen intermingled with sandy soil.

The oil is currently produced by large scale strip mining of the tar sands, which then must be heated with steam to lower the viscosity so that the oil can be separated from the sand. Methods for in situ processing are being developed. Steam and/or solvents are injected into the soil to free the oil for extraction.

Another technique being examined involves injecting oxygen into the tar sand formation and actually burning some of the bitumen to heat the remainder for extraction. The latter two technologies for extraction are more expensive, but lend themselves to obtaining oil too deep for surface mining techniques. After the bitumen is separated from the soil; it still must be processed before it can be sent by pipeline as the native bitumen has a consistency of cold molasses.

Virtually all of the Canadian tar sands production comes from the Athabasca tar sands formation in Northeastern Alberta. This oil supply is available due to the proximity to natural gas which is used to produce heat for extraction and hydrogen production for conversion of the bitumen into a lighter form of crude oil wthat flows through a pipeline. And herein lies one of the problems with production of crude oil from tar sands.

The production of fossil fuels as an energy source is absolutely and completely dependent on the energy returned on energy invested (EROEI). If it takes more energy to obtain a fossil fuel than the fossil fuel delivers on use, then it is not an energy source. It is a waste of energy.

Consider the EROEI of some other fuel sources. In the earlier decades of the 20th century, the EROEI for crude oil in the U.S. was close to 100:1, that is to say one barrel of oil invested in exploration/production produced about 100 barrels of oil. Conventional crude oil today has an EROEI of about 20:1, compared this to EROEI for tar sands of less than 3:1. Paraphrasing a late-night infomercial, BUT WAIT, THERE’S MORE. (the caps are necessary as they always seem to be shouting). Lower EROEIs mean greater amounts of greenhouse gasses emitted for useful energy produced. Fuels such as natural gas have relatively low greenhouse gas emissions compared to conventional crude oil, which has less than coal. The low EROEI means that bitumen processing and use makes it as bad as coal in terms of greenhouse gas emissions.

Finally, massive amounts of water are required to process the tar sands. Roughly 5-10 barrels of potable water are converted to oil fouled waste for each barrel of oil produced. Although there are tar sands in Utah and thereabouts, the resource may never be extracted due to the lack of process water. 



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