New Report Caculates Shale Oil's Enormous Carbon Footprint

Vast deposits of oil shale in the American west are being eyed for development to reduce reliance on foreign sources of oil and bring down the price of fuel. A recent report Dr. Adam Brandt at the University of California Berkeley, as reported by greencarcongress, tallies the environmental cost.

Here's the bottom line: oil shale releases 21% to 47% more greenhouse gases (GHG) than conventional oil production, consumes scarce water resources and threatens grounwater flow and quality.

The analysis assumes the oil is extracted from shale using the in-situ conversion process (ICP) developed by Royal Dutch Shell. The process works by literally heating the Earth to depths of 1000 feet for two or more years with massive electric heaters inserted into the ground. The extraction process is so energy intensive that it produces only 1.2 to 1.6 times more energy than it consumes, so it might be thought of as energy conversion as much as it is energy production.

Despite these questionable trade-offs and environmental risks, Dick Kempthorne, Secretary of the Interior Department, recently announced proposed regulations for developing shale in three western states and has given oil companies six leases for demonstration projects.

The US has bountiful supplies of oil shale, 60% to 70% of the world's deposits. It's estimated that our shale holds three times as much oil as all of Saudi Arabia and for that reason has long been considered a potentially enormous oil supply waiting for the right time, the right technology and the right price. A recent Rand study says extraction isn't profitable unless oil is selling for $70 to $95 per barrel although Shell has said it could be competitive at $30/bbl. With oil around $120/bbl now, it should be economically competitive and with Americans very unhappy about the price of gasoline, expect increasing political pressure to tap the shale reserves. The current battle over offshore drilling is a precursor of a much bigger fight.

Extraction

Oil shale is a sedimentary rock containing an oily substance called kerogen, which is a solid organic precursor of oil and gas.
There are two ways to process oil shale. The traditional method is to mine it, heat it in a large drum (or retort ) to break down and release the kerogen, and then refine the output. The second technology is Shell's in-situ (Latin: "in place") conversion process, which they started working on during the last energy crisis 30 years ago.

According to an earlier presention by Dr. Brandt, ICP starts by creating a freeze wall about 1.6 meters thick around the perimeter of a 300 meter by 300 meter heating zone. Holes are drilled about every 8 meters, electric resistance heaters are inserted and the shale is heated to 650 degrees F over the course of 2 or more years. The freeze wall keeps groundwater from getting contaminated and also prevents it from cooling the shale in the heating zone. All of these operations go to a depth of 300 meters, so there is a cube of shale being processed that is roughly three football fields long on each side.

The kerogen is transformed into gases (natural gas, propane, butane) and light oil, which are extracted with conventional wells. Evidently this process performs what millions of years of geological heat and pressure did for typical petro deposits, turning kerogen into oil and gas. It also seems to do some partial refining since the the oil requires much less refining than normal crude. After the extraction is done, remediation is performed by flushing the zone with water to collect any mobile hydrocarbons and then thawing the freeze wall.

A Bad Neighborhood

Shale oil is not the only controversial energy source. The Alberta Tar Sands likewise requires extra extraction to get something comparable to crude oil, but they produce only an extra 15% to 20% more GHG. Ethanol from corn is likewise controversial because it doesn't produce much more energy, if any, than is consumed in production.

Increasing GHG is also not the only environmental impact of ICP. It consumes considerable amounts of scarce western water and threatens groundwater. An earlier report said:

For in-situ processing, there is little understanding of the long-term impact on ground-water flow and quality.

With heating wells every 8 meters, hunting, forestry or recreation isn't realistic, so another issue is the end of any multiple uses for that land.

Dr. Brandt, the author of the report, went to some effort to suggest a way to reduce the GHG impact of ICP: don't use fossil fuel to generate the electricity for heating the shale, use nuclear, wind or solar power instead.

It is an odd and ironic suggestion -- to use clean energy to produce dirty energy.

(Note: Access to the full paper requires a subscription, but the abstract can be viewed here.)

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