Shale oil: Pros and cons
Shale oil is derived from oil shale which is slate-like soft rock having kerogen (a solid but waxy mixture of hydrocarbons). Kerogen-containing rock is crushed and heated to get vaporized and finally condensed to develop heavy and slowly flowing deep brown shale oil with its viscosity reduced and finally with its impurities like sulphur and nitrogen compounds removed.
Oil shale is a natural resource and it has well-recognized global presence. The first recorded use of shale oil occurred in Switzerland and Austria in the early 1300s. Estonia that has been a part of the U.S.S.R. till the last decade of the last century has hardly any other energy resource save kerogen. China, Brazil, Israel, Germany and Jordon have accepted it as one of the energy resources. Nearly a quarter million square miles in the central and eastern region of the U.S.A. is rich with kerogen-containing rocks. Consideration for exploration of shale oil has stirred America time and again. Whenever the issue of energy resources has surfaced as a challenge to the nation kerogen has reminded its existence.
Pros and cons with regard to shale oil may be considered in the following way.
The costs and risks of exploration and drilling have been estimated as comparatively less. The abundance of oil shale along the shorelines of ancient lakes and rivers stands helpful. Complication in exploration is manageable. Outcrop samples, a few core holes, and some seismic data usually suffice.
There is every possibility that ventures in the shale oil industries will appear as a bliss to the unemployed in a time when huge downsizing or retrenchment and even closures of number of factories are features of the present day recession-afflicted globe.
On the other hand, recovery of shale oil is expensive. Crushing of kerogen is not enough. Kerogen is to be put under high temperature and the shale oil must be treated with hydrogen to convert into synthetic crude oil which after further refinement into gasoline and other petro-products may be used commercially.
In case of retorts on the surface, millions and millions of tons of the rock are to be extracted and after retorting is complete the same amount will have to be shifted to some area. This operation is a challenge undoubtedly.
Added to this is the environmental consideration. The massive materials mined and processed will leave a great amount of disposable wastes which must have large amount of heavy metals and toxins and soluble salts. A part of this may be disposed duly and at times this will not be in accordance with the environmental regulations. A part of it, again, will be overlooked. Ground water, rainfall and snow will take them to aquifers and surface streams. Thus, the soil where plants will grow and water which is a daily necessity for the animals and air surrounding the region will be polluted to a greater extent.
And it is a fact that waste management technology is still in its infancy in the globe.
Still human beings have been glorified for astonishing faculty down the ages. People love to remain busy to counter the technological challenges. We have heard about in situ and modified in situ operations where the retorts will be built up underground. Yes, it is not unknown that disposable wastes may find channels through the permeable layers and water will have a role to percolate the pollutants to the surroundings.
Still there are reasons to be hopeful.
Shell has been engaged in an expansive research efforts scheduled to run until 2010. Shell has developed and patented a true in-situ technology known as the “In-situ Conversion Process” (ICP). According to Shell, the ICP can potentially produce high quality transportation fuels from oil shale, oil sand, and coal in a technically, economically, and environmentally sound manner.
Shell uses an innovative freeze-wall technology to exclude groundwater from the zone to be retorted. A ring of boreholes is drilled around the zone, and a refrigerated liquid is circulated through the holes. The refrigerant freezes the water between the boreholes and forms a barrier wall. Water within that wall is pumped out, and heating commences. The freeze wall must be maintained until all the oil shale is retorted.
Yes, there are reasons to be hopeful. And let this be true at the face of global warming which is already in a mature stage in our time.