Dept of Life Sciences, University of the West Indies

Tar or oil sands are comprised of sand, clay, water and bitumen, the latter of which is black, heavy and viscous oil. Our world is still dependent on fossil fuels and one way of satisfying this need is through the use of tar or oil sands.

Currently, Canada has a large scale commercial production of oil from tar sands, while Venezuela carries out commercial oil production from this source on a small scale and tar sand deposits are found in our country. So why is this of environmental importance? In this article I will go into how this type of sand is extracted and how it affects the environment.

With such a name one might be under the impression that it can be pumped from the ground. But, because the fossil fuel is in the form of bitumen, it cannot be pumped out, instead the tar sand deposits must be mined, using open pit and strip mining techniques. However, if the oil is to be pumped from these deposits, underground heating in addition to other upgrades has to be implemented.

Approximately two trillion barrels of the world's oil is found in the form of tar sands, however not all is recoverable from tar sands. The recovery of oil from tar sands requires two types of processes; in the first stage, the bitumen is separated from the sand, clay and water. In the second stage, additional upgrading is needed before it can be refined. Finally, because of its viscous nature, it has to be diluted with lighter hydrocarbons so that it can be pumped through pipelines. Upgrading is the term given to pre-processing of the tar sands before it is fit for conventional refineries. There are three key components of upgrading.

The first step involves the removal of sand, water, physical waste and lighter products. The second component involves purification by removing metals, sulphur and nitrogen. Finally, hydrogen is added by the action of catalysts or through carbon rejection, the latter of which is very wasteful and inefficient. However, the upgrading processes utilise large amounts of water and energy and emit huge amounts of carbon dioxide, greater than conventional oil production.

Since the oil is made to flow into wells like conventional crude oil by injecting steam, solvents into the tar sands. The disadvantage of this is that it uses large amounts of water and energy. Another disadvantage from gaining oil from this source is that access to many of these tar sand deposits require mining, it means that the vegetation in the area as well as valuable top soil has to be removed. Therefore, in addition to the loss in biodiversity of both flora and fauna, the area is prone to erosion. Without the vegetation more water flows into watercourses resulting in flooding when heavy rainfall occurs. Also tar sands contain different metals, so that if allowed rainwater and water pumped in for use in the upgrading process can release toxins into our watercourses.

However, as I mentioned earlier, the processing of tar sands into oil requires much energy for steam injection and refining. The process produces two to four times more greenhouse gases for every barrel produced than the conventional process. The greenhouse gases produced by oil production from sands, in particular carbon dioxide, contributes to climate change. It is well known that carbon dioxide contributes to global warming.

The effects of oil production from tar sand on organisms, in particular aquatic organisms are not clear. There are conflicting results, with one body of research indicating no effects.

The other indicates that some of the chemicals produced which include carcinogens that cause cancer, can cause deformities in aquatic organism such as tumours.

Therefore it can be seen that in a time when our world is in search of renewable energy sources, turning to untapped sources of fossil fuels in Trinidad & Tobago may not be the answer.