The world currently burns through an estimated 88.25 million barrels of oil per day. As the supply of sweet, light crude diminishes, it is being replaced by unconventional alternatives, including tar sands. Tar sand
is extreme oil in every way. Tar sands are a combination of clay, sand, water, and bitumen, a heavy black viscous oil. Tar sands recovery processes include extraction and separation systems to separate the bitumen from
the clay, sand, and water that make up the tar sands. Its extraction is particularly energy and water-intensive, polluting, and destructive. It is either strip mined or produced by injecting high pressure steam into the ground to melt the bitumen and get it
to flow to the surface. Some of these extraction methods require large amounts of both water and energy (for heating and pumping). To process it into usable fuel requires complex upgrading and refining that
is also highly energy intensive and polluting. Bitumen requires additional upgrading before it can be refined. Because it is so viscous, it requires dilution with lighter hydrocarbons to make it transportable by pipelines. These techniques help turn
tar sands into something a bit closer to what we call oil.
Extracting oil from tar sands is more complex than conventional oil recovery. About two tons of tar sands are required to produce one barrel of
oil. Currently, tar sands extraction and processing require several barrels of water for each barrel of oil produced, though some of the water can be recycled. They have to use a lot of natural gas to upgrade this heavy, sticky,
almost tar-like stuff to make it fluid enough to use. The average "energy returned on investment," or EROI, for conventional oil is roughly 25:1. In other words, 25 units of oil-based energy are obtained for every one unit of other energy that is invested
to extract it. Tar sands retrieved by surface mining has an EROI of only about 5:1. Tar sands retrieved from deeper beneath the earth, through steam injection, fares even worse, with a maximum average ratio of just 2.9 to
1. That means one unit of natural gas is needed to create less than three units of oil-based energy.
The energy return on tar sands is very low and companies that produce tar sands oil had to wait for the price of petroleum to rise before it
was economically viable to mine. Fossil fuels are finite, they are considered to be a nonrenewable resource. Canada's tar sands oil reserves remain at a finite 168.6 billion barrels, enough to keep the world fueled for less than six years. Plus, using a lot
habitat, wastes enormous volumes of water, pollutes air and water, and degrades and defiles vast swaths of land. It's an issue of diminishing returns. Fuel efficiency, public transit, better urban planning, and a new generation of vehicles are better
investments to reduce foreign imports.