Читать книгу Climate Change For Dummies - Elizabeth May - Страница 91

No matter what the name suggests, the tar sands (also called oil sands) aren’t a tarry version of the Sahara Desert. They’re boreal forests (coniferous forests, found between 50 and 60 degrees North latitude, across northern Canada, Russia, Alaska, and Asia, as well as Scandinavian Europe) and muskeg (a type of wetland found in boreal and arctic areas) that cover a sandy soil that’s 10-percent bitumen, a viscous material that resembles tarry molasses. To get the oil, you have to squeeze this bitumen out of the sands.

The Athabasca tar sands hold 165 billion barrels of proven retrievable oil. These reserves make it the second-largest oil patch in the world, after Saudi Arabia. Reaching the bitumen involves stripping away the muskeg and boreal forest — a single mine may need more than 6,500 hectares (16,000 acres) of forest cleared, which also has bad consequence by removing more potential carbon sinks from the landscape.

After removing the muskeg and forest, oil companies dig the bitumen out of open-pit mines that are 245 feet (75 meters) deep. To extract the bitumen that lies even deeper, they have to pump huge amounts of water and steam into the ground to loosen it up and bring it to the surface. This process called in-situ mining uses between 2.5 and 4 barrels of water for every barrel of oil extracted, depending on how deep the bitumen lies. In-situ mining produces even more GHG than the open pit mines. This process creates a lot of wastewater, full of toxic waste, that they store behind enormous dikes. The tailings ponds of contaminated water cover 85 square miles (222 square kilometers).

The Alberta government permits the oil sands operation to use more than 1,177 cubic feet (359 million cubic meters) of water annually — twice as much as the city of Calgary, which has a population of more than a million people, uses in the same period. A 2006 report by the Canadian National Energy Board (now called the Canadian Energy Regulator) questioned whether the project’s massive water use was sustainable. Many towns and communities, such as Fort McMurray, also rely on the river from which this water is drawn for their drinking water — the water that the mining uses may one day seriously stress the water source of Fort McMurray residents.

Heating up the bitumen and extracting it from the oil sands takes a lot of energy — energy that’s supplied by … burning fossil fuels. These operations use the equivalent of a third to a half a barrel of oil for every barrel of oil produced. (Anyone see a losing cycle here?)

So, the mining industry consumes a huge amount of energy in order to produce oil, which primarily the United States buys for cars that don’t have proper energy efficiency standards (California excluded!).

Canada’s decision to keep expanding and developing the oil sands is an example for other nations of what not to do — while making oil development a top priority, it’s impossible for Canada to decrease its GHG emissions. The report compared it to the American decision to encourage coal as a form of energy independence and to Brazil’s clearing of rainforests.

Natural gas is almost pure methane by the time it reaches your doorstep. A quarter of the world’s energy comes from natural gas. The Intergovernmental Panel on Climate Change (IPCC) reports show that the Earth contains more natural gas than regular oil, but that natural gas is patchy and spread out in comparison to oil, making it harder to tap into.

Because of how relatively clean it is when burned, some energy analysts have promoted natural gas as a clean-energy fuel to replace coal in power plants. But this solution may not be all it’s cracked up to be. Natural gas

 Increasingly comes from nonconventional sources requiring fracking: This involves fracturing of bedrock formations with water and chemicals under high pressure to release otherwise inaccessible sources of gas. It produces a huge volume of GHGs by releasing methane in the process.

 Is difficult to transport: Moving natural gas involves liquefying it first, which requires a lot of energy. This liquefying process also creates carbon dioxide emissions, depending on the source of energy. (For instance, coal-fueled energy would create more emissions than hydroelectric energy.)

 Is potentially dangerous: Concerns exist around possible pipeline explosions as well as the environmental damage created by gas exploration. Leaks and explosions do happen: On December 14, 2005, the community in Bergenfield, New Jersey, awoke to a tremendous explosion caused by a leaking natural gas pipeline that demolished an apartment building and claimed three lives.

 Has larger impacts: Including increasing the number of (generally small) earthquakes.