Energy supply-case study

Question 1

Alaska

Answer 1

Alaska’s North Slope has extensive oil deposits- -the largest are at Prudhoe Bay. North Prudhoe Bay
Development of the North Slope oil reserves started in the 1960s, and the area now has around 20 oil fields that cover more than 2500 km², as well as a number of offshore wells. At their peak in the 1980s, they produced over 720 million barrels of crude oil each year.

Question 2

Infrastructure

Answer 2

Infrastructure has been constructed to support the oil fields - more than 800 km of roads, 20 airports, 3000 km of pipes and two refineries have been built on the North Slope. The Trans-Alaska oil pipeline transports oil from Prudhoe Bay to Valdez in the south of Alaska - from there, it is shipped to other parts of the world.

Question 3

Climate change-production

Answer 3

Over 60 000 tonnes of nitrogen oxides are released from the oil fields each year, polluting the air. Pollutants from Prudhoe Bay have been detected hundreds of kilometres away. Oil extracted at Prudhoe Bay usually comes mixed with natural gas, which has to be burnt off. This is known as gas flaring, and it causes the release of greenhouse gases, such as carbon dioxide and methane, which contribute to climate change.

Question 4

Freshwater-production

Answer 4

Freshwater is pumped from lakes to use during oil extraction, which reduces the amount available for animals. If too much water is removed, a lake may become so shallow that its entire depth freezes during winter, damaging or destroying lake-bed ecosystems.

Question 5

Ecosystem- production

Answer 5

Fragile tundra habitats have been destroyed by the development of the oil fields. Wildlife has been disturbed, e.g. surveying close to polar bear dens can cause females to abandon their young.
Groundwater is also brought to the surface by drilling-it often contains salt, oil and other chemicals, which can kill vegetation. Tundra vegetation grows slowly, so it takes a long time for the ecosystem to repair itself.

Question 6

Fish-production

Answer 6

Offshore exploration and drilling generate noise and vibrations that can disturb marine creatures, e.g. bowhead whales. Offshore platforms and embankments built to support oil drilling alter fish migration patterns.

Question 7

Pipelines-Distribution networks

Answer 7

Pipelines transporting oil can develop leaks-pipes are so long and pass through such remote areas that leaks are often not noticed for a long time. For example, a leak discovered near Prudhoe Bay in February 2001 is thought to have started in early December 2000. By the time it was stopped, around 270 000 litres of crude oil had been spilt, contaminating wetlands and freshwater lakes. There are concerns that the Trans-Alaska pipeline is becoming corroded, which may result in more leaks.

Question 8

Oil spills-Distribution networks

Answer 8

Oil spills can also occur from ships transporting oil, damaging marine ecosystems. For example, in 1989 the oil tanker Exxon Valdez ran aground just offshore of Valdez, spilling over 50 million litres of oil. The oil washed up on over 1600 km of coastline and killed hundreds of thousands of animals, including sea otters, herring, killer whales and seabirds. The populations of some species still haven’t recovered.

Question 9

Standing water-distribution networks

Answer 9

Standing water collects on road surfaces during the summer, changing the water cycle in the region and creating new habitats for mosquitoes. Dust blown up from roads can settle on vegetation, adding nutrients to the ecosystem and changing the species that grow there. Thick dust deposits can smother small plants.