6.4 - Distribution of Natural Energy Resources

Learning Objectives

I. Global Reserves and Distribution

• Fossil fuels exist in proven reserves, which are estimates of how much fuel remains. These estimates change as new areas get explored.

• All fossil fuels are non-renewable and will eventually run out. New extraction techniques only offer short-term extensions.

• Why the distribution isn't even (geologic history): Fossil fuels and ores only form where the right geologic conditions happened millions of years ago, so they are clustered in some regions and missing from others.
• Oil and natural gas: form from tiny marine organisms (plankton) that piled up on the floors of ancient shallow seas and were buried and slowly cooked by heat and pressure. They only collect where porous rock like sandstone is sealed by an impermeable cap rock. The Middle East sat under a warm, shallow sea for millions of years and has huge rock traps, which is why it holds almost half the world's oil.
• Coal: forms from swamp plants that were buried before they could decay. Many big coal beds formed about 300 to 360 million years ago (the Carboniferous period), when swamp forests covered parts of what are now the eastern U.S., Europe, and China.
• Ores: metal deposits form where magma and hot fluids concentrate metals, often along plate boundaries. Chile, the world's top copper producer, sits along the subduction zone that built the Andes Mountains.
• Uranium: also unevenly spread. Kazakhstan mines the most by far (around 40% of the world's supply in recent years), followed by Canada, Namibia, and Australia.

• Why it matters: Countries without reserves have to import fuel (Japan imports almost all of its oil, coal, and natural gas), while countries with big reserves earn money and political influence from exporting them, like the oil-exporting members of OPEC.

II. Fracking (Hydraulic Fracturing) for Natural Gas

• Fracking is a natural gas extraction method where water is piped underground at high pressure to fracture the shale rock trapping the gas.

• Mechanism: Pressurized water breaks the rock, letting the gas, which is trapped in semi-permeable sedimentary rock like shale, flow into the well and get pumped out.

• Impact: Fracking opens up new areas of previously unrecoverable natural gas, which temporarily extends current estimated reserves.
• Example: Since the U.S. expanded fracking around 2008, natural gas consumption and production have shot up dramatically.

III. Oil and Tar Sands Extraction

• Tar sands (oil sands) contain bitumen, a thick, sticky, dense form of crude oil mixed with impurities.

• Location: Canada’s Alberta region holds the world’s largest oil sands reserve.

• Extraction process: Recovering crude oil from bitumen requires very high energy and water inputs. Steam and hot water have to be injected to melt the bitumen into a liquid that can flow through pipes.

• Impact: Oil sands extend the supply of petroleum, which drives increased production to meet high world demand for oil.

• Value of petroleum: Crude oil is so useful because it produces a diversity of products, including gasoline, motor oil, asphalt (from bitumen), and plastics.

IV. General Environmental Impacts of Fossil Fuel Extraction

• Mining resources, all of which are finite and non-renewable, involves removing overburden (soil and rock).

• Removing overburden and vegetation causes habitat loss and extensive topsoil erosion, which raises stream turbidity as sediments flow into waterways.

• When mining coal via subsurface methods, methane has to be vented out of the mine to prevent explosions. That methane is a potent greenhouse gas that contributes to climate change.