Summary
Highlights
Key producers of coal include Russia, the US, and China. Oil reserves are largest in Iran, Saudi Arabia, Venezuela, and Canada. Natural gas is primarily found in the US, Russia, and Iran. Energy consumption trends show countries shifting from biomass to fossil fuels and then to more advanced sources like nuclear power as they industrialize. Energy use is also influenced by price fluctuations, availability, and government regulations.
Non-renewable resources like fossil fuels (oil, natural gas, coal) are finite and take millions of years to form, making them irreplaceable within our lifetime. Renewable resources, such as solar, wind, geothermal, and hydropower, are easily replenished or continuously available. Biomass is renewable if used sustainably, otherwise, it can be considered non-renewable. Resource distribution varies globally, impacting which energy sources are viable in different regions.
Biomass, including wood, peat, and charcoal, is a cheap and accessible energy source often used in less developed countries for cooking and heating. However, burning biomass releases particulate matter and carbon compounds, causing pollution. Coal is acquired through mining, which has significant environmental impacts. There are three types of coal: lignite (low heat, low sulfur), bituminous (high heat, high sulfur, most common), and anthracite (high heat, low sulfur, limited supply). All coal burning releases particulate matter and carbon pollution.
Crude oil is drilled from the ground and refined into fuels. Its conversion to energy is inefficient due to the second law of thermodynamics, with much energy lost as heat. Burning crude oil releases carbon compounds (contributing to global warming) and particulate matter. Combustion, the process of burning fossil fuels, often results in incomplete combustion and significant pollution. Cogeneration can improve efficiency by using excess heat. Natural gas is extracted through fracking, which is linked to earthquakes and groundwater contamination. While cleaner than other fossil fuels, it releases methane, a potent greenhouse gas.
Coal-fired power plants burn coal to heat water, producing steam that spins a turbine connected to a generator, creating electricity. Nuclear power plants use uranium-235 in a chain reaction (fission) to generate heat, which then produces steam to power turbines and generators. Nuclear power is clean in terms of air emissions but poses challenges: radiation (requiring strict containment), and high-level radioactive waste disposal. Thermal pollution from heated water discharged into local reservoirs is another significant environmental concern.
Significant nuclear accidents include Three Mile Island (USA, 1970s) a partial reactor meltdown; Chernobyl (Ukraine, 1986), a human error meltdown with widespread radioactive contamination; and Fukushima (Japan, 2011), caused by an earthquake and tsunami that led to multiple reactor meltdowns.
Photovoltaic cells convert sunlight directly into electricity, with the ability to store energy. Passive solar design uses building materials and practices to absorb and retain solar heat, though this heat is not storable. Hydroelectric power, primarily from dams, uses flowing water to spin turbines and generators. Dams can impact fish migration (addressed by fish ladders) and alter river ecosystems, but also provide flood control and water resources. Geothermal power harnesses Earth's internal heat to create steam for electricity, best suited for geologically active areas like Iceland. Downsides include high plant costs and potential for hydrogen sulfide pollution during drilling.
Hydrogen fuel cells combine hydrogen and oxygen to produce electricity with only water as a byproduct, making them extremely clean. However, they are expensive to produce, and safely containing hydrogen remains a challenge. Wind power uses large turbines, where wind spins blades that power a generator. While clean, wind farms can be noisy, visually impactful, and pose a risk to birds and bats. Ideal locations are open, unpopulated areas like farmlands.