Global Energy Resources: Sustainability, Pollution, and Future Trends

Understanding Energy Resources

Key Definitions of Energy Resources

• Renewable Resources: Resources that are not used faster than nature replenishes them (flow-limited).
• Non-Renewable Resources: Resources used faster than nature replenishes them (stock-limited).
• Sustainable: A resource use model that can be maintained over the long term with minimal environmental harm or loss of energy. Note: Sustainable is not equivalent to “renewable.”
• Conventional Energy: Energy derived from established sources like fossil fuels, hydroelectricity, and nuclear power.
• Alternative Energy: Energy derived from sources such as biofuels, solar, geothermal, and wind.

Conventional Energy Sources: Fossil Fuels

Advantages of Conventional Fuels

• They are cheap and have established infrastructure for transport and use.
• The U.S. has a large supply of natural gas, contributing to energy independence.
• They exist in some form in most countries.
• They possess high energy density (high quality).
• They are portable, versatile, and flexible.
• Conversion technologies are simple and available at many scales.
• They are excellent fuels for transportation.
• They serve as excellent feedstocks for chemicals, plastics, medicines, and more.

Disadvantages and Security Concerns

• Significant environmental and health impacts occur at every stage of utilization.
• Many countries are dependent on foreign sources of oil, raising potential security issues.
• We are depleting the cheapest and easiest-to-extract forms of oil.

Current Energy Trends

• Wind energy is the fastest growing energy supply.
• Solar energy is becoming cheaper.
• Natural gas is cheaper than coal and is experiencing a boom.
• In recent years, the U.S. trend shows less coal usage and increased natural gas consumption.

Fossil Fuel Combustion and Pollution

The Combustion Equation

The general combustion equation is:

C_xH_y + O₂ → CO₂(greenhouse gas) + H₂O + heat + pollutants

Sources of Pollution

Burning fossil fuels gives rise to different kinds of pollution, primarily through incomplete combustion, which yields:

• Carbon Monoxide (CO)
• Carbon (C), commonly known as soot
• By-products from impurities (e.g., SO_x, NO_x, metals, radioactive materials)

Impurities and Environmental Impacts

Fossil fuels contain various impurities:

• Coal: C + impurities
• Oil: C_xH_y + impurities
• Natural Gas: CH₄ + impurities

Specific impurities lead to severe environmental consequences:

• Sulfur (S): Leads to SO_x, which causes acid rain (H₂SO₃, H₂SO₄).
• Metals: Nickel (Ni), Lead (Pb), Mercury (Hg), and Cadmium (Cd) pose significant health hazards.
• Nitrogen (N): The high temperature of combustion oxidizes nitrogen in the atmosphere (N → NO_x), leading to low-level ozone and smog formation.

Unconventional Hydrocarbons

Oil Shales: An organic-rich, fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be extracted.

Tar Sands: A combination of clay, sand, water, and bitumen, a heavy black viscous oil. Tar sands can be mined and processed to extract the oil-rich bitumen, which is then refined into oil.

Challenges of Nuclear Energy

Nuclear Waste Management

Spent Fuel Rods (1% of total waste, but the most concerning):

• They last 3–4 years, then must be replaced.
• Currently, there are over 200,000 tons of spent fuel rods in the U.S. alone.
• They are highly radioactive, and many decay products have very long half-lives—potentially taking tens of thousands of years to decay to safe levels.

Major Nuclear Accidents

Notable historical accidents include:

• Three Mile Island
• Chernobyl
• Fukushima Daiichi

Security and Operational Risks

• Security: Threat of terrorist attack.
• Water Requirements: Nuclear plants require large amounts of water to operate and cannot function if river levels are too low.