8.2 Fossil Fuels

Notes

Fossil fuels formed from the remains of ancient plants and plankton buried and compressed over millions of years.

• Coal: most abundant fossil fuel; releases the most $CO_2$ per unit of energy plus $SO_2$, mercury, and ash. Mining can cause land damage and acid mine drainage.
• Oil (petroleum): refined into gasoline, diesel, and plastics. Risks include oil spills and air pollution. Drilling methods include offshore drilling and extraction from tar sands (which is energy intensive).
• Natural gas: mostly methane. It burns cleaner than coal or oil (about half the $CO_2$ of coal for the same energy), but methane leaks are a powerful greenhouse gas. Hydraulic fracturing (fracking) extracts gas and oil from shale but raises concerns over water use and groundwater contamination.
• Advantages: high energy density, existing infrastructure, reliable. Disadvantages: finite, air pollution, and climate change.
• Burning fossil fuels is the largest source of human $CO_2$ emissions.
• Example: switching a power plant from coal to natural gas lowers $CO_2$ and $SO_2$ emissions but does not eliminate them.