• Question
– What is “chemical” energy?
• A form of potential energy
• Potential energy is stored in the (valence) electrons of atoms and molecules
• Lecture Questions
– What are exothermic and endothermic chemical reactions?
• Exothermic reaction: produces energy, usually as heat or light
• Endothermic reaction: consumes energy as it proceeds
– Why do some reactions produce energy (and some consume it)?
• Chemical reactions
– Consists of breaking and forming bonds
– The formation of bonds always yields energy
– The breaking of bonds always requires energy
– The balance between these two processes determines the net energy yield/requirement of a chemical reaction

• What are the main fossil fuels?
– Coal, oil (petroleum), natural gas
Gas
26% Coal
30%
Gas
26%
Coal
25%
Global
Oil
44%
• How are they mostly used?
– Coal: electricity
– Oil: transportation, heating
– Natural gas: heating, electricity, cooking
Oil
49%
OECD

• Lecture Questions
– What is coal?
• A solid mixture consisting largely (about 85%) of carbon
– Representative formula is C
135
H
– Plenty of other impurities
96
O
9
NS
» Toxic metals like Pb, Hg, As
» Radioactive isotopes of various types
– Three broad grades of coal
» Anthracite (hard coal). Highest carbon content and heat value.
» Bituminous coal (soft coal)
» Lignite (brown coal). Lowest carbon content and heat value.
– How is coal formed?
• Originated as plant matter in hot, muggy regions
– Most current coal formed 200-350 million years ago
– Plant matter decays under conditions of low oxygen, high heat and pressure
» First converted to peat

• What is natural gas?
– Gaseous mixture of hydrocarbons
• Mostly methane, CH
4
• Others: C
2
(60-80%)
HCs (5-9%), C
3
HCs (3-18%), C
4
• How is it formed?
HCs(2-14%)
– Decomposition of plant and animal remains that had been buried
• Again: lack of oxygen, high heat and pressure
• Methane is produced by anaerobic respiration
– Plenty produced in sediments and landfills
– Often accompanies coal and oil deposits

• What is oil (petroleum)?
– A very complicated liquid mixture of hydrocarbons
– Liquid HCs start at C
4
-C
5
– Almost always contains dissolved natural gas as well
• How is it formed?
– Again, decomposition of biological matter
• Most probably originated from ocean-dwelling microorganisms

• Gasoline Formation
– Conversion of other oil fractions to gasoline
– Cracking
• Breaking apart larger molecules into smaller ones
• Thermal cracking
• Catalytic cracking
• Gasoline enhancement
– Purpose
• Make it burn better of cleaner
• Example: antiknock agents
– Tetraethyl lead (TEL)
– MTBE
– Oxygenated Gasoline
• Reduce CO emissions
• MTBE, ethanol, methanol
– Reformulated Gasoline (RFG)
• Oxygenated gasolines with fewer volatile hydrocarbons
• Reduce CO emissions
• Reduced smog
• May have reduced impact on groundwater (lower BTEX)

• What are the environmental impacts of using fossil fuels as energy sources?
– Extraction
• Coal mining
• Oil and gas drilling
– Storage and Transport
• Leaks, spills
– Combustion
• Contributes to global warming, acid rain, smog, PM, eutrophication, toxic metals, exposure to radioactivity
– All contribute to global warming, nitrate PM, eutrophication, and acidification due to HNO
3
– Coal is the main culprit for SO
2
, metal and radionuclide emissions. It is also the worst of the three for PM.

• Nonrenewable resources
– They will eventually be exhausted and need to be replaced
– Global warming may accelerate the replacement (or not)
• Reserves and Resources

• When will we run out of oil (and natural gas)?
– Most important question is maybe: when will production begin to decline ? (ie, “when will peak oil production occur?”)
– In March 1998, two retired petroleum geologists (Campbell and Laherre) claimed that oil would peak in the first decade of the 21 st century

• Unconventional Sources of Oil
– Potentially a very large resource
• Oil shales, tar sands, heavy oil
• Extends peak production by 2-3 decades
– Problems
• More energy intensive (thus more expensive); more environmentally damaging