1. Fuels & Energy IB Option AP/IB Chemistry Chanlder High School

2. Present Sources of Energy – Fossil Fuels A.Fossil fuels A.Fossil fuels Petroleum Petroleum thick, dark liquid composed mainly of hydrocarbons thick, dark liquid composed mainly of hydrocarbons formed from the remains of marine organisms that lived ~500 million years ago formed from the remains of marine organisms that lived ~500 million years ago

3. Fossil Fuels hydrocarbon chains range from 5 to 25+ carbons hydrocarbon chains range from 5 to 25+ carbons chains separated based on number of carbons chains separated based on number of carbons separation occurs through a boiling process separation occurs through a boiling process chains with fewest number of carbons boil off first, leaving heavier chains behind chains with fewest number of carbons boil off first, leaving heavier chains behind

4. Fossil Fuels commercial uses of petroleum fractions summarized in table below: commercial uses of petroleum fractions summarized in table below: Petroleum Fraction with Respect to # of Carbons Major Uses C 5 – C 10 Gasoline C 10 – C 18 Kerosene; Jet fuel C 15 – C 25 Diesel fuel; Heating oil; Lubricating oil >C 25 Asphalt

5. Fossil Fuels importance of gasoline led to a new separation process called pyrolytic cracking importance of gasoline led to a new separation process called pyrolytic cracking heavier petroleum molecules are heated to very high temperatures heavier petroleum molecules are heated to very high temperatures high temperatures cause the large molecules to break into smaller molecules that can be used as gasoline high temperatures cause the large molecules to break into smaller molecules that can be used as gasoline

6. Present Sources of Energy – Natural Gas Natural Gas Natural Gas combination of methane, ethane, propane, and butane (predominantly methane) combination of methane, ethane, propane, and butane (predominantly methane) formed in conjunction with petroleum formed in conjunction with petroleum

7. Present Sources of Energy – Coal Coal Coal complex organic molecule with empirical formula of CH2O and molecular mass of ~500,000 g/mol. complex organic molecule with empirical formula of CH2O and molecular mass of ~500,000 g/mol. formed from the remains of plants that were buried and subjected to high pressure and heat formed from the remains of plants that were buried and subjected to high pressure and heat

8. Coal matures through four stages matures through four stages lignite (71% C, 4% H, 23% O, 1% N, 1% S) lignite (71% C, 4% H, 23% O, 1% N, 1% S) subbituminous (77% C, 5% H, 16% O, 1% N, 1% S) subbituminous (77% C, 5% H, 16% O, 1% N, 1% S) bituminous (80% C, 6% H, 8% O, 1% N, 5% S) bituminous (80% C, 6% H, 8% O, 1% N, 5% S) anthracite (92% C, 3% H, 3% O, 1% N, 1% S) anthracite (92% C, 3% H, 3% O, 1% N, 1% S)

9. Coal currently supplies 20% of energy consumed in U.S. currently supplies 20% of energy consumed in U.S. expensive and dangerous to mine expensive and dangerous to mine burning high sulfur coal  sulfur dioxide air pollutants  acid rain burning high sulfur coal  sulfur dioxide air pollutants  acid rain burning coal adds to the greenhouse gas problem burning coal adds to the greenhouse gas problem

10. New Energy Sources – Coal Conversion Coal conversion Coal conversion Coal is broken down into smaller, more economical molecules via coal gasification Coal is broken down into smaller, more economical molecules via coal gasification coal is treated with oxygen and steam at high temperatures coal is treated with oxygen and steam at high temperatures this breaks carbon-carbon bonds, and new carbon-hydrogen or carbon-oxygen bonds are formed this breaks carbon-carbon bonds, and new carbon-hydrogen or carbon-oxygen bonds are formed this produces a product called synthetic gas (syngas) this produces a product called synthetic gas (syngas)

11. Coal Conversion Syngas is used both as a fuel and as a raw material to produce other fuels Syngas is used both as a fuel and as a raw material to produce other fuels The process of producing syngas involves both exothermic and endothermic reactions The process of producing syngas involves both exothermic and endothermic reactions If correct concentrations of coal, oxygen, and steam are maintained, no external energy is required If correct concentrations of coal, oxygen, and steam are maintained, no external energy is required

12. New Energy Sources – Hydrogen Hydrogen Hydrogen Combustion of hydrogen is highly exothermic (2.5 times that of natural gas per gram) Combustion of hydrogen is highly exothermic (2.5 times that of natural gas per gram) No harmful product produced, only water No harmful product produced, only water Produced from the reaction of methane with water Produced from the reaction of methane with water CH 4 + H 2 O  3H 2 + CO **this is not very economical because it is a highly endothermic reaction

13. Hydrogen Three main problems to using hydrogen as fuel Three main problems to using hydrogen as fuel expensive to produce – virtually no hydrogen exists as free hydrogen molecules expensive to produce – virtually no hydrogen exists as free hydrogen molecules storage – hydrogen decomposes to atoms on metal surfaces; these small atoms cause structural damage to the metal storage – hydrogen decomposes to atoms on metal surfaces; these small atoms cause structural damage to the metal transport – amount of energy per unit volume is small; very large amounts must be transported to be useful transport – amount of energy per unit volume is small; very large amounts must be transported to be useful