Unit 6: Energy Resources and Consumption Study Guide

Topic 6.1 - Renewable and Nonrenewable Resources

Fundamental Definitions: * Nonrenewable Energy Sources: These resources exist in a fixed amount and involve energy transformations that cannot be easily replaced or replenished within a human lifetime. * Renewable Energy Sources: These resources can be naturally replenished at or near the rate of consumption and can be reused indefinitely.
Categories of Nonrenewable Resources: * Fossil Fuels: Ancient organic matter converted into high-energy fuels (e.g., coal, oil, natural gas). * Nuclear Fuels: Supplies derived from radioactive materials (e.g., Uranium). * Key Characteristic: These supplies are finite and can effectively be "used up."
Categories of Renewable Resources: * Potentially Renewable: Energy sources that can be regenerated indefinitely as long as they are not overharvested. Examples include forest trees and biofuels. * Nondepletable Resources: Renewable resources that cannot be exhausted on human life scales regardless of consumption. Examples include: * Wind * Solar power * Hydroelectric power * Wave energy * Geothermal energy

Topic 6.2 - Global Energy Consumption and Trends

Universal Units of Energy (SI): * Joule ( $J$ ): The basic unit of energy. * Kilojoule ( $kJ$ ): $1,000$ Joules ( $10^{3}$ ). * Megajoule ( $MJ$ ): $1,000,000$ Joules ( $10^{6}$ ). * Gigajoule ( $GJ$ ): $1,000,000,000$ Joules ( $10^{9}$ ). * Terajoule ( $TJ$ ): $1,000,000,000,000$ Joules ( $10^{12}$ ). * Exajoule ( $EJ$ ): $1,000,000,000$ Gigajoules.
Developed vs. Developing Countries: * Developed Countries: Typically industrialized with stable economies. Examples: United States, Canada, Australia, Austria, France, Germany, Italy, Japan, and the United Kingdom. These nations use more energy resources per capita. * Developing Countries: Non-industrialized, often poor, and seeking to develop resources. Examples: India and China. These nations often depend on biomass (fuelwood, dung) for cooking and heating.
Energy Distribution and Industrialization: * As developing countries industrialize, their reliance on fossil fuels typically increases. * Leapfrogging: Some developing nations bypass heavy fossil fuel usage and move directly to solar or renewable applications (e.g., China's current shift toward solar and wind). * Commercial Energy Sources: Bought and sold (oil, coal, natural gas). * Subsistence Energy Sources: Gathered by individuals for immediate needs (straw, sticks, animal dung).
Regional Use in the United States: * Midwest and Southeast: Primarily rely on coal for energy production. * West and Northeast: Use a mix of nuclear, natural gas, and hydroelectricity. * Seasonal Variations: * Northern U.S.: Higher energy use in winter for heating. * Southern U.S.: Higher energy use in summer for air conditioning.
Energy Return on Energy Investment (EROEI): * Formula: $\text{EROEI} = \frac{\text{Energy Obtained}}{\text{Energy Invested}}$ * A larger EROEI value indicates a more efficient and desirable energy source.

Topic 6.3 - Fuel Types and Specialized Uses

Wood and Charcoal: * Common in developing countries due to easy accessibility. * Wood use in the U.S. has seen the steepest decline over the last $200$ years. * Charcoal is superior to wood; it is lighter, contains twice the energy by weight, and produces less smoke. * Environmental Impact: Overharvesting leads to deforestation and soil erosion.
Peat: * Partially decomposed organic material used for heating. * Damaging to the climate; produces less energy than coal but higher $\text{CO}_2$ emissions per unit. It is harvested from bogs (e.g., in Ireland).
Coal Categories (Lowest to Highest Heat Content): 1. Peat: Precursor to coal. 2. Lignite: Low heat content, high moisture. 3. Bituminous: High heat content, high sulfur, most commonly used. 4. Anthracite: Highest heat/carbon content, lowest sulfur, rarest and most desirable.
Natural Gas: * Composition: $80\text{-}95\%$ methane ( $CH_4$ ), $5\text{-}20\%$ ethane, propane, and butane. * Considered the "cleanest" fossil fuel as it emits half the carbon of coal during combustion. * Shortcoming: Methane has $25$ times the global warming potential of $\text{CO}_2$ .
Petroleum (Crude Oil): * Liquid mixture of hydrocarbons, water, and sulfur. * Refining: Fractional distillation separates components based on boiling points (e.g., asphalt, diesel, gasoline). * Unconventional Sources: * Tar Sands: Combination of clay, sand, water, and bitumen. Alberta, Canada has the world's largest deposits. * Oil Shale: Contains kerogen (waxy hydrocarbon mixture). Difficult and energy-intensive to extract.
Cogeneration: Using a fuel source (like steam) to generate both useful heat and electricity simultaneously to improve overall efficiency.

Topic 6.4 - Distribution of Natural Energy Resources

Geological Logic: Energy resources are not uniform; they depend on a region's geological history.
Crustal Abundance: Four elements make up over $88\%$ of Earth's crust: Oxygen, Silicon, Aluminum, and Iron.
Global Reserves: * Coal: U.S. ( $28\%$ ), Russia ( $18\%$ ), China ( $13\%$ ), Australia ( $9\%$ ), India ( $7\%$ ). * Oil: Venezuela, Saudi Arabia, Canada, Iran, Iraq. * Natural Gas: Russia, Iran, Qatar, United States, Saudi Arabia. * Uranium: Australia, Kazakhstan, Canada, Russia, South Africa.
Historical Formations: * Banded Iron Formations (Michigan): Formed $3,700$ million years ago from oxygen produced by photosynthetic cyanobacteria reacting with dissolved iron. * Appalachian Coal: Formed $330$ million years ago when the region was near the equator and covered in swamplands.

Topic 6.5 - Fossil Fuels in Power Generation

Formation Environment: Requires anaerobic (oxygen-poor) conditions (swamps, river deltas) so decomposers cannot fully break down detritus.
Combustion Chemistry: * Complete Combustion: $\text{Fuel (Hydrocarbon)} + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{Heat}$ * Incomplete Combustion: Occurs when oxygen is limited, producing Carbon Monoxide ( $CO$ ) and soot (carbon).
Electricity Generation Process: 1. Fuel is burned in a boiler. 2. Heat converts water into steam. 3. Kinetic energy of steam turns a turbine. 4. Turbine turns a generator to produce electricity. 5. Electricity travels via the electrical grid (network of transmission lines).
Extraction Methods: * Surface Mining: Uses area strip mining or power shovels to remove overburden (soil/rock on top). Creates "spoil banks." * Underground Mining: Essential for deep deposits but hazardous to workers.

Topic 6.6 - Nuclear Power

Nuclear Fission: A neutron strikes a large nucleus (Uranium-235), splitting it into smaller atoms (e.g., Barium, Krypton) and releasing more neutrons and immense heat.
Reactor Components: * Fuel Rods: Contain the Uranium fuel pellets. * Control Rods: Inserted between fuel rods to absorb neutrons and slow/stop the reaction to prevent meltdowns. * Moderator (Water): Slows down neutrons so they can trigger further fission.
Radioactive Waste: * Low-level: Contaminated clothing/tools; stored for $100\text{-}500$ years. * High-level: Spent fuel rods; stored for at least $10,000$ years. Currently stored on-site at power plants. * Yucca Mountain, Nevada: Proposed geologically stable repository for waste.
Half-Life Calculation: The time required for half of a radioactive sample to decay. * Example: $U\text{-}235$ has a half-life of $704$ million years.
Major Nuclear Accidents: 1. Three Mile Island (1979, US): Partial meltdown; halted new U.S. plant construction for years. 2. Chernobyl (1986, Ukraine): Explosion/fire; released massive radiation across Europe; $31$ immediate deaths, thousands of thyroid cancer cases later. 3. Fukushima (2011, Japan): Tsunami-induced cooling failure; released radioactive gases.

Topic 6.7 - Energy from Biomass

Carbon Neutrality: Theoretically, $\text{CO}_2$ released during biomass combustion equals the $\text{CO}_2$ the plant absorbed while growing, resulting in no net atmospheric increase (unlike fossil carbon).
Solid Biomass: Wood, charcoal, and dried animal manure. * Indoor burning causes $3$ million deaths annually due to respiratory issues (particulates, $CO$ ).
Liquid Biofuels: * Ethanol: Produced from corn (U.S.) or sugarcane (Brazil). Sugarcane ethanol has an energy return $8$ times higher than corn. * Biodiesel: Produced from vegetable oils. * Algae: Can produce $10$ times more energy per area than other plants but currently remains too costly to refine.

Topic 6.8 - Solar Energy

Passive Solar Design: No mechanical equipment. Includes south-facing windows, dark roofs, and thermal mass (stone/concrete) to absorb/release heat. * Solar Ovens: Use reflectors to cook food; essential in regions like Darfur to reduce wood gathering risks.
Active Solar Energy: * Solar Water Heaters: Liquid circulated by pumps to heat water for homes/pools. * Photovoltaic (PV) Cells: Purified Silicon wafers convert light (photons) directly into electricity (DC), then converted to AC by an inverter. * Concentrating Solar Thermal (CST): Use mirrors/lenses to focus sunlight into a beam that produces steam for turbines. Best for desert areas (e.g., Ivanpah, CA).

Topic 6.9 - Hydroelectric Power

Mechanism: Moving water turns a turbine. Generated via: * Large-scale Dams: Create reservoirs storing potential energy. * Run-of-the-river: Low dams with no reservoir; less flooding but intermittent generation. * Tidal Energy: Uses ocean tides (France, Nova Scotia, South Korea).
Environmental Trade-offs: * Pros: Cheap power, flood control, recreation. * Cons: Siltation (reservoirs fill with mud), methane emissions from rotting submerged plants, fish migration disruption (mitigated by fish ladders).
Questions & Discussion: * Joke 1: Why can't I have any water? "You can't have any of this dam water." * Joke 2: What did the fish say when it hit the wall? "Dam!" * Joke 3: What if you stack dams? "It will be two dam high." * Joke 4: What did the beaver say? "Dam it."

Topic 6.10 - Geothermal Energy

Source: Radioactive decay of elements within Earth's core. Not solar-derived.
Usage: Iceland uses geothermal for $60\%$ of its energy (heating and electricity).
Ground Source Heat Pumps: Cycle fluid underground. In winter, fluid absorbs heat from the ground ( $50\text{-}60^{\circ}\text{F}$ ) and transfers it to the house. In summer, the process reverses.
Risks: Can cause land subsidence or small earthquakes (e.g., $5.5$ magnitude quake in South Korea, 2017).

Topic 6.11 - Hydrogen Fuel Cells

Process: Combines Hydrogen ( $H_2$ ) and Oxygen ( $O_2$ ) to form Water ( $H_2O$ ) and release electricity.
Efficiency: $80\%$ efficient compared to $35\text{-}50\%$ for thermal plants.
Challenges: Hydrogen must be created (via electrolysis or burning natural gas), it is highly explosive, and requires a new distribution infrastructure.

Topic 6.12 - Wind Energy

Origin: Unequal heating of Earth's surface by the sun (high vs. low pressure).
Growth: Fastest growing source of electricity globally. China is the top producer; Denmark gets $37\%$ of its power from wind.
Drawbacks: Kills birds/bats, noise pollution, and turbine blades are currently not recyclable (ending up in landfills).

Topic 6.13 - Energy Conservation

Conservation vs. Efficiency: Conservation is using less energy (turning off lights), Efficiency is doing the same work with less energy (using LED bulbs).
Individual Actions: Using power strips to stop "phantom loads," programmable thermostats, and tankless water heaters.
Governmental Tools: * Tiered Rate Systems: Higher usage results in higher costs per unit. * CAFE Standards: Mandated fuel economy for vehicles.
Sustainable Design: * Green Roofs: Soil/plants on roofs to provide insulation and improve air quality. * Xeriscaping: Landscaping with drought-resistant native plants to save water.
Transportation: Hybrid vehicles use gasoline engines + electric motors. Batteries require rare earth elements and have high environmental mining costs.