Unit 6: Energy Use

Renewable and Non-Renewable Resources

• Non-Renewable Resources:
  • Exist in a finite amount worldwide.
  • Are consumed upon use and cannot be easily replaced.
  • Examples include coal, oil, and natural gas.
  • These fossil fuels take millions of years to form, making replacement within a human lifetime impossible.
• Renewable Resources:
  • Energy sources that are easily replenished.
  • Sources that do not get used up, such as the Sun (solar energy) and wind energy (powered by the Sun).
  • Geothermal energy comes from the heat of the Earth.
  • Hydropower comes from river flow.
  • Tidal energy comes from the ocean.
  • Biomass (wood and plant matter) is renewable if used sustainably (replaced at the same rate it is used).
    • If biomass is used faster than it can be replaced, it becomes non-renewable.
• Uneven Global Distribution:
  • Access to resources varies by country and region.
  • Hydropower is popular in Brazil due to numerous rivers.
  • Nuclear energy is popular in France.
  • Solar power is effective in the Southeast United States but less so in the cloudy Pacific Northwest.

Global Distribution of Fossil Fuels

• Coal:
  • Largest amounts found in Russia, the U.S., and China.
• Oil:
  • Largest reserves in Iran, Saudi Arabia, Venezuela, and Canada.
• Natural Gas:
  • Most commonly found in large reserves in the U.S., Russia, and Iran.
• Reserves Definition:
  • Available amount of fossil fuel that can be extracted.

Energy Trends

• Industrialization Shift:
  • Countries shift from biomass subsistence energy (wood for heating and cooking) to fossil fuels and nuclear power as they industrialize.
  • Example: In the U.S., coal consumption increased during the Industrial Revolution (around 1883), while wood usage declined.
  • Petroleum use increased, becoming a primary fuel source.
  • Natural gas usage increased after the 1950s.
  • Nuclear power increased after World War II.
  • Hydropower remains relatively stable.
• Factors Influencing Fuel Use:
  • Changes in price, availability, and government regulations.
  • Increased gas prices may lead to more fuel-efficient car purchases.
  • Unrest in the Middle East (e.g., 1970s oil crisis) can cause fuel prices to rise.

Biomass

• Definition:
  • Often used as a subsistence form of energy for cooking and heating in less industrialized countries.
  • Includes wood, peat (compacted decaying plant matter), and charcoal (a wood-based product, not coal).
• Advantages:
  • Easily accessible and cheap for less developed countries that may not afford coal, oil, or natural gas.
• Disadvantages:
  • Pollution issues: burning wood releases particulate matter affecting lung health and carbon compounds when burned.
  • Not pollution-free despite being renewable.

Coal

• Acquisition:
  • Acquired through mining, which has significant environmental impacts (land disturbance, deforestation, erosion, fossil fuel use).
• Types of Coal:
  • Lignite:
    • Lower heat content and lower sulfur coal.
  • Bituminous:
    • Most commonly used coal due to large supply and excellent heat content.
    • High in sulfur, leading to pollution and acid deposition (acid rain).
  • Anthracite:
    • High heat content and low sulfur, making it low-polluting.
    • Limited availability.
• Pollution:
  • Releases particulate matter affecting lung health and carbon pollution (carbon dioxide and other greenhouse gases) contributing to climate change.

Crude Oil

• Extraction:
  • Drilled and pumped from the ground.
• Uses:
  • Converted into fuels for vehicles, airplanes, and machinery.
• Energy Conversion Inefficiency:
  • Second law of thermodynamics: energy transformations result in less usable energy as some energy is lost as heat.
  • Burning fuel in a car releases much of the energy as heat, making it rather inefficient.
• Pollution:
  *Releases particulate matter, $(CO_2)$, carbon compounds leading to global warming along with other pollutants.

Combustion

• Definition:
  • Chemical reaction where fossil fuels react with oxygen to release energy.
• Incomplete Combustion Byproducts:
  • Releases carbon dioxide, water vapor, and other particulates.
• Cogeneration:
  • Using excess heat from power generation (e.g., burning coal) for other purposes like heating buildings, increasing overall efficiency.

Natural Gas

• Extraction:
  • Extracted through fracking (hydraulic fracturing).
• Fracking Process:
  • Drilling into shale rock and injecting water, sand, and chemicals at high pressure to shatter the rock.
  • Sand keeps cracks open, allowing gas bubbles to rise and be collected.
• Problems with Fracking:
  • Can cause earthquakes.
  • Potential for groundwater contamination from injected chemicals.
• Advantages:
  • One of the cleanest fossil fuels; burns cleanly with little particulate matter.
• Disadvantages:
  • Releases methane, a potent greenhouse gas that contributes to global warming.

Power Plants

• Coal-Fired Power Plants:
  • Coal is burned in a furnace to produce heat.
  • Heat vaporizes water into steam.
  • Steam spins a turbine.
  • Turbine's mechanical energy allows a generator to produce electricity that is then sent out into the community.
• Nuclear Power Plants:
  • Uses uranium-235, a radioactive isotope of uranium, to create a chain reaction (fission).
  • Neutron hits a uranium atom, causing it to rupture and release more neutrons, generating heat.
  • Heat is captured to power turbines and generators.
  • Radiation is released during fission, which is harmful to human tissues and DNA and can cause mutations and cancers.
  • Containment is essential to keep radiation inside the reactor.

Nuclear Power Plant Function

• Containment Structure:
  • Contains the nuclear reactor.
  • The reactor contains nuclear fuel rods (producing heat) and control rods (regulating the reaction).
• Steam Generation:
  • Water is heated by the reactor to create steam.
  • Steam spins a turbine, which powers a generator to produce electricity.
• Thermal Pollution:
  • Hot water from the reaction is sent to cooling towers but may still be warmer than the water in the local reservoir when emitted back.
  • Warmer water can affect the behavior and health of fish and other aquatic organisms.
• Radioactive Waste:
  • High-level radioactive waste must be disposed of safely.
  • Often stored on-site in dry storage casks.
  • Deep underground injection is a disposal method but has risks of contamination.

Nuclear Disasters

• Three Mile Island (Pennsylvania, 1970s):
  • Partial reactor meltdown; possible cancer increases in later years.
• Chernobyl (Ukraine, 1986):
  • Most famous reactor meltdown due to human error during a test.
  • Area remains radioactive.
• Fukushima (Japan, 2011):
  • Caused by a 9.0 Richter scale earthquake and resulting tsunami.
  • Four of six reactors melted down due to damage.

Renewable Sources of Energy

• Solar Energy:
  • Photovoltaic Cells:
    • Capture the sun’s energy and transform it into electric energy via a conductive material.
    • Energy can be stored for later use, like at night.
    • Concerns: solar farms can block sunlight from reaching the ground, negatively impacting ecosystems.
  • Passive Solar Energy:
    • Uses building practices and heat-retaining materials to absorb solar radiation during winter (thermal mass).
    • Heat is not storable.
• Hydroelectric Power:
  • Dams (most common):
    • Turbines spin as water passes over them.
    • Turbines power a generator to produce electricity.
    • Alter the flow of the river; dams are not single-use and can reduce flooding.
    • Reservoirs (man-made lakes behind dams) can be used for irrigation, drinking water, and recreation.
  • Benefits:
    • No pollution issues.
    • Alleviates the effects of flooding.
  • Fish Ladders:
    • Help fish migrate from one side of the dam to the other.
  • Wave hydroelectic Power:
    • Uses wind turbines to harness wave and tidal energy.
• Geothermal Power:
  • Uses heat from the center of the earth to heat water, producing steam that spins a turbine to generate electricity.
  • Best in geologically active areas (e.g., plate boundaries).
    • Iceland, is located on a divergent plate boundary, and is an excellent for geothermal use.
  • Downsides: expensive plants and potential release of pollution (hydrogen sulfide).
• Hydrogen Fuel Cells
  • Use hydrogen and oxygen to react and create an energy source.
  • Only byproduct is water.
    • Extremely clean.
  • Currently are expensive to produce, and have containment issues.
• Wind Energy:
  • Large turbines generate electricity when wind spins their blades.
  • Turbines power a generator, creating electricity.
  • Downsides: large, noisy, potential to kill birds and bats.
    • Best in open areas like farmland, away from populated areas and bird/bat migration routes.