Unit 6 - Human Activity and Earth's Atmosphere

6.1

exploration 1 - analyzing energy consumption

• energy - comes from fossil fuels

  • ex: oil, gas, solar energy

• combustion = burning wood

  • wood/plant matter are made of cellulose

    • celliulose: glucose molecules linked together to form long chains

    • Fuel + Oxygen → Carbon Dioxide + Water

• wood burning vs metabolism of glucose in our cells

  • burning wood is fast and uncontrolled —> releases heat

  • metabolism of glucose is slow and helps store energy in the body —> releases energy in small amounts

    • breaks down glucose from food and converts it into usable energy

• as the population on earth increased, the demand for fossil fuels like gas became greater

  • biomass - wood

    • heavily used before industrial revolution

    • coal was the most used after the industrial revolution (1712-1850)

    • petroleum and natural gas - 1900

    • nuclear energy/renewable resources (hydroelectric, solar, wind) - 2000s

  • increased concentration of CO2 in the atmosphere

    • lower atmosphere and surface are rapidly warming (ice/snow)

    • rising sea level

• renewable energy resources must become more affordable and practical

exploration 2 - evaluating energy sources

• cost-benefit analysis

  • cost-benefit ratio: worthwhile if ratio is > than 1

• fossil fuels - buried in earths crust

  • nonrenewable

  • coal

  • petroleum

  • natural gas

• coal

  • thick layers of dead organic matter —> changed into dense coal by heat and pressure

    • burned coal: releases energy, impurities (ex: sulfur, aluminum, mercury, lead)

      • pollute water, air, soil

        • humans rely on healthy functioning ecosystems

    • subsurface coal mining - drill holes through earth’s surface, removing coal, transporting it to the surface

      • negatively affects worker health

    • surface mining - strips away overlying rock to expose coal

      • pollution, destroy natural habitats

• petroleum - crude oil

  • composed of remains of ancient marine organisms —> buried on ocean floor —> liquid —> carbon

    • trapped under rock formations

      • petroleum is pumped from the ground

  • burned: releases 40-60% more energy/gram than coal

  • refined to make gasoline

    • special blends of gasoline (hydrocarbons) + tax = reduced emissions

    • transported by pipelines, trains, trucks

      • risks: explosion/spills —> affects properties of buildings

• natural gas - formed by remains of marine organisms

  • lightest hydrocarbon (methane)

  • burned to generate electricity —> burns completely (cleaner)

  • CO2 output is 30% less than petroleum

  • CO2 output is 43% less than coal

• hydraulic fracturing (fracking)

  • increasing extraction of petroleum/natural gas from underground

    • injecting water, sand, detergents (salts, acids, alcohols, lubricants, disinfectants) into rock at high pressure

    • rock fractures and releases petroleum/natural gas —> pumped out with water (contaminated with chemicals) —> hazardous waste (ground and surface water)

    • leaking natural gas: unburned methane has a stronger impact on earth than CO2

    • gas deposits are under the ocean floor

    • offshore platforms/oil rigs - used for drilling/extraction

      • anchored or floated on the surface

      • fuel is processed and stored on the platform until it can be transported to shore —> refined and distributed

        • housing for workers (not ideal)

  • tar sands/oil shales

    • petroleum sources are expensive

    • surface mining causes:

      • habitat loss

      • increased soil erosion

      • runoff of polluted water

    • requires a LOT of water and energy —> hazardous materials

• primary energy sources - occur naturally

  • ex: fossil fuels

• secondary energy sources - made from primary sources

  • ex: liquid fuels (gas, diesel — refined oil)

• vehicles - internal combustion engines

  • converts released energy from combustion reactions into mechanical energy

  • chemical energy in fossil fuels produces electrical energy

    • most heat generated in the combustion reaction is wasted (unavailable)

      • some is lost as the water is turned into steam

      • some is lost by friction from the spinning turbine in the generator

    

• efficiency - ratio between the useful energy produced and the energy input to the system

  • % value

  • ex: efficiency rate for a power plant loses energy in many stages of the conversion process —> efficiency rate: 33-38%

  • ex: operation of vehicle engine, cooling system electrical systems operating an air conditioner

  • additional losses: transmission of electricity from resistance in the wires

    • energy is wasted when fuel is completely burned

• renewable resources - replenished as often as they are used

  • wind

  • solar

  • geothermal

  • water

  • biomass

How Molecules Absorb Energy

• Molecules soak up infrared light and start vibrating.

• Example: Like how your skin heats up in the sun.

How CO₂ and CH₄ Molecules Move

• CO₂: Bends and stretches unevenly when it absorbs heat.

• CH₄ (Methane): Wiggles and stretches in different ways to soak up energy.

• Example: Think of CO₂ and CH₄ dancing when they get hit by heat.

Fuel Efficiency, Cost, Safety, and Performance

• High MPG cars save gas and money (ex: Toyota Prius).

• New engines give both good speed and low fuel use (ex: Honda Accord Hybrid).

• Safer designs help protect you better in crashes (ex: Tesla Model 3 with top crash ratings).

Reducing Pollution and Making Cars Better

• Burn fuel better so less dirty gas comes out.

• Catalytic converters clean the exhaust (like a filter for your car).

• Lighter cars (ex: cars made with aluminum) and sleek shapes (ex: Tesla Model S) use less gas.

• Government rules (like CAFE laws) force carmakers to make cleaner cars.

Energy Sources Made Simple

1. Nuclear Power

• Splits atoms to make huge energy.

• No smoke, but dangerous waste.

• Example: Diablo Canyon Nuclear Plant (closing in 2025).

2. Solar Energy

• Turns sunshine straight into electricity.

• Big solar farms power whole neighborhoods.

• Example: Topaz Solar Farm.

3. Wind Energy

• Wind spins big turbines to make power.

• Needs steady wind — too fast or too slow is bad.

• Example: San Gorgonio Pass Wind Farm.

4. Geothermal Energy

• Uses hot rocks under the ground to make steam and electricity.

• Always available (not like sun or wind).

• Example: The Geysers in California.

5. Water and Ocean Energy

• Hydropower: Water falling through dams spins turbines (ex: Hoover Dam).

• Ocean energy: Waves or water heat can make power but can hurt boats.