APES UNIT 6

⚡ Energy

The capacity to do work or cause physical change in a system.

☀ Sun: The Primary Energy Source

• Provides energy for most life on Earth.

• Energy is produced through nuclear fusion in the Sun’s core.

🔋 Forms of Energy

1⃣ Chemical Energy – Stored in bonds between atoms.
2⃣ Electrical Energy – Results from moving electrons.
3⃣ Electromagnetic Energy – Travels in waves (e.g., light, radio).
4⃣ Mechanical Energy – Includes:

• Potential Energy – Stored energy (e.g., a stretched rubber band).

• Kinetic Energy – Energy in motion (e.g., a rolling ball).
  5⃣ Nuclear Energy – Stored in atomic nuclei, released by fission (splitting) or fusion (joining).
  6⃣ Thermal Energy – Due to movement of molecules; related to heat.

⚖ Units of Energy & Power

• British Thermal Unit (Btu) – Heat needed to raise 1 lb of water by 1°F.

• Btu/hr – Used in air conditioning.

• Horsepower (HP) – Used in cars; 1 HP = 746 watts.

• Kilowatt-hour (kWh) – Measures energy usage (used in electricity bills).

📜 Laws of Thermodynamics

1⃣ First Law (Conservation of Energy) – Energy cannot be created or destroyed, only transformed.
2⃣ Second Law – Energy conversions are never 100% efficient; some energy is always lost as heat.
3⃣ Zeroth Law – If A = B and A = C, then B = C (basis for temperature measurement).

🌍 Renewable Energy

• Energy from naturally replenished resources on a human time scale.

• Found in wide geographical areas, unlike fossil fuels, which are concentrated in a few countries.

⛽ Nonrenewable Energy

• Not sustainable because formation takes billions of years (e.g., fossil fuels).

⚖ Arguments for Continued Use of Fossil Fuels

1⃣ Abundant supply → Leads to low prices for consumers.
2⃣ High net-energy yield → Concentrated and efficient fuel.
3⃣ Existing infrastructure → Already in place for extraction, processing, and delivery.
4⃣ Political factors → Fossil fuel industries hold economic and political influence.
5⃣ Established technology → Technology for fossil fuel use is already widespread.

🔥 Fossil Fuels

Formed from past geological remains of living organisms.

🌲 Burning Wood Fuel

Produces CO₂, heat, steam, water vapor, and wood ash.

🌱 Peat

• Partially decayed vegetation from wetlands (e.g., mosses, sedges, shrubs).

• Forms in acidic and anaerobic conditions.

⛏ Coal Formation

Dead plant matter decays into peat, then heat & pressure over millions of years convert it into coal.

🛢 Types of Coal

1⃣ Lignite → "Brown coal," most harmful to health, mainly used for electric power generation.
2⃣ Bituminous → Primarily used as fuel in steam-electric power generation.
3⃣ Anthracite → Used for residential & commercial space heating.

🌿 Clean Coal Technology

Carbon Capture & Storage (CCS) → Pumps & stores CO₂ underground.

🔥 Natural Gas

Formed from buried plants & gases exposed to intense heat & pressure.

🛢 Oil

Fossil fuel from decomposed organic material under high temperature & pressure for millions of years.

⚡ Cogeneration (CHP - Combined Heat & Power)

Generates electricity & heat simultaneously, improving efficiency.

🛠 Pollutant Removal Technologies

1⃣ Baghouse Filters → Fabric filters reduce particulates.
2⃣ Burning Pulverized Coal → Fine coal powder reduces emissions.
3⃣ Coal Gasification → Converts coal into "syngas" with lower emissions.
4⃣ Cyclone Separator → Uses spinning effects & gravity to remove particulates.
5⃣ Electrostatic Precipitator → Uses electric charge to remove dust & smoke.
6⃣ Fluidized-Bed Combustion → More air than normal combustion, reducing NOx, SOx & particulates.
7⃣ Scrubbers → Inject chemicals to "wash out" acidic gases.
8⃣ Sorbents → Charcoal, calcium compounds, or silicates trap gaseous pollutants.

📈 Law of Supply

• As price increases, quantity supplied increases.

• Suppliers maximize profits by increasing production.

📉 Law of Demand

Higher price = Lower demand (Inverse relationship).

🔥 Fossil Fuels Formation

• Coal → Formed from land vegetation over millions of years.

• Natural Gas → Formed from marine organisms, relatively cleaner than coal & oil.

• Oil → Liquid fossil fuel, formed from marine organisms, trapped in rock & sediment, extracted by drilling.

⛽ Other Nonrenewable Fossil Fuel Resources

1⃣ Methane Hydrates (Clathrates)

• Found in permafrost, ocean floor, & continental shelves.

2⃣ Oil Shale

• Fine-grained rock containing kerogen, which can be converted into shale oil.

3⃣ Synfuels

• Fuels derived from coal, natural gas, or biomass via chemical conversion.

4⃣ Tar Sands

• Contain bitumen (semi-solid oil), extracted via strip mining or in situ methods (steam injection).

🔥 Combustion Reaction of Fossil Fuels

• Carbon dioxide (CO₂) is released, contributing to global warming due to the greenhouse gas effect.

⚡ Steps from Fuel to Electricity

1⃣ Extract thermal energy from fuel to raise steam.
2⃣ Convert thermal energy into kinetic energy in the turbine.
3⃣ Use a rotary generator to convert mechanical energy into electrical energy.

💧 Hydraulic Fracturing (Fracking)

• Injects water, sand, and chemicals at high pressure to create & expand rock fractures.

• Used in low-permeability rocks (e.g., sandstone, shale, coal beds).

• Increases oil/gas flow from petroleum-bearing rocks.

⚛ Nuclear Fission

• Atom splits into smaller nuclei + by-product particles.

• Releases heat, which can be controlled for electricity.

• Uncontrolled reaction → Meltdown (severe reactor accident).

🔥 Nuclear Meltdown

• Overheating in a nuclear reactor → core damage.

🔋 Nuclear Fuels

1⃣ U-235

• Less than 1% of natural uranium.

• Critical Mass: Minimum amount needed for a chain reaction.

2⃣ U-238

• Most common uranium isotope.

• Half-life: 4.5 billion years.

• Decays into Pu-239 when hit by a neutron.

3⃣ Pu-239

• Half-life: 24,000 years.

• Produced in breeder reactors from U-238.

• Provides 1/3 of total energy in nuclear power plants.

🔧 Nuclear Reactor Components

1⃣ Core

• Holds up to 50,000 fuel rods (each packed with fuel pellets).

2⃣ Fuel

• Enriched U-235 (concentrated uranium).

• 1 uranium atom fission = 10 million times the energy of a coal atom combustion.

3⃣ Control Rods

• Absorb neutrons to slow down reaction.

4⃣ Moderator

• Slows neutrons for a sustainable chain reaction.

5⃣ Coolant

• Removes heat → Produces steam → Generates electricity.

🌱 Biomass

• Biological material from living or recently living organisms.

• Burned to create steam → generates electricity.

• Can be grown on marginal land (not suitable for agriculture)

🦠 Anaerobic Digestion

• Microorganisms break down biodegradable material without oxygen.

• Produces methane gas → burned for energy.

• Benefits:
  ✅ Reduces reliance on coal & oil.
  ✅ Lowers land disturbances from coal mining.
  ✅ Reduces methane emissions from landfills (helps fight global warming).

⛽ Biofuel

• Liquid fuel from living organisms.

• Biodegradable & can be converted into:
  🚗 Biodiesel
  🚜 Bioethanol (powers vehicles).

• Renewable & can be produced anywhere (unlike fossil fuels).

☀ Solar Energy

• Collects & harnesses radiant energy from the sun.

• Generates heat & electricity using:
  🔋 Photovoltaic (PV) cells
  🌡 Solar collectors
  🔥 Central solar-thermal plants

🏡 Passive Solar Heating

• No mechanical devices.

• Uses building features to absorb & release heat slowly.

• Helps maintain temperature naturally.

⚡ Active Solar Heating

• Generates more heat than passive systems.

• Requires three components:
  1⃣ Solar collector (absorbs energy)
  2⃣ Storage system (stores heat)
  3⃣ Heat transfer system (moves heat where needed)

🔋 Residential Photovoltaic System

Converts sunlight → electricity using:
📌 Solar panels (absorb sunlight)
🔄 Solar inverter (DC → AC conversion)
🔋 Battery storage & backup system

🌊 Hydroelectric Power

• Dams trap water, which is released through turbines to generate electricity.

• Hydroelectric generation accounts for:
  🔋 44% of U.S. renewable electricity
  ⚡ 6.5% of total electricity in the U.S.

🏗 Dams in the U.S.

• ~75,000 dams.

• Block ~600,000 miles (~1 million km) of once free-flowing rivers.

✅ Advantages of Dams

✔ Control flooding
✔ Long life span
✔ Low maintenance & operating costs → affordable electricity
✔ Moderate to high net-useful energy
✔ No polluting waste
✔ Water storage for cities & farms

❌ Disadvantages of Dams

❗ Expensive to build
❗ Displace people by flooding large areas
❗ Destroy wild rivers & wildlife habitats
❗ Prevent fish migration
❗ Reduce agricultural land
❗ Sedimentation buildup requires dredging

🌊 Causes of Floods

🌧 Heavy rainfall & fast snowmelt
🏗 Dams, levees, or pump failures
🔥 Wildfires (reduce vegetation that absorbs rain)
🏙 Impervious surfaces (asphalt/concrete) increase runoff
🌪 Severe winds over water
🌊 Tsunamis, storm surges, & high tides

🔥 Geothermal Energy

• Heat stored in underground rock and fluids.

• Comes from magma, hot dry-rock zones, and warm-rock reservoirs.

• Produces steam and hot water pockets underground.

• Used to drive turbines → generate electricity.

⚡ Hydrogen Fuel Cell

• Operates like a battery with two electrodes.

• Oxygen passes over one electrode, hydrogen over the other.

🔬 Reaction Process

• Hydrogen reacts with a catalyst → forms electrons (-) and hydrogen ions (H⁺).

• Electrons flow out → used as electrical energy.

• Hydrogen ions move through a membrane.

• H⁺ combines with oxygen and electrons → produces water (H₂O).

• Unlike batteries, fuel cells never run out!

🌬 Wind Turbines

• Convert wind into electricity (opposite of a fan).

• Wind turns blades → powers generators to produce electricity.

⚡ Wind Farms

Clusters of wind turbines generating large amounts of power.

🌱 Efficiency & Impact

• Most efficient method of producing electricity.

• 1 megawatt of wind energy offsets ~2,600 tons of CO₂.

🏡 Wind Energy in the U.S.

• 6% of electricity demand comes from wind energy.

• Current wind capacity powers ~20 million homes.

🌊 Offshore Wind Energy

Major opportunity to power coastal cities.

🌍 Global Wind Energy

• Largest turbines can power 600 U.S. homes.

• China has the largest installed wind energy capacity, followed by the U.S..

• 25% increase in wind turbine use in the last decade, yet wind still provides only a small percentage of global energy.

🏠 Home Insulation & Sealing

• Add insulation & seal air leaks to reduce energy waste.

• Improving attic insulation can save 10%+ on annual energy bills.

🌡 Programmable Thermostats

• Adjusts heating & cooling automatically for efficiency.

• Can save up to 15% on heating & cooling costs.

💡 Efficient LED Lighting

• Consumes less energy than incandescent bulbs.

• Contains no mercury → safe for household disposal.

🔌 Phantom Loads

• Energy consumed by electronics when turned off.

• 75% of home electronics' energy use comes from phantom loads.

• Unplug devices or use smart power strips to reduce waste.

⚙ Energy-Efficient Appliances

Use less electricity, reducing energy consumption & costs.