M5 Earth science
What I Need to Know
The Sun is the main energy source; almost all life depends on solar energy. Plants use photosynthesis; this links to fossil fuels formed from ancient plants.
Main energy sources: fossil fuels, geothermal, hydroelectric. Objectives: describe how fossil fuels form; explain tapping heat from the Earth's interior (geothermal) and flowing water (hydroelectric); address environmental concerns. MELCs describe fossil-fuel formation and tapping heat from inside Earth and from flowing water.
Key terms: renewable energy (not used up in a short time) vs nonrenewable energy (limited supplies).
Fossil Fuels: Formation and Types
Formation: remains of plants and animals existed years ago; buried in swamps/seas; heat and pressure form hydrocarbons. Coal is solid; oil is liquid; natural gas is gas.
Coal types (in order of formation): peat (first stage), lignite, bituminous, anthracite.
Oil: liquid fossil fuel; formed from marine organisms; refined into gasoline, diesel, kerosene; used as feedstock for wax, plastics, fertilizer.
Natural gas: mainly methane; forms like oil; usually found above oil; used for cooking and heating.
Nonrenewable: limited supplies; long replenishment times.
Renewable Energy Sources
Solar energy: sunlight converted to electricity via PV cells; solar power plants.
Wind energy: kinetic energy of wind turns turbines to generate electricity.
Geothermal energy: heat from beneath the Earth; hot water/steam drives turbines.
Hydroelectric energy: flowing water turns turbines to generate electricity.
Biomass / Dendrothermal: biofuels from crops or algae; methanol and ethanol.
Nuclear energy: energy from nuclear fission; large electricity output; no direct greenhouse gas emissions but waste and safety concerns; modern reactors and thorium concepts reduce waste.
Geothermal Power Plant Types
Steam power plants: use natural underground steam.
Flash-steam power plants: underground hot water; steam flashed to drive turbine.
Binary cycle power plants: hot water transfers heat to a secondary refrigerant to make steam.
Enhanced geothermal systems: hot dry rocks; water injected to absorb heat and drive the cycle.
Hydroelectric and Biomass Energy
Hydroelectric: uses volume/flow of water to run turbines; multiple sites in the Philippines (examples: Maria Cristina Falls, Angat Dam, etc.).
Dendrothermal energy / Biomass: biomass processed to biofuels (e.g., ethanol, methanol) for engines.
Environmental Concerns and Mitigation
Fossil fuels: air pollution, oil spills, acid rain, climate change; mitigation includes carbon capture and storage.
Geothermal: potential effects on water quality/minerals; mitigated by reinjecting used water.
Hydroelectric: flooding and ecological disruption; dams provide irrigation/recreation as added benefits.
Nuclear: radioactive waste; safety and terrorism concerns; modern reactors safer; some designs reuse spent fuel (e.g., thorium cycle).
What’s New / Renew-a-Strip Activity (Summary)
100 energy strips: 50 renewable (white), 50 nonrenewable (black).
Simulates annual energy use; tracks depletion of nonrenewables; emphasizes conservation and transition to renewables.
What Is It? Discussion Summary
Renewable sources replenish naturally over short timescales; nonrenewables replenish slowly.
Encourages conservation and exploration of alternatives (solar, wind, biofuels, atomic energy).
Quick Practice: Energy Source Classification
Renewable examples: sun, wind, geothermal, water, biomass.
Nonrenewable examples: coal, oil, natural gas.
Energy products can be used as heat, power, electricity, or mechanical work.
Quick Recall: Key Assessment Points
Fossil fuels formation milestone: years ago.
Major renewable sources and how they work: solar PV, wind turbines, geothermal steam, hydro turbines, biomass.
Environmental concerns and mitigation strategies for each energy type.
Geothermal plant types and how heat is extracted.
Nuclear energy basics and safety considerations.