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AP Environmental Science Unit 6 Visual Review

A 13-slide visual walkthrough of every Topic 6.1-6.13 concept — renewable and nonrenewable resources, fossil fuels, nuclear power, and every major renewable energy source — built right into the page.

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TOPIC 6.1 Renewable & Nonrenewable Resources Renewable solar, wind, biomass Nonrenewable coal, oil, gas, uranium regenerates on a human timescale takes millions of years to reform Renewable Naturally replenished within a human lifetime — sunlight, wind, and flowing water don't run out. Even biomass counts, since new plants grow back in years, not eons. Nonrenewable Fossil fuels take millions of years to form from ancient organic matter — we consume them far faster than they can regenerate, so the usable supply is effectively fixed. Renewable does not automatically mean impact-free — building solar panels and turbines still uses mined materials. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.2 Global Energy Consumption energy use per capita developing nations developed nations A wide, unequal gap Developed nations consume far more energy per person — driven by industry, transportation, and higher standards of living. As developing nations industrialize, their demand is rising fast. The mix matters too Not just how MUCH energy is used, but which SOURCES supply it. Wealthy nations can afford to diversify into renewables; many developing nations still rely heavily on coal and biomass. The developed world holds a minority of the population but consumes the majority of global energy. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.3 Fuel Types & Uses Coal Mostly electricity generation. Highest CO2 per unit of energy of any fossil fuel. Oil (petroleum) Dominates transportation (gasoline, diesel, jet fuel) and makes plastics & petrochemicals. Natural gas Electricity & home heating. Burns cleaner than coal or oil, but still releases CO2 and methane leaks. One fuel, one job Each fossil fuel dominates a different sector of the economy — coal for the power grid, oil for vehicles, natural gas for both electricity and heating. That's why a single "switch to renewables" plan has to solve several separate problems, not just one. Electrifying transportation (replacing oil) and the grid (replacing coal/gas) are two very different challenges. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.4 Distribution of Natural Energy Resources Region A Region B huge oil reserves Region C Geology decides, not fairness Fossil fuel deposits formed under specific ancient geologic conditions, so they're concentrated in a handful of regions — the Middle East, Russia, and a few others hold most of the world's proven oil reserves. Geopolitical consequences Nations without domestic reserves must import energy, creating dependence and price exposure. This uneven distribution drives resource conflicts, trade alliances, and strategic reserves. Renewables like solar and wind are far more evenly distributed — a rare exception to this pattern. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.5 Fossil Fuels drilling / fracking deposit Formation & extraction Ancient organic matter, buried under heat and pressure for millions of years, becomes coal, oil, or gas. Fracking injects fluid at high pressure to crack rock and release trapped gas. Combustion's byproducts Burning fossil fuels releases CO2 (climate), sulfur dioxide (acid rain), nitrogen oxides (smog), and particulate matter (respiratory illness) — extraction itself can also contaminate groundwater near fracking sites. Fracking has unlocked huge new gas reserves, but its groundwater contamination risk remains hotly debated. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.6 Nuclear Power U-235 neutron in fission splits the atom, releasing heat + more neutrons The upside Fission releases enormous energy with almost no direct carbon emissions, providing reliable baseload power — steady output, unlike intermittent solar or wind. The risks Radioactive waste stays dangerous for thousands of years with no permanent disposal solution in most countries. Meltdowns are rare but catastrophic (Chernobyl, Fukushima), and plants are expensive and slow to build. Nuclear is the rare low-carbon source that produces steady baseload power — the tradeoff is waste, not emissions. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.7 Energy from Biomass Wood / crop waste / manure Direct burn Convert to biofuel heat/electricity ethanol, biodiesel Carbon-neutral in theory Growing plants absorbs roughly the CO2 that burning them later releases — but growing, fertilizing, and transporting biomass crops still burns fossil fuel, so it's rarely truly neutral. The land-use tradeoff Growing corn for ethanol competes with growing corn for food — dedicating farmland to fuel crops can raise food prices and drive further deforestation elsewhere. Waste-derived biomass (crop residue, manure) sidesteps the food-vs-fuel tradeoff that dedicated fuel crops don't. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.8 Solar Energy photovoltaic (PV) array Two technologies Photovoltaic (PV) cells convert sunlight directly into electricity via the photoelectric effect. Solar thermal systems instead concentrate sunlight to heat water or fluid. Tradeoffs Intermittency — no output at night or in heavy cloud, so it needs storage or backup. Land use — utility-scale solar farms require large open areas, though rooftop panels don't. Rooftop solar sidesteps the land-use tradeoff entirely — it uses space that's already built on. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.9 Hydroelectric Power reservoir dam turbine water continues downstream How it generates power Water stored behind a dam falls through a turbine, spinning a generator. Reliable and renewable — but only where river flow is consistent enough to sustain it. Ecological tradeoffs Dams block fish migration (like salmon spawning runs), flood upstream habitat and sometimes human communities, and trap sediment that would otherwise nourish downstream ecosystems and deltas. Fish ladders are a partial fix for migration blockage, but they don't solve the sediment or habitat-flooding problems. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.10 Geothermal Energy magma heat cold water in steam out → Tapping Earth's own heat Water pumped underground is heated by magma and returns as steam, which spins a turbine — or is piped directly for heating buildings without any conversion at all. Location-limited Only economical near tectonically active regions (recall Topic 4.1) where magma sits close enough to the surface — Iceland, parts of the western US. Not viable everywhere. Geothermal is a direct payoff of Unit 4's plate tectonics — the same boundaries that cause volcanoes also enable this. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.11 Hydrogen Fuel Cell H₂ O₂ fuel cell (membrane) electricity H₂O only The reaction Hydrogen and oxygen combine electro- chemically to produce electricity, with pure water as the only tailpipe byproduct — no combustion, no direct CO2. The catch: where does H₂ come from? Hydrogen isn't a natural energy source — it must be produced, usually from natural gas (emitting CO2) or via electrolysis, which is only clean if the electricity used is clean too. The clean water byproduct is real, but the overall footprint depends entirely on how the hydrogen was made. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.12 Wind Energy wind → How it works Wind spins the turbine's blades, which turn a generator inside the housing. Output scales roughly with the CUBE of wind speed, so siting consistently windy locations matters enormously. Siting tradeoffs Best sites are often ridgelines, plains, and offshore waters — but turbines can kill birds and bats, generate noise complaints, and face "not in my backyard" opposition despite producing no operating emissions. Like solar, wind is intermittent — grid planners pair it with storage or other sources for windless days. The Review Hub · AP Environmental Science Unit 6 TOPIC 6.13 Energy Conservation Efficiency LED bulbs, insulation, high-efficiency appliances — do the same task using less energy. Behavior Turning off lights, mass transit, lower thermostat settings — reducing DEMAND directly, no new tech needed. Building design Passive solar orientation, smart grids, and better urban planning cut demand at the systems level. The cheapest gigawatt is the one you never generate Conservation avoids the entire environmental cost of generation — no emissions, no land use, no waste — because that energy is simply never produced. Dollar for dollar, efficiency upgrades often cut more emissions than building new renewable capacity, which is why utilities increasingly fund efficiency programs directly. Reducing demand and switching sources aren't competing strategies — the cheapest path uses both together. The Review Hub · AP Environmental Science Unit 6
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How to use the visual review

Spend 30 seconds per slide before clicking next. Look at the diagram, then ask yourself: "Could I draw this from memory and explain it?"

Use the fullscreen button () on desktop for the best experience. Use arrow keys to navigate. Tap "Show all slides" to jump around.

This covers every one of Unit 6's 13 CED topics, from renewable vs. nonrenewable resources through energy conservation.