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APES unit 6
| Question | Answer |
|---|---|
| Renewable Sources Definition | Can be replenished naturally, at or near rate of consumption & reused. |
| Depletable Renewable meaning + sources exmaples | Can run out if overused Biomass (wood, charcoal, ethanol) |
| Nondepletable renewables meaning + examples | Do not run out if overused Ex. Solar, wind, hydroelectric, geothermal |
| Nonrenewable sources definition | Exist in fixed amounts on earth & can’t easily be replaced or regenerated |
| Nonrenewable Energy Sources examples | fossil fuels (coal, oil, natural gas,) nuclear energy |
| Fossil Fuels definition | Fossilized remains of ancient biomass that take millions of years to form (coal, oil, natural gas,) |
| Rate of Consumption for Renewable Energy Sources | Rate of use must be at or below rate of regeneration for renewables |
| Why will fossil fuels run out? | They take far longer to regenerate than the rate we use them |
| Who uses more energy per Capita? Who uses more energy in total and why? | Developing countries = more energy in total because higher population that is growing rapidly Developed countries: more energy per Capita because individuals have a higher standard of living and the country is more industrialized |
| Top 3 must used energy sources | 1. Fossil Fuels by far 2. Hydroelectric energy 3.Nuclear energy |
| What are these types of fossil fuels used for: Coal, Oil, Natural gas | Coal: main fuel for electricity gen. Oil: Used as gasoline, main fuel for vehicles Natural gas: secondary fuel for electricity gen. & main fuel for heating |
| What type of energy source do less developed national depend on? | subsistence fuels - biomass that they can easily gather/purchase Examples: wood, charcoal, dried animal manure\ |
| What will happen to fossil fuel consumption as developing nations develop? | The consumption of fossil fuels will increase |
| Three factors that affect energy source use | Availability (fossil fuels use depends on discovered reserves & accessibility of these reserves), Price (depends on discovery of new reserves or depletion of existing ones, more availability decreases prices and increases use), Government regulation |
| What the government can do regarding energy sources | Can: Use Taxes increases to discourage companies from building FF power plants Rebates, or tax credits to encourage companies building renewable energy power plants mandate certain energy source mixes (25% renewable by 2025) |
| What the government can not do regarding energy sources | Can not: directly raise or lower prices of energy sources (ex: raise gas to $10/gallon) |
| Two of the most common fuel sources in developing nations + the effects | Charcoal: made by heating wood under low oxygen conditions for a long time Effects: Can cause deforestation & habitat loss |
| What is peat | Partially decomposed organic matter (often ferns or other plants) found in wet, acidic ecosystems like bogs and moors It can be dried and used as a biomass fuel source |
| Formation of coal | Pressure from overlying rock & sediment layers compacts peat into coal over time |
| Most valuable form of coal or highest quality and why | Anthracite Why: The deeper a coal reserve is buried, the more pressure from overlying rock layers & the more energy dense, More energy dense = more energy released when a fuel source is burned |
| More dense coal vs more steam | More dense coal + Hotter/longer fire More steam: more electricity |
| What is natural gas mostly made of and how is it formed? | Methane (CH4), found on top of trapped oil deposits Forms when oil is trapped in a porous, sedimentary rock, underneath a harder, impermeable rock layer that doesn’t let the gas escape |
| Benefits of natural gas | - Considered the "cleanest" fossil fuels -Produces about ½ as much CO2 as coal when burned to generate electricity - Produces virtually no PM (ash/soot) - Produces far less SOx, NOx than coal or oil, and NO MERCURY |
| How can crude oil ((petroleum) be recovered? | Extracted by drilling a well through the overlying rock layers to reach the underground deposit and then pumping liquid oil out under pressure and by tar sands |
| What are tar sands? | combination of clay, sand, water, and bitumen bitumen: think, sticky, semi-soild form of petroleum (not liquid) |
| Downsides of tar sands | - Water intensive Water needs to be heated to create steam that’s piped down into the tar sand to melt the bitumen into a liquid that can flow up a pipe Water is used to serperate oil from impurities Energy intensive - energy to create steam |
| Fractional distillation | Crude oil is burned in a furnace and vapor passes into a column where different hydrocarbons are separated based on their boiling points |
| Where do hydrocarbons gather based on their boiling points? | Lower boiling points = Gather at the top of the column Higher boiling points = gather at the bottom of the column |
| Some products hydrocarbons are used for | Petroleum gas Gasoline (fuel for cars) Naphtha (used to make plastic) Jet fuel Diesel fuel Motor oil Bitumen (asphalt for roads) |
| #1 Countries for different fossil fuels reserves (coal, oil, natural gas) | Coal: U.S. Natural gas : Russia Oil: Venezuela |
| Fracking (Hydraulic fracturing) Definition + It's benefits | Vertical well is drilled down to sed. rock layer, turns horizontally into the rock layer and pressurized water is pumped into well at high pressures to crack it Gas trapped in semi-permeable, sedimentary rock layers, such as shale, is released |
| Where is the largest tar/oil sand reserve? | Canada (Alberta region) |
| What does the reaction between oxygen and fossil fuels release? | - Energy as heat -H20 & CO2 |
| Explain how fossil fuels release CO2 | WHen fossil fuels are burned, the Co2 in them reacts with 02 in the air to form Co2. |
| Explain how fossil fuels generated electricity (the steps) | These steps of electricity gen. are the same, no matter what you’re burning to produce the initial heat Heat →Water into Steam → Steam turns a turbine → Turbine powers generator → Generator produces electricity |
| Environmental consequences of Coal | - habitat destruction to clear land for mining - Releases more CO2 than any FF when burned for electricity gen - PM - toxic ash with lead mercury arsenic, can leak into waters or soil - Release SOx & NOx irritate resp. systems/ lead to smog & acid pre |
| How effective are coal, CHP, and natural gas of generating electricity | Coal - 30% Natural gas - 60% CHP - 90% |
| What does the energy “lost” or not converted into electricity become? | Heat |
| Cogeneration meaning | when the heat produced from electricity generation is used to provide heat (air & hot water) to a building |
| Environmental consequences of tar sands | - Habitat destruction to clear land for roads, drilling equipment, digging to reach deposits - Ground or nearby surface water depletion - water contamination (tailing ponds can overflow) - CO2 released during extraction, transport, refinement |
| Environmental consequences of oil | - possibility of spill from tanker ships or pipelines breaking - spills in water: cover sun, clog fish gills, stick to birds' - spills in land: toxic to plant roots, water contamination - habitat loss or fragmentation when land is cleared |
| Fracking benefits | Benefits: increases & extends supply of natural gas |
| What happens to flow back water? (used fracking fluid) | flows back out well & is collected and stored in containers or ponds nearby |
| Fracking environmental consequences | Well can leak & contaminate groundwater with fracking fluid, hydrocarbons Ponds can overflow, contaminate waters with fracking fluid Depletion of waters nearby Increased earthquakes linked with wastewater injection wells Hab. loss CH4 (GHG) release |
| Describe nuclear fission | A neutron is fired into the nucleus of a radioactive (unstable) element, such as Uranium Nuclei breaks apart and releases lots of energy (heat) + more neutrons that break more nuclei apart, releasing more energy |
| Radioactviity | the energy given off by the nucleus of a radioactive isotope |
| Radioactive half life | the amount of time it takes for 50% of a radioactive substance to decay (breakdown) |
| Where is uranium-235 stored? | In fuel rods |
| What are control rods? | lowered into reactor core to absorb neutrons and slow down the reaction, preventing meltdown |
| What is the water pump? | brings in cool water to be turned into steam and also cools reactor down from overheating |
| Cooling tower | allows steam from the turbine to condense back into liquid and cool down before being reused (this gives off H2O vapor) |
| Benefits of Nuclear Energy | - High energy density - No air pollutants (PM, SOx/NOx) or CO2/CH4 released when electricity is generated - Only GHS released from electricity generation is water vapor |
| Drawbacks of nuclear energy | Meltdowns used fuel rods remain radioactive 4 a long time & need to be stored in lead containers leftover rock & soil from mining can have radioactive that can contaminate water or soil nearby require lots of water thermal shock in surface water |
| Three most famous nuclear meltdowns & Where were they | Three Mile Island (US), Fukushima (Japan), and Chernobyl (Ukraine) |
| Describe Three mile Island | partial meltdown due to testing error; radiation released but no deaths or residual cancer cases |
| Fukushima | an earthquake and tsunami triggered cooling pump failure that lead to a meltdown (explosion of reactor core) & widespread radiation release |
| Chernobyl | stuck cooling valve during test lead to complete meltdown (explosion of reactor core), several deaths, and widespread radiation release |
| Environmental consequences of nuclear meltdowns | - Genetic mutations + cancer - contaminated soil - radiation can be carried by wind long distances |
| Describe the difference between biomass and biofuels | Biomass: organic matterburned to release heat - primarily for heating homes/cooking - biofuels: liquid fuels (ethanol, biodiesel) created from biomass (corn, sugar cane, palm oil), used as a replacement for gasoline |
| Describe the difference between modern and fossil carbon | modern: CO2 that was recently sequestered, or taken out of the atmosphere fossil: Co2 that has been stored for millions of years |
| What type of carbon does burning biomass release? | Modern carbon unlike burning FF's considered carbon neutral,m does not increase atmospheric Co2 levels like FF's |
| Consequences of biomass burning | - releases CO, NOx, PM, and VOCs, respiratory irritants - burning indoors worsens effects (worsened asthma, bronchitis, eye irritation) - deforestation, hab. loss, soil erosion, loss of CO2 sequestration, air& H20 filtration - air pollutants |
| How biofuels are made | 1. Corn & sugar cane are fermented, converting their sugars into ethanol 2. the ethanol is then mixed with gasoline |
| Environmental consequences of biofuels | -Soil erosion, hab. loss, GHG release (ag. soils, tractors, fertilizers) H2O use - Lots of corn needed |
| Alternative method to corn biofuels | Algae |
| What are Biodiesels | Liquid fuels produced specifically from plant oils (soy, canola, palm) |
| Why is palm oil biodiesel so harmful to the environment and what is more a sustainable way of using palm oil? | - Produces 98% MORE GHGs than FFs, due to clearing of forest for palm plantations - Sustainable method: if already cleared land is used, or if plantations are continually replanted |
| What is passive vs active solar energy? Provide examples of each | Passive: absorbing or blocking heat from the sun, w/out use of mechanical equip. (Ex. using sun’s heat for a solar oven) Active: use of mechanical/electrical equip. to capture sun’s heat (solar water heater, concentrated solar thermal, PV cells) |
| Photovoltaic Cells (PV) | “solar panels”; contain semiconductor (usually silicon) that emits low voltage electrical current when exposed to sun |
| What do photons (particles carrying energy from sun) do regarding electricity? | cause separation of charges between two semiconductor layers (n & p); electrons separate from protons & flow through circuit to load, delivering energy (as electricity) |
| Drawback of PV cells + Soultion to this | intermittency (solar energy can only be generated during the day) Solution: cheaper, larger batteries that can store energy generated during the day for use at night |
| What are Concentrated Solar Thermal (CST) and how do they generate electricity? | Heliostats (mirrors) reflect sun’s rays onto a central water tower in order to heat water to produce steam to turn a turbine → electricity |
| Drawbacks of Concentrated Solar Thermal (CST) | habitat destruction & light beams frying birds in mid air |
| Pros of solar energy | No air pollutants (PM, SOx, NOx) released to gen. electricity No CO2 released when gen. electricity Renewable No mining of fossil fuels for electricity production |
| Cons of solar energy | Semiconductor metals (silicon) still need to be mined to produce PV cells (solar panels) - can disrupt habitats & pollute water with mine tailings, air with PM - Silicon is limited -Solar panel farms can displace habitats |
| How does hydroelectricity generate power? | Kinetic energy of moving water 🌊 → spins a turbine (mechanical energy) ⚙️ → turbine powers generator ⚡ ater moves either with natural current of river or tides, or by falling vertically through channel in a dam |
| Explain what a dam is | It is a man made built in a river where a large artificial lake is created behind the dam. water from the reservoir comes into the dam through the channel and is released into the river |
| Upstream vs downstream of a dam | Downstream: the river Upstream: the reservoir before the dam wall that goes into the dam |
| Explain how a dam generates electricity | water flows through channel, turns turbine, turbine powers generator - releasing electricity |
| Benefits of dam | 1. allows for control of flow downstream, prevention of seasonal flooding due to high rainfall 2. Reservoirs are also a source of recreation money (boating fees, tourism, increased property values, fishing, etc.) |
| Big impacts of a dam | flooding of ecosystems behind dam & sedimentation (buildup of sediments behind dam) |
| How does a run of river system generate electricity? | Natural current of the river turns the turbine...powers the generator...⚡ Instead of a dam, a portion of the river is diverted through a pipe to the turbine. |
| Benefits of run of river system | 1. Less impactful to surrounding ecosystem since no reservoir is formed & ecosystems behind dam aren’t flooded 2. Doesn’t stop natural flow of sediments downstream like water impoundment systems do |
| Downsides of run of river system | Doesn’t generate nearly as much power & may be unavailable in warmer seasons when river water levels are lower |
| What is tidal power | tidal ocean flow turning turbine (coastal areas only) |
| Ecological impacts of hydroelectricity dams | Reservoir floods habitats behind dam (forests/wetlands → gone Prevents upstream migration of salmon need to go up 2 reproduce Upstream: warmer less O2, rocky bc sediments Downstream loses nutrients, decreased water level, loses streambed hab. |
| Environmental impacts of hydroelectricity dams | - FF combustion during dam construction - increased evap. due to larger surface area of reservoir - methane release due to anaerobic decomp. of organic matter in reservoir |
| economic impacts of hydroelectricity dams | homes & businesses relocated due to reservoir flooding Initial construction is very expensive (does create long-term jobs though) sediment buildup must be removed by crane Loss of ecosystem services from downstream wetlands, loss of fishing rev. |
| Fish ladders + Benefits | Cement “steps” or series of pools that migratory fish like salmon can use to continue migration upstream, around or over dams Benefits: continued breeding for salmon, food source for predators like large birds, bears, and fishing revenue for humans |
| Benefits of hydroelectricity dams | No GHG emissions when producing electricity Reservoir/dam can be tourist attractions Jobs to maintain dam Reliable electricity source generated for surrounding area No air pollutants during electricity gen. Control of downstream seasonal floodi |
| How does geothermal energy generate electricity? | naturally heated water reservoirs deep (thousands of meters) underground are drilled into or water can be piped down into heated mantle Hot water can be converted into steam → turbine → elect. or be used to heat homes directly |
| What happens to the water used in geothermal electricty | Water is cooled in cooling tower & returned to the ground to start the process over |
| is geothermal energy renewable and how could it not be? | Renewable since heat from earth’s core won’t run out; but only if groundwater is returned after use |
| What is a ground source heat pump? Is it the same thing are geothermal energy? | Heat absorbing fluid is pumped through a pipe into the ground where it either takes on heat from the ground, or gives off heat to the ground not warmed by geothermal energy from magma - so not technically geothermal energy |
| In summer and winter with the ground source heat pump does the house get cooled or warmed? | Summer: house gets cooled winter: house gets warmed |
| Benefits of geothermal energy | Potentially renewable, only if water is piped back into the ground for reuse Much less CO2 emission than FF electricity No release of (PM/SOx/NOx/CO) as is case with FFs |
| Cons of geothermal energy | - Not everywhere on earth has access to geothermal energy reaching close enough to surface to access it - Hydrogen sulfide can be released, toxic and can be lethal to humans & animals - Cost of drilling deep in the earth can be very high initially |
| How do wind turbines generate electricity? | Kinetic energy of moving air (wind) spins a turbine; generator converts mechanical energy of turbine into electricity |
| What type of wind can wind turbines generate electricity in | 8-55 mph winds |
| % of total possible Energy wind turbines can generate | 15 - 30% capacity factor |
| Where and how are wind turbines located? WHy? | Clustered in groups (wind projects or farms) in flat, open areas (usually rural) Bc: Locating them together makes service, repair, and building transmission lines to them easier |
| What are offshore winds and what do they require to work? | Offshore wind = wind farms in oceans or lakes needs: faster wind speeds and transmission lines built across long distances to reach land though |
| Wind Energy Benefits | Non-depletable (isn’t decreased by its use) No GHG emissions or air pollutants released when generating electricity No CO2 (climate change) or NOx/SOx/PM Can share land uses (don’t destroy habitat or cause soil/water contamination |
| Wind Energy Drawbacks | Intermittency (isn’t always available) can’t replace base-load power (sources that are always available) Can kill birds and bats (especially larger, migratory birds) Can be considered an eyesore or source of noise pollution |
| What are the inputs and waste product of Hydrogen Fuel Cell? | Inputs: H2 gas and O2 waste product: H20 |
| How does hydrogen fuel cell generate electricity? | - H2 gas enters fuel cell where it’s split into protons (H+) and electrons (e-) by an electrolyte membrane that only lets protons pass through - Electrons take an alternative route (circuit) around the membrane, which generates an electrical current |
| How is H20 generated as a water product for hydrogen fuel cell? | O2 molecules enter fuel cell break apart into individual O atoms and combine with two hydrogens (H+) to form H2O as a by product |
| What is the most common a[application of hydrogen fuel cell? | Vehicles |
| What is the key challenge of Hydrogen Fuel Cell? | Key challenge to H fuel cells is obtaining pure H gas, seperating H2 gas from other molecules is very energy intensive |
| Two main processes to separate H2 gas from other molecules | steam reforming (95% of all H production) and electrolysis (less common, but more sustainable) |
| What is steam reforming & the consequences | burning natural gas (CH4) & using steam to separate the H gas from the methane (CH4) consequence: Emits CO2 & requires NG (FF) input |
| What is Electrolysis and what is the consequence | electrical current is applied to water, breaking it into O2 and H2 Consequence: No CO2 emission, but does require electricity |
| Hydrogen fuel as energy pros | -H2 gas can be stored in pressurized tanks, so can be transported to create electricity later, in a different location - Can be used as fuel for vehicles, ammonia for fertilizer, chemical industry no air pollutants/Co2, only H20 80% efficent in convert |
| Hydrogen Fuel Cells Drawbacks | - since 95% of H2 production requires methane, H fuel cells are based on non-renewable/emits Co2 source only as sustainable as the electricity source when electrolysis widespread H distribution network gas needs larger tanks than with gasoline |
| Small scale energy conservation | - Lowering thermostat to use less heat or AC - Conserving water - Energy efficient appliances, better insulation to keep more heat in home |
| Large scale energy conservation | - Improving fuel efficiency (fuel economy) standards - Subsidizing (tax credits for) electric vehicles, charging stations, and hybrids - Increased public transport (buses & light rails), green building design |
| Ways to create a sustainable design (block out or take advantages of sun’s natural heat, or keep in heating/cooling to decrease energy required) | - Deciduous shade trees for landscaping (leaves block sun in summer, but allow it in during winter) passive solar designs to trap sun’s heat & useless energy from heating system (heat absorbing wall) - Well-insulation to trap heat/cool air from AC |
| Ways to conserve water | - Native plants require less watering than traditional lawns - Low-flow showers, toilets, and dishwashers (less total water) - Rain barrels catches rain water to be used for watering plants or washing cars |
| Ways to conserve energy through transportation | - improving fuel economy of US vehicles, less gas needed to travel same distance - Hybrids (Prius) have both a gasoline & electric engine, so higher MPG ratings Electric vehicles - no gas, but only as sustainable as elect source Publictransit/carpool |
| What is sustainable Building design | Decreasing the amount of energy required to build larger buildings & heat/cool them |
| What are ways to create a sustainable building design | Green roof or walls: decrease runoff, absorb sun’s heat, less energy needed 4 cooling, less heat island effect Sun lights on roof/windows on sides can lessen elect. used for lighting Recycled materials= less energy required to make new ones (glass/wood |
| What is peak demand? | the time of day or year (often early night time hours or very hot weather events) that electricity demand is highest |
| What happens if demand exceeds supply? What is done to prevent this? | - Rolling blackouts occur - Prevention: some utilities use a variable price model for electricity (Users pay a higher rate during peak demand hours/events to discourage use, Users pay a lower rate/kWh when using less energy to encourage lower use |
| What is Smart Grid and provide some examples. | Smart Grid: the idea of managing demand & energy sources in a more varied way Examples: using smart meters for variable price models, allowing rooftop solar to direct electricity back to grid, integrating more total energy sources (especially renewable) |
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