Energy

Question 1

Coal, Oil, Natural Gas and Biomass electricity generation

Answer 1

Material is combusted, releasing stored energy as heat, which heats water, which creates steam. Steam spins a turbine, which spins a generator, which generates electricity and is distributed through a grid

Question 2

Hydroelectric generation

Answer 2

Release of water through gates, gravity causes water to fall through turbines. Kinetic energy spins the turbine, which spins a generator, which generates electricity.

Question 3

Active Solar electricity generation

Answer 3

Photovoltaic cells use semiconductors. When sunlight hits these sheets of metal, they release electrons and generate a low voltage current. Wiring captures the electrical current and combines it with power from other solar cells

Or concentrated solar rays:

Question 4

Wind electricity generation

Answer 4

The kinetic energy of the wind spins the blades of the wind turbine. Blades transfer this kinetic energy to the gearbox, which transfers energy to the generator, which generates electricity

Question 5

Geothermal heat electricity generation

Answer 5

Water is pumped down an injection well
Stored heat form the Earth’s interior turns water into steam
Steam rises from production well
Kinetic energy from steam turns turbine
The turbine turns a generator
The generator produces electricity

Question 6

Nuclear electricity generation

Answer 6

Uranium is mined and split into small pellets which are stacked into fuel rods (inside a containment structure). Goes through a nuclear reaction, where we fire a neutron at a relatively large nuclei, causing fission. Splits into more parts, releasing additional neutrons, continuing nuclear fission chain reactions that release an enormous amount of energy as heat. Control rods are released to absorb additional neutrons and end chain reaction. This heats up water, which generates steam, which spins a turbine, which spins a generator

Question 7

Hydrogen fuel cell

Answer 7

Hydrogen (in liquid or gas form) is added to the cell. In the first reaction layer, the hydrogen is split into a proton and electron, or is split into positive and negative components. Protons travel through the membrane of the cell. That negative powered electron takes a different path, and is free to create an alternate route, creating a flow of electric energy. In the second reaction layer oxygen molecules are split and combined with protons and electrons, generating water vapor as the only emission. These are primarily talked about to fuel electric motor in vehicles.

Question 8

Identify which energy sources used in transportation

Answer 8

Hydrogen fuel cells are predicted to be used the most in electric motors of automobiles over fuel combustion engines.

Fossil fuels including crude oil are used in gasoline and diesel

Biofuels: Includes ethanol, which is added to gasoline, and biodiesel, which is a replacement to diesel.

Question 9

Coal advantages

Answer 9

-Cheaper than other fossil fuels, -Abundant, energy-dense.
-No refining necessary
Economic backbone of small towns
-Relatively easy and safe to mine/transport, and process

Question 10

Coal disadvantages (environmental)

Answer 10

-Releases heavy metals, (Hg, Pb, As) in addition to COs (highest emitter). Releases SOx, NOx, and particulates.
-Combustion = ash as a waste product, with super concentrated impurities of coal being stored in pools. These pools can leak, causing rivers of ash.
-Ccid rain from release of sulfur (large contributor)
-Mining dramatically alters landscape and habitats

Question 11

Coal disadvantages (societal and economic)

Answer 11

-Subsurface mining requires more technology, is dangerous and bad for human health
-Coal cleaning compound/ ash spills that can enter homes

Question 12

Crude oil advantages

Answer 12

Convenient to transport and use
-energy dense.
Cleaner burning than coal
Better for cars because lots of energy in small volume

Question 13

Crude Oil disatvantages

Answer 13

-(significant) refining process can be a dangerous and large financial investment
-Significant dust and emissions from fossil fuels used to power earth-moving equipment
-Possibility of leaks when mining from wellhead/pipes and transported (pollutes water/habitat).
-Mining of tar sands is much more energy intensive than conventional drilling, since it must remove sand and water. (efficiency is lower, CO2 release is greater)
-Mining destroyes habitat
-Pollutant and Greenhouse Gas emissions: Second highest emitter of CO2, hydrocarbons, hydrogen sulfide and still releases S, Hg, Pb.
-Human rights/environmental justice issues developing in countries that export oil
-Will be much less available in 40 years

Question 14

Natural Gas advantages

Answer 14

-Efficient for cooking, home heating
-Fracking created jobs
-Cleanest of the fossil fuels, 40% less CO2. No impurities, just carbon and hydrogen.

Question 15

Natural Gas disadvantages

Answer 15

-Releases CH4 (methane -very potent greenhouse gas).
-Fracking still produces carbon dioxide, fugitive natural gas,
-Fracking fluid/machinery produces VOCs (human health)
-Fracking - destruction of habitat (+uses lots of water)
-Fracking fluid (chemicals)/ natural gas possibly contaminating nearby aquifers.
-Suspected earthquakes

Question 16

Nuclear power advantages

Answer 16

Generates the most energy!!
Low costs (after initial construction)
Does not produce air pollutants, considered cleaner. (only 10% of coal’s CO2)
No mining for fossil fuels

Question 17

Nuclear power disadvantages

Answer 17

-Very high initial costs (billions)
- Releases thermal pollution and hazardous (radioactive) solid waste fuel rods) that must be contained in concrete (daughter products with half life that have thermal radiation).
-Mining (for uranium/construction materials) = destruction of habitat/emissions
-Possible meltdown or fire
-Concerns of released radioactivity into air and water, and radioactive waste could enter hands of nuclear weapons

Question 18

Biomass advantages

Answer 18

-Available to everyone + minimal technology required (easy for developing countries to use for heating and cooking.)
-Energy + heat for cheap (cheaper than mining)
-Combustion produces modern carbon = carbon neutral
-Can be produced domestically. —Potentially renewable.
-Eliminates waste from environment

Question 19

Biomass disadvantages

Answer 19

-Decreases precipitation and CO2 sequestration, leads to soil erosion and degradation (can cause insecurity in food chains)
-Combustion releases PM, CO, NOx, CO2, and VOCs
-Possible net increase in greenhouse gas emissions
-Destruction of habitat/can lead to over-harvesting of trees and fuel wood (unsustainable)
-Typically burned indoors intensifying health effects of pollutants (3 million deaths annually)

Question 20

Biofuels advantages

Answer 20

Substitute for gasoline - sometimes cheaper
Modern carbon emissions - biodiesel technically carbon neutral
Biodeisal requires less land than ethanol
Potentially renewable
Can reduce our dependence on fossil fuels
Reduce trade deficit (increase domestic production vs. imported oil)

Question 21

Biofuels disadvantages

Answer 21

-Not as energy dense - lower gas mileage, need more
-Loss of agricultural lands = higher food costs
-Everything that goes into growing the plants (corn for ethanol) impacts environment: (pesticides, fertilizer)
-creates and releases CO2 emissions .. possible net increase in greenhouse gas emissions

Question 22

Passive solar advantages

Answer 22

Relatively inexpensive and low maintenance
Use of solar oven reduce firewood deforestation
If unsafe to travel, allows people (in refugee camps) to avoid attacks in search of firewood

Question 23

Passive solar disadvantages

Answer 23

Some aspects are difficult to implement retroactively
Energy cannot be collected or stored

Question 24

Active solar advantages

Answer 24

-Can use on large and small scales
-small scale solar-energy system are cheaper for homes far from grids
-Taxing and rebates making solar electricity and water heating more affordable
-(cells + solar water heating systems) After initial investment no cost to harvest energy
-No air pollution, low impact in environmental systems
Can install them so they won’t disturb environment
(cells + solar water heating systems )
-Nondepletable resource
-Produce electricity during peak demand hours

Question 25

Active solar disadvantages

Answer 25

Expensive to manufacture and install (although prices are coming down). Limited by sunlight High initial costs Solar panels contain toxic materials (silicone) that need to be mined, manufacturing requires energy. Limited lifespan of non renewable PV cells (20-30 years) must recycle solar cells (and batteries) Large fields of PVC (farms) can disrupt ecosystems (fragile desert habitats, migrating specialists) Manufacturing materials requires input of metals and waters: some pollution generated during manufacturing of panels No plan in place to recycle solar panels

Question 26

Hydroelectric advantages

Answer 26

Cheaper than nuclear electricity or natural gas - low cost to run Draws tourism/recreation (tidal energy) after initial investment no cost to harvest energy (Dams) Lots of energy without air pollution or waste Creates a reservoir for habitat, tourisms Run-of-the-river: Relatively little flooding occurs upstream, and seasonal changes in river flow are not disrupted Fish ladders can be used for fish (salmon ) to move upstream Nondepletable resource Reservoirs can be used by people for fishing, irrigation, etc. Can provide flood control and recreation

Question 27

Hydroelectric disadvantages

Answer 27

Run-of-the-river systems are limited by water flow (intermittent electricity generation, no generation during hot, dry perdios) Impoundment dams can flood agricultural lands or canyons with large aesthetic High construction costs Loss of habitat, agricultural land and cultural heritage; displacement of people Concrete wall from impoundment dam impacts fish migration that try to travel upriver Stops sediment flow that carries nutrients downriver (natural overflow to nearby areas). Siltation - Sediment builds up behind the wall, and can cause damage after a while. Dedrey (removal) requires machinery that runs on fossil fuels. Reservoir can lead to flooding habitats and displace people Construction (of cement) is invasive (pollutants like CO2) Disrupts flow rate (many organisms’ life cycle depend on seasonal changes in water flow (salmon) Buildup of dead plants/organisms release methane Alsters/destroys habitats - threats to river ecosystem Tidal - potentially disruptive to marine organisms Not many more sites that can have dam built - limited number can be installed in any given area Tidal - geographically limited

Question 28

Geothermal advantages

Answer 28

Not dependent no variable factors like solar or wind After initial investment no cost to harvest energy No combustion or CO2 emissions Non Depletable resource

Question 29

Geothermal disadvantages

Answer 29

Expensive deep drilling to find where hot water is Emits hazardous gasses and steam - drilling releases hydrogen sulfide (rotten egg smell) and methane from disturbing rocks when drilling. Sulfide from tailings, methane from natural gas. Could deplete groundwater if not used sustainably (normally water is restored and cycled back ) Geographically limited: Not accessible in many parts of the world where the hot water is too deep (no there/available). Best at tectonic plate boundaries.

Question 30

Wind advantages

Answer 30

After initial investment no cost to harvest energy Low upfront cost No emissions, nondepletable Nondepletable resource Clean energy that shares land - dual purpose if land is used or agriculture and wind turbines. Wind turbines can also be built offshore near the water, where it is very windy.

Question 31

Wind disadvantages

Answer 31

Maintenance is required - must trade out parts Storage batteries required for some off-grid systems (expensive to produce and a challenge to dispose and recycle) Death of birds and bats - killed if they fly into the spinning turbine blades… also electrocuted from transmission lines Turbine noise: Noise pollution (not aesthetic) Geographically limited to windy areas near transmission lines + need backup power on days that are not windy

Question 32

Hydrogen fuel cells advantages

Answer 32

Efficient Uses an electric motor, which is much more efficient (60%) compared to an internal combustion engine (20%) Water is only by-product - zero pollution

Question 33

Hydrogen fuel cells disadvantages

Answer 33

Hydrogen is rare and flammable This is new technology so the research and resources are pretty expensive (this price should decrease as production increases) Platinum and other rare earth materials (uses as catalysts) are raw, rare materials Producing hydrogen is an energy-intensive process: Hydrogen is rare, must separate it from other molecules with heat or electricity. Energy-intensive separates hydrogen from natural gas, but pollutes with carbon dioxide and pollutants. Must find a way to obtain hydrogen without producing more fossil fuels Lack of distribution network + hydrogen storage challenges. Would be hard to transport to consumers, and would have to store it as gas in a heavily pressurized tank. Vehicle fuel tanks would have to be much larger… Tank could rupture, causing hydrogen to catch fire/explode

Question 34

Examples of passive solar designs

Answer 34

In the Northern Hemisphere, constructing a house with south-facing windows will allow the Sun’s rays to penetrate and warm the house in the winter when the Sun is more prominent in the southern sky. During the summer, an overhanging roof blocks out sunlight during the hottest period, cooling the indoors and reducing the need for ventilation vans/air conditioning. Double-pane windows insulate while still allowing incoming solar radiation to warm the house. Carefully placed windows also allow natural lighting to reduce need for artificial lighting. Dark materials on the roofs or exterior walls of buildings absorb more solar energy than light-7colored materials, further warming the structure. Materials with a high thermal mass to absorb heat and retain the heat after the sun has set. Developing countries use solar cookers

Question 35

Identify an energy source as renewable or nonrenewable or possibly renewable

Answer 35

All fossil fuels + nuclear = nonrenewable Biomass + biofuels = possibly renewable Wind, hydroelectricity, geothermal, solar and hydrogen fuel cells = renewable

Question 36

Describe how fossil fuels are formed

Answer 36

Plant matter (trees, ferns) or organisms (phytoplankton for natural gas) are quickly buried underground in anaerobic environment (specifically tropical regions for coal and oil). Over hundreds of millions of years, intense heat and pressure cause this matter to transform into crude oil, natural gas, and coal. The longer it sits, the more efficient it becomes.

Question 37

Describe process of fracking

Answer 37

1.drill down creating well (cement lined) 2. Insert pipe 3. Pump fracking fluid, water mixed with chemicals (+sand), breaking the rock (causing fractures) 4. Natural gas flows out

Question 38

Describe pros and cons of fracking

Answer 38

Pros: Fracking creates jobs and has lowered the price of natural gas Cons: Still produces carbon dioxide and fugitive natural gas Fracking fluid (chemicals)/ natural gas possibly contaminating nearby aquifers. (if well note sealed properly) Fracking fluid/ machinery produces VOCs Causes destruction of habitat (+uses lots of water)

Question 39

Identify which sources supply most energy

Answer 39

Fossil fuels sup[ply the most energy. The U.S is moving away from coal and more to natural gas. Oil has stayed relatively the same.