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AP Environmental > Renewable Energy Sources > Flashcards

Renewable Energy Sources Flashcards

1
Q

What is biomass?

A

Any material derived from a living organism (Ex: wood, crops, animal waste)

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2
Q

What is biofuel?

A
  • Processed biomass (Ex: ethanol, gasohol ethanol)

- Processed biomass that is renewable, but is limited by the rate of use and production

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3
Q

What is hydroelectricity?

A

Form of energy that harnesses the power when water is in motion

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4
Q

How is water harnessed to create energy?

A
  • It utilizes the gravitational potential energy of water in reservoirs behind dams
  • The water flows and is directed through pipes to the powerhouse, turning the turbines which turn the generator to create energy
  • The higher the volume of water and further distance it falls, the greater amount of energy is produced
  • The water doesn’t have to be in a dam to generate electricity. As long as water flows past the turbine, which turns the generator, it can create electricity
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5
Q

How does using hydroelectric power affect the environment?

A
  • Hydroelectric power does not generate air pollution or waste, but the construction of power plants can be very expensive, and there may be a loss of or change in habitats following the construction of dams
  • When people install dams, it can often disrupt the fish population, and change the habitat of aquatic environments
  • There can be flooding of land for the reservoir
  • Places to build hydropower are limited, using all limited land can cause a loss in habitats, biodiversity, and even agricultural land
  • It could also change the water temperature and the river’s flow, thus affecting the aquatic organisms living there
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6
Q

What are the four generations of biofuels and their characteristics?

A

1st Generation:
- Grown on arable lands and are often food crops (ex: sugarcane or corn)
2nd Generation:
- Produced from crop byproducts; cellulose biomass not sugars or oils
3rd Generation:
- Based around algae with high lipid oil content; grown in bioreactors or wastewater ponds
4th Generation:
- Living material used to produce energy directly

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7
Q

Advantages of Hydroelectric Power

A
  • High net energy gain
  • High efficiency
  • Reservoirs used for recreation and irrigation
  • Provide flood control
  • Long life spans
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8
Q

Disadvantages of Hydroelectric Power

A
  • High construction costs
  • River diversions during and often after construction
  • High initial CO2 production from rotting material within the reservoir
  • Dams interfere with fish migration
  • Possible flooding of river valleys behind dams
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9
Q

How does the use of biomass affect the environment and human health?

A
  • The burning of biomass produces heat for energy at a relatively low cost, but it also produces carbon dioxide, carbon monoxide, nitrogen oxides, particulates, and volatile organic compounds (which can cause breathing issues in humans)
  • The overharvesting of trees for fuel also causes deforestation
  • Using wood as a source of heat can become dangerous; If not properly disposed of, it can lead to forest fires, which damages existing resources
  • Overcropping causes soil erosion because depleted soil cannot sustain vegetation and holds less soil moisture
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10
Q

Describe methods of conserving energy

A
  • Unplug electronics when they are not in use
  • Turn off lights when you leave a room
  • Use energy-efficient appliances
  • Use natural light instead of electricity when possible
  • Wash your clothes in cold water and air dry
  • Avoid your oven and use the microwave instead
  • Take short and cold showers
  • Utilize natural ventilation
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11
Q

Where are water sources found globally?

A
  • Rivers, oceans, lakes, etc.
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12
Q

Where are resources for biomass-produced energy found?

A
  • Crops (where agriculture takes place)
  • Forests (South America)
  • Small plants and grasses
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13
Q

What is wind energy?

A

Wind turbines use kinetic energy to convert wind into electricity

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14
Q

What is solar energy?

A
  • Solar panels convert sunlight into electricity
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15
Q

How are photovoltaic solar panels and concentrated solar panels different?

A
  • Photovoltaic solar panels have 2 layers of silicon: the sun strikes the silicon, excites electrons, and creates energy
  • Concentrated solar panels have mirrors: the sun strikes the mirrors, it creates heat and steam which then enters a turbine that creates electricity
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16
Q

How does wind energy work?

A
  • Much like other forms of energy production, wind creates energy by turning a turbine that’s part of a generator
  • Unlike fossil fuels, however, wind turbines use the kinetic energy of the wind to rotate the turbine.
17
Q

What are wind farms? Where are they usually located? What is the benefit of wind farms?

A
  • Wind Farms: large areas where wind turbines are grouped together
  • Used to better harvest wind energy, placed in areas with high wind activity, typically mountains or close offshore
  • Land can still be used for other purposes, like agriculture, bc wind turbines have minimal impact on land
18
Q

What are the pros of wind energy?

A
  • Renewable
  • A fastest growing renewable resource
  • A wind farm can be built in a few years which is very fast compared to other energy sources
  • Affordable
  • No greenhouse gas emissions once it’s built
19
Q

What are the cons of wind energy?

A
  • Wind is intermittent, meaning that it only makes power when the wind is blowing
  • Wind turbines kills birds and bats
  • Building of wind turbines requires mining for metals which causes erosion, contamination of groundwater, and pollution
  • Many people don’t want to live near wind turbines, but if you place them offshore away from people, then it becomes a lot more expensive
20
Q

How do solar panels harness energy from the sun to convert into electricity?

A
  • Solar panels are comprised of one positively charged layer of silicon and one negatively charged layer of silicon
  • When the sun strikes the solar panels, the electrons between the layers are excited
  • The electric field produced by the solar panels force the electrons to flow towards the conductive metal plates that line the panel
  • This is called an energy current and the electricity that the panel can produce is determined by how strong this current is
  • The current is then directed into wires, which allows for usable forms of electricity.
21
Q

What are the pros of solar energy?

A
  • Environmentally friendly: no greenhouse gas emissions
  • Cheap
  • Low-maintenance
  • Easily installed because panels are small and lightweight
  • Market is growing rapidly – lots of jobs
22
Q

What are the cons of solar energy?

A
  • There is a high upfront cost of solar panels
  • Initial production will result in pollution
  • The intensity of the sun varies throughout the year and no energy is produced at night
  • Solar farms need very large areas of land in order to operate which displaces wildlife
  • Some resources that are needed to make solar panels are scarce
  • Chemicals and metals, which are hazardous waste products, are disposed into landfills after they stop working
23
Q

What is geothermal energy?

A
  • Heat from the earth’s core harnessed into energy
  • Heat is far down in the earth’s crust and can be expensive or not a viable energy source when heat is not easily accessible
24
Q

Where and how are geothermal reservoirs found in the earth? Where are the most active geothermal reservoirs?

A
  • Geothermal reservoirs are deep underground and difficult to detect
  • In order to locate them, you must drill a well and test the temperature
  • The most active geothermal reservoirs can be found near large tectonic plate boundaries
  • However, geothermal energy within the Earth can be tapped into almost anywhere, from a few feet to a few miles underground
25
Q

What country is the largest producer of geothermal energy? Where is most geothermal energy found in the United States?

A
  • In the US, most geothermal energy resources are found in the West and Hawaii, where geothermal resources are closer to the surface and easier and cheaper to access
  • There are 7 states with geothermal power plants: California, Nevada, Utah, Hawaii, Oregon, Idaho, and New Mexico
  • It accounts for 0.4% of total U.S. energy production for a total of 17 billion kWh in 2020
26
Q

How is heat harnessed to produce electricity?

A
  • Water is pumped down an injection well
  • Heat in Earth’s interior turns that water into steam
  • Steam rises in the production well
  • Kinetic energy of steam turns a turbine
  • Turbine turns a generator - produces electricity
27
Q

How can geothermal energy help with heating/cooling houses? What are its benefits and disadvantages compared to traditional AC/Heating systems?

A
  • Can move energy between a house and the ground to heat/cool down home
  • Pipes filled with water circulate between the home and the ground; the air is blown over pipes and the air turns to the temperature of the pipes
  • more expensive than traditional AC/Heating systems to install (around 200ft. )
    Benefits: cheaper to maintain, long-lasting, sustainable
28
Q

Benefits of Geothermal Energy

A
  • Constant electricity production - regardless of weather
  • Small Environmental Footprint (uses less land per Gigawatt Hour than coal, wind, or solar)
  • Emits no greenhouse gasses
  • Uses less water than other sources of electricity (natural gas, coal)
  • 4x less greenhouse gas emissions than solar as a whole
  • Renewable - heat within the earth is constantly being produced
  • Multiple uses (heating, electricity, cooling)
29
Q

Cons of Geothermal Energy

A
  • Economic viability of geothermal is not always available
  • High Cost vs. Low Energy
  • Hydrogen sulfide gas is released during drilling and processing
  • Possible short-term depletion of heat
  • Can impact groundwater
30
Q

How do hydrogen fuel cells generate electricity?

A

They use hydrogen as fuel, combining the hydrogen & oxygen in the air to form water & release energy (electricity) in the process.

31
Q

What are the emissions from hydrogen fuel cells?

A

Water

32
Q

What is the difference between a hydrogen fuel cell and a typical battery?

A
  • In a typical battery, the chemicals are in a closed container.
  • Once used, the battery must be charged or discarded.
  • in a hydrogen fuel cell, the chemical reactants can be added continuously
  • The fuel cell does not “go dead”
33
Q

What is the first step of the hydrogen fuel electricity generation process? What happens in the two separate layers of reaction for a hydrogen fuel cell?

A

First Step: Hydrogen fuel (H2) is added to the cell

  • This can be in liquid or gas form
  • In the 1st reaction layer, hydrogen molecules are split into protons (H+) & electrons (-)
  • Protons & electrons take different paths.
  • Protons move across the membrane
  • Electrons are free to take an alternate route, creating a flow of electric current
  • In the 2nd reaction layer, Oxygen molecules (O2) are split & combine with protons & electrons
34
Q

What are the inputs and products of hydrogen fuel cells in vehicles?

A
  • Hydrogen gas is pumped in from a fuel pump
  • Oxygen is taken in from the air
  • Product is water vapor and heat
35
Q

Where does hydrogen gas come from? How is it extracted from these substances? What are potential environmental consequences?

A

Usually found in compounds like water or natural gas

  • Can come from water (H2O):
  • Electrolysis - electric current used to split water into hydrogen & oxygen
  • Can come from natural gas:
  • Splitting methane (CH4) using heat (in the form of steam), results in CO2 pollution
36
Q

What factors of hydrogen fuel cells’ electricity generation process decrease its net energy?

A
  • Since we must create the hydrogen gas (isn’t found naturally) and it takes electricity or heat to break apart water or methane, this decreases the net energy of hydrogen as a fuel source
37
Q

Net Energy

A

It is the amount of energy produced by the source minus energy used, lost, or wasted in the process of generating the useful energy

38
Q

Benefits of Hydrogen Fuel Cells

A
  • No CO2 emissions (if produced from water)
  • Electricity is more efficient than internal combustion (seen as the future of transportation & energy needs)
  • Could be sustainable if the energy used to produce hydrogen is produced using sustainable sources (ie solar PV)
  • Range of the fuel tank is about the same as a conventional car
39
Q

Negative Consequences of Hydrogen Fuel Cells

A
  • Technology is expensive
  • Producing hydrogen fuel from fossil fuels is not clean
  • Currently producing hydrogen fuel requires a relatively high amount of energy
  • At the moment most of the hydrogen for fuel cells is produced by steam reforming from natural gas and the rest is produced by electrolysis.
  • Operation is limited by the amount of available fuel: lack of infrastructure

AP Environmental (50 decks)

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