unit 6 Flashcards
ethanol
- not efficient because it takes a lot of energyto produce it and there’s not a lot of energy that comes out of it
Light energy absorbed by cells → semiconductors transfer energy to electrons that move in electrical current and produce electricity
Depends on amount of sunlight available
Installed fast and affordable
light -> energy to electrons -> move in electric current–> produce electricity
photovoltaic cell
Uses electrical and mechanical equipment to convert light energy into electrical energy
More expensive
Collects, stores, and distributes energy
Active system solar power
Absorb heat directly from sun
Cheap and low maintenance
Cannot be collected nor stored
crude oil
Pros: relatively environmentally friendly and “clean energy”
Cons: limited by nature, can be expensive, large farms can harm desert ecosystems
Issues: create hazardous waste after natural disasters and contribute to climate change and excessive mining
pros, cons, issues of solar power
easy to store and transport, cheap form of energy, reliable source
pros of fossil fuels
nonrenewable, pollutes the enviornment, very dangerous to mine and create energy rrfrom
cons of fossil fuels
High-temp exothermic redox reaction
A chemical reaction between the fuel and oxygen
Produces energy and carbon dioxide (greenhouse gases)
combustion
Examples: crude oil, natural gas, and petroleum
Fossil fuel plants burn fossil fuels to create heat
The steam (!!) from the heat is captured and used to drive turbines which generate electricity
how do fossil fuels?
Surface Mining - removing rock and soil layers above the coal before extracting it
Underground Mining - creating tunnels/shafts through which fossil fuels are extracted
Drilling - drilling holes into the ground to reach the fossil fuels
Hydrologic Fracking - Drilling operators force water, sand, and chemicals into horizontally drilled shales to make them crack and release natural gas and oil
extraction of fossil fuels
The anode receives fuel, such as hydrogen, while the
cathode receives air.
2. Protons and electrons from hydrogen molecules are split
up by a catalyst at the anode of a hydrogen fuel cell and
go in distinct directions to the cathode.
a. Protons pass through the membrane
b. Electrons go into the circuit and produce heat
3. A current of electricity is produced when the electrons
pass through an external circuit.
4. Protons from hydrogen and oxygen connect to make water
The hydrogen reacts with oxygen across an electrochemical cell— similar to a battery—to produce electricity, water, and small amounts of heat. Hydrogen fuel cells are currently used to power the electrical systems on spacecraft and to supply electricity on earth
how do fuel cells work
Clean energy
- No harmful emissions
- Silent when operating
- Quick start-up time
- Renewable
- Hydrogen is the most common
element
pros of hydrogen fuel cell
Hydrogen fuel is expensive
- Hydrogen fuel is not widely
available/easy to refuel
- Hydrogen gas is highly flammable!!!!!1
- Process to get hydrogen fuel gives
waste!!!
- No current/stable infrastructure to
obtain hydrogen fuel!!!!!
cons of hydrogen cell
●does not emit co2, BUT….
- Platinum (MINING!!)
○ Required to make hydrogen fuel cells
○ Mining for platinum may cause
environmental degradation (soil erosion,
water pollution, etc.)
● Hydrogen Fuel
○ Since hydrogen molecules are tiny and
light, it is prone to leaking (TOXIC)
○ Compressing and transferring hydrogen
gas is energy-intensive
enviornmental impact of hydrogen fuel cells
Renewable
● Non-Depletable
● Free
● One of the cleanest forms of energy
● Advances in technology
● Doesn’t take up land or disrupt farmland
operations
pros of wind energy
Noisy
● Expensive Upfront Cost ($$)
● Dangerous to some wildlife
● Unreliable/Unpredictable
● Visual pollution
cons of wind energy
Instead of using electricity to make wind, wind turbines use wind to make electricity
● Wind turbines use blades to collect the wind’s kinetic energy
● Wind flows over the blades creating lift (similar to the effect on an airplane’s wings), which causes the blade
to turn
● The blades are connected to a drive shaft that turns an electric generator
● Wind turns the propeller-like blades of a turbine around a rotor, which spins a generator, which creates
electricity
how wind energy works
Horizontal-Axis- These are your typical turbines and what you would normally picture a turbine to look like. They
have three blades and operate “upwind,” with the turbine pivoting at the top of the tower so the blades face into the
wind.
Vertical-Axis- These turbines are omnidirectional, meaning they don’t need to be adjusted to point into the wind to
operate.
wind energy-turbines
Wind energy is a renewable
- Decreases the amount of released greenhouse gasses
● If there are complications on the wind turbines, the land nearby can be damaged
- For example, if a wind turbine catches fire the land surrounding it will also catch fire therefore the
soil will become infertile
environmental impacts of wind energy
At the plant level, water flows through a pipe—also known as a penstock—and then spins the blades in a turbine, which, in turn, spins a generator that ultimately produces electricity
A higher slope from the reservoir to the turbine means higher kinetic energy as the water flows down, creating more electricity (Prevents debris from entering and possibly blocking the turbine)
how does hydroelectric power work
Hydroelectric power is credited for being more environmentally friendly that fossil fuels and do not directly emit pollutants into the air. Still, dams created to generate electricity have numerous environmental impacts, including displacing wild/marinlife and creating resevoirs and ponds from rivers. Dams are needed to redirect water from its natural flow in a river into a hydropower plant to produce electricity. Thus, this disrupts physical characteristics of the river, cover significant natural areas/agricultural land, and archaeological sites, as well as the water’s natural temperature, chemistry, and silt loads.
Hydroelectric power also releases carbon emissions into the environment through producing concrete and steel used, as well as carbon dioxide and methane formed in “aerobin and anaerobic decomposition of biomass in the reservoirs” created from the dams.
enviornmental impact of hydroelectric power
Clean source of energy
Less dependent on seasonal factors for production
More control over the energy
Countries with rivers and rainfall benefit more
pros of hydroelectric power
Construction of dams has an environmental impact
Displaces many people
An extreme cost of constructing the hydro plant
Climate change
cons of hydroelectric power
Organic matter produced by photosynthetic producers, Total dry weight of all living organisms at each trophic level in a food web
biomass
Method #1
Burning Biomass to create heat
Dung, Reeds, Wood, Trash
Biomass must not be removed faster than can be replaced
Developing countries
Burning takes nutrients from fields
Method #2
Gaseous Biofuels
Liquid Biofuels
Convert solid biomass into gas and liquid biofuels
Ethanol
distilled and fermented grains
Methanol
prod. from sewage sludge, wood, agricultural wastes, garbage & coal
biomass
Grain stocks (corn) can be fermented by bacteria (yeast) which can then be burned as fuel
Cons: pesticides, fertilizers, CO2 emissions, land could be used for food!
ethanol
Traditional: corn fermentation
New: algae make ethanol. Same process 🡪 use algae instead of corn to ferment by yeast.
Algae can be farmed and harvested in smaller facilities.
Algae: Sargassum, Glacilaria
ethanol v algae
Use plantations to grow wood 🡪 use pesticides, fertilizers which pollutes drinking water.
Soil erosion 🡪 sedimentation
Little nutrients go back in soil.
Loss of habitat for orgs.
Burning releases CO2, CO, NOxs, PMs and VOCs
disadvantages of biomass
A renewable resource if managed
Makes use of agricultural or timber wastes.
LOTS of biomass (readily available)
pros of biomass
Wood smoke creates air pollution which can lead to:
bronchitis, emphysema, cancer
air pollutants (biomass and biogas)
biogas- liquid and gaseous biofuels (methane)
-landfill
-old landfill mound
-gas extraction well
-gas compressor
-turbine for electricity
partially decomposed organic material that can be burned for fuel
peat
Three types of coal used for fuel are lignite,
bituminous, and anthracite. Heat, pressure, and
depth of burial contribute to the development
of various coal types and their qualities.
anthracite- highest rank of coal, hard brittle, black, “hard coal,” high % of fixeed carbon and low % of volatile matter
Bituminous- middle rank coal, high heat content, is used frequently for energy, blocking, thin, alternating shiny and dull layers
Lignite- brown, low grade coal, least concentration of carbon, low heating value and high moisture content, mainly used in electricity generation
crude oil extraction:
bitumen: “tar sands” oil
enviornmental impact:
- freshwater sources are depleted
- lagoons of toxic waste
- disruption of land and marinelife eccosystems
- air and global pollution
natural gas, “cleanest” of fossil fuels
- mainly nh4
- burns few emissions for nearly all types of air pollutants but produces much c02, can leak into the atmosphere from oil and gass mills, distubs vegetation and soil with drilling vehicles, might require cleaning, contaminated water, etc.
cracks in and below Earth’s surface are opened and widened by injecting water, chemicals, and sand at high pressure. Some resources extracted through fracking are called “tight oil” or “tight gas,” because these pockets of fossil fuels are tightly trapped in hard shale rock formations.
fracking
- adjusting thermostat to reduce heat and air conditoning
- conserving water
- use of energy-efficient appliances/conservation landscaping
conserving energy on the micro level/in the household
- improving fuel economy for vehicles
- bevs (battery electric vehicles) and hybrid vehicles
- transportation and implementing green building
conserving energy on a larger scale
wood is the most common source of energy for ledcs because of how readily available it is (charcoal and firewood)
- nuclear power is generated through fission and heat + radiation is produced
- ## nuclear power plants produce much of us energy (around 20%)
how is nuclear power generated?
benefits: “clean power”, supports many jobs, nuclear waste is being reduced and does not DIRECTLY emit air pollutants
pros of nuclear energy
- dangerous and unstable
- radiation
- thermal pollution
cons of nuclear energy
- geothermal heat comes up from earth’s core heats water which turns into steam
- (hot water) placed into a low to high pressure tank to create steam
- turbine spins with steam which generates mechanical energy and then electrical energy for use
how does geothermal energy work
- renewable and sustainable
- low greenhouse gas emissions
- efficient
- power plants, very efficient
- used in many industrial processes and heating/cooling systems
- low greenhouse gas emissions
pros of geothermal energy
- dependent on location
- expensive
-high water usage
-land use impact
can cause earthquakes!! - chemical releases and leaks from extraction processes
- resource depletion
cons of geothermal energy
