APES ch. 19 Alternative Energy
Terms in this set (47)
what are alternative energy sources?
energy sources other than fossil fuels
how are alternative energy sources grouped
grouped according to whether or not they are renewable or non-renewable
what is the difference between renewable and nonrenewable resources
renewable: can be regenerated by the sun within reasonable time frame
nonrenewable: cannot be replenished easily
which of the alternative resources are renewable?
solar, win, water and biomass energy. All derived from sun's energy
which alternative energy source is potentially depletable?
biomass and water energy because there is potential for a shortage due to climate conditions
what is considered nonrenewable of the alternative energy sources?
nuclear and geothermal energy
how does the US energy information administration classify geothermal energy?
they consider it nonrenewable because rates of extraction are greater than rates of natural replenishment
how are water and biomass fundamentally different from solar and wind energy
-they have slight environmental impact whereas others have less it any impact
what are some reasons that renewable energy sources arent used as much as fossil fuels?
-not as much is known about alt energy
-fossil fuels create such a large amount of energy today because the infrastructure is there and the technology is advanced
-tech is there for alt energy but its generally more expensive
what is the difference between direct and indirect solar energy
direct- energy that is directly converts sunlight to electricity
indirect- solar power which goes through more than one change to become usable energy
which alternative energy sources are direct?
which alternative energy sources are indirect
passive solar energy systems and active solar energy systems
what is the difference between passive and active solar energy?
passive doesnt involve mechanical devices whereas active solar energy use external sources of energy to power types of equipment to collect, store and convert solar energy
how does passive solar design work
involve architectural designs that enhance the absorption of solar energy by using and adjusting for natural changes that occur throughout the year without requiring mechanical power.
costs and benefits of passive solar
-less energy is used to create energy
-depends greatly on climate
how does active solar work
uses mechanical power, usually electric pumps and other apparatuses, to circulate air, water, or other fluids from solar collectors to a location where the heat is stored until used.
costs and benefits of active solar design
-some energy is stored. if unable to produce (weather) there's no panic
-large land area is required to generate a large amount of energy.
-large variety of metals, glass, plastics and fluids are used to manufacture and use solar equipment-->may cause environmental problems by accidental release of toxic materials
What are photovoltaics (PV)?
Photovoltaics is a technology that converts sunlight directly into electricity.
What are the environmental costs and benefits of photovoltaic systems?
Pros -can produce energy from light other than the sun, its significant to developing countries that do not have the financial ability to build large plants.
-in some locations, the cost of photovoltaics is comparable with the cost of using grid-connected power.
Cons: -doesnt work when cloudy or rainy
-low efficiency (14-25%)
-PV panels use some toxic chemicals like cadmium and arsenic
What is solar thermal electric generation?
Concentrating the sun's heat to create steam to drive turbines. Done on a large scale.
A device absorbs the sun's thermal energy either for heating or energy creation purposes. The energy produced is created through the use of steam turbines. These steam turbines are turned by steam being forced through them to turn them
Where in the US is solar energy potential the greatest
Places that are sunny year-round, southwest
What are the major advantages of using hydrogen as an energy source?
no emissions (greenhouse gases), high efficiency, no fossil fuels used, pure water is a product. No contribution to global warming, air pollution or acid rain. Hydrogen can be stored and used later to produce electricity on cloudy days/night/when wind isn't blowing
why isnt hydrogen energy widely used>
dont have necessary infrastructure for storage, transportation and fueling stations for hydrogen. still in research and development
How are fuel cells used to get energy from hydrogen?
Hydrogen can be stored in fuel cells that are somewhat similar to batteries. This hydrogen produced by wind/sun/etc. can be stored for later.
-A fuel cell combines hydrogen and oxygen to produce electricity.
What is hydroelectricity?
electricity generated by hydropower, Electric power produced by rushing water
how much of the US electric supply is generated by hydroelectric power plants?
What are the advantages of using hydroelectric energy?
pros: renewable, can be created constantly, no pollutants or byproducts, water isn't used up(returned to its source of origin), creates reservoirs, dams create can also shut their gates and conserve the water for use when power is in high demand
what are the disadvantages of using hydroelectric energy
expensive to build, can create flooding which can destroy some habitats, may cause water access problems (dam in one spot can minimize water flow down the river), block fish and aquatic animals, increase DO levels, increase dissolved nitrogen(picked up when falling and could be ingested, which would kill organisms), trap sediment, increased evaporation compared to pre-dam conditions
What is tidal power
type of water power derived from ocean tides. Dam is built across entrance to bay or estuary, creating reservoir. When tide rises and falls, water is let in and out of the dam. By doing this, a turbine turns and creates electricity.
What is wind power
The creation of electricity by using wind to spin a turbine
What limits the use of wind power
amount of wind
What are the advantages and disadvantages of wind power?
pros: renewable, use of wind power can reduce fossil fuels consumption, no pollutants, land around turbines can still be used
Cons:Threat to wildlife, wind cannot be predicted, uses up a lot of land, low environmental resources
What is biomass energy
The energy that may be recovered from biomass, which is organic material such as plants and animal waste.
What is the difference between ethanol and biodiesel?
-ethanol is a renewable fuel made from biomass which is ground up into a flour, fermented and the alcohol is extracted.
-biodiesel is similar to diesel fuel but is derived from a vegetable oil or animal fat.
what are the advantages of using ethanol
renewable, burns more cleanly than petroleum (less soot and CO), reduces CO2 emissions
what are the disadvantages of using ethanol
lower heat of combustions than petroleum(low fuel economy), large amounts of arable land is required to grow the crop to make ethanol. Environmental effects from disposal of fermentation liquors, typical engines require modification to use high concentrations of ethanol.
what are the advantages of using biodeisel
renewable energy source, less polluting than petroleum, can be used in existing oil heating systems and diesel engines without alterations, considered carbon neutral to some because carbon produced when burning is offset by carbon consumed by plants they came from. Reduce dependence on foreign oils
what are the disadvantages of using biodeisel
machinery required to make biofuels does create carbon emissions, land for biofuel crops means less land for food crops, possibly unethical because of lack of food crops (opinion of some countries), more expensive than petroleum, requires energy to produce biodiesel, infrastructure needs improvement
What is geothermal energy?
Natural heat from the interior of the Earth that is converted to heat buildings and generate electricity. Nonrenewable! Only available in certain places. Ground source heat pumps can be used to heat and cool buildings
How can electricity be generated using geothermal energy (3 ways
dry steam, flash steam, binary
dry steam geothermal energy
drawn from underground sources of steam. Steam is piped from ground to plant where it is directed to turbine/generator unit. (Geysers in northern california and Yellowstone National Park)
flash steam geothermal energy
most common. use geothermal reservoirs of water with temperature more than 360F. water flows up wells in the ground under own pressure. As flows, pressure decreases, becomes steam, separated from water and used at turbine/generator. Leftover water and condensed steam are injected back into the reservoir (sustainable)
binary geothermal energy
operate at lower temperature of 225-360F. Plants use the heat from hot water to boil a working fluid (usually organic compound with low boiling point). Fluid is vaporized in heat exchanger and used to turn turbine. Water is injected back into ground to be reheated. The water and working fluid are separate for the whole process, little to no emissions.
why is geothermal energy a limited source?
considered nonrenewable when rates of extraction are greater than rates of exchange
How does a geothermal groundwater heat pump work?
central heating and/or cooling system that transfers heat to or from the ground. Uses the earth as heat source or heat sink in summer and winter. Geothermal heating and cooling systems take advantage of the stable temperature underground using a piping system, commonly referred to as a "loop." Water circulates in the loop to exchange heat between your home, the ground source heat pump, and the earth, providing heating, cooling, and hot water at remarkably high efficiencies
what are some advantages of geothermal energy?
open loop system have less loss in heat transfer, lower heat pump energy costs, renewable (as long as not too much is pumped at once), no pollution, no greenhouse gases
what are some disadvantages of geothermal energy?
cannot be set up anywhere desired. Must have right location w/ right rocks. Risk of running out of steam. dangerous gases and minerals from ground can find their way up and cause issues.
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