APES Alternative Energy Terms
Terms in this set (38)
What are alternative energy sources?
Any energy source not derived from fossil fuels.
What is the difference between renewable and nonrenewable sources?
Renewable sources are things we percieve to have an endless supply of, or things which will replenish their reserves before we can exhaust them. Sun, water, wind and biomass.
Name the different types of alternate energy sources.
Passive Solar, Solar water heating, Photovoltaics, Solar Thermal electric, Hydrogen, Ethanol, Wind, Hydroelectric, Biodiesel, Geothermal electric, Geothermal Ground source heat pumps, Tide energy
Which alternative energy source is potentially depletable?
Biomass and water
Why is geothermal energy nonrenewable?
Rates of extraction are greater than rates of replenishment
How does the US Energy Information Administration classify geothermal energy?
How are water and biomass fundamentally different from wind and solar energy?
Water and biomass are portable, shippable goods whereas sun and wind are highly dependent on the geography of the area and the weather on a given day. Some places have no wind or very little sun; but even in places with high winds or sunny days you can have a day where the air is calm or it is cloudy and then you cannot gain energy from these sources.
What are several reasons that rewenable energy sources are not used as much as fossil fuels?
Due to government subsidies the use of coal is still much cheaper. Also alternative sources of energy are not available in all climates; for instance, you cannot effectively use solar energy in Alaska. Also, several sources can be unreliable, such as solar when its cloudy and raining, or wind when there is little wind movement on a given day.
What is the difference between direct and indirect solar energy?
Direct takes energy DIRECTLY from the sun's rays
Indirect is an INDIRECT manifestation of stored solar power; such as the sun growing crops used in biomass fuel
Which alternative solar energy sources are indirect?
hydropower, wind, biomass
Which alternative solar energy sources are direct?
PV, thermal conversion, passive building design
What is the difference between passive and active solar energy?
Gathering and holding heat from the sun with no moving parts is passive solar energy. EX: passive design
Any exchange of heat using a system of pumps is active solar energy. EX: thermal conversion, PV panels
Passive Solar Design
-Use of solar power through design; building faces south and has a shading so that the summer sun cannot penetrate the house (therefore cooling it down) but the lower winter sun can. The walls and floor will be made of a special black tile that absorbs heat from the sun and continiously releases it throughout the day and into the night. A tree will sometimes be used as a further shield against high summer sun; leaves block sunlight in the winter but bare branches let in light during the fall and winter
-No fossil fuel emmissions, cheap if part of the original building design because no special technology is needed to capture the solar energy
-Weather can make the design unreliable, as can architectural human error, and it is expensive to put in place if being added retroactively to a house that has already been built.
-Effectiveness varies seasonally
Active Solar water heating
-Sunlight hits a heat collector placed on the outside of the building, transfers heat to the water in the pipes
-saves money on electricity, reduces emissions by 50%, adds value to property
-costs a lot to install, decreases visual quality, efficiency depends on your location
-PV panels absorb photons from the sun, photons "knock loose" electrons from silicon layers inside panels, electrons move to conductor strip from silicon layers, propelled out of cells to form an electric current. Converts solar heat directly into electricity.
-no pollutants, can power entire systems when sunny, 100% renewable, can last up to 20 years and is becoming cheaper
-Needs direct sunlight, panels made of cadmium and arsenic which can cause major pollution problems if handled incorrectly, only 15-20% efficiency
-3rd most common alternative source of power in the US
Solar Thermal electric generation
-Uses solar collectors (curved mirrors) to heat synthetic oil (water, air, liquid metals or molten salts) that flows through heat exchangers containing water; makes steam that turns turbines. Oil is recycled. Steam needs to be superheated by natural gas
-expensive, takes up space and is unattractive
Where in the US is solar energy potential the greatest?
Southwestern states where sunlight is strongest and most constant.
-Gaseous hydrogen goes through a catalyst that splits the electrons from the atoms and creates two parts; the positively charged atom ions and the negatively charged electrons. The electrons are directed through an electric current to preform work.
-Hydrogen is the most abundant element, only by product is water, very powerful and efficient
-Hydrogen does not occur naturally in a gas form and therefore requires some fossil fuels to extract and vaporize, highly expensive, extremely dangerous due to explosive propeties of hydrogen
-Anyone can harness the power of hydrogen, as it is the most abundant element in the Earth's atmosphere.
-Water from a reservoir created by a dam flows down a slope into the powerplant where the fast moving water turns a turbine and spins a pole connected to a generator which then generates electricity.
-12% of US electricity is generated by hydroelectric power plants
-no burning emmissions, dams have other uses, efficient
-expensive to build and maintain, dams can cause loss of flood control and destruction of wildlife habitat
-Dam is built across the entrance to a bay or estuary to create a reservoir. Tide rises, water is intially prevented from entering the bay landward of the dam. When the water pressure is sufficient to run the turbines, the dam is opened and the flood of water into the bay turns the turbines. When the tide lowers, there is more water in the reservoir than at ocean level and the gate is opened. The flood of water back into the sea also turns the turbines, which are reversible.
-takes advantage of the natural force of the ocean but can have damaging effects on marine ecosystems
-uses wind to turn and power a turbine
-highly unreliable in consistency or intensity and highly dependent on location
-Ideal locations in the US for wind power: Northeastern USA, Northern Texas, Rocky Mountain states and Dakotas
-has no emmissions but kills birds and degrades asthetic quality of landscape, isn't enough energy alone to replace any energy system but can help reduce use of coal.
-Fat/oil is purified and reacted with alcohols in the presence of a catalyst, usuall methanol, then purified for human use
-Non-toxic, renewable, replenished through recyling and farming, can be used in its pure form
-Massive amount of water use, increases the cost of food crops, could potentially operate differently or not operate at all in convential vehicles built for fossil fuels
-Reasonably abundant in the US and North Carolina especially due to large agricultural plots of land that produce reject food crops unfit for human consumption
What is the difference between ethanol and biodisel?
Ethanol is an alcohol-based fuel made by fermenting and distilling starch crops, such as corn. It can also be made from "cellulosic biomass" such as trees and grasses. Biodisel is a fat or oil refined by a reaction with alocohol (to remove glycerin), often made from spent frying oils or soybean oil.
-natural heat from the interior of the Earth that is converted to heat buildings and generate electricity
-average heat flow from Earth's interior is very low--about 0.06 W/m^2, but in some areas flow is sufficiently high enough to tap into
-areas where mountains are being uplifted/volcanic activity
-only releases 12% of the carbon dioxide/sulfur dioxide of coal and fossil fuels
-dangerous potential for "using up" hot springs, on-site noise, emissions of gas, diturbance of land at drilling sites
What is the difference between geothermal electric and ground-source heat pumps?
geothermal is radioactive decay
Ground-source-low energy, temperature is fairly consistent, water in pipes makes contact with warm ground and heats water.
What is biomass?
Biomass is plant material from trees, grasses or crops that can be converted into heat energy to produce electricity.
Three different types of steam that turns turbines:
-Flash (high pressure causes immediate vaporization)
-small maitenence cost, used directly, occupy small area
-number of sites limited, small total generation, high instalation cost, economically risky
US electricity generation from coal
US electricity generation from natural gas
US electricity from nuclear power
US electricity from petroleum
US electricity from alternative sources
Alternative electricity from Hydropower in US
Alternative electricity from wind in US
Alternative electricity from biomass wood in US
Alternative electricity from biomass waste in US
Alternative electricity from geothermal in US
Alternative electricity from solar in US
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