chapter 16 test 4
The year 2030 goal set by the US Department of Energy is to generate __________.
20% of electricity using wind-powered systems Wind power will be only part of the solution to sustainable energy. Solar and other energy sources will still be required.
Which of the following is true regarding renewable electricity production in the United States?
As of 2013, wind power had more electricity-generating capacity than solar photovoltaic power. As of 2013, wind power had a generating capacity of about 61.1 gigawatts, whereas solar PV power had a capacity of only about 12.1 gigawatts.
Where is wind power being harvested, and what is the future potential for wind farms?
At wind farms. Wind power is an affordable, efficient and abundant source of domestic electricity. It's pollution-free and cost-competitive with energy from new coal- and gas-fired power plants in many regions.
In the solar panel system presented in the video, which of the following was necessary to generate usable electrical current for a home?
DC power had to be converted to AC The solar panel generates DC current, which is not usually used in homes. Thus, the DC current must be converted to AC, which is the standard in homes.
What is the potential for developing more hydroelectric power in North America versus developing countries, and what would be the environmental impacts of such development?
Ecological disruption (i.e. downstream: sediments at dam, fish migration halted; in reservoirs: flooding, sediment retention, pollution)Disruption of people, loss of cultural resources, risk of failure, high rates of evaporative losses.
Describe current policy for renewable energy and energy efficiency as an outcome of recent government programs.
Energy Policy Act of 2005, Energy Independence and Security Act of 2007, and the American Recovery and Reinvestment Act of 2009.
In order to make a rapid transition to renewable energies, countries such as the United States will have to
reduce subsidies to the fossil fuel industry.
if a home uses a large supply of solar panels to generate electricity, but has no battery system, surplus electricity that is produced is usually __________.
released into the power grid for others to use, generating a credit to the homeowner This surplus energy therefore generates value to the homeowner whenever more electricity is produced than is needed. This helps to further offset the cost of the solar panel system.
The ultimate source of energy that drives wind power is __________.
the sun Sunlight heats the Earth's surfaces unevenly. Wind is the movement of air between these different regions.
Which of the following best describes the energy conversion sequence in the solar panel system described in the video?
Photons carrying energy from the sun chemically react with silicon crystals to generate a flow of electrons. The energy of the sun has to be converted into electricity.
Why is it important for renewable energy sources to replace fossil fuels? What are the prospects for getting it done?
The salient reason is global climate change. Clearly the manufacture of wind turbines, PV panels, transmission lines, concentrated solar power plants, electric vehicles, recharging stations, and so on would have to take place in a relatively short period of time and this would require massive government support. Another barrier to accomplishing this transition is the way in which government subsidies.
Advantages and disadvantages of renewable energy sources
advantages no fossil fuel required for production-hydroelectric, solar, wind generation process is pollution free- solar and wind production can be increased on demand-hydroelectric infinitely renewable-solar and wind disadvantages- geographically limited and harmful to nearby wildlife- hydroelectric, solar, wind
How do fuel cells work, and what is being done to adapt them to power vehicles?
Fuel cells are devices in which hydrogen or some other fuel is chemically combined with oxygen in a manner that produces an electrical potential rather than initiating burning. Fuel cells are now powering 150 buses in many cities. "Concept" cars operating on fuel cells have been developed by all the major car manufacturers.
Electricity in a wind turbine is generated __________.
when spinning magnets move past a coil of copper wire This is the typical way that electricity is generated in many power systems.
What biofuels are used for transportation, and what is the potential for increasing biofuels in the United States?
Currently, 2 fuels are seeing rapid expansion rapidly: Ethyl alcohol and biodiesel.To stimulate the industry in the U.S., federal tax credits have been extended to biofuels, which make them even more competitive. Biodiesel sales have reached 800 million gallons of fuel, which is very competitive with petroleum diesel fuel because of a hefty $1-per-gallon production tax credit.
Solar collecting panels would be most effective if they were positioned
nearest to the equator.
How do active and passive solar hot-water heaters work?
In an active system, the heated water is moved by means of a pump. In a passive solar water-heating system, the system must be mounted so that the collector is lower than the tank. Thus, heated water from the collector rises by natural convection into the tank, while cooler water from the tank descends into the collector.
Producing electricity using wind instead of fossil fuels __________.
generates no carbon dioxide in the process The use of fossil fuels generates tremendous amounts of atmospheric carbon dioxide, which contributes to global warming.
A typical wind farm in the United States consists of __________.
many very large wind turbines clustered in a region with a low human population Very large wind turbines are more efficient systems
Which of the following is a challenge to using solar-generated electricity in places not connected to a power grid?
the lack of efficient and inexpensive battery technology Current research in battery technology hopes to address this important need, which may also benefit the electric car industry.
What are some ways of converting biomass to useful energy, and what is the potential environmental impact of each?
Burning firewood, burning wastes, and producing methane. Recall that 2 patterns of use determine how forest resources will be exploited: Consumptive use and productive use.
How can hydrogen gas be produced via the use of solar energy? How might hydrogen be collected and stored to meet the need for fuel for transportation in the future?
The electrical power produced by these methods would then be used to produce hydrogen gas by electrolysis. The plan would start by building arrays of solar-trough or photovoltaic generating facilities in the deserts of the southwestern U.S.
Which of the following would indicate that a home is using solar power to generate electricity and is NOT using batteries?
There are solar panels on the roof and power lines going to the home. When the solar panel system is not generating enough electricity, or any at all at night, the home can draw upon the power grid. Therefore, the home does not require or use batteries for backup.
How can a building best be designed to become a passive solar collector for heat?
Typically, passive solar heating involves: The collection of solar energy through properly-oriented, south-facing windows. The storage of this energy in "thermal mass," comprised of building materials with high heat capacity such as concrete slabs, brick walls, or tile floors.
About how much of the sun's radiation would strike the Earth if the Earth did not have its atmosphere?
About twice as much
How does a PV system work, and what are some present applications of such cells?
Each cell consists of two very thin layers of semiconductor material separated by a junction layer. The lower layer has atoms with single electrons in their outer orbital that are easily lost. The upper layer has atoms lacking electrons in their outer orbital; these atoms readily gain electrons. The kinetic energy of light photons striking the two layer "sandwich" dislodges electrons form the lower layer, creating a current that can flow through a motor or some other electrical device and back to the upper side. Thus, with no moving parts, solar cells convert light energy directly to electrical power, with an efficiency of 15-20%. PV cells a already in common use in pocket calculators, watches, and numerous toys. Panels of PV cells provide power for rural homes, irrigation pumps, traffic signals, radio transmitters, lighthouses, offshore oil-drilling platforms, Earth-orbiting satellites, and other installations that are distant from power lines.
How much solar energy is available, and what happens when it is used? What are some problems with harnessing solar energy?
Full sunlight can deliver about 700 watts per square meters to Earth's surface when the Sun is directly overhead. At that rate, the Sun can deliver 700 MW of to an area of 390 square miles. The Sun delivers 10,000 times the energy used by humans. If humans were to capture and obtain useful work from solar energy, it would still be converted into heat and lost in accordance with the Second Law of Thermodynamics. The overall energy balance would not change. The main problem with using solar energy is one of taking a diffuse and intermittent source and concentrating it into an amount and form, such as fuel and energy, that can used to provide heat and run vehicles, appliances, and other machinery. Also overcoming such obstacles must be cost effective.
What is geothermal energy, and what are two ways is it being harnessed?
There are springs that yield hot, almost boiling, water. Natural steam vents and other thermal features are also found in the area. They occur where the hot, molten rock of Earth's interior is close enough to the surface to heat ground water, particularly in volcanic regions. Using such naturally heated water or steam to heat buildings or drive turbogenerators is the basis of geothermal energy. Enhanced geothermal systems and Geothermal heat pump.
Describe two concentrated solar power systems, how they work, and their potential for providing power.
Wind power is the age-old concept that has proved most practical with wind-driven propeller blades. The propeller shaft is geared directly to a generator. Wind farms are now producing pollution-free, sustainable power for around 5 cents per kilowatt-hour that is competitive with the rates of traditional sources. Moreover, the amount of wind that can be tapped is immense. Burning firewood for heat is the oldest form of energy that humans have used throughout history. In addition to burning wood in a stove, major means of producing biomass energy include burning municipal waste, paper, and other organic waste, generating methane from the anaerobic digestion of manure and sewage sludge, running power plants on wastes from timber operations, and producing alcohol from fermenting grains and other starchy materials. Fuelwood is the primary source of energy for heating and cooking from some 2.6 billion people, amounting to about 9% of total energy use from all sources.