ENERGY BASICS APES
Terms in this set (46)
-ability to do work or make something move
Various forms of energy (and some examples of each) (7)
-Potential energy is stored energy, usually high quality.
-chemical - coal, oil, natural gas, food
-nuclear - stored in atomic bonds
-gravitational - water behind a dam, object at top of hill
-Solar energy is light from sun (EMR), energy source for Earth's biota
-Kinetic energy - due to objects motion
-Heat refers to the random motion of molecules (heat ≠ temperature)
1st Law of Thermodynamics
-Energy cannot be created nor destroyed (it can be converted from one form to another) ** conservation of energy
2nd Law of Thermodynamics
-When energy is changed from one form to another, some energy is converted to hear
-entropy increases (disorder, randomness, ≠ energy)
-Energy cannot be recycled or go from low to high quality.
-disorder, randomness, ≠ energy
-availability of energy to do work
-High quality: organized, easy to convert to work
-Low quality: disorganized
-is exerting a force over a distance (Work = force X distance)
-Sequence when work is done: Potential energy --> kinetic energy --> heat; entropy increases, energy quality decreases.
Unit for work
What happens to energy quality and entropy when work is done?
-The ratio of output obtained from given input, expressed as %
-energy efficiency involves designing equipment to yield more energy output from a given amount of input energy (first-law efficiency) or better matches between energy source and end use (second-law efficiency).
1st law effciency
-1st law efficiency = work done/energy used
2nd law efficiency
-2nd law efficiency = minimum energy needed/actual energy used
-How well matched the energy end use is with the quality of the energy source; how much you used vs. the minimal amount needed to do the work.
-If it's low it indicates where improvements in energy technology and planning may save significant amounts of high quality energy.
What is the approximate efficiency of: an average coal fired power plant? (how much actually becomes light? What happens to the rest?)
-Most of the energy not being light is waste heat.
What is the approximate efficiency of: An incandescent light bulb? (how much actually becomes light? What happens to the rest?)
-Most of the energy not being light is waste heat.
What is the approximate efficiency of: A fluorescent light bulb? (how much actually becomes light? What happens to the rest?)
-Most of the energy not being light is waste heat.
What does it mean if the 2nd law efficiency is low?
-Low 2nd law efficiency means that energy is wasted
Describe the relationship between standard of living and energy consumption. The US has 5% of the world's population and accounts for what % of world energy consumption?
-There is a direct relationship between a country's standard of living (as measured by gross national product) and energy consumption per capita.
-People living in industrialized countries make up a relatively small percentage of the world's population, but they consume a disproportionate share of the total energy produced in the world.
-25% of world energy consumption.
What % of US energy comes from fossil fuels?
-91% of US energy comes from fossil fuels
-are produced from plant and animal materials and are forms of stored solar energy in our geological resource base
What are the 3 main fossil fuels?
-coal, oil, and natural gases
What are alternative energy sources?
-are sources to replace fossil fuels (geothermal, nuclear, hydropower, and solar)
What are renewable energy sources?
-are sources that cannot be depleted (wind and solar)
The overall 1st law efficiency for the US is 50%. If we used 100 exajoules of energy in 2004, how many exajoules were actually used to do useful work. What happened to the rest of the energy?
-Only 50 exajoules of energy were used to do useful work, the rest of the energy (50 exajoules) is lost as heat.
Know the units used to measure energy and how they are used: Joule
-metric unit, defined by amount of work it can perform.
-1 Joule = 1 N⋅m (the force of 1 Newton applied over 1 meter).
-KJ = kilojoules = 1000 joules
-MJ = megajoule = 1,000,000 joules
-GJ = gigajoule = 1,000,000,000 joules
Know the units used to measure energy and how they are used: Calorie/ kilocalorie
-Calorie = amount of energy needed to raise 1 g (ml) of H2O 1° C.
-1 calorie = 4.18 joules; 1 joule = 0.239 calories
-1 kilocalorie (Kcal) = 1000 calories (this is the food Calorie!)
Know the units used to measure energy and how they are used: BTU
-British Thermal Unit (BTU) = 252 calories = 1055 joules
Know the units used to measure energy and how they are used: Quad/ exajoule
-Quad = 1 quadrillion (1015) BTU's = approximately 1 exajoule
-exajoule = 1018 joules or a billion gigajoules = approx 1 quad
Know the units used to measure energy and how they are used: Kwh (how is this unit derived? How many joules are in 1 Kwh?)
-kilowatt-hour (kwh) = 3,600,000 joules
What is power and how is it different from energy?
-Power is the rate of doing work or using energy (must be per unit time) while energy is the ability to do work.
What are the units used to measure power?
-watt = 1 joule/second = 1 N⋅m/ sec
1 kilowatt = 1000 watts
1 megawatt = 1 million watts
1 gigawatt = 1 billion watts
-horsepower = 747 watts
-Use less. What do you really need?
-Conservation of energy refers to getting by with less demand for energy.
-using waste heat to do work
-cogeneration includes a number of processes designed to capture and use waste heat rather release it as a thermal pollutant.
-Negawatts are theoretical units of power representing an amount of energy saved.
The 3 areas that have the greatest potential for energy savings are building design, industrial energy use, and automobile design. Briefly describe how each can be made more efficient.
-Building design can save energy by taking advantage of passive solar potential (passive solar energy systems collect solar heat without using moving parts), insulation, caulking, weather-stripping, installation of window coverings and storm windows, and regular maintenance are all ways to be more energy efficient.
-For industrial energy use efficient machinery, cogeneration and solar energy.
-Automobile design can be more energy efficient by fuel conservation, cars that are smaller with lighter engines, and the combination of a fuel-burning engine with an electric motor.
What is meant by hard path energy policy?
-Hard path emphasizes quantity over quality ( hard = hardware)
-more power plants built to satisfy peak demand, find more oil
-Hard path energy policy involves finding greater amounts of fossil fuels and building larger power plants and emphasizes quantity over quality.
What is meant by soft path energy policy?
-Soft Path: changing behavior, increase conservation and efficiency
-Conservation: Use less. What do you really need?
-Efficiency: getting more from energy you do use (improve technology, fuel efficiency)
-Integrated energy management: use a diversity of fuels, renewable fuels
-Soft path energy policy involves changing your behavior to a conservation and efficiency mindset.
integrated energy management
-use a diversity of fuels, renewable fuels
sustainable energy development
-Sustainable energy development provides reliable sources of energy, does not cause destruction to global environments, and ensures future generations will inherit a good environment with good resources.
-Micropower is electrical power that is generated or utilized in relatively small quantities
Is there enough energy to go around? What are the major factors that go into this calculation?
-standard of living
-average per capita energy use rate
Look back at the case study at the beginning of the chapter. What are the major criticisms environmentalists have cited with the Energy Policy Act of 2005? How would you describe this type of energy policy?
-Major criticisms: favoring large centralized energy production from fossil fuels and nuclear sources with not enough emphasis on alternative energy sources
-Describe type of energy policy: favoring production from fossil fuels and nuclear sources instead of alternative energy (hydrogen, wind and solar), emphasizes that we have made improvements improvements in energy conservation and are continuing development of alternative energy sources
How electricity generated is transmitted from the power plant to your house - see web assignment.
-The distribution electricity is reduced to the end use voltage (120/240 volts single phase) via a pole mounted or pad-mounted transformer. Power is delivered to the residential customer through a service drop line which leads from the distribution pole transformer to the customer's structure, for overhead lines, or underground.
The structure of a power plant (just the working parts) Electromagnetic induction
-is the production of an electromotive force across a conductor when it is exposed to a varying magnetic field
The structure of a power plant (just the working parts) Grid: advantages and disadvantages of the grid system
Convenient local positioning avoids transmission and distribution losses
Generation adjacent to loads allows convenient use of heat energy (combined heat and power [CHP])
Convenient local positioning enables available sources of energy to be used, for example waste products or renewable resources may be easily utilized to supplement fossil fuels
Convenient local positioning allows the use of available single or three phase generation
Conventional distribution systems need adequate protection in order to accommodate exchange of power
Signaling for dispatch of resources becomes extremely complicated
Connection and revenue contracts are difficult to establish
********The structure of a power plant (just the working parts) susceptibility of the grid
The structure of a power plant (just the working parts) Peak load
-The maximum load, or usage, of electrical power occurring in a given period of time, typically a day.
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