Introduction
History of the Energy System
Human Energy Needs
Science Notes
Energy Transformation
Measuring Matter, Force, & Energy
Energy Accounting & Balance
Fundamental Forces of Nature
Energy and Chemical Stability
Chemical Formations
Chemistry of Fossil Fuels
Energy Use, Efficiency, and the Future
Energy Sources, Technologies, & Impacts
Exercises
Internet Links
Other Resources
Energy System PDF
Printer-Friendly Web Version
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Power Choices
Pick a common source of “power” and describe the various influences necessary before it came into widespread us. Use a concept map.

 

Alternate Energy Source
Pick a nontraditional source of energy that may be used for societal needs. Discuss the pros, cons, fundamental force, what is needed to capture the energy and transform into useful work, and what is needed to foster widespread use in our society.

 

Food Chain
Draw a pyramid to represent the food chain. Assume that a human’s only sustenance is fish. Trace through the food chain to determine how many plants are needed to sustain a human for 1 year.

 

US Energy Sources
Which energy sources do we (the USA) use most and where do they come from? State in percentages. Which are nonrenewable versus renewable? Note that the definition of renewable depends on the ability of the resource to be replaced within a relatively short time period in our societal frame of reference.

 

Transformation of Energy
Trace the transformations of energy from kinetic to potential (and indicate the fundamental force) for a pot of water boiling on an electric stove that is powered by a coal-fired power plant.

 

Power Plant
A 600-MWe power plant has an efficiency of 36% with 15% of the waste heat being released to the atmosphere as stack heat and the other 85% taken away in the cooling water (see figure below). Instead of drawing water from a river, heating it, and returning it to the river, this plant uses an evaporative cooling tower wherein heat is released to the atmosphere as cooling water is vaporized. At what rate must 15°C makeup water be provided from the river to offset the water lost in the cooling tower?

 

Electric water heater
(mass and energy transfer)
An electric water heater heat at 140°F is kept in a 70°F room. When purchased, its insulation is equivalent to R5. An owner puts a 25-ft2 blanket on the water heater, raising its total R-value to 15. Assuming 100% conversion of electricity into heated water, how much energy (kWhr) will be saved each year? If electricity cost 8.0 cents/kWhr, how much money will be saved in energy each year?

 

Reducing Pollution by Adding Ceiling Insulation
A home with 2000ft2 of poorly insulated ceiling is located in an area with an 8-month heating season during which time the outdoor temperature averages 40°F while the inside temperature is kept at 70°F (this could be Chicago, for example). It has been proposed to the owner the $2000 be spent to add more insulation to the ceiling. raising its total R value from 11 to 30 (ft2-°F-hr/Btu). The house is heated with electricity that cost 8 cents/kWhr.

a. How much money would the owner expect to save each year and how long would it take for the energy savings to pay for the cost of insulation?

b. Suppose 1 million homes served by coal plants could achieve similar energy savings. Estimate the annual reduction in SO2, particulate, cooling water, bottom ash, and carbon emissions that would be
realized.


Assume: 1kWhr electricity results in: 450 g coal used (250g C, 45g fly ash (particulates), 9g S) 13.5g bottom ash 6120 kJ cooling water
  ©Copyright 2003 Carnegie Mellon University
This material is based upon work supported by the National Science Foundation under Grant Number 9653194. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.