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EPS219 – Energy and the Environment
Homework#4 – Due in class, Thursday, February 12, 2015
1) (10 pts) Explain how energy use changes over the course of a day. If the bulk
of the energy is coming from a base load such as coal or nuclear, explain why is it
not energy efficient to set the base load level at either the highest or lowest
energy demand levels.
The demand for energy fluctuates over the course of a day. If you set your base
load (usually a less-expensive source of power) at the highest level, then you
throw away energy at the low-demand times. If you set the base level at the
lowest-demand time, then you have to pay a lot to use another source to supply
the peak-time energy. Best to set it somewhere in the middle, and store energy
during off-peak times.
2) (10 pts) Explain how the appeal of coal and natural gas differs depending
upon how energy density is defined.
Coal has a high energy density in joules/volume, but only a moderate energy
density in joules/mass. Natural gas has a very low energy density in
joules/volume, but a very high energy density in joules/kg.
3) (10 pts) Ch8, #12: What are the effects of the Clean Air Act on the use of coal
for electric generating plants? Check the web.
(Accept many different answers, as long as they address the fact that the CAA
puts regulations on the pollutants that coal power plants release)
4) (10 pts) Explain the geologic process that can allow layers of coal to occur
over very broad areas of continents.
As sea levels rise and fall, coastlines move back and forth over continents, both
depositing organic materials from coastal swamps and burying them.
5) (10 pts) Ch8, #16: Why do you expect photochemical smog to be a greater
problem in a city like Los Angeles than in a heavy industrialized city like
Pittsburgh? What air pollution problems are prevalent to the latter?
Smog is due primarily to NOx and VOC and sunlight. Pittsburgh has more
industrial emissions of particulates and SO2.
6) (10 pts) Ch8, #22: Why might you expect indoor air pollution to be more of a
factor for a person living in a house built in 1995 than for one built in 1895?
Houses are more tightly sealed and insulated to be more energy efficient.
However, this also means that indoor air pollution, radon gas, etc., cannot escape
as easily.
7) (10 pts) One possible location for sequestering carbon dioxide is putting it
into the ocean. Explain why this is not a good idea.
Carbon dioxide in the ocean leads to acidification of the ocean. Increased ocean
acidification is already having very negative impacts on fish, corals, and other
ocean life forms.
8) (10 pts) Which common air pollutant is primarily released through the
combustion of coal? What is the effect on the environment of this pollutant?
Sulfur dioxide is a major pollutant from the combustion of coal. It is directly
related to acid rain and the increased acidification of land lakes and streams.
(Other answers are acceptable)
9) (10 pts) Explain why North America has so much coal. Why is anthracite so
rare?
The North American tectonic plate was at the equator for much of the past 500
million years, so it was frequently covered with swamps and rain forests that
became our coal deposits.
Anthracite forms from the deep metamorphism of coal deposits, and you only
get it where tectonic plates collide for form mountains.
10) (10 pts) What are the concerns with mountaintop removal of coal? Check on
the web.
(Many answers acceptable) Basically, the disruption to the environment and life
forms that live there is extreme and cannot be adequately restored.