Question 6: In the United States, which sector utilizes the most energy?
Correct Answer: A. Industry
Explanation: The industries in the United States account for around 36% of the energy used. When
compared to the other sectors, like transportation and electricity generation, its percentage is much
higher than those.
Question 7: The chart projects the smallest rise from 2007 to 2035 in the use of ______ to provide
energy worldwide.
Correct Answer: D. Nuclear Power
Explanation: When comparing all the energy sources on the graph, the slope of the nuclear energy graph
is much smaller than the others. This means that the projected use of nuclear energy would increase the
least from 2007 to 2035 with its slope following the same trend.
Question 14: Uranium-235 is considered ideal from nuclear reactors due to...
Correct Answer: B. Its fissionability
Explanation: Uranium-235's ability to be split apart easier makes it the best choice to be used in a
nuclear power plant because the splitting of it releases heat energy that generates the plants' electricity.
If it was difficult to split, it would be inefficient to use it in the plant.
Question 25: The use of petroleum as a fuel rose dramatically due to all the following except...
Correct Answer: B. Its abundance in the contiguous United States
Explanation: The United States has increased its use of petroleum as a fuel, but not because we have
found an abundance of within our own bounds. We have been importing petroleum from other
countries because of its price and efficiency.
Question 36: The environmental costs associated with CTL, liquified coal, include all of the following
except....
Correct Answer: C. Lower greenhouse emissions than regular coal, but more than petroleum
Explanation: CTL lower greenhouse emissions than regular coal would be an advantage, not an
environmental cost. Creating lower emissions into our atmosphere than our more used coal would make
it a better source to help the environment because less heat trapping gas would be put into the
atmosphere.
Question 34 FRQ correction: While much of the discussion about climate change focuses on the
use of oil, natural gas, and coal are also commonly used energy fuels
(a) Name 2 disadvantages of natural gas and of coal: A disadvantage of natural gas is that it
releases methane into the atmosphere which is 25 times more efficient as a greenhouse gas
than carbon dioxide. Natural gas is also not available everywhere because it must be
transported via specific pipelines. Disadvantages of coal are its high emissions of carbon dioxide
and the trace amounts of toxic metals (like sulfur and mercury).
(b) Explain how electricity is generated and describe how cogeneration can allow a power plant
to increase efficiency: Electricity is generated by the burning of coal in a boiler. The heat
generated from this combustion heats up water which then turns into steam. This steam moves
turbines which then turn into a generator. This generates usable electricity. Using cogeneration
methods can increase the efficiency of a plant because steam that is used for industrial
purposes of to heat buildings first turns a turbine. This can increase efficiency to as high as 90
percent.
(c) Electric heaters are 99% efficient in terms of the conversion of electricity to hot water, while
a natural gas water heater is about 60% efficient. However, electric water heaters are not
always more efficient overall. What other factors might be considered when looking at the total
system efficiency of each water heater? Other factors that might be considered when looking at
the total system efficiency of each water heater would be the how much energy was used to
extract the materials used in it, how much energy was taken to process those resources, and
how far did the materials needed to be transported. If the conversion of electricity to heat
happens inside of the tank of water, it would lose very little energy and be around 99 percent
efficient. A heater with a flame under the tank that runs on the combustion of coal would be
around 80 percent efficient. When a heater gets its electricity from a coal plant, it would have a
much lower efficiency.