CHAPTER
12
Review
SUGGESTED ANSWERS
1.
No. Energy cannot be created; it can only be transformed. Electrical energy is produced by transforming
another type of energy (solar, mechanical, nuclear, etc.) into electrical energy.
2.
Renewable energy sources can be generated over and over, and do not pollute as much as non-renewable
sources
3. (a)
Hydro-electric energy can be generated by taking advantage of the rivers.
(b)
Since an MP3 player is usually portable, its likely power source is an electric cell (either primary or
secondary).
(c)
A home could be connected to many different kinds of power plants—nuclear, hydro-electric, fossil
fuel burning, wind, biomass, geothermal, or tidal. Solar energy can also be generated at home.
(d)
A cottage may be more remote, and therefore power sources such as solar cells or hydro/wind may be
used, but it would likely be connected to the local power plant.
(e)
A fuel cell would be used for a spacecraft because it can provide continuous power as long as there is
enough fuel.
(f)
A car would use a secondary cell. A secondary (rechargeable) cell would be more efficient to use than a
primary cell.
(g)
A primary cell that has a very long shelf life would be best for a flashlight that it is not used often.
4.
MW are megawatts; 27 000 MW 5 27 000 000 000 watts and 24 000 MW 5 24 000 000 000.
GW ? h are gigawatt ? hours, a unit of electrical energy.
5.
Watts are the measure of electrical power. A 60 W bulb uses 60 joules of energy every second when it is
operating.
6.
Coal, oil, and natural gas are natural resources found in many places in the world. They are cheap, easy to
transport, and easy to use. That is why fossil fuel generating stations are so common.
7.
Sample answer: Wind turbines are relatively inexpensive to set up, and wind power produces no pollution,
compared to the high pollution levels of a coal plant. Coal plants are cheap to use once they are built, and
coal is a cheap substance. Compared to a coal plant a wind turbine is a much better choice. However, wind
turbines need back-up power sources because the wind does not always blow.
8.
Sample answer: A nuclear power plant might work, but would cost more than a town of 100 000 people
could support. Establishing wind turbines along the water (converting as much wind energy as possible)
would probably work best.
9.
Sample answer: Turn off electrical devices when leaving the room. Limit the use of electrical devices. Limit
the number of devices that require batteries.
10.
I would consider the price and cost of operating the device over time. The device on the left uses less
electricity, so over time it would be more economical.
11.
The motor has an efficiency of 69 %.
NEL
55219_03_ch12_p799-850_pp4.indd 845
Chapter 12 Electrical Energy Production
845
12/8/09 1:25:46 PM
12. (a)
(b)
The total cost of running the appliances for a year is $604.62.
Sample answer: The data are similar to my house, except my house has two computers and two TVs,
which are usually on for four to five hours every day.
13.
Sample answer: The company is probably already connected to a power plant for their electricity. An energy
officer might look at what it currently costs for electricity. Then the officer would look for ways to save
money by being more efficient with its use. And that might include looking for an alternate electricity
source. A sample calculation might show that the company needs 100 000 kW?h of power per day on
heating a furnace that uses 10 000 kW for 10 hours each day: 10 000 kW 3 10 h 5 10 000 kW?h.
14.
18 % of 150 000 000 kW?h 5 27 000 000 kW?h
CO2 from coal 5 25 650 000 kg
CO2 from natural gas 5 15 930 000 kg
Difference: 25 650 000 kg – 15 930 000 kg equals 10 000 000 kg less CO2 is produced from burning
natural gas instead of coal. Emitting 10 million fewer kilograms of carbon dioxide is worth making
the change.
15.
Sample answer: When electricity cannot be delivered to a community, it can be dire. In the short term, the
most important thing to do is get another tanker to the area with the needed oil. However, this is a clear
example of why we need to start depending less on oil. In northern Canada, there are few trees, which
means that wind generating farms would likely work well to provide energy to the areas in question.
16.
Sample answer: It is always best to conserve, or reduce, electrical energy use because even though
renewable resources can be replenished and are environmentally friendly, they are not without drawbacks
or problems. First, many renewable resources cannot be used on a large scale for big cities. Tidal generation
and hydro-electric plants need to be near water, limiting where they can be located and who can be served.
Wind power is also limited to places where wind is constant enough to provide a steady supply of electrical
energy and has been criticized because the turbines may be dangerous to migrating birds.
17.
Sample answer: An electrical energy source needs to be something you can count on. Maybe some kind of
solar or wind electrical energy system would work. Look for areas near the house where there is six to eight
hours of daily sunlight or areas of steady wind for a wind turbine. Ultimately, a fuel-powered generator
may still need to be used as the main source of electricity. There are energy efficient generators available.
Consider getting a fuel-powered generator that is as energy efficient as possible and uses biodiesel.
REFLECT ON YOUR LEARNING
18.
Sample answer: The houses in my neighborhood get electricity from a nuclear generating plant. I thought
that electrical energy using radioactive uranium was more efficient than burning fossil fuels, but it turns
out that is not the case. And even though nuclear power plants do not create air pollution, like burning
fossil fuels, both are non-renewable. To help use less non-renewable uranium I plan to turn off lights and
appliances when I am done using them. I will also encourage my family to buy energy-efficient appliances
and replace incandescent bulbs with more efficient CFL bulbs or LEDs.
WEB CONNECTIONS
19.
846
Sample answer: Many industrialized countries are looking for ways to reduce electrical energy consumption
and ultimately lower green house gas emissions. Ontario plans to ban the incandescent bulb by 2012.
That will mean that businesses will be banned from selling them to consumers. Homeowners will not be
penalized for using incandescent bulbs, but I think it will make people feel empowered to be able to do
something about energy use and ultimately climate change. Old incandescent bulbs will mostly be replaced
with compact fluorescent bulbs (CFLs), which use about 75 % less electricity. So the average home could
save 75 % of the energy used to light the home. However, lighting is not what most energy in a home is
used for (heating and cooling use much more energy), so it would not save 75 % of total home energy use,
only 75 % of lighting energy.
Unit E: The Characteristics of Electricity
55219_03_ch12_p799-850_pp4.indd 846
NEL
12/8/09 1:25:46 PM
20.
Sample answer: Sir Adam Beck advocated publicly owned utilities. He realized that Ontario had a huge
renewable resource with the falling water of Niagara. He created cheap unlimited power that made lights
come on all over Ontario with his 450 megawatt Queenston-Chippawa power plant. In 1950, the power
plant was renamed Sir Adam Beck 1. In 1954, a second power plant, named Sir Adam Beck 2, came
online.
21.
Sample answer: There is a small amount of mercury in CFL bulbs. Mercury is a neurotoxin. The mercury
inside each bulb poses no risk to anyone until it is time for recycling. Disposing of used CFL bulbs is tricky
because when they are tossed into a bin, they can break. At that point they are dangerous to be around.
Waste removal and landfill workers are at risk. It is especially dangerous to children and unborn children.
People need to realize that such items should be considered hazardous waste and disposed of properly.
NEL
55219_03_ch12_p799-850_pp4.indd 847
Chapter 12 Electrical Energy Production
847
12/8/09 1:25:46 PM