D. Physics: Principles and Applications of Electricity · Electricity: Charges, Circuits and Energy

Producing Electrical Energy: Sources, Benefits and Challenges

D1.1 D1.2 A2.3 A2.4 A1.1About 75 minutes

Learning goals

I can describe how electrical energy is produced from different sources, and the energy transformations involved.
I can describe Ontario's mix of electricity sources using real data.
I can assess the social, environmental and economic benefits and challenges of each source.
I can evaluate how producing and using electrical energy affects different communities, locally and globally, including First Nations communities.

Words to know

generator
A device that transforms kinetic energy into electrical energy by moving magnets and coils of wire relative to each other.

turbine
A wheel with blades that is spun by moving water, steam or wind, and turns a generator.

renewable energy source
A source that is naturally replaced within a human lifetime, such as flowing water, wind, sunlight or plant material.

non-renewable energy source
A source that cannot be replaced within a human lifetime once it is used, such as natural gas or uranium.

supply mix
The share of electrical energy that comes from each type of source.

greenhouse gas
A gas, such as carbon dioxide (CO₂), that traps thermal energy in the atmosphere and contributes to climate change.

intermittent
Not available all the time. Wind and solar output change with the weather and time of day.

grid
The network of generating stations, transmission lines and distribution lines that delivers electrical energy.

Remember from Grade 6

In Grade 6 you learned that hydroelectric dams, wind turbines, nuclear and natural gas stations, and solar panels produce electrical energy, and you looked at some of their impacts in Canada. In Grade 9 you will use real data, look at the science of each method, and assess the benefits and challenges in a balanced, evidence-based way.

Flip a switch: where does the energy come from?

When you switch on a light in Ontario, the energy was produced only a fraction of a second earlier, in a generating station that might be hundreds of kilometres away. Most stations work the same basic way: something spins a turbine, and the turbine spins a generator. In the generator, magnets and coils of wire move relative to each other, which pushes charges through the wire. The difference between stations is what spins the turbine.

How most generating stations work. Nuclear stations use heat to make steam that spins the turbine; natural gas stations use hot gases from burning the fuel (and often steam too); hydroelectric and wind stations use moving water or air directly. Solar panels are different: they have no turbine and turn light directly into electrical energy.

Ontario's supply mix

Ontario's electrical energy comes from a mix of sources. Ontario stopped producing electricity from coal in 2014, which greatly reduced the province's air pollution and greenhouse gas emissions from electricity.

Ontario's system-wide electricity supply mix in 2024 (Ontario Energy Board data; numbers are rounded). Nuclear and waterpower together supplied about 72% of the province's electrical energy.

Source	Energy transformation	Benefits	Challenges
Nuclear (uranium)	Nuclear → thermal → kinetic → electrical	No greenhouse gases while running; large, steady output; skilled jobs	Radioactive waste must be stored safely for a very long time; high building costs; uranium is non-renewable
Hydroelectric	Gravitational potential (water) → kinetic → electrical	Renewable; very low emissions while running; can adjust output quickly; stations last a long time	Dams flood land and change rivers and fish habitat; flooding has affected First Nations communities and their traditional lands; good sites are limited
Natural gas	Chemical → thermal → kinetic → electrical	Can start up quickly to meet peak demand and back up wind and solar	Burning gas releases CO₂ (a greenhouse gas); fuel prices change; non-renewable
Wind	Kinetic (wind) → kinetic (blades) → electrical	Renewable; no fuel cost; no emissions while running; income for landowners and communities	Intermittent; needs back-up or storage; land use; concerns about birds and bats; some residents object to noise and views
Solar (photovoltaic)	Radiant → electrical	Renewable; works on rooftops close to where energy is used; no moving parts	Produces only in daylight and less in winter; needs storage; panel manufacturing and recycling have impacts
Bioenergy	Chemical (plant material) → thermal → kinetic → electrical	Can use wood waste; available on demand	Burning releases CO₂ and other pollutants; needs a steady supply of fuel

Assessing sources of electrical energy: social, environmental and economic benefits and challenges.

Worked example

Example 1: Reading the data

Using the 2024 supply mix, what percentage of Ontario's electricity came from (a) renewable sources, (b) sources that emit greenhouse gases while running?

(a) Renewable = waterpower + wind + solar + bioenergy = 23.4 + 9.0 + 2.2 + 0.4 = 35.0%.
(b) Of the sources listed, natural gas (with oil and other) emits greenhouse gases while running: 16.6%. (Bioenergy also releases CO₂ when burned, adding 0.4%.)
Nuclear (48.5%) is not renewable, but it does not emit greenhouse gases while running.

(a) About 35% renewable. (b) About 17% from sources that emit greenhouse gases while running. Most of Ontario's electricity is low-emission, but not most of it is renewable: these are different questions.

Worked example

Example 2: A balanced assessment

A town is choosing between a natural gas station and a wind farm with battery storage. Give one social, one environmental and one economic point for each.

Natural gas. Social: reliable on cold winter evenings when demand is high. Environmental: releases CO₂ every hour it runs. Economic: cheaper to build, but fuel must be bought for its whole life and prices change.
Wind + storage. Social: some residents may object to the turbines; local landowners or First Nations partners can earn income. Environmental: no emissions while running, but land use and wildlife need study. Economic: higher up-front cost, but no fuel cost.
Weigh the points: which matter most for this community?

A strong assessment gives evidence for both sides in all three areas, then makes a decision and explains which factors were most important and why.

Different communities, different impacts

The same choice can affect communities in very different ways.

Remote First Nations in northern Ontario. Many remote communities without road access have depended on diesel generators. The diesel fuel is expensive to fly in or bring over winter roads, spills can harm land and water, and the generators limit how much power a community can use, which has slowed building of new homes and services. The Wataynikaneyap Power project, in which 24 First Nations together own a 51% controlling share, built a transmission line of roughly 1800 km to connect remote First Nations to the provincial grid; the first community, Pikangikum First Nation, was connected in 2018.
Communities near large dams. Hydroelectric development in the past flooded land that First Nations used for hunting, fishing, travel and gathering, often without their agreement. Today, many First Nations in Ontario are owners and partners in hydroelectric, wind and solar projects.
Cities. Lower-emission electricity means cleaner air. Electrical demand is growing as people switch to electric vehicles and heat pumps.
Globally. Hundreds of millions of people around the world still do not have reliable access to electricity, which affects schooling, health care and jobs. Burning fossil fuels for electricity anywhere adds greenhouse gases that affect the climate everywhere, including the Arctic, where Inuit communities are seeing big changes to sea ice.

How to assess an issue

Gather evidence from reliable sources (government data, scientific organizations, affected communities themselves).
Sort the impacts into social, environmental and economic, and into benefits and challenges.
Consider whose perspective each point comes from, and who is missing.
Make a decision and justify it with your strongest evidence.

Hands-on activity

Research: where is your electricity coming from right now?

You need: a device with internet access.

Visit the website of Ontario's Independent Electricity System Operator (IESO) and find its power data showing how much electricity each type of source is producing right now.
Record the output from nuclear, hydro, gas, wind, solar and bioenergy at one time of day. Calculate each one's percentage of the total.
If you can, check again at a different time (for example, a calm evening versus a windy or sunny afternoon) and compare.
Choose one source. Build a table of at least two social, two environmental and two economic benefits and challenges. Note the source of each fact.
Write a short paragraph: should Ontario produce more or less from this source? Justify your answer.

What to look for: nuclear is usually the steadiest; wind and solar change with the weather and time of day; gas output often rises in the evening when people get home. Strong answers give evidence for both sides before deciding.

Safety (grown-up note): Help your teen judge whether websites are reliable (government, utility, university and community sources) and avoid entering personal information.

Just for fun

Why does everyone like wind turbines?

Because they are such big fans of clean energy.

Your turn

What do nuclear, natural gas, hydroelectric and wind stations have in common?

Give the energy transformations in a hydroelectric station.

Which source supplied the largest share of Ontario's electricity in 2024, and about what percentage?

Give one benefit and one challenge of nuclear power.

Why are natural gas stations useful even though they emit CO₂?

Why have many remote First Nations communities depended on diesel generators, and what are the drawbacks?

More practice: warm-up

Name three renewable sources of electrical energy.

Which device in a station transforms kinetic energy into electrical energy?

In what year did Ontario stop producing electricity from coal?

What does intermittent mean?

Name one non-renewable energy source used in Ontario.

More practice: on your own

Explain the difference between "renewable" and "low-emission", using nuclear power as the example.

Why does adding more wind and solar to a grid often increase the need for energy storage or flexible stations?

Give one social, one environmental and one economic impact of connecting a remote First Nation to the grid instead of using diesel.

Wind supplied 9.0% of Ontario's electricity in 2024 and solar 2.2%. How many times larger was wind's share?

A classmate says, "Hydroelectric power has no negative impacts because it is renewable." Respond with evidence.

Challenge

Ontario's electricity demand is expected to grow as more people use electric vehicles and heat pumps. Propose a mix of new sources to meet the extra demand, and justify it with at least one social, one environmental and one economic reason.

On a calm, cloudy winter evening, Ontario's demand is high. Using what you know about each source, explain which sources are likely to be supplying most of the electricity, and why.

Burning natural gas for electricity in Ontario affects people far away. Explain this global connection, including an example from northern Canada.

Check your understanding

Quiz

In most generating stations, the generator is turned by:

Which source supplied the largest share of Ontario's electricity in 2024?

Which is an environmental challenge of hydroelectric dams?

Why are wind and solar called intermittent?

Which source is non-renewable but does not emit greenhouse gases while running?

What was a main goal of the Wataynikaneyap Power transmission project?

For parents and teachers

Big idea: Expectation D1.1 asks students to assess the social, environmental and economic benefits and challenges of producing electrical energy from various sources, and D1.2 asks how production and use impact various communities locally or globally. A strong answer always considers more than one perspective and supports a decision with evidence.

About the data: The supply mix percentages are Ontario's 2024 system-wide figures published by the Ontario Energy Board. The live mix changes hour by hour; the IESO website shows current output by source.

Common difficulties:

Renewable vs low-emission. Nuclear is low-emission but not renewable.
One-sided answers. Every source has benefits and challenges.
Indigenous perspectives. Present First Nations, Métis and Inuit communities as current decision-makers and partners, not only as people affected in the past.

How to help: Look at the IESO live data together at two different times of day and talk about why the mix changes.