Unlike radio waves, electrical energy does not travel through the air.
Seven electricity essentials
Electricity is an extraordinarily safe, powerful and versatile energy. It can be generated from a number of sources, some of which—such as moving water, wind and sun—are clean and renewable.
However, as amazing as it is, electricity can’t work without certain key elements in place.
Electricity moves through conductive wires. Without a continuous connection between a power source and a device, the device cannot function.
Sometimes the power source is close at hand, like a rooftop solar panel that powers a device. But in most cases, the source is hundreds if not thousands of kilometers away from its users.
To enjoy the benefits of electricity, you need wires.
For example, it would take the combined efforts of approximately 108 million serious amateur cyclists to generate the electricity used on a cold winter morning in Québec.
A very good amateur cyclist on a stationary bike can generate 350 W (0.35 kW) of energy over the course of an hour. In winter, when demand reaches 38,000,000 kW, meeting it would take the combined pedal power of over 108 million such cyclists… who would have to be replaced after an hour, due to extreme fatigue!
Electricity can also be generated from sources other than cyclists on stationary bikes. 😉
- Some sources—coal, fuel oil, natural gas, etc.—are non-renewable and produce a high level of greenhouse gas emissions.
- Others like water, sun and wind are clean and renewable. These sources produce few emissions.
Here in Québec, the vast majority of our electricity is generated by harnessing the power of moving water, which is where the name “hydroelectricity” comes from.
Hydroelectricity has some incredible advantages. It produces the lowest level of greenhouse gases; the energy it generates is clean and renewable; and hydropower facilities have a very long lifespan.
However, building a hydroelectric generating station involves two essential requirements:
- A course of running water (river or stream)
- A powerful water flow and a significant drop in elevation
In a hydropower plant, energy is generated by water flowing down a slope. The greater the height between the slope’s top and bottom (the drop in elevation), and the greater the volume of water that descends the slope (the flow), the more energy we obtain.
In Québec, the sites that are favorable to a high level of hydroelectricity generation are mostly located far from major load centers. That’s why we had to build long power lines to connect the power plants to the cities.
Whenever a subway train accelerates, whenever a baseboard heater starts up, whenever the streets light up, the electricity must be there—instantly.
The power grid has to react in real time. Is demand increasing? Then we have to generate more right now. Is demand falling? Then we need to generate less. At every single minute of every day, supply must match demand. Maintaining this balance is a complex and demanding task.
This situation has another very important consequence: the power grid must be able to meet any surge in demand, no matter how short, that occurs during the year.
Here in Québec, peak events are most liable to occur during winter cold snaps, towards the end of the day when it is already dark outside and industrial activity is high. Later on, we’ll see how we can spread out or reduce peak events. Doing so is very important, since it means we don’t have to build new electrical facilities or expand our equipment just to ensure supply for a mere few hours a year.
The bigger the line, the more electricity it can carry. For example, the wire that feeds electricity to a table lamp will be much smaller than the one used to power a heater.
The same applies to transmission lines. Carrying large amounts of electricity over great distances takes large-gauge wires. The bigger a wire, the heavier it is. Supporting these heavy power lines takes very strong structures (known as towers).
As for voltage, it’s a bit like the water pressure in a hose. The higher the pressure, the more water the hose will carry over a given period.
The voltage in your average home is set at 120 or 240 V. Compare this to power lines, whose voltage ranges from 49,000 V to over 765,000 V.
>The higher the voltage, the more electricity the line can carry. For example, a 735,000-V line can carry as much electricity as fifteen 230,000-V lines.
However, the higher the voltage, the taller the towers that support the lines must be, since the wires in power lines are insulated only by the surrounding air.
That’s why transmission lines are located in open spaces known as rights-of-way. For reasons to do with safety and reliability, these rights-of-way must be maintained to prevent the vegetation from growing too close to the lines.
For reasons both technical and economic, overhead transmission lines are uninsulated—meaning their wires have no protective sheathing. This is true all over the world. Insulation would vastly increase the size and weight of the wires, which means the towers would have to be even bigger and taller. Not only that, but any deterioration to the sheathing would also cause safety issues.
In principle, one large line should be enough to power your city…. provided everything goes smoothly. However, the moment there’s a glitch, you’ve got a general blackout on your hands.
Ensuring reliable electricity service in a given area takes more than one line. That’s why you’ll often see multiple power lines forming system loops around cities.
Similarly, all across Québec, some lines are used to stabilize grid operations and distribute the energy between regions based on demand at any one time.
The substations along these line routes will reroute the electricity toward different lines as needed.
You’ve surely noticed these substations at some time or other. They sit in fenced-off spaces of varied dimensions and have lots of very odd-looking equipment.
Basically, the more interconnected substations and lines the power grid has, the more stable it is and the more flexible and reliable the service.
A substation is a little like the electrical panel in your home—just a whole lot bigger. Substations distribute electricity between multiple power lines. And, much like the circuit breakers on your home panel, they have devices that can instantly cut the power in the event of a problem. They’re also where the line voltage is raised or lowered, thanks to giant transformers.
There are many reasons:
The useful life of a power line or hydroelectric facility is quite long—in some cases, up to 100 years. However, if the equipment is to stay reliable and in service throughout its lifespan, then maintenance work is a must.
And then there are increasingly stringent reliability requirements, emerging technologies and rising demand, all of which may require a facility to be modernized.
Still, even with the most careful maintenance in the world, nothing lasts forever. You need to make the right decisions at the right time. It’s a bit like with a car: you have to maintain it, but there comes a time when it’s best to just trade it in, especially if you want avoid a breakdown.
With all the attendant risks. But it doesn’t pay to wait. The more you leave things till the last minute, the riskier it all becomes and, in general, the more you have to spend.
New equipment must also be planned based on emerging needs, wherever they may be.
The planning process must take into account multiple technical and economic factors in addition to meeting social acceptability criteria.
It must also consider the fight against climate change and the fact that using less fossil fuels will increase the demand for clean, renewable energy in the coming years.