Post 2 of 3

In the previous post, we looked at the trend for Ontario to use more natural gas to power electricity generation. In this post, we’ll look at some of the trends in the market, and the changing role of renewable energy in the province’s electrical grid.

Base versus peak load
There’s what utilities call “base load” – the power drawn to meet the ongoing necessities of life – your refrigerator, the always-on lights in many buildings, wastewater treatment plants, and many businesses that run 24 hours a day.

Then there’s “peak” load, which comes from the fact that power demand fluctuates throughout the day. There is a daily period of low power demand at around 4:00 AM, but then as people wake up and start their day, power demand quickly escalates. There is a bit of a lull in demand until 5:00 or 6:00 PM, when another peak in demand occurs. The need for extra power generation to meet peak load is largely what’s around talk of power blackouts in Ontario.

In Ontario, the base load is largely met with nuclear power and some hydro. Nukes are on all the time, and it takes time to increase or decrease their power generation levels. Hydro power can more easily be increased or decreased to meet peak load, but there are limits.

If nuclear plants are like an elephant – slow but inexorable – gas-fired power is more like a gazelle, fleet of foot and moved to action quickly. Ontario’s gas plants are largely built to meet peak load. They’re relatively expensive to run, so are cost-competitive largely when the price paid for power is highest, at peak times.

Dispatchable versus non-dispatchable power
It’s also necessary to understand another distinction – “dispatchable” versus “non-dispatchable” power. This has to do with whether the power source can be turned on and off (“dispatchable”) when needed. Gas-fired and some hydro power (and coal and oil, not part of the picture in Ontario) are all dispatchable.

Nuclear power and some run-of-river hydro (without a dam and reservoir) are considered non-dispatchable.

So are most sources of renewable, clean energy – wind and solar. The operator of a wind farm doesn’t know when there will be calm conditions and they will have no power to sell. And the utility doesn’t know whether wind-generated wind power will be available when they need it. Solar power is only slightly more predictable, but can be unavailable under cloudy skies or rain.

This non-dispatchable aspect is one of the chief barriers in the way of greater expansion of wind power. For some proponents, the solution is more turbines – “It’s always got to be windy somewhere!”. But even where there are more wind turbines – like Germany – there are times when the whole country has calm wind conditions, with most turbines standing motionless from the Baltic Sea to the Alps.

This means that as a way to meet peak power demands, most renewable energy is not currently a practical answer. There has to be a way to take the power they generate when the wind blows and the sun shines, and make it available at other times – particularly, at peak demand times.

In our next post, we’ll look at solutions to this puzzle, and what you can do to help.