Nearly every Australian has felt the heat lately. It seems like a no-brainer to turn our air-conditioning on to beat the heat, but it’s now looking like it won’t be that simple. South Australia, Victoria and New South Wales have in previous years experienced power shortages, leaving more than 200,000 homes without power as energy demand exceeded supply. It seems like a nightmare, but it does beg the following questions: how will our electricity grid cope with the pressures of increasingly extreme weather? How do we moderate our energy consumption if there’s a chance power supplies can’t cope with our needs?
How can our electricity grid handle a heatwave?
Demand is changing
Power is divided into demand-based categories – base and peak. “Base,” or average, is relatively constant and similar to day-to-day usage. Peak demand is the maximum demand, and may only happen for a few hours on a few days of the year (like mid-afternoon on the 35+ degree days when air-conditioners are in full force).
Electricity demand in Australia is getting ‘peakier’. On average, we use less electricity per day as people and businesses become more efficient. However, more electricity is being used on particularly hot days, such as what we’ve seen in the past few weeks.
In some cities, the peak demand can be double the average demand. This is a real challenge – to avoid blackouts, electricity generating and carrying capacity is required to supply peak demand. That capacity, however, is only used a few days of the year.
Managing base and peak demand
In order to keep our lights on and manage peak demand periods, there are small actions you can take to reduce your power consumption, such as keeping your air-conditioning temperature at 24-25°C, closing the blinds and turning appliances off at the switch.
However, there also needs to be a change from our electricity generators, classified as ‘baseload’ or ‘peakers,’ to cope with our growing population.
Traditional, baseload generators have been the steady, on-all-the-time electricity generators that supply constant electricity. In Australia ‘baseload’ generators have usually been large coal-fired power stations.
Generally, baseload generators are fairly slow in changing the amount of electricity they generate. To match sudden changes in electricity from peak demand, we use ‘peaking’ generators which are more flexible and dynamic in producing electricity. They quickly ramp up or down to match changes in demand and are usually based on hydro or gas generators. However, the electricity that peaking plants (especially gas) produce is more expensive than baseload coal plants. A suggested solution is for cheaper coal-powered plants to supply baseload, and more expensive gas plants (or hydro) to supply the variable peak component of our demand.
A role for renewables
To ensure reliability, we need an electricity supply to closely match demand. Electricity systems around the world are showing this can be achieved without ‘baseload’.
These systems have:
- Flexible generation that can quickly vary its output, like wind and solar.
- ‘Demand management’ techniques that can vary electricity demand to match supply. For example, electricity loads such as hot water or pool pumps can be turned on/off, matching the available supply, and the consumer would never notice any change.
- Energy storage (for example, batteries or pumped hydro) to fill in any short-term gaps between supply and demand.
These concepts, matched with sophisticated load and generation forecasting schemes and careful control, mean that electricity systems can operate reliably with a large amount of renewable energy without needing baseload generation.
More about reliability
Australia needs to be certain of exactly what percentage of renewable energy our power system can cope with while staying reliable. Is it 40 per cent? 60 per cent? 100 per cent?
We don’t yet know how far this can be pushed, or more accurately, what the trade-offs are between cost, reliability and variable renewable energy penetration. It is likely supply could be reliable with 100 per cent renewable energy in the grid, but this might be much more expensive than (for example) only 90 per cent renewable energy.
Our ongoing energy research is focused on solving these challenges, and ensuring a secure, affordable and sustainable energy future for Australia.
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