The need to decrease emissions from the energy industry has motivated the use of hydro, solar and wind power in Australia, and the development of more efficient buildings that have less energy. And these solutions have indeed slightly reduced the planet’s per-capita energy emissions. But once renewables really do become dominant, the whole idea of “energy efficiency” will become obsolete.

Essentially, energy efficiency is related to the amount of energy used to produce an outcome that benefits people such as warmth, transportation or amusement. In practice, especially when applied to buildings and cities, this goal translates to “decreasing all energy intake anytime”.

Such approach makes sense in the case of energy that is generated from fossil fuels, in power plants which allows the power to be readily switched on and off according to the demand. There’s a simple and direct link: if you use less electricity, less gas or coal will be burnt, and not as much carbon will be emitted.

But renewable energy alters matters. The sun and wind are both free and almost infinite, and consequently every extra unit of energy generated is not just clean but also basically free. With little drawback to using more electricity when it is available, we will have to rethink energy efficiency.

Is less always more?

The crux of the issue is the requirement to balance supply and demand. In power systems, both must be evenly matched at all times or the machine will collapse, leaving everybody from private housings in rural areas to major buildings in the city such as the likes of the Melbourne stadium, without power. This is not a big issue as most power generation process is controllable which gives the providers time to react to fluctuations in the demand/supply balance, for example, if a large generator suddenly has an issue or when 26m people all turn on their electric kettle at the same time.

The picture is totally different when the electricity is renewable. At this time there could be larger and more regular last-minute changes in creation, perhaps resulting in fluctuations in the amount of wind or sunlight. And, as turbines and solar panels could have largely displaced standard power plants, there could be fewer controllable generators to balance supply and demand (panels and turbines can of course be emptied, but the wind and sun cannot be turned on). In fact, some power plants will operate solely for the sake of balancing the system.

In this circumstance, what happens if there is a surplus? It won’t necessarily be possible to reduce the output signal of controllable (mainly fossil-fuel) generators, either because they cannot react fast enough or because they will need to remain online to help balance the system in the not too distant future. It may be possible to keep some of the excess electricity in a battery to be used afterwards, but batteries are still very expensive. We’re a long way from having enough storage in order for this to become a realistic choice. With more electricity being generated than used, clean and inexpensive electricity can go to waste.

It is a matter of time

Timing is essential. If individuals are concentrated on minimising how much power they use at all times afterward they will ultimately lose out on the advantages of using fresh and clean cheap, renewable power for laundry, preheating homes, charging cars or alternative time-flexible services. They could even switch from gas to electrical heating occasionally when the electricity comes from renewable energy sources, a movement that would boost electricity consumption but reduce overall energy prices and emissions.

Consumption would ideally be reduced at times when that meant switching off fossil-fuel generators, instead of solar or wind farms. Really customers are already being compensated to use more electricity through intervals of high renewable energy excess. These “demand response” schemes where flexible consumers gain from changing their intake (not simply decreasing it) are an efficient approach to make energy cheaper and cleaner.

Location matters

The timing of decreased electricity consumption matters, but so will the place. In most cases, consumptions of electricity is less concentrated on the area it is produced at more so than it is in areas where there is a concentration of big buildings such as the conference venues in Melbourne or residential areas.

The system that links both can become saturated — particularly through periods of high demand or generation surplus. At these points, bottlenecks may prevent considerable quantities of renewable generation in 1 part of their community from being hauled to customers in another. That need may instead be met with electricity from fossil fuels while the renewable generators are curtailed. This can ultimately raise costs for bill-payers.

All people who want to see a cleaner, more affordable energy system will have to reevaluate”energy efficiency” into account for the importance of location and timing. Bear in mind that using less energy saves more emissions and money at several times of the day and in certain areas compared to other people. Though it may be counter-intuitive, in times and places where renewable production would otherwise be curtailed, it’s actually needed to use more electricity.

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