TECHNOLOGY

The network is not ready for the renewable revolution


You can almost You hear the electric grid creak and groan under the weight of the receiver, as two forces converge to push it – quite often – to the breaking point.

One force is climate change, which can exacerbate disasters that destroy parts of the network, as Hurricane Ida did this summer, Currently knocking on New Orleans just like a The heat wave has settled. Or, severe weather can cause a sudden rise in energy demand only when the grid is less able to supply it, such as during Texas freeze last winter and subsequent power system failure.

Paradoxically, another force is the massive spread of renewable energy – the best way to combat climate change and avoid these kinds of disasters. But this will require a fundamental rethink of how the network works. Gas and coal power plants generate continuous power by burning fuels, and the amount of their combustion can be adjusted based on electricity demand. But solar and wind generation fluctuates. The sun does not rise at night, and the turbines do not spin without wind.

This can create a mismatch between supply and demand. Imagine there is a heat wave. You get home from work at 6pm and your house is very hot, so you turn on the air conditioner. The problem is that everyone else does it, too. This is the time of day when people use the most energy, coming back from work and starting cooling their homes, cooking, and running washing machines and dryers.

However, by 6 pm the sun is setting, and the solar panels are not producing much energy. And the winds can stop blowing at any time, leaving a gap between demand and generation. (The ability of utilities to load giant batteries with solar energy in the morning and store them when customers need more power is currently Still very limited.)

This puts a tremendous strain on the network, which must exist in constant equilibrium. Utilities have sophisticated systems to predict when demand will rise and fall, so most days this is not a problem. They can purchase additional power from nearby utilities if needed. Or they can achieve that balance by burning more fossil fuels – but that, of course, scatters more carbon. But if there is an unexpected rise in demand and a utility does not have the required power, it has to restore equilibrium by reducing demand – with blackouts.

As renewables take up the energy mix, utilities will not be able to rapidly increase supplies by burning fossil fuels. So, a future grid running on an often intermittent supply of power from renewables will need to be much more flexible to compensate.

Kelly Sanders, an environmental engineer at the University of Southern California, who studies how the grid evolves, is looking into a strategy called pre-cooling, in which home users turn on AC power early in the day when the grid is teeming with clean solar energy. Essentially, they shifted peak demand away from the rush to go home. “You can get a lot of electricity customers to use much more electricity at sunset, and then reduce that use when the sun goes down, so it’s better to align our behavior with the availability of wind and solar energy,” Sanders says.

The same principle applies to heating. In some of the colder parts of the United States, demand rises during the winter at 6 or 7 a.m., when people wake up in frozen homes. Here people can start heating their homes at 4 am. Sanders envisions that local officials might also adjust the operation of critical infrastructure to match the availability of renewable energy — perhaps a region timing its drinking water treatment when there is plenty of solar power available.



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