A major power outage in Spain and Portugal has raised concerns about how renewable energy like solar and wind affect electricity grids.
Power grids must keep a constant balance between how much electricity is made and how much is used.
This balance is measured by frequency: 50 Hz in Europe and 60 Hz in the US. If the frequency drifts too far, it can cause failures.
Traditional power sources like coal, gas, and nuclear use spinning turbines that help keep this frequency stable.
If demand spikes or a power source fails, these turbines release stored energy to help stabilize the system.
Solar and wind energy don’t use spinning machines, so they don’t offer the same stabilizing support.
Experts say renewables must develop added controls to help the grid, especially by contributing to inertia (energy stability).
Hydroelectric and nuclear power may become more essential for this support because they still use turbines.
There are several technologies to help renewables support the grid, such as gravity storage, liquid air, compressed air, and flywheels.
In the UK, flywheels are being used to store extra energy and release it when needed.
On April 28, solar and wind produced 70% of Spain’s power, but because they are weather-dependent, they need reliable backup or storage.
Backup today often comes from thermal, hydro, or nuclear power.
To support renewables, countries need to expand energy storage, with common options being water reservoirs (pumped storage) and large batteries, which are increasingly used and mostly made in China.
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