On very windy and sunny days the energy production of renewables skyrockets, but what happens to all that electricity that doesn’t get consumed? Is it all dispersed in the ground/heat or am I missing something?
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Most of the time, production is simply slowed. You can disengage the turbine on an windmill or dam, and you can simply burn less coal/gas/etc. in a traditional plant. Balancing production vs. demand is a **huge** part of energy production.
Some energy can also be stored and used later. We can, for example, use excess energy to pump water back above a turbine, releasing it when we need more power.
If energy producers don’t react the system survives that for about 15 minutes. Otherwise emergency shutdown triggers a massive blackout to prevent wires from overheating.
Luckily there is a very sophisticated system that decides wich powerplant will reduce power output, and wich windfarm curtails power by turning their blades out of the wind etc.
You can destroy electrical energy by turning it to heat, but for those amounts you’d need huge hardware to handle it, so it’s easier to just adjust the production instead
Most of the time, production is simply slowed. You can disengage the turbine on an windmill or dam, and you can simply burn less coal/gas/etc. in a traditional plant. Balancing production vs. demand is a **huge** part of energy production.
Some energy can also be stored and used later. We can, for example, use excess energy to pump water back above a turbine, releasing it when we need more power.
In general other power stations are turned off since operating actually cost money and fuel. In addition some generators are powered in reverse to create energy at a later date like pumping water up hill. Some industries are notified when there is a power surplus so they can work with really cheap electricity like aluminium smelters where electricity is their largest cost.
In general other power stations are turned off since operating actually cost money and fuel. In addition some generators are powered in reverse to create energy at a later date like pumping water up hill. Some industries are notified when there is a power surplus so they can work with really cheap electricity like aluminium smelters where electricity is their largest cost.
With a traditional power grid powered by spinning generators, if production exceeds demand, the extra energy goes into making the generators spin faster. This means that the frequency of alternating current increases. Power plant operators constantly keep an eye on that, and “take their foot off the gas”, lowering power production until the system comes back into balance.
But the generators only store a small amount of energy, so the system needs to be actively balanced, from minute to minute. There’s no long-term storage.
Solar panels don’t have a big hunk of spinning metal to store energy, the electronic circuits that add energy to the power grid just follow the frequency set by the spinning generators. So grid operators are a little concerned for the future: if we get rid of the spinning generators, will the future grid remain stable? This can be resolved with use of batteries and smart electronics, but it’s important to think about.
If energy producers don’t react the system survives that for about 15 minutes. Otherwise emergency shutdown triggers a massive blackout to prevent wires from overheating.
Luckily there is a very sophisticated system that decides wich powerplant will reduce power output, and wich windfarm curtails power by turning their blades out of the wind etc.
You can destroy electrical energy by turning it to heat, but for those amounts you’d need huge hardware to handle it, so it’s easier to just adjust the production instead
No, it doesn’t just go to heat. It is much worse than that.
Without the grid’s resistance, all generators start spinning faster. That drives the AC frequency up – which also make all big industrial motors to spin faster, as they are synchronized to the grid.
Raising generator speed also raises voltage (“electrical pressure”) which, if raised unchecked, can burn all electrical equipment on the grid.
That’s why it is very important to match consumption and production. Fortunately, the AC grid “automagically” equally distributes the rotation speed between all generators and motors, and because their total mass is quite big – it gives a bit of delay before any critical spinning up happens.
Most of the power plants connected to the grid does so with a generator. This includes coal, gas, hydro, nuclear and geothermal power plants but not wind or solar. A three phase generator is the exact same component as a three phase electric motor, it just depends on how it is installed. If the power production in a grid is higher then the power consumption then the generators will start working as motors and spin faster. Due to the high rotating mass of the generators and connected turbines it takes a lot of energy to change the speed so it takes some time for the generators to speed up.
Meanwhile the grid controllers will detect that the generators speed up because the frequency of the grid goes up. So they will start shutting down power production. Because solar and wind energy can not be stored they will not shut down this but they will reduce production from the other power plants starting with the most expensive ones. After some time the electricity production will be lower then the consumption and the generators will start slowing down and the grid frequency will return to normal.
So the power generated by wind and solar can be stored in the rotating mass of the generators of the other power plants, at least for shorter amounts of time. There is another concept which involves storing electricity in batteries which are connected to the grid and simulating a rotating generator. A few of these have been built, mostly small test plants. But there is a big production scale plant installed in South Australia.
In some cases though there is a need to stop production from wind and solar. When the grid controllers have extinguished all their options and the wind and solar plants is able to power the entire grid without any other power plants active and all the lines out are at capacity they will order these power plants to shut down as well. Wind turbines can change the pitch of their blades in order to optimize their power production based on the amount of wind. But it is also possible to change the pitch of the blades so the wind turbines produce less power. Even stopping the wind turbine entirely. In this case the wind energy is able to pass through the wind farm without getting collected. Solar cells can also safely be disconnected from the grid. The excess energy from the sun will then not be collected by the solar cells and just end up heating up the cells.
With a traditional power grid powered by spinning generators, if production exceeds demand, the extra energy goes into making the generators spin faster. This means that the frequency of alternating current increases. Power plant operators constantly keep an eye on that, and “take their foot off the gas”, lowering power production until the system comes back into balance.
But the generators only store a small amount of energy, so the system needs to be actively balanced, from minute to minute. There’s no long-term storage.
Solar panels don’t have a big hunk of spinning metal to store energy, the electronic circuits that add energy to the power grid just follow the frequency set by the spinning generators. So grid operators are a little concerned for the future: if we get rid of the spinning generators, will the future grid remain stable? This can be resolved with use of batteries and smart electronics, but it’s important to think about.
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