Eli5: how will a power grid that is mostly powered by many non synchronous renewable generators (solar and wind etc) remain stable, when the stability of the grid is currently reliant on the collective inertia of the large scale base load generators of fossil fuel and nuclear power plants?
In: 84
It won’t.
It will never not be funny watching people think companies have some sort of fandom towards certain energy sources over others. They only care what works. And you should too.
This episode of the podcast, Volts, does a really good job in delving into the various techniques that can be used in the future to supplement the core of renewable energy (i.e. wind and solar).
https://podcasts.google.com/feed/aHR0cHM6Ly93d3cudm9sdHMud3RmL2ZlZWQ/episode/aHR0cHM6Ly93d3cudm9sdHMud3RmL3Avd2hhdHMtbmV4dC1mb3ItY2xlYW4tZW5lcmd5LWFuZC1jbGltYXRl?ep=14
Electrical engineer here. Bigger scale wind and solar are required to aid auxiliary services, which include grid stability. Like a power plant with synchronous generators, they will have to put more power into the grid if frequency drops and remove more if frequency rises according to their droop ratio. This means the plants need to have a reserve of energy available and therefore can’t always be as efficient as possible unless their services are covered by someone else.
The real ELI5 answer is: we don’t know at scale. But it is being investigated by a number of groups, namely the NERC and their Inverter Based Relay Working Group (link below).
Others have mentioned grid forming inverters can “reset” the grid in the event of a blackout, but I think your question is about the ability to withstand adverse events… like if a hurricane comes through Florida and everything is inverter-based will we need to worry about the whole Eastern Interconnection blacking out (basically everything East of Texas)? And we can’t say because it really isn’t close to happening.
Inverter-based resources are growing at an unprecedented rate and you see headlines about how “Texas was run entirely off wind”, but the reality is we’re not past a critical tipping point yet and utilities are still building synchronous generation (mainly gas for a variety of reasons).
Climate change is the buzz word for renewables, but for non-environmental government bodies, if (likely when) we do transition blackout resistance/recovery, transmission infrastructure (to get the power from the middle of nowhere to cities) and energy storage (because wind and sunshine are intermittent) are the biggest hurdles that aren’t getting much media attention.
(On mobile, formatting, etc..)
https://www.nerc.com/comm/RSTC/Pages/IRPWG.aspx
Battery and storage technology advancements are necessary to replace the base load providers.
However, base load could be also be replaced with green energy sources like tidal, geothermal, and hydro.
It won’t. We need ludicrous numbers of nuclear plants built much faster than peruke are comfortable building them.
If all else fails, a bunch of giant fly wheels that will also double as energy storage over night.
It won’t. Switching transistors inside inverters can’t respond to large load fluctuations fast enough. Small fluctuations are ok, but most solar and battery systems are on small grids, or small portions of large grids, and the load changes they see are frequently too large to support.
Traditional rotating power generators, like turbines in dams and coal/nuclear plants, provide stored energy that loads can extract for brief periods of time, giving controllers time to adjust fuel and/or voltage set points. The inertia dampens “real” loads, while the electromagnetic field stored in the air gap of the generator dampens “reactive” loads. Solar and battery inverters have neither, so they do a very poor job supporting large changes in load. The result is frequent overload conditions and the renewables open their breakers, making them useless.
Inverters use silicone based diodes and transistors to convert DC to AC. All of the current must pass through these components, but they have a fundamental limit to their current carrying capacity. That limit is for lower than copper or steel, and the end result is a severely restricted ability to provide fault duty currents. When a large load turns on, the electrical components inside have to energize before work can be done. This is called in rush, and it’s much higher in reactive loads. A rotating genset made of copper and iron can provide 5-8 times the nominal nameplate capacity as fault duty for very brief time periods. An inverter might provide 1.2 times nominal. From personal empirical observation, a 5hp industrial motor powering a large fan consumes ~5kW and ~2kVAR at steady state, so a 5-10kVA genset can run it all day long. That same fan pulls ~30kVAR at start up, which requires ~100kVA of generation to support, which is far more than the 5-10kVA genset can handle. It would require 5-10 times that much generation in the form of battery inverters to support the same in rush.
In case there’s no other technology, we can just keep spinning large masses, just without turbines or power generation.
Quantity…..and hydro electric(dams)/tidal(wind turbines underwater), with support from nuclear as well.
This is theoretically how it is done. Statistically you can plot enough solar/wind coverage to have a “stable” enough supply of electricity.
The problem is, this requires a massive amount of investment to build. The almighty $$$ and it’s cousin the bottom line are the only enemy to solving every problem in humanity..other than humanity itself.
Capitalism has it’s downsides. Just like everything else.
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