[cptcobalt]

Indeed, if we're assuming that they'll charge during the day to discharge at full power at night, it won't cover all of overnight use, but with the current composition of grids typically it's what you need to cover after sundown until most go to sleep (and energy use reduces). A project like this doesn't need to reduce base load, but there surely needs to be renewable (or nuclear) energy projects to replace base load. (This is an over simplification, but base load supply is built to be more steady state, less real-time reactive to the needs of grid.)

Also, the "time" of the battery is just a function of storage size and inverter sizing at peak discharge. It's often selected based on how the operator expects it to be used. (For example, Tesla sells megapacks in 2hr/4hr variants [1], and I think a lot of other grid-scale storage works this way. A 2hr megapack replaces some battery bays with more inverters.) While the battery is 4 hour capable, the operator could really intend for this to provide a constant overnight supply, and it could certainly provide that.

[1]: https://www.tesla.com/megapack/design

[throwaway894345]

Interesting, but does this assume Morocco won’t have a cloudy week or something (I understand that Morocco’s climate is almost always sunny, but even still)? I always assumed the threshold for “reliable renewable energy” began at a week’s worth of storage.

[cptcobalt]

This project also includes wind, which doesn't require sun.

"A week's worth of storage" feels somewhat like an armchair simplification. It roughly sounds on target if we're moving toward the march of nines for real-time zero-carbon power supply, but...that honestly doesn't need to be the target expectation for today. Long term goal, yes. Today's targets really should be to get to 90-95% renewable, since chasing the last 5% will be the hardest and most expensive—and that's probably where we can acceptably use some dirtier backup sources. With the state of the grid today, there's lots and lots of power sources that can be replaced for cheaper and cleaner before we need to chase the long tail of 100% renewable at all hours during every season.

The reality though, is that all of these requirements are modeled, and the operator surely has their install min/maxed for typical use.

At the risk of being off topic, I personally have what energy-wonks could consider a "three hour" system (10kW solar, 15kW/43.5kWh battery, my typical daily energy use is between 25-50kWh, higher if I need to charge the car) and have done two weeks fully off-grid last summer, which included some cloudy weather. (True off-grid: the utility breaker was open to hard disconnect from the grid). While I could probably live full-time off grid in the summer, I definitely feel its better to have my system help clean up the grid where possible. So there's really a lot of flexibility to be had depending on the system's requirements.

[throwaway894345]

> "A week's worth of storage" feels somewhat like an armchair simplification.

It is. The way I've heard it explained by energy experts (or people who were introduced by the media as such) was that storage needs to be on the order of days/weeks, not hours. I'm sure that's something of a crude oversimplification for a lay audience and certainly not a rugged analysis for this particular project.

> With the state of the grid today, there's lots and lots of power sources that can be replaced for cheaper and cleaner before we need to chase the long tail of 100% renewable at all hours during every season.

I'm of the impression that "clean carbon" peaker-plants are fairly inefficient because there's a fair amount of overhead in starting them and consequently they don't actually end up being that much cleaner. :/ Unfortunately, I wish I had more to offer than "this is what I've heard an alleged energy expert say". :(

[ncmncm]

You might want a week or month of storage, eventually, but first you want to have installed enough spare generating capacity to charge it while still servicing full load. And, you probably want your week's or month's worth to cost way less than that amount of battery.

[fauigerzigerk]

Not that I know anything about this, but isn't it the job of "the grid" to make sure all sources of energy combined can provide the necessary power at all times? No individual power source is ever completely reliable.

Please forgive my naive question. I have exactly zero relevant expertise.

[cptcobalt]

Yes!

The grid is one of the world's largest real-time reactive machines. Power is generated on the fly as you need it. You could draw a direct path from your home A/C switching on all the way back up the chain to some source needing to push power to meet your demand.

The supply of the grid is a big mix of diverse sources: renewables, natural gas, hydro, nuclear, coal—whatever. Each power source has different pros and cons, and you cannot really over-index on one to have a reliable grid. For example, nuclear is a fantastic and relatively clean source for base load (obviously, when handled responsibly), but not great to provide power that reacts to the shifts of demand through the day. Solar, obviously, doesn't work at night. The grid operator has to build a supply mix that fits the needs of their region. (And that's typically by facilitating energy market with different energy products where generators bid and participate.)