Isn’t this a 75% solved problem, because power generation and use were already out of sync due to people not working at night and a significant fraction of power generation being fixed-output such as nuclear?
No, power generation and use are definitely not out of sync today. Generation is very very tightly synchronized to usage and has to be for the grid to work at all without storage. Quite a bit of effort goes into managing generation output in real time to maintain proper voltage and frequency.
The solution is storage, but at current pricing the amount required for a full renewable grid would be obscenely expensive. Luckily battery prices have been dropping quickly for years and continue to do so.
Grid battery storage is a pretty mediocre solution to variability in supply from renewables except in a few cases (e.g. where pumped water storage is readily available). It's expensive and inefficient.
Market driven demand side flexibility is not very well tapped, doesn't require any technological leaps and there's a lot of room for improvement there. For example:
* Aluminum smelting plants that vary their usage depending on spot cost (actually already happening in Germany).
* Smart electric storage heaters that turn on when electricity is cheap.
* Smart electric vehicle chargers that take electricity spot price and current charge levels in to account when deciding when and how much to charge.
When there are millions of EVs on the road charging by day at workplaces and discharging at night at consumer homes, I don’t think they’ll be observed as mediocre solutions.
1. Cars have very very large batteries. You'd be hard-pressed to use more than a third of the capacity of a high-end Tesla Model S over night (100 KWh!). Sure, maybe you're driving a Nissan Leaf and its battery is only a third of that capacity, but in a few years 100 KWh might actually be common. What if you want your car battery to be at 100% in the morning so you can go on a roadtrip? Just make sure your car is aware of it.
2. There's going to be a marked for used batteries from old, retired electric cars. You might only need 20-40 KWh of remaining capacity to live comfortably in a fully off-the-grid solar setup.
Tesla battery longevity data shows this isn’t a concern. You’re not going to deep cycle the battery every night, and while I can’t speak to other auto manufactures, Tesla will be increasing their pack sizes, allowing for more “spare capacity “.
Or we’re going to subsidize residential storage (such as the 50k home project in Australia).
For example, where it's hot, people are running aircons during the day. Where the weather is cold, you need to run heating, but (1) often that's not electric, and (2) heat stores relatively well (in e.g. hot water tanks). In temperate climate, the uncomfortable power surge happens at ~6pm, when people get home from work and start turning on the light and running home appliances (stove to cook dinner, opening the fridge which must cool, etc).
The main power draw during the day are in the morning and at the end of the day, not in the middle of the day when the solar is most efficient. That's why it's called a duck curve.
Some areas in Europe do offer spot pricing (~hourly interval IIRC) for electricity, even for consumers. I don't have such a contract, so I'm not sure how good the pricing APIs are for autoscaling your consumption.
Several utilities in the states offer hourly rates. Most use human behavior inputs (sms messages) to drive the changes but others actually deliver the spot prices via smart meters.
A less smart version already exists. In the UK, some domestic energy is supplied at different costs at different times of day. This is optional and typically used for heating, but means that night time energy is cheap compared to daytime energy.
