We're using natural gas peaking so far, but this is actually still not that cheap. I am of the attitude that even with no additional fossil fuel infrastructure

We're using natural gas peaking so far, but this is actually still not that cheap. I am of the attitude that even with no additional fossil fuel infrastructure constructed, we would be fine if we made an effort. A mix for new generation of something like 70% solar/wind/batteries, 10% better grid interties, 10% expanded peaking hydro, and 10% a better system of load modulation, works just fine. Load following with a market rate for things like water heaters, car chargers, and various industrial processes is something that's been implemented in other countries half-seriously, but only treated as an epithet or a scam here. To actually work, you can't just "Charge people a market rate" and expect them to fiddle with the breaker box, you have to actually integrate that feed into a decision-making algorithm run by home automation, which can make distinctions like "We need the car to be 90% full by 7AM, but we can adjust between charging at 1KW and charging at 6KW to minimize expected billing based on a minute to minute rate schedule. The water heater can range between 130F and 160F as required due to a mixing valve. The average dew point in the HVAC system needs to stay between 40F and 60F on a three-hourly basis, but can be modulated in ten minute increments according to demand." These sorts of interfaces need to be simple enough that Grandma can establish them conversationally. Grid interties allow Los Angeles to sell Boston sunlight and Chicago to sell Houston wind. Peaking hydro is just pumped storage minus the new pump and the new dam. An existing hydroelectric dam just gets refitted for twice as many generators and starts running on a 50% duty cycle, while allowing more variation in the water level.