Or solar / wind (which mostly anticorrelate) + biomass + storage + interconnectors + smart demand.

The amount of baseload we technically need can be pretty slim.

Take Denmark: fossil powers just 9% of their electricity generation, the majority of it is wind and solar. Wind is strong in evenings/nights, solar during the day.

Then they have biomass (indirect solar) as a form of baseload, more sustainable than coal/gas.

Then there's interconnectors, they're close to Norway which can pump hydro, and Sweden, each day about 25% of the electricity is exchanged between these two countries, and that's a growing figure.

With more east/west interconnectors you could move surplus solar between countries. Import from the east in the morning before your own solar ramps up, export your midday surplus west before theirs peaks, and import from the west in the late afternoon as yours fades.

With interconnectors you can also share rather than independently build peaker capacity. Because a lot of peaker plants only run a small amount of time and therefore much of the cost is in the construction/maintenance, not the fuel.

And of course there's storage, which will take a while to build out but the trendlines are extremely strong. Just a fleet of EVs alone, an average EV has a 60 kWh battery, an average EU household uses 12 kWh per day so an average car holds 5 days worth of power a home uses.

And then finally there's smart demand. An average car is parked for more than 95% of the day, and driven 5% of the time. Further, the average car drives just 40km a day which you can charge in 3 minutes on say a Tesla. Given these numbers (EVs store 5 days of household use, can sit at a charger for 23 hours a day, and can smartly plan the 3 minutes a day of charging it actually needs to do) just programming cars to charge smartly, is a trivial social and technical problem in the coming 10-20 years.

Given this, baseload coal/gas can really be minimised the coming decades. It's not going to go away as a need, but I don't think it requires gas/coal or nuclear long-term going forward.

The issue with "base load" is that people usually omit to mention how much GW they are talking about and for how long. Which makes it a bit of a bull shit argument.

As an insurance against unspecified lack (how much for how long?) of wind and solar (and batteries, cable capacity, hydro, etc.) base load is supposed to swoop in and save the day when those temporarily fail locally. So, it's a valid question to ask how much insurance we need against that. Nobody seems to really know. There are loose estimates of course. And people seem to assume it's months and that renewables are going to 100% be offline throughout that very very long period. In reality in most connected energy markets, we have a short gap of a few weeks or so in winter at higher latitudes of reduced output that we already manage to cover with flexible generation.

It's more constructive to think in terms of dispatchable power rather than base load. When the sun doesn't shine or there is no wind, it's nice if you can quickly bring online additional generation, tap into battery reserves, or bring in power from elsewhere (via cables). That favors flexible power, not inflexible power. Nuclear and older coal plants are a bit inflexible. Shutting down and starting up a nuclear plant is really slow and expensive and requires a lot of planning. And especially older coal plants need quite a bit of time to bring their boilers up to temperature such that they build up enough steam pressure to generate power. Until then, they are just blowing smoke out of the chimney. Modern coal plants are a bit better on that front. Same with gas plants.

The modern ones only need about 10-20 minutes or so. Still quite slow but something you can plan to do. Slow here means expensive as well. Because shutting them down when there is a surplus of renewables (which is a very common thing now) is really inconvenient. Which means consumers have to pay extra for perfectly good electricity from renewables to be curtailed. That happens by the GW in some markets and keeps consumer prices higher than they should be because they have to pay for gas/coal that is technically not actually needed.

Batteries have a much lower LCOE than gas or coal plants (never mind nuclear) and it's being produced by the TWH per year now. A lot of markets are serving much of their peak demand using batteries now. Australia and China are good examples. Even in the US, you see batteries being deployed at a large scale now. That's starting to push gas and coal out of the market. A gas peaker plant that rarely runs is just really expensive.

A requirement for base load is a fallacy promulgated by fossil fuel preservation lobbying

it actually is a choice between nuclear and PV, because base load supply is an obsolete concept. Because actually nuclear is terrible in a grid increasingly full of nearly-free variable sources (solar&wind). The nukes need to stay at 100% all the time selling their power at a high fixed price to have any remote chance of being economical. Cheap variables push nuke's expensive power off the grid during the day, and increasingly into the evenings with batteries. This is unavoidable in an open energy market, and is fatal to the economics of nuclear. You cannot make them work without massive state subsidies.

Gas is far better suited economically to backstop a variable grid. I wish it werent true, because i dont hate nukes, but it is just economics.

I will also point out that california is down to 25% fossil sourced power in 2025, from 45% in 2022. Due to renewables and batteries, and there's far more coming. The amount left to backstop on gas in a few years could plausibly be 10%! which is amazing.