It isn't good enough due to variability.
We don't have efficient energy storage so that means you have to build massive overcapacity, like 5x as much.
We should have some renewables but we can't base the entire energy supply on them.
We don't have efficient energy storage so that means you have to build massive overcapacity, like 5x as much.
We should have some renewables but we can't base the entire energy supply on them.
The case study that demonstrates this is Denmark, which has about 50% of its energy produced locally from renewables, mostly wind. They plan to increase this to 84%. They hardly had to overbuild, and they sell the excess capacity to their neighbors. Even if the overcapacity wasn't sold and was wasted, it's still much cheaper than nuclear.
This shows us that a bigger country could easily get >80% from renewables without storage. Two reasons. First, more terrain means more variability cancelling from wind. Second, solar cancels out wind, and Denmark has very little solar. Solar and wind are significantly negatively correlated, because it's less windy in Summer.
You can do even better by having a network of countries, each selling overcapacity.
Storage or gas makes up the small remaining shortfall. Luckily battery costs are declining on a super-linear learning curve.
I'm all for nuclear power, it works fine and is far better than fossil fuels. But I'm more for renewables as a mass scale solution. It's cheaper and we can have it sooner.
That's a problem already solved: Storage. Germany alone has 3.4 GWh of home-battery storage installed as of today. And it's constantly increasing. Averaged over a year, renewable energy sources operate at about 30% of their capacity. So even in a worst-case scenario with no storage whatsoever you would need to build 3x "overcapacity".
> We should have some renewables but we can't base the entire energy supply on them.
We surely can and will! Mark my words.
I don't think that calculation is valid. Even assuming perfectly sunny days solar power e.g. runs at less than 100 % of its capacity simply due to the day-night-cycle. However that doesn't mean that overbuilding solar by just "1 divided by average capacity utilisation %" will be enough to get you round-the-clock-power – in fact no amount of overbuilding will get you any solar power at all at night.
What you'd actually have to look at is define a desired reliability factor for your electric grid, calculate the minimum guaranteed power output for that reliability factor (so to remain with the solar power example – even during the daytime you need to calculate the likelihood and impact of cloudy weather, but in any case as soon you as you want more reliability than there are even theoretical sunshine hours in a day, guaranteed power output drops to zero – unless of course you finally attempt to include some storage) and then overbuild according to that calculation.
https://model.energy/?results=f476509869f9cee1582db8e09905fd...
It's stupid (arguably even stupider than a 100% nuclear grid and twice as expensive), but it works.
Luckily storage does exist and electrolyser prices and needs for rare metals are dropping precipitously, so you don't have to do something stupid.
Is it twice as expensive after you factor in selling the excess capacity?
There's only so far you can take these counterfactuals, but presumably you'd be selling it at, say, $10/MWh (because things like hydrogen are already profitable at this cost) which might cover part of the distribution costs (which are not in that model) and bring it down to roughly on par.
That said, there are a bunch of risks and externalised costs in a zero storage strategy not captured by simple prices. Many of the objections of the nuclear industry are actually true in such a scenario.
Overbuilding solar 4-8x with current tech would cause alot of CO2 emissions from silicon refining, it would strain silver and copper supplies. Overbuilding wind by a similar amount would require vast amounts of steel, strain niobium production, and cause CO2 emissions from concrete. Even if your system was on par with nuclear on a dollar basis, it would still produce too many emissions (half or more of 100% gas) and quite fragile.
Relying on cross continent links to reduce overbuild ratio is a massive strategic risk, and if someone in the chain does a texas and has a bunch of equipment fail, you'd have a real version of the scenario the anti-wind campaogners are imagining in europe right now.
A good strategy is a mix of everything aiming to remove as many emissions with each dollar spent. If that means aiming initially for 50% net solar availability, and 30% net wind availability with 20% surplus and keeping the gas turbines running through winter to provide the remaining 40% for a few years whilst shotgunning money at research for abundant batteries, electrolysers, and tidal to see which one sticks, then that is far better than using the same funds to pay for 20% nuclear that will be online in 2050.
Another good strategy would be to build out scalable storage (thermal batteries, electrolysers and pumped hydro) immediately and go all in on wind/solar asap. The amount of concrete required for the pumped storage might he prohibitive though and it won't cost a great deal less than nuclear (although it will be online sooner).
Even a strategy with 10-20% nuclear like what China is pursuing is tolerable (including the very likely chernobyl scale incidents that will happen if it's pursued worldwide -- which are vastly preferable to the consequences of coal) in countries that aren't controlled by neoliberal systems which are fundamentally incapable of operating any large scale project that won't pay off visibly in an election cycle. It's just the constant shouting of "stop all the wind and only build nuclear" that's imbecilic.