[bratbag]

Cost factor isn't as relevant as you think, as this is an apple's to oranges comparison.

Renewables are too unreliable to act as baseline generation for a country.

In the UK last year for example we had very little wind, so we had to ramp up our gas power output to make up for our shortages in renewables. We burned through much of our gas reserves before the Ukraine war started, because of Renewable power unreliability.

Fission is the replacement for that baseline role that hydrocarbons currently fill, not the unpredictable-but-clean role that renewables fill.

The ideal future has both, with renewables producing as much power as possible and fission running on low capacity and ready to ramp up when renewables fall short.

[cycomanic]

Just repeating the baseline myth does not make it true. Nuclear does not compete with gas it competes with coal and renewables. It is often technically difficult but more importantly economically prohibitive to run nuclear as on demand sources. So for both renewables and nuclear you need some sort of storage or peakers.

Moreover nuclear is not the beacon of reliability, Frances nuclear plants were running to only 60% capacity due to maintanance and weather (when it gets hot nuclear plants have to shut down or reduce output significantly). Guess who was picking up the shortfall... German renewables and gas.

Finally, cost is absolutely the main measure: if the cost of nuclear is 3x wind/solar (and the cost of solar is falling exponentially) and you want to replace fossil fuels as quickly as possible the obvious way is to build renewables, you can overbuild 300% at the same cost. At that point you're close to being able to run your grid if you are sufficiently geographically distributed (even without batteries). Moreover in 10 years when your nuclear plant is finished building the price differential is like >5x due to the cost decreases.

[ascar]

> So for both renewables and nuclear you need some sort of storage or peakers.

One thing I don't understand here is the problem with overproduction. If we actually have excess electricity (as in not needed as electricity later) can't we dynamically use that for active carbon capturing? The efficiency of that process isn't even that important then as the main goal is to remove carbon from the atmosphere with carbon free energy.

Having carbon free overproduction sounds like a good thing to me. It's the occasional underproduction that's hard to handle.

[tuatoru]

See Casey Handmer[1]. We are underproducing solar PV by at least 4.8 TW (nameplate) per year: we're only producing about 4% of what we need.

There is no such thing as overproduction, there are only manufacturing bottlenecks in batteries, electrolyzers, and reverse osmosis water plants.

1. https://caseyhandmer.wordpress.com/2022/07/22/were-going-to-...

[toxik]

Calling it a myth doesn’t make it a myth. Power companies have been saying exactly this for years: they need PLANNABLE power generation. Building 3x solar or wind plants means 3x volatility.

[ncmncm]

Building 3x renewables in widely distributed places radically reduces volatility.

Wind is always blowing somewhere. Sun is always out somewhere. Storage is transportable.

[ascar]

> Building 3x renewables in widely distributed places radically reduces volatility.

Is that actually true? Serious question. That sounds like a claim that seems so obvious, but won't hold up to the degree you might think in reality. Just one scenario I'm thinking of are giant storms that have clouds spanning multiple countries. And in that storm scenario even wind power shuts down to prevent damage.

[cinntaile]

https://doi.org/10.1016/j.rser.2015.12.318 has tried to analyze this for the EU. I'm not convinced that daily data provides the necessary granularity though, but more detailed data for the mentioned time span probably doesn't exist. I would try to find some more articles and check if there is a consensus.

[ncmncm]

Such giant storms are rare, and short-lived. A few days' storage outlasts them.

[ascar]

A few days of storage is a lot though isn't it?

[Galaxeblaffer]

Is storage really transportable ? Like how much energy in any form could you realistically transport for any meaningful distance without using too much of the energy that you are transporting ? Since you made the claim I'd like you to paint any kind of realistic scenario.

[tuatoru]

Hydrocarbons, especially medium-chain liquid hydrocarbons, can easily and safely be transported 10_000 kilometres and further.

Doing exactly that is presently about a quarter of total global international trade by value.

Their advantages of high energy density, safety, and undemanding environmental and handling requirements (distribution can be performed in temperatures from -40 to +40 celsius by almost untrained teenagers), and effectively unlimited storage duration and volume, far outweigh the energy inefficiency of producing them from atmospheric carbon. Especially once PV gets cheap enough.

Edit: I notice I didn't answer your question. For liquid hydrocarbons, I believe the answer is in the single digit percents, perhaps five percent. For LNG, the energy cost is much higher, perhaps as much as a third of the total energy value.

[ncmncm]

TFA is entirely about synthesizing transportable hydrocarbon energy storage.

But making methane is inferior to making ammonia, because extracting the diffuse carbon you need from air takes up energy. It does not displace any more CO2 emission, because somebody will burn it and dump the CO2 back into the atmosphere again.

So, the only reason to make hydrocarbons is for things like your chainsaw or A320 that are not worth replacing immediately.

[_ph_]

High voltage DC lines are quite practical over 1000 kilometers and more - Germany already operates an 1.4GW line to Norway, using the Norwegian grid as a storage for electricity.

[ncmncm]

There will be a very great deal of ammonia synthesis, worldwide, just because ammonia is so useful for so many things, ultimately billions of tons annually. Ammonia is very transportable.

Even liquified hydrogen is about as transportable as LNG, which is shipped all over.

[snovv_crash]

It reduces volatility, it doesn't eliminate it. There will still be days when the sun and wind aren't out in a large enough fraction of places that there will be a shortage. It is less likely, but it will still happen. Factories can't just shut down, people can't just choose not to charge their cars or boil their kettles if there's a shortage.

[ncmncm]

When generation flags and local storage looks likely to be depleted, utilities will order a shipment of ammonia from any of numerous solar farms in the tropics.

Most of the time a utility will prefer cheaper local generation, local storage, or transmission-line power before spending on shipped-in synthetic fuel.

[snovv_crash]

I have friends who work in industrial refrigeration, and I have to say, transporting ships full of ammonia around the world is a horrific idea.

[Schroedingersat]

If the goal is 1 unit net, then min(3x, mean(x)) has massively lower variance than x.

The extra power when 3x > mean(x) is just incentive for developing flexible loads and arbitrage.

[toxik]

You’re not listening. They are literally calling for plannable power. I don’t think they’re stupid people either. You cover the base consumption using plannable sources, then use gas/hydro turbines for short term variation. The problem now is that when the wind/solar vary, you can only compensate so much with stored hydro before you empty the reservoir. Then electricity becomes expensive because you burn gas etc, or buy from elsewhere - which is EXACTLY what has happened.

[Schroedingersat]

When solar is 1/8th the price of current fission projects for the same net capacity and falling by double digit percentage per year you have a hell of a lot of money left over for moving the energy around.

Fission is around $10/watt with a mostly-plannable capacity factor of 60-80%. Fission is a cakewalk compared to fusion.

Solar is around $0.5/watt with a capacity factor of around 25% and falling rapidly.

The operating and capital costs of a gas plant are around the same with a plannable capacity factor in the high 90s.

So by spending $6 on solar, and $2 on a gas plant. You have $7/watt left over to figure out how to turn free electricity into hydrogen or methane at 50% efficiency and store it for a year.

We already have electrolyzers that work for $0.5 to $1.5 watt at around 50% efficiency.

Hydrogen storage is hard, but that left over $5 per 4kWh/yr should take care of it. If it doesn't, sabatier rractors are getting cheaper too.

The only thing we have to do for people to start using them is stop the coal and gas subsidies.

This is also just one of many options. Salt cavern CAES is similarly viable

[toxik]

So then according to your analysis there is no problem with solar/wind, and the power companies are basically lying when they say they need plannable power.

Meanwhile people are resorting to paying with their savings to pay the 10-fold increase in their power bills.

[pfdietz]

China is selling electrolyzers at $0.30/watt.

[tuatoru]

> It is often technically difficult but more importantly economically prohibitive to run nuclear as on demand sources.

I'd just like to point out that the US Navy has an excellent track record running nuclear reactors that ramp up to full and down to zero rapidly, in submarines.

The US Navy does not have quite the same financial constraints as commercial land-based power, but constraints still exist.

I fully agree that solar PV and wind, especially PV, are much more atttractive to investors because you can be earning cashflow from your first MW of capacity while you're installing the second (which takes weeks (or days!) instead of years), and you can iterate and scale this all the way to 10 TW or more of capacity, as the demand requires.

[Schroedingersat]

> Frances nuclear plants were running to only 60% capacity due to maintanance and weather (when it gets hot nuclear plants have to shut down or reduce output significantly).

It's important to use the real deal-breaking flaws when pointing these things out. The relevant figure is availability because capacity also includes energy that could be produced but was not due to having nowhere to put it.

Availability is 70-80% in France and UK and 80-90% in the US.

But due to the long timeline of refuelling cycles you still need a full baseload backup. So nuclear needs long term storage or other uncorrelated backup more than renewables if anything.

The upside is it's easy to have two uncorrelated nuclear plants, so overprovisioning by 30% is sufficient.

That makes something that is already more expensive than solar with the same overprovisioned net capacity factor, and a green hydrogen plant with capacity sufficient to cover, and full gas backup infrastructure even more expensive though. Probably not enough to cover the costs of hydrogen storage yet or someone would be doing it (ignoring massive nuclear subsidies), but prices of batteries, solar panels, and electrolyzers are dropping rapidly. Hydrogen storage or green methane production only needs to become marginally cheaper to make it start happening even sans subsidies.