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Comment by greenthrow | Hacker News Reader

Nuclear takes way, way too long to get online to help with global warming.

Renewables absolutely can and are "getting us there." It's a solved problem.

Fusion is always some long period of time away. It is not close to being a viable source of power, and there are convincing arguments it never will be.

And regardless, why do we need to waste so much money trying to turn into a viable source of power when we have solar and wind now and they are cheaper than any other form of power?

By all means keep researching fusion for scientific reasons, but enough with the empty promises about it being the ultimate power source. And fission can die off as the existing reactors reach the end of their lives. It is too expensive, too environmentally dangerous and totally unnecessary.

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Renewables have yet to demonstrate the ability to replace fossil fuels in any meaningful way. They seem to top out at 10-20% of the energy mix. France achieved net 0 many decades ago because they went all in with nuclear whereas their neighbors that went with renewables haven’t gotten anywhere close to that.

The best time to plant a tree is 20 years ago. The second best time is now.

France hasn’t achieved net 0, not even close. And there are several countries with more than 20% renewable energy in their grid.

I agree with the first part but not the second. Up until recently (when a lot of their nuclear went offline) they were one of the lowest emitters in Europe. They were comparable to Sweden and Iceland, which have substantially smaller (and more centralized) populations. I'll agree that thinking nuclear will get us all the way to net zero energy emissions is silly, but let's not undermine the great accomplishments France has made. They have been leagues ahead of the rest of Europe. Even at significantly reduced capacity they are still one of the lowest emitters.

https://app.electricitymaps.com/zone/FI

And even those countries in the EU such as Denmark rely on France for electricity imports because no country in the world has any large scale storage solution for renewables.

It would be stupid to put money into storage before there is excess renewable capacity to charge it from. So, people instead put money into generating capacity.

When we have any use for storage, we will build out storage.

France imports large amounts of energy during winter, largely from gas and coal producing neighbors.

Renewables have long since demonstrated ability to replace fossil fuels, and are being built out at an always increasing rate, already exceeding 20% in many places.

France is importing power.

This is plain wrong. France has been one of the most reliable exporters of electricity in EU for over a decade https://en.m.wikipedia.org/wiki/Electricity_sector_in_France...

Some of the time. Not this summer, e.g.

> Renewables have yet to demonstrate the ability to replace fossil fuels in any meaningful way. They seem to top out at 10-20% of the energy mix.

Denmark has reportedly reached 53.3% of electricity consumption with wind and solar.

"The first half of 2022 has been a record-breaking period for green energy production in Denmark. Danish windmills and solar panels produced 10,9 TWh in the first six months of the year – a significant 12% increase from the previous record from 2020. Another all-time high, the fraction of wind and solar power in the total electricity consumption was 53,3%."

https://stateofgreen.com/en/news/green-danish-energy-product...

> France achieved net 0 many decades ago because they went all in with nuclear whereas their neighbors that went with renewables haven’t gotten anywhere close to that.

Unfortunately even France no longer seems able to build new nuclear generation capacity at a reasonable cost. While wind, solar, and batteries get ever cheaper, nuclear has gotten more expensive over time.

For what it's worth I used to agree with you that Nuclear seemed the only viable way forward, after reading https://www.withouthotair.com. However much has changed over the past 14 years since it was published.

Denmark reached 100% wind capacity in 2013, 9 years ago, and is today completely dependent on Norway and Sweden to supply hydro energy when demand exceed supply. Around 50% of the energy Denmark consume is from imports.

Denmark wind and solar farms do sell a lot of energy to other countries when the weather is optimal, but when its not they have to buy that energy from somewhere. EU ruled a while back that the Swedish energy grid must sell energy to Denmark if there is available energy, and so the Swedish grid and the Danish grid is thus tied in a way that removes any distinctions between the two.

Denmark is thus a terrible example of wind replacing fossil fuels, unless they suddenly would forgo imports and live with only having power 50% of the time. They are a great example of how you can invest in renewable energy as long the issue of grid stability can be solved through imports.

Denmark sounds like a big success story. You've got half of locally consumed energy being generated locally from wind and solar, and you're also sending renewable energy to other countries which reduces the amount of fossil fuel they have to burn.

They should build even more so they can send even more and have an even bigger impact. And if their neighbors did the same thing and sent excess capacity to each other, then it'd all net off to not needing much storage at all. Maybe 10 percent of supply needs to be met with gas peaker plants when variability gets really bad, prior to storage solutions becoming cost effective.

So this case study of Denmark shows there is little substance to the criticisms of renewables.

With about 50% average effectiveness, overcapacity is fairly simple to calculate. With 100% capacity you get what we have today, ie around 50% from renewables and 50% from imports. At 200% capacity you get 75% from renewables, 25% from imports. at 400% capacity you get 87.5% from renewables, 12.5% from imports. At 800% capacity you get 93.75% from renewables, 6.25% from imports. at 1600% capacity its 96.875% from renewables, 3.125% from imports (assuming that renewables can scale down to that low weather conditions).

Obviously, running at high overcapacity results in significant less profits unless you can sell the overcapacity to other countries. When Denmark hit 100% wind capacity the growth of new wind halted dramatically down to basically the same as consumption growth. There is a limit on how much you can dump, i mean export, to other countries before there is no one willing to buy excess energy during periods of optimal weather conditions.

This isn't the scaling law we'd see.

Firstly, Denmark's renewables are largely wind. But wind and solar are negatively correlated. As they add more solar, the variability will cancel out.

Secondly, variability is heterogeneous across geography. You're not building the second wind turbine in the same location as the first. As you connect countries up, or as you build in locations that don't currently have it, the variability cancels out.

Denmark is tiny. If the EU takes it up as a project, significant amounts of variability cancelling will happen, as you mix offshore wind, onshore wind, and solar, across the continent.

So, > 80% of EU's energy, from wind and solar, without any storage, should be achievable.

> running at high overcapacity results in significant less profits

Still better economics than nuclear. Even if you're at 3x overcapacity, it's still cheaper[1]. Not to mention you can sell most of that overcapacity (even to countries outside the EU) and get the money back, or convert it into green hydrogen and sell that.

[1] https://ourworldindata.org/cheap-renewables-growth

Well, Denmark is tiny so if its not windy in one location then its unlikely to be very windy in an other. Same for the sun.

EU has however already taken it up as a project. It is called the European energy grid, which as I describe above forces countries to sell to each other. There is an economical limit to this from transit and transport costs, but in concept the whole union is already a single grid connected from the southern part of Italy to the polar circle in northern Sweden and Finland.

Denmark consumes around 33 Terawatt of electricity. They import 20 Terawatt. They also sell about 14 Terawatt of renewable energy. Sweden (hydro + nuclear), Norway (hydro), and Germany (coal, gas) are the main players that provide those 20 terawatt of electricity to Denmark.

This far up north the sun doesn't cancel out the still periods of wind. Demand for heating during winter far exceeds the few hours of sun that you get.

Green hydrogen, as nice as it is for reducing the emissions from steel industries, still costs about 10x of nuclear if you use that green hydrogen to produce power. There is a big economical reason why no one is doing that at this point in time. Estimates from researchers in the field varies from around 2035 to 2055 before we will have our first commercial green hydrogen power plant in operation. Still green hydrogen would be a nice way to recover costs if Denmark did decide to go for 300% overcapacity, but they would still need to heavily depend on Sweden, Norway and Germany to provide the electricity when demand exceeds supply. Their own grid will not suffice.

Why doesn't solar cancel wind far up north like it does elsewhere? The sun shines longer in the summer, and it's less windy in the summer.

  "Well, Denmark is tiny so if its not windy in one location then its unlikely to be very windy in an other. Same for the sun."

That's true to a large extent for Denmark, but untrue to a large extent for the EU or larger countries. That's why I said that the EU can get over 80 percent of its energy just from renewables without storage, for a cost significantly cheaper than nuclear.

There are of course windy days where wind generates more electricity than is consumed, but the 53% figure is for the first half of the year.

The U.K. is up to around 40% of annual electricity consumption from renewables too. (43% of generation which I think excludes the 8% from imports.)

Net Zero is a good target but ultimately it’s getting most of the way there which is important. We need to replace heating, transport and industrial uses so we have to build out as much emissions free generation capacity as we can as quickly as we can. Renewables currently seem like the most cost effective approach.

Renewables obviously enable us to mostly stop using fossil fuels, fossils have just been too cheap because of unpriced externalities. (replace is the wrong word because some of the fossils use can and should just be stopped and not replaced by other energy)

There isn't anything mysterious we expect to empirically discover through demonstrations approaching 100%, though of course engineering does incrementally improve and progress.

Relevant: https://en.wikipedia.org/wiki/List_of_countries_by_renewable...

> Renewables have yet to demonstrate the ability to replace fossil fuels in any meaningful way. They seem to top out at 10-20% of the energy mix.

This is just utterly wrong.

In the UK 43% of power came from renewables in 2021: https://www.nationalgrid.com/stories/energy-explained/how-mu...

Even in California renewables are at 33%: https://www.energy.ca.gov/data-reports/energy-almanac/califo...

nearly 50% for Germany

https://www.tagesschau.de/wirtschaft/strom-erneuerbare-energ...

Renewables absolutely can and are "getting us there." It's a solved problem.

I hope that's true. So does that mean there's no need for the sweeping societal changes that prominent environmentalists are demanding because we'll be able to maintain our high-energy lifestyles with nearly 100% renewables?

Renewables are a solved problem, but storage of energy to combat the unreliability of renewables isn't.

NPP's take about 7 years to build. The latest EPR builds are taking more due to an over complicated design.

Storage is not, in fact, a problem. Numerous methods using century-old tech are cheap and practical, and only need to be built out.

They are not being built out yet because there is not excess renewable generating capacity to charge them from.

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