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Comment by cedilla | Hacker News Reader

Nuclear energy is sustainable only with technology we don't have yet. All the affordable reactor designs with no risk of accidents or proliferation are just 10 years away like they have been for four decades.

And the sea water plan relies on technology that has been shown to be theoretically possible but not yet shown to be remotely feasible. At the proposed scale of kilotons per year, this would require filtering hundreds of billions of tons of sea water every year, even if we disregard the fact that most seawater isn't easily accesible.

But the problem nuclear is that either way, it's far too late. Even if we managed to build nuclear reactors faster than at any other time in history, we would be far too late to stop climate change.

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>"But the problem nuclear is that either way, it's far too late."

Sadly I see no other viable alternative. Wind and Solar are seemingly clean but require a ton of resources, have a massive footprint, and just don't scale with on-demand needs during bad weather.

>"All the affordable reactor designs with no risk of accidents or proliferation are just 10 years away like they have been for four decades."

No risk of accidents is an impossible standard. I know this will sound snarky, but, if you agree with the idea that the danger of climate change is existential, affordability is a relatively minor concern in comparison. Especially when you consider that a big factor as to why Nuclear is so expensive today is because we don't build them anymore, outside of places like China and India, which already have nuclear weapons.

> Wind and Solar are seemingly clean but require a ton of resources,

We pull 700 million tonnes of oil out of the ground every year. The resources required to build a clean energy infrastructure is significantly less than that.

> have a massive footprint,

Powering the US with solar requires a smaller footprint than footprint of parking lots in the US. Wind is even less because while a wind farm is massive, it doesn't prevent the land from being used for other things.

> and just don't scale with on-demand needs during bad weather.

Hitting 99% renewables is straight forward. You get above 90% if each solar plant is overbuilt enough to handle a cloudy day and has enough batteries to handle a single day/night cycle. This isn't expensive, it only roughly doubles the cost of your plant.[1] Interconnect a bunch of those plants along with some wind will get you the next 9%. Then use a gas peaker for the last 1%.

1: https://www.energy-storage.news/developer-8minute-says-more-...

Except we need to ban also the gas peaker, and suddenly calculations might show that a) storage isn't as easy b) a lot of locations might need overbuilding on ratio of 10x IF there was good storage c) that gas peaker is going to run quite a lot otherwise

Or you build a bit more capacity and use excess production on good days to produce co2 neutral gas (power to hydrogen to methan) that can also be stored in existing infrastructure.

if by bit more you mean 10x, sure, and that's only cheaper than nuclear if you have convenient geological storage.

Overground storage quickly goes more expensive than nuclear.

What's the massive footprint you talk about? If we put enough solar panels to provide electricity for all humans into the Sahara desert, it only covers a small area.

When I say footprint, I'm alluding to installations like the Taihang Solar Farm in China: https://www.youtube.com/watch?v=n731JjYSySY And, by footprint I mean the amount of space these panels occupy on the landscape.

Putting solar farms in a desert is an attractive idea and way less impactful than covering hillsides in green and temperate areas. My understanding, though, is that the transmission of all that energy is the real issue. You can build a giant solar farm in the Mojave desert but distributing it to farther parts of the U.S. is a problem.

Even if we created all our power from solar, it's negligible in land use compared to things like roads or agricultural land.

I don't think this is a meaningful comparison because they are not interchangeable and they exist independently of each other. The large footprint of farmland and roads doesn't make solar appealing in comparison, it just means that other facets of civilization are worse in terms of land use. To me, at least, just because something is way worse does not mean the other thing is acceptable because of it.

I also believe the amount of land we would need to convert to solar would be mostly be newly developed land. We probably wouldn't be converting already productive and utilized land.

It is a meaningful comparison. Agricultural and road use is huge. The solar installation you linked looks huge, but really, I could just as easily link an image of a uranium mine. Some of them are positively enormous - but that doesn't mean that land use for nuclear is.

A pessimistic scenario for Germany requires about 2.5% of the area for 100% renewable energy with today's technology. In a very densely populated country not exactly blessed with loads of sunshine hours. Taking into account the possibility of dual use (PV on buildings, wind turbines on farmland etc) we'll probably use about two times as much land for renewables than we use for cemeteries. It's very manageable.

And you would cause untold destruction to amazon rainforests, among other things.

No, you can't just pave desert with panels and magically solve power generation without ugly environmental consequences, that doesn't work even in computer games.

> And you would cause untold destruction to amazon rainforests, among other things.

Why would putting all the panels in a desert do that to a rainforest on a different continent?

And how much of the Sahara do you think we’d need to cover in PV if for some strange reason we didn’t put any on rooftops, brownfield land, parking lots, car bodies, and (for most of the world) closer deserts?

http://www.wolframalpha.com/input/?i=area%20sahara%20%2F%20%...

Because, surprisingly, various ecosystems including Amazon rainforests are dependant on sand picked by wind from Sahara. Ecology can be weirder than you think, and having intercontinental dependencies is surprisingly common.

Sensitive enough that 0.5% land use change would do that?

I don't remember the exact numbers from studies, but EU-funded research in that area suggested vastly higher numbers as part of removing fossil fuel dependency

I suggest following the Wolfram Alpha link I gave above. My assumptions, to explain the magic numbers visible in that formula, are 20% efficient and 25% capacity factor.

(And the other person was actually saying electricity, which is what WA is inferring in that calculation)

Except it is not practical to colocate all of the worlds solar power in a single location, and wind farms are even less space efficient by orders of magnitude when compared to energy density of nuclear per area.

> All the affordable reactor designs with no risk of accidents or proliferation are just 10 years away like they have been for four decades.

So, like storage for renewables?

Seems to me, we're not concerned on R&D budgets, so we should pursue all relevant methods of decarbonisation, of which nuclear is a very promising one.

While I’m fine with making as much nuclear as is economical because it’s cheaper than batteries right now, we have had storage for renewables since at least the Hoover Dam (if not before), and electrification of cars alone (which we have to do anyway) is a larger scale of battery use than we need for meeting the needs of the electricity grid.

We are concerned on R&D budgets. Costs matter because costs represents material and personnel that needs to be devoted. We are also tight on time. Nuclear reactors take at least a decade to build.

Oh, and while we have lots and lots of people and know-how in renewables, battery tech and transmission technology. We don't have that many people who can build reactors, due to the anti-nuclear trend of the last three decades. You can bemoan that, and maybe building up nuclear during that time would have been a solution to climate change, but that doesn't change the fact that even if we wanted to build hundreds of nukes today, we would lack the specialists.

We also have a) existing working designs for nuclear power b) existing paper designs for improved nuclear power.

Meanwhile c) we are working on getting paper designs for storage that might or might not work to get renewables good enough.

The starting point is vastly different.

> we're not concerned on R&D budgets

Just curious, why do you think so? I do think this should be the case, but I just don't see it happening.

Mistyped, should have said "constrained".

In the planetary scale, paying a few $10bns or $100bns is nothing, especially against the backdrop of global warming damage. I don't think we should skimp on researching nuclear in this context, "because renewables are cooler".

I think we need a new "nuclear Trinity project" (only this time for energy generation!) or a SpaceX-type enterprise. Iterate, build a simple, single, safe design, and deploy it widely. Or fail, but not without trying.

Nuclear energy is already sustainable with technology we have, breeder reactors and fuel reprocessing. They have been built since the 60s, some are still in operation, and more are under construction in India and China, where there is still an appetite for nuclear power.

We have this stuff on paper.

Stuff tends not to work out in practise. It costs more, it's unreliable etc.

If this were a solved problem why is there so much nuclear waste that has not been bred and reprocessed?

Reprocessing works fine in practice, as others have mentioned, it’s uncommon because it’s politically unpopular. Partially because everything related to nuclear anything is politically unpopular, partially because having high-purity plutonium lying around poses nuclear weapon proliferation risks. Though this can be avoided by breeding and reacting in situ.

> why is there so much nuclear waste that has not been bred and reprocessed?

You may be inclined to wonder why there is so much nuclear waste at all. After all, we could just melt it, dilute it into a slag with a bunch of silicon, cart it off to a boat and dump it into a deep ocean trench if we wanted to be safely rid of it. But we don’t want to be rid of it. It’s extremely expensive to produce and extremely valuable, and any permanent solution for storing nuclear waste needs to be reversible in case we ever want it back for reprocessing.

>If this were a solved problem why is there so much nuclear waste that has not been bred and reprocessed?

Because naysayers have had a dominant influence over nuclear policy since Chernobyl.

Because reprocessing is problematic politically, not technically. Yes, reprocessing involves some ridiculous chemistry, but we know how to deal with it. What we don't have is political will, especially when anti-nuclear activists are joined hand-in-hand with war mongers crying about nuclear weapons if anyone tries to go for plutonium economy (France and Japan are considerable way there).

I do not understand why this comment is getting votes. The doomer perspective alone should be disqualifying... While we can't completely prevent any climate change, we have already significantly bent the curve and our efforts now are important - 2 degrees warming vs. 4 degrees is incredibly material.