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Comment by nostromo | Hacker News Reader

Nuclear is low-carbon, but it's not renewable. Earth has a set amount of uranium that is destroyed when creating energy.

Currently we have about 200 years of uranium available for economical extraction. But if we tried to replace all coal with nuclear, we would be out within a few decades. Then we'd need to move to other non-renewable materials (thorium?) or start mining astroids.

http://www.scientificamerican.com/article/how-long-will-glob...

And the mining of uranium looks awfully similar to the mining of coal. (Of course you need far fewer uranium mines for the same amount of energy.)

https://en.wikipedia.org/wiki/Uranium_mining#/media/File:Ara...

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Sure, but the need to transition away from non-renewable energy is not the goal that Bret is working on (limiting anthropogenic CO2 and therefore its atmospheric concentration). I think everyone agrees there is a much longer "grace period" before those resources would be depleted than there is for even the slowest of hypothesized AGW scenarios. So if accelerating the depletion of uranium (ha) would solve the more pressing issue then it makes sense.

Perhaps your concern is that people would get complacent with what can only be a temporary solution (even if temporary means thousands of years), but if AGW is regarded as an urgent and critical problem to solve, I don't think you can afford to ignore the opportunity.

> Currently we have about 200 years of uranium available for economical extraction.

In that 200 years a whole lot more uranium will become available for economical extraction, exactly the same as what happened with oil and natural gas.

Peak uranium is about as believable as peak oil. And given that uranium is a tiny fraction on the operating cost of a nuclear plant, it is viable at much higher prices. Which means much lower yield ores can be used for fuel. |

And then there is thorium, which we have more of than we know what to do with.

Then there's mining Uranium from the Ocean which puts a ceiling on the price of Uranium at 15x the current price. Economically unfeasible today, but it is the max it could ever cost.

http://spectrum.ieee.org/energy/nuclear/nuclear-fuel-from-th...

Why is peak oil not believable? There might be more of than we thought, but we're pretty sure there's not infinitely much. It has to happen eventually.

When I say peak oil isn't believable, I mean in the sense that over the last 15 years, especially before shale oil, the west was bombarded by "experts" saying peak oil had already occurred, and oil would be unafforadable in just a few years as prices skyrocketed. Any argument that involved technological progress in reducing the cost of mining hard to get oil was mocked and lambasted as hopelessly naive.

I of course don't believe that there's an infinite supply of oil. Only that we haven't exhausted the millions of years of dead trees, which before the the emergence of white fungus with the ability to eat them, covered the Earth a hundred meters deep in some places.

It is a fact that conventional oil has already peaked, sometime in the last 5-10 years. Shale oil, tar sands and the like are picking up part of the slack, though their EROI is lower (though still a little better than renewables) and have a bunch of other technical and environmental issues. At some point we'll have to bite that bullet.

The problem with your remark was caused by the doomers who took the flag of Peak Oil (TM) to claim that everything was going to crash and burn when the peak reached. Then when reality turned out to be more nuanced than that, the general public just went on to laugh the whole thing off and keep ignoring the real issues.

In an ideal world, we should be in the middle of a crahs program to retool the whole industry to work with renewables and mitigate the effects of other related issues like climate change/global weirding... but instead, we are doing too little and too late.

You say doomers took the flag to claim everything is going to crash, but then say we should be in a crash course to change off of oil. Yet we have several decades of known oil reserves, maybe dozens, with room to grow usage.

And given the rapid pace of EV cars, the market is going to solve the oil problem far faster than any mandated crash problem, well within the dozens of years of oil reserves we have left are exhausted.

It takes decades to retool the whole industry. Inventing new forms of energy is just the begining, you have to make those available in wide scale. Whole new industries have to be born and old industries have to be let fade and die.

It is not that the house is on fire right now. It is that we live in a house with no fire alarm and not up to code, but everybody is dragging their feet to fix that because "it has never happened before".

And since you mention EV cars... where do you think the electricity to power them is comming today? What percentage comes from non-reneweable sources? And what percentage of the car market lives near the bigger sources of reneweable sources?

Peak oil and peak uranium are a simple deduction from the fundamental theorem of calculus.

The only thing to dispute is "when."

Along with the fact uranium is not the only source of nuclear energy, "nonrenewables" that can supply current rates of consumption for thousands of years are effectively not "nonrenewable" in the sense we usually mean.

Sure, it can't carry us to a Kardashev Type II civilization, but we're only responsible for the problems of today.

Is that a problem (the non-renewability)? Even if we deplete our available uranium while transitioning to fully renewable energy, we've still quit dumping carbon into the atmosphere. At that point, economic pressures are adequate to force us to renewable energy, I think.

From your first link:

> Two technologies could greatly extend the uranium supply itself. Neither is economical now, but both could be in the future if the price of uranium increases substantially. First, the extraction of uranium from seawater would make available 4.5 billion metric tons of uranium—a 60,000-year supply at present rates. Second, fuel-recycling fast-breeder reactors, which generate more fuel than they consume, would use less than 1 percent of the uranium needed for current LWRs. Breeder reactors could match today's nuclear output for 30,000 years using only the NEA-estimated supplies.

Unless we build a very large number of conventional reactors over the next couple decades, which isn't likely, we've got time to develop more advanced reactors.

> Nuclear is low-carbon, but it's not renewable.

Sure it is, Nuclear doesn't just mean uranium fission, fusion reactors are nuclear as well and they will be a big thing in the future and we get better at doing it.

Just 20 more years now... ;-)

Progress takes time, but it is the future of energy.

> fusion reactors are nuclear as well and they will be a big thing in the future

I used to think this as well, but I'm not sure I believe it anymore. I suspect that by the time we're able to make fusion power work, the solar/wind/batteries combo may be so cheap as to make fusion pointless for mainstream power generation.

Solar is fusion being mainstream :) however, smaller more local reactors will I think still be a huge part of our future as well.

> Nuclear is low-carbon, but it's not renewable.

So is the sun.

But seriously, the amount of fissile fuel we have available greatly would suffice for hundreds of years of energy, and leave very little waste, if we only invested in nuclear technologies a bit more.

This reminds me of Mendeleyev's concerns about major environmental problem of the XXth century city - horse poo. Megatons of horse poo. How could possibly we handle that? History proved that technology can save us from predicted environmental impact of horses made by one of the brightest minds of its time. Same thing with uranium depletion problem. In 100 years we probably shall have effective thorium reactors, thanks to Norway and China, solar power stations on the Moon and who knows what else. Just lets don't stop thinking and tinkering.

Nuclear is not really low carbon when you take into account the amount of concrete you need to build a modern reactor.

Unless we have a major breakthrough in mining uranium or we actually manage to make breeder reactors safe and cost effective then nuclear is not really a viable option.

Edit. I should have been more precise in my language. By low carbon I am meaning minimal carbon, not just lower carbon. Natural gas is lower carbon, but it is not low carbon.

It really doesn't matter too much because there just isn't enough uranium to make it a viable alternative at the scale we need to have a significant impact on carbon emissions.

In the time honoured tradition of shooting ourselves in the foot by making better the enemy of best?

Neither concrete, nor uranium mining have to burn fossil fuels (and CO2 sequesting concrete is a real thing). They are decoupled from their fuel source, but the lack of incentives to improve that situation at present (due to the near entirety of electrical generation being fossil fuels) is the bigger problem.

Making cement by its nature releases a large amount of CO2 and accounts for 5% of total emissions [1]. I do agree that we are not really creating the right incentives to improve things.

1. https://en.m.wikipedia.org/wiki/Environmental_impact_of_conc...

But note from that page: energy use is 40% of the CO2 expense of concrete. So assume we can pretty much eliminate that by other means.

That leaves a 50% chunk due to chemistry. For that we have things like eco-cement, or carbon sequestration technologies.

In addition to what XorNot7 said, the amount of concrete needed to build a nuclear power plant is trivial compared to the total amount consumed annually by the construction industry.

> Nuclear is not really low carbon when you take into account the amount of concrete you need to build a modern reactor.

That sounds really preposterous.

It's less than the concrete for an equivalent amount of wind power. Neither is all that significant compared to fossil fuels.

It is not just the the total mass of concrete needed, it is the technical requirements and the difficulty of building the nuclear structures that uses massive amounts of carbon derived energy.

I'd like to see specific numbers on how that difficulty translates into carbon emissions.

Estimates I've seen that showed large CO2 emissions from nuclear were wildly overblown. In one case, they assumed that nuclear power would lead to full-scale nuclear war and included the carbon impact of the war.

In any case, if the NRC would let companies start building molten salt reactors, we could have much simpler construction. For starters, they'd be at atmospheric pressure, eliminating the need for large steel-reinforced containment domes and high-pressure reactor vessels. We could mass-produce reactors in factories or shipyards.

>I'd like to see specific numbers on how that difficulty translates into carbon emissions.

So would I. Getting good data in this area is near impossible.

For something complex you can use the rough rule of thumb that the dollar cost is proportional to the emissions - as complexity increases the actual emissions converge towards the economy wide average. On this basis the emissions from building a current generation nuclear power plant is very high.

Nuclear plants cost a lot up front but they produce a lot of power for a long time. Per MWh they're not that expensive compared to renewables. Taking the government's estimates for capital cost, we have onshore wind at $58/MWh, nuclear at $70/MWh, hydro $71, advanced coal $77, solar PV $109, offshore wind $168, solar thermal $192.

But I don't think anyone would claim that the construction of a modern coal plant has significant emissions compared to actually burning the coal.

https://www.eia.gov/forecasts/aeo/electricity_generation.cfm

How many recent Nuclear plants have been built that will be able to generate power at $70/MWh? All the recent ones have had massive cost and time overruns.

This report from the UK is interesting reading [1].

1. http://www.parliament.uk/documents/post/postpn_383-carbon-fo...

Yes, that report is interesting. It says, "Nuclear and renewable generation generally have a low carbon footprint." In the charts, nuclear has a significantly lower carbon footprint than solar PV, geothermal, and small/medium wind, and only a slightly higher footprint than large wind.

Getting accurate information on the carbon footprint of nuclear energy is hard. The best paper I have seen on this is Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation [1]. Their range is from 9 to 110 g CO2-eq/kWh by 2050.

1. http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012....

Ok let's go with that. By comparison, coal is around 900, and gas around 500, according to the U.K. document and the EIA [1].

Once we have molten salt reactors, nuclear's impact should drop further, both because they need much less concrete, and because they need much less uranium. Even Terrestrial Energy's basic version is 6 times more fuel-efficient than conventional light-water reactors. Transatomic's is 75 times better than LWRs, and can be fueled by our existing nuclear waste stockpiles, which could power all of civilization for decades, no mining required.

But maybe you want to stay with currently deployed technology. In that case, you have to take into account that we mostly back up renewables with natural gas, which is five to fifty times worse than nuclear.

1. https://www.eia.gov/tools/faqs/faq.cfm?id=74&t=11

That's an interesting reference; turns out they have similar estimates for other power sources. For wind they have 3 to 45 g CO2-eq/kWh, not counting fossil backup.

http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012....

It is still a drop in the bucket compared to coal-powered generators running 24x7

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