[credit_guy]

Here, I'll come up with a proposal. If Congress is serious about climate change, then they can ask (and allocate the budget) the Department of Energy to procure and operate a bunch of naval nuclear reactors. With whatever internal regulations they have, the US Navy has not had a single incident in their entire history of operating nuclear reactors. They are also quite cost effective, for example the cost of the 2 reactors A1B [1] that power a Gerald Ford carrier is about $1 BN. That comes to about $2BN/GW, which is about a tenth of what a civilian reactor costs. The US Navy builds about 1 carrier every 4 years so that comes to 1 reactor every other year. If the DoE gets the Congressional mandate to procure a few reactors per year, the cost is going to surely come down. Also these reactors don't need refueling for about 2 decades, while civilian reactors are refueled every 1.5 years.

[1] https://en.wikipedia.org/wiki/A1B_reactor

[sir_bearington]

This is not a very good idea for several reasons. Naval reactors require fuel that is much more enriched than normal reactors. They also produce significantly lower electricity. The Palo Verde facility produces 3GW of electricity and cost $11B in 2019 dollars. Each of the A1B reactors generates 125 MW. Life span of the reactor is not specified, but it's predecessor the A4W had a 23 year life span. By comparison, new nuclear plants are slated to last 50-80 years.

The net cost per GWh of electricity of the naval reactor is significantly worse than commercial plants. This is to be expected, because naval reactors are built to be compact and withstand the rocking of a ship at sea. Commercial reactors can leverage the efficiency of larger scale, and are built to be much more long lasting.

[credit_guy]

An A1B generates 125 MW electricity, but also 260 MW of additional thermal power used to power the propellers. If you convert the latter one to electricity at a 45% efficiency (typical efficiency for a generation IV nuclear power plant steam turbine), you get 117 MW, for a total of 242 MW. Two reactors could produce then about 0.5 GW. At a $1 BN cost, that's $2 BN / GW.

Palo Verde was brought online more than 30 years ago. If you look at Vogtle 3-4 (to be brought online in the next 2 years... if we are lucky) or Hinkley Point C, you'll see projected costs of respectively $25 BN for 2.5 GW and $32 BN for 3.2 GW. In both cases that comes at $10 BN/ GW. That is 5 times more expensive than the naval reactor.

Now, as you said, the cost of a naval reactor is very likely inflated by the exacting demands of its military usage. It needs to be compact, to work on a rocking ship, presumably it needs to be able to survive a certain amount of abuse that's to be expected if a ship/boat actually participates in combat, and I'm sure there are 100 other things that I'm missing here. All these factors make military devices absurdly expensive compared to the same devices intended for civilian use.

The logical conclusion is that if DoE wants to repurpose naval reactors for civilian use, then it can achieve significant cost savings. What I'm saying is that even not factoring these savings in, you still end up 5 times cheaper than the civilian reactors that are currently being built.

Edit: The lifespan of a Gerald Ford-class carrier is expected to be 50 years. The Nimitz aircraft carrier was launched 49 years ago. They do not replace their reactors. So, a naval reactor is designed to work for at least 50 years.

[sir_bearington]

You also need to build a secondary containment vessel for the reactor, which is a significant expense. Because the cost of this containment is a function of surface area and generating capacity is a function of volume it's better to increase size. You also need to build steam turbines, heat exchangers, transformers, etc. The cost of the reactor is only a portion of the cost of the whole nuclear plant.

> Palo Verde was brought online more than 30 years ago. If you look at Vogtle 3-4 (to be brought online in the next 2 years... if we are lucky) or Hinkley Point C, you'll see projected costs of respectively $25 BN for 2.5 GW and $32 BN for 3.2 GW. In both cases that comes at $10 BN/ GW. That is 5 times more expensive than the naval reactor.

And by comparison you have the Taishan plant built for $7.5B with 3.5 GW generating capacity. If we want to go around cherry-picking examples we can also cherry-pick the cheap plants.

We have already tried using maritime nuclear reactors for grid generation. The first nuclear plants brought online for grid generation were maritime reactors repurposed for grid production. Larger purpose-built reactors won out.

[epistasis]

Vogtle and Hinckley aren't cherry picking expensive plants, it's cherry picking middle of the road.

VC Summer is expensive, many billions spent and nothing to come of it ever.

Where do your cost numbers from Taishan come from? How do you come to costs that are believable from massive Chinese construction, or at least a cost that might be transferable at all to the rest of the world?

The history of nuclear is very clear: keep on increasing costs throughout construction, just enough that, taking into account the sunk cost fallacy, it makes sense to soldier on. VC Summer overshot that, and had massive corruption in the auditing of all parts of the project. Somehow Vogtle continues.

We literally do not know how to build nuclear in a cost effective manner any more. We can't structure contracts in the right way, we can't perform engineering to a high enough degree to make constructive plans. At Vogtle they literally poured the wrong concrete, and had to go back and get the design recertified with the NRC, because the original design was impossible to build, and on site they just plowed ahead with what they thought they could build. This is the level of incompetence, ball dropping, and bad contract structure.

Perhaps this sort of thing is fixable, but not on any reasonable timeline. The management is rotten from the top, so there's nobody that we can even order a nuclear reactor from.

Suppose you had $7.5B and wanted 3GW of nuclear at one of the many sites in the US that would welcome nuclear and its jobs. Who do you even bring that money to in order to build it? Rosatom? Are they going to meet NRC standards?

[bob29]

Great by the same logic you should use a commercial reactor over a naval reactor, you should also just use a different power source over nuclear.

[sir_bearington]

What other power source generates carbon-free energy without intermittency or geographic dependency?

[lostlogin]

The construction, fuelling and cleanup of a site is far from carbon zero. There is also a geographic dependency, or should be.

Nuclear power puts out more CO2 than solar or wind according to Nature (hydro isn’t mentioned for some reason).

“carbon emissions ranged from 1.4 grammes of carbon dioxide equivalent per kilowatt-hour (gCO2e/kWh) of electricity produced up to 288 gCO2e/kWh. Sovacool believes the mean of 66 gCO2e/kWh to be a reasonable approximation.”

https://www.nature.com/articles/climate.2008.99

[epistasis]

Solar + wind with storage and a grid. The parts are all there, and it's cheaper than nuclear today.

[sir_bearington]

No, the storage part is not there. Hydroelectric storage is expensive, takes a long time to build, and is geographically dependent to boot. Only ~5 minutes of global electricity storage can be provided with batteries using all known lithium deposits. Only 19 minutes worth of storage is available with all the lithium we can mine with today's equipment [1].

This is why plans for a solar and wind grid assume that some silver bullet is going to provide dirt-cheap and nigh-infinitely scalable storage.

1. https://dercuano.github.io/notes/lithium-supplies.html

[epistasis]

These are not particularly relevant or helpful comparisons for knowing whether lithium ion is ready to deploy now (it is), or whether storage will be achievable with lithium ion and other chemistries (it will).

This is only looking at currently known reserves, a number which has doubled in only a few years. It also compares it to total energy consumption, a meaningless comparison for the coming decades.

Further, the same industrial capacity for lithium ion batteries also works for sodium chemistries. We have only focused on lithium because the primary applications are in mobile things at the moment: cars and mobile devices, where the weight advantage of lithium is important.

For grid storage, weight and specific energy are not important, and sodium chemistries will be ideal. There are also entire classes of flow chemistries that are in their infancy.

But what is mature and cost effective is lithium ion storage. The only place where we have open data about the feelings of investors, the PJM and ERCOT interconnection queues, storage is being deployed in GW comparable to new natural gas GW. This number alone, the GW and not the GWh, tells us that investors think this new tech is ready and deplorable. And it is falling in cost exponentially. Other battery tech is following and dropping in cost too, but lithium ion is benefitting from having existing markets that can fund massive learning.

[imtringued]

Nuclear power plants are thermal power plants and that means they need cooling. The power density of nuclear power plants is so high that most of them can't be placed near rivers because rivers have a variable flow rate.

If the flow rate is too low you risk killing aquatic life in the river ecosystem so instead the nuclear plant is turned off. You can avoid this by placing the nuclear power plant near the ocean. That's what the Japanese did with the Fukushima power plant even though it's a tsunami prone area.

[sir_bearington]

What gives you the idea that nuclear power plants can't be placed near rivers? Almost all that aren't on the coast are near rivers.

And they don't need to use potable water. The Palo Verde plant uses wastewater.

Because humans need water to survive, all population centers are built with access to water. Thus, cooling is available pretty much anywhere one would want to build a nuclear plant.

[bob29]

So you can build nuclear in a tsunami zone? in a seismic zone? in an area without cooling?

So you can mine and enrich uranium without carbon?

Nuclear does none of the things you fantasize it to do really.

[sir_bearington]

> So you can build nuclear in a tsunami zone? in a seismic zone? in an area without cooling?

Yes, you harden the structure against tsunamis and earthquakes. That's part of why nuclear plants are so expensive.

Atmospheric cooling can indeed be done anywhere. It's typically easier and more efficient to use water cooling. And humans need water to survive, and thus population centers are built near sources of water, water cooling is almost always an option. Also nuclear plants can be cooled with seawater.

This is in stark contrast to hydroelectricity which needs both a river and a valley to be viable. Geothermal power needs magma near enough to the surface to heat water into steam.

> So you can mine and enrich uranium without carbon?

I don't see why not. Use electricity produced by nuclear plants to drive centrifuges. Also use said electricity to power mining equipment.

And you didn't answer my question: What other carbon-free sources provide energy 24/7, besides ones that need very specific geography like hydroelectricity and geothermal power?

[thomasmg]

> What other carbon-free sources provide energy 24/7

Wind + solar + biofuels + waste + batteries.

Batteries are primarily for peak usage, and it could be car batteries (V2G).

Biofuels are primary for seasonal usage (e.g. winter).

Nuclear is too expensive if you take into account the risks, which are currently externalized.

[bob29]

Easy, there’s many: 1) Solar + transmission lines. It’s always sunny somewhere

2) wind + transmission lines, always windy somewhere

3) use some energy produced by hydro to manufacture some concrete river beds and reservoirs

4) use some of the energy produced by 1-3 to dig real deep for geothermal everywhere

5) Ocean thermal energy conversion

Don’t get me wrong , I’m not anti nuclear , I’m a huge fan of the big reactor in the sky it produces all we need with perfect reliability there’s no reason to do something as dumb as trying to build terrestrial reactors

[rurounijones]

> So you can build nuclear in a tsunami zone? in a seismic zone?

Why not? It worked at Onagawa: https://www.sciencedirect.com/science/article/pii/S259012302...

[lostlogin]

It’s also failed. Why not just avoid it? That’s the approach taken according to your link.

The solution to the problems faced at Onagawa were to decommission the plant, and this process would take longer than the duration for which the plant actually ran.

“the 2011 events strongly influenced the decision to decommission the Onagawa Unit 1 early, brought to attention the length of the decommissioning process (which will surpass the operation stage)”

[philipkglass]

The US stockpile of HEU would be depleted a lot faster this way, but enrichment could start again. I don't see major downsides to this proposal. Thanks for providing a specific and plausible idea!

[Hammershaft]

Thats a great idea. I'm trying and failing to find gotchas.

[credit_guy]

There is a potential gotcha: proliferation potential. The naval reactors use highly enriched uranium; if it falls in the wrong hands, you can end up with someone being able to build a bomb. That's why I said such a program needs to be run by the Department of Energy, the same department that has to maintain the nukes. I don't have a personal objection to this, but a lot of people would be unhappy with an essentially military program to be established for a problem that is not military in nature.

[obelos]

Hopefully the DOE will continue to be led by a person who didn't previously campaign on disbanding it!