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I sometimes wonder if you could make a much safer nuclear plants with TEGs. There would be next to no active processes and moving parts, no pumps and coolant an
by rich_sasha 1y ago
I sometimes wonder if you could make a much safer nuclear plants with TEGs. There would be next to no active processes and moving parts, no pumps and coolant and circulation. Use nuclear magic to make the hot side, cool with ambient temperature.
No doubt this would be less energy efficient, but perhaps you reap so much savings by not having to worry about water circulation that it's worth it.
- deleted 1y ago[deleted]
- jkkr 1y agoNuclear plants sometimes aren’t even worthwhile at their current efficiency. Even if TEGs simplified things mechanically, you’d still face the problem that nuclear often can’t compete (with renewables) in direct a comparison (setting aside overall strategy for base load and stuff).
- iTokio 1y agoYes I wonder if with the current trend, solar might become the real alternative, less expensive, less risky. But to be fair, you have to consider your « aside », because nuclear has the tremendous advantage of working when it’s cloudy, dark and you need the energy the most in the winter. I do not think that we can just compare the prices, or maybe we should also add the cost of storage (that is going down too) for solar. But currently a mix is probably the pragmatic approach.
- kristopolous 1y agoIt's going to be solar + wind + battery. That's where the economics are at. Sodium batteries are just coming online now https://en.m.wikipedia.org/wiki/Sodium-ion_battery https://en.m.wikipedia.org/wiki/Sodium-ion_battery - lithium is getting phased out. Nuclear can't compete. https://en.m.wikipedia.org/wiki/Levelized_cost_of_electricity https://en.m.wikipedia.org/wiki/Levelized_cost_of_electricit... Maybe in some far off future nuclear will have a role... But the global energy investment markets paint a very clear picture: solar + wind + battery is the way.
- ekianjo 1y agoWind + solar is just adding another failure mode for when there is no wind. There are many places without adequate wind speed. Nuclear does not care about either, and has the highest energy density on top of that.
- masklinn 1y ago> when there is no wind. Or when there’s too much and you’re melting your grid.
- thomasmg 1y agoNo, you just turn off some windmills.
- masklinn 1y agoThat's genuinely not how it works. You can see it every spring as Germany wholesale prices go negative to try and offload as much electricity as fast as possible to keep their grid from falling over.
- thomasmg 1y agoWind turbines can, and are, turned off (by turning, feathering the blades, and braking). There are two main cases: high wind / storm, and too much electricity in the grid. Photovoltaics can also be turned off. The main reason for negative electricity prices are inflexible generators, eg. nuclear and coal, because they can't easily (cheaply) ramp down or shut off. Sometimes it is cheaper to let prices go negative than to use emergency mechanisms (that do exist). Negative prices are not all bad: they are an incentive for storage / flexible demand to step in. Specially, a negative price does not mean the grid is melting.
- jacquesm 1y ago'Too much electricity in the grid' is a wrong way of expressing it, just like you can't have 'too much fluid in a pipe'. What happens is that the line voltage creeps up because loads are lagging further behind compared to generation. And like you wrote, that's controlled. Agreed with the rest of your comment, especially the bit that pricing is mostly controlled by the worst parties, not by the best. What we are simply finding out is that a grid designed mostly for baseline loads needs fast response generation (for instance: half of the UK putting their kettle on during half time requires so much extra power that pumped storage becomes a good alternative). And conversely, that if you change the mix considerably that you're going to have to have more control over the cumulative effect of many smaller generators. But there are already standards for dealing with that even absent remote control of resources: as soon as the local grid voltage that the inverters in modern wind and solar plants see exceeds a very specific maximum for a proscribed period of time they fully autonomously back off their capacity until they are well below those maximums again, and then slowly ramp up to avoid causing grid instability due to oscillation. What grid balancing is all about is to make this all financially optimal, it has relatively little to do with the safety of the grid, it is simply a way to extract maximum capacity without affecting that safety. A coarser mechanism would simply incur some more waste, but given the amounts of money involved it pays off to tune this.
- MrBuddyCasino 1y ago> setting aside overall strategy for base load and stuff Energy got increasingly expensive in Germany the further the Energiewende agenda advanced, to the point that we’re now rapidly deindustrialising. Turns out base load kinda matters.
- peterashford 1y agoNothing to do with being reliant on Russian oil at all? All the fault of renewables?
- MrBuddyCasino 1y agoYes its a doubly idiotic fuckup. Unfortunately we we have incredibly dumb leadership, deciding to retire our last nuclear reactors even though our last hope, cheap Russian energy, has halted.
- jacquesm 1y ago> to the point that we’re now rapidly deindustrialising That's not exclusively due to the price of energy, though it is a factor, there are other factors (such as the price of wages) that are much larger factors. The biggest simply being that China is outcompeting Germany on its own strengths through a combination of a lack of environmental regulations, cheap labor and state subsidies at a level that the EU would not tolerate.
- derriz 1y agoWhere are you getting your numbers? The numbers I’ve seen indicate that non-household electricity prices in Germany have been stable for decades - fluctuating around the 35€/MWh mark until the crisis in 2021 - which affected all European countries - and is currently back at roughly that level. Taking into account of inflation, the wholesale cost of electricity in Germany has fallen slightly over the last 2 decades in real terms.
- realusername 1y ago> (setting aside overall strategy for base load and stuff). You can't really set aside the reality of the electric grid, you have to do with it.
- cenamus 1y agoEspecially at their price point, the new british one is bound to cost like 40 billion pounds in total, that's far off from solar+batteries. I'd love to have more modern nuclear, but I don't see it happening anymore, no expertise in building them anymore, cost and time overruns all over...
- somat 1y agoSort of, They are called Radioisotope Thermoelectric Generator (RTG) used where you need a small amount of super reliable power. Mainly used on deep space missions where there is not enough sunlight. The soviets also used them in unmanned deep north lighthouses. https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge... Neat tech, but very inefficient, to make it efficient fluids start needing to be moved around which hurts reliability. The next step up are pebble bed reactors, I don't think any have been built but the idea is to have self contained fuel "pebbles" enriched enough to get hot but with enough built in moderation so they can never melt down. Then a traditional heat engine is bolted on. https://en.wikipedia.org/wiki/Pebble-bed_reactor https://en.wikipedia.org/wiki/Pebble-bed_reactor
- rich_sasha 1y agoRTGs aren't quite the same, in that they use simple radioactive decay, no? And cooling in space is really hard.
- prox 1y agoWould this increase in performance they discovered make deep space satellites more powerful?
- jacquesm 1y agoNot for the ones already launched and we're not launching any of those in the near future, especially not with the current batch of governments. And I'm not convinced that particular discovery would yield that kind of performance increase for such an application. There are just too many things different in the environment alone.
- deleted 1y ago[deleted]
- perlgeek 1y ago> Use nuclear magic to make the hot side, cool with ambient temperature. If you use ambient temperature for cooling, you are severely limited in your total power output. Like, we're talking about less than a megawatt output (depending on how big the ambient heat dispensers are) compared to the ~1GW of a regular old nuclear plant. You might say: that's fine, let's just build many small ones. But you still need to track your radioactive material, make sure it's not stolen etc., which is a lot of overhead per installation.
- rich_sasha 1y agoI don't entirely follow. A lot of existing nuclear plants use ambient temperature for cooling, via cooling towers, no? They use pumped coolant to get the heat out of the reactor, sure, but the cold end is just air. Also, I guess you could have the hot end very hot too..? This improving efficiency. Especially if, by virtue of cooling being safer, you could run it at a higher temperature (less safety margin needed).
- Retric 1y agoCooling towers are active not passive cooling. They don’t work without pumps.
- rich_sasha 1y agoThey aren't passive but only dump heat into ambient temperature. Which I thought is the bit you objected to.
- Retric 1y agoActually they use evaporation not just ambient temperature. Explanation starts at ~minute 4. https://www.youtube.com/watch?v=tmbZVmXyOXM https://www.youtube.com/watch?v=tmbZVmXyOXM
- perlgeek 1y agoI'm familiar with some civil nuclear power plants, my father worked for decades in the industry, and I did some internships too. (No contact with nuclear power on submarines / carriers) All the designs I know of have a pumped (active) cooling loop for the reactor, then a secondary loop where the coolant (typically water) evaporates and drives a turbine, and that secondary loop is then coupled to either river water cooling or evaporation towers. (There might even be another intermediary cooling loop, not entirely sure). (You don't want potentially radioactive water to interact with your turbine directly, makes it a nightmare to maintain). > Also, I guess you could have the hot end very hot too..? There are some limiting factors: * melting point of your fuel (you really want that to remain solid, so you can control where it is) * The reactor core is usually contained in a pressure vessel, which is made out of steel. Steel becomes weaker with higher temperatures. Switching to other materials is super expensive (harder to machine, fewer people are good at machining it etc.) * You really want to be able to reliably move fuel rods and control rods in and out of the reactor; thermal expansion must be taken into account. At the same time, you want as little leakage as possible out of the reactor core.
- amelius 1y agoWhy is it safe to have no coolants around when things run out of control?
- gonzo41 1y agoYou can build fixed power reactors where they don't go critical if cooling is lost. It's just the cost more and they have a capped output. Pebble bed reactors are like this.
- amelius 1y agoI mean, you probably want multiple layers of safety ...
- rich_sasha 1y agoAlmost the entirety of safety issues with existing reactors is around cooling them. Bad things happen when you can't cool them. There's many ways in which this can happen in existing reactors. You may have a catastrophic leak and lose the coolant - and you can't just send some welders in, what with radiation, superheated steam etc. The pumps that push the coolant around might fail. Etc. etc. Even when you "switch off" the chain reaction, the fuel rods keep emitting heat from the decay of transient radioactive elements, enough to need active cooling for days or weeks. So a lot of new reactor designs revolve around eliminating such failure modes. NuScale for example, IIRC, don't use pumps to circulate the coolant, and that's one thing less that can break. What I'm daydreaming about simply cannot stop working, in terms of cooling. You have something hot in the middle, you let all the heat get our naturally, and you harvest some of it along the way.
- DeepSeaTortoise 1y agoNuclear power plants aren't inherently any more unsafe than the nuclear material itself before having been mined. What makes them potentially unsafe is nuclear technology having an incredible energy density, which can be misused and the radioactive material being active even without prior activation. The latter makes many radioactive isotopes a very effective poison. And misuse or bad practices are a general problem. One can build awful buildings, toys or government structures, too. And if you have a look at what the worst reasonable non-political consequences from a nuclear powerplant meltdown can be, they're surprisingly harmless. We have to Soviets to thank for their absolutely incompetent response to the Chernobyl meltdown, that we have a good idea of the long term effects. The powerplant never stopped operating, people kept working there every day for decades. Hundreds of people were never evacuated and hundreds more returned within weeks. Just to put this into perspective: Chernobyl was effectively a dirty super-bomb dispersing 50t of highly active radioactive materials and yet the death count among anyone who didn't approach into rock throwing distance remains 0.
- JumpCrisscross 1y agoCould you run a plant with less-refined fuel if it doesn’t need to temp up to boil water?
- aeonik 1y agoYou could literally run it on the waste. The question becomes is the power production worth the operation and maintenance costs.
- privatelypublic 1y agoAny nuclear reactor capable of generating power via TEGs can be made to have an identical safety profile, but run turbines. Outside of RTGs.