10 ms·

The keyword in Small Modular Reactor is Modular. 5mw is not "too small for actual usage." You can connect many of them together in one plant to produce however

The keyword in Small Modular Reactor is Modular. 5mw is not "too small for actual usage." You can connect many of them together in one plant to produce however much power you want. Just like wind turbines, a typical design includes more than one.

masklinn 4y ago
Seriously, 5MWe is what, a few thousand homes? Low thousand if you need to plug in local commons and you’ve got lots of EVs around maybe. Alongside a few MWt to shed into district heating, that seems pretty nice in a distributed grid context. > Just like wind turbines, a typical design includes more than one. Wind farms are a thing because location is an issue, and there’s a lot of nimby-ism, so if you can plop down turbines you plop down a bunch. Though I guess nimby would also affect SMRs, location is way less of an issue, if you have space for a farm you might as well use a classical nuclear plant. Plus the capacity factor of nukes is way higher than turbines. Assuming SMRs follow the nuclear norm you don’t need to overbuild to compensate.
- pencilguin 4y ago
  Wind farms are a thing because a wind turbine can only be so big: for more power, you put up more of them. They are so cheap because all the costs are transparent, there is noplace to bury wholly-legal graft. A big farm amortizes fixed project management cost. Capacity factor of nukes is not so much more than of wind turbines, though if you have a bunch of nukes, it would be rare to have many of the nukes down at once other than for urgent retrofits. Steam turbines are down a lot, so nukes are always built with two or more. But the main thing is that nukes cost far, far more than the wind farm that produces as much; or, a wind farm at the same price produces many times the power, with near zero lead time and possibly negative decommissioning cost. After their contribution to the grid gets large enough, you build out storage, which incrementally reduces the fraction of time you spend burning NG or, later, ammonia. A farm of small nukes would cost quite a bit more to build than a big nuke of the same capacity, because all the systems are duplicated throughout. On the up side, the farm might be built incrementally with much less of the graft always attached to monster public works; you might save 75% vs a big nuke just on that basis. If you could get the first one going early, its revenue might help pay for subsequent units. But whatever the heat source, anything with a steam turbine is just not competitive anymore. That is another reason why fusion is a dead end: it is just very hard to compete with zero opex.
- mcbits 4y ago
  Speaking of farms, 5 MW is enough to power LED grow lights equivalent to 5-10 acres of sunlight (napkin/google math) that could be packed in small-footprint building with hundreds of layers of hydroponics. It still wouldn't be economical in the short term due to construction, water, nutrients, etc. But it's something solar can't possibly provide because there's only so much sunlight per acre. Long term, we could stop trying to farm every square inch of arable land on the planet, of which we're already farming about half.
  - acjohnson55 4y ago
    The idea of reducing the farm footprint is pretty exciting to me.
  - titzer 4y ago
    > we could stop trying to farm every square inch of arable land on the planet, It'll still be cheaper, thus it will still be done. Mark my words, we're giving nothing back to nature.
    - midoridensha 4y ago
      >It'll still be cheaper, No, it won't. One problem with arable land (i.e., land that's really good for growing crops) is that it's also usually land where people really want to live. Non-arable land is places like deserts and tundra, and almost no one wants to live there, for obvious reasons. So farmers are in competition with developers (and eventually property buyers) for using the best land.
      - titzer 4y ago
        I see you have not been to Iowa.
        midoridensha 4y ago
        Iowa, like that whole part of the continent, has brutal winters. There's a reason people don't want to live in the interior of the country: the weather on the coasts is much better overall. However, it is really good for growing certain crops, and that's why it's used for that, and also why America has historically had a huge advantage by being the "breadbasket for the world".
- derefr 4y ago
  Compare/contrast this question: electric car batteries are just big volumetric arrays of 18650 cells. If you know you need that much wattage — and you're manufacturing them yourself anyway — then why not make bigger cells, to reduce per-cell fixed-cost overheads and inefficiencies? I assume there is a good answer to "why not" here; and it's one that's probably related to the "why" for SMR.
  - XorNot 4y ago
    Cooling is one reason. Bigger batteries increase the surface area to volume ratio: heat produced in the active part of the battery has to be lost through the casing and into whatever cooling system you're system. Bigger have less surface area. You also have packing issues: cylindrical cells are basically optimal, because they distribute any internal pressure equally. If you play with something like the prismatic Prius batteries, then despite being larger you have far less options to pack them because you need to counter-pressure them horizontally or they swell and then fail.
- c2h5oh 4y ago
  > Seriously, 5MWe is what, a few thousand homes? Charging 20 teslas at maximum charge rate. Or 1k houses, provided it's general use and not electric heating. 5MW is 43.8GWh/year or an average annual power consumption of 8-12k people in the west (per capita consumption - so includes industry use). Accounting for peak vs average this is likely enough for 3-5k people.
  - CHY872 4y ago
    Charging 20 Teslas at maximum rate sure, but that could also be viewed as fully charging 1600 Teslas per day, or steady state providing the energy for about 12k Teslas (assuming 10-15k miles per year per car). Likewise, based on my own electricity bills, 1k houses is closer to 3000-5000. Obviously, peak load vs average load is very important so I wouldn’t expect the energy to go that far, but connected to a big battery… probably, right?
- stubish 4y ago
  One of the use cases for SMRs is to install them in decommissioned coal and gas power plants. They have a roof, and are already connected to the grid and roads, and near enough people to supply workers but not so close to supply protesters. The locals are much more supportive, because some of the jobs remain but the pollution they have first hand experience with will go. One of the major reasons for wind farms rather than isolated turbines is the economic and environmental cost of grid connections and roads needed for installation and maintenance.
  - masklinn 4y ago
    There are no jobs, one goal of SMR is to be completely enclosed and self-safe. When the fuel runs out, you swap the SMR.
- azinman2 4y ago
  The use case for these nuclear batteries isn’t to power NYC. It’s to be able to replace industrial needs for energy and heat at the source. A glass or cement factory could have its own power source that’s carbon free. It also means that hydrogen production can be considered green. It’s also great for rural communities that might otherwise have expensive/dirty electricity. The goal is for them to be autonomous for this reason: install it at some industrial site without any nuclear expertise. Have it shipped in fueled, and then shipped out to maintain or refuel. These are absolutely the future.
- cycomanic 4y ago
  Actually the capacity factor of offshore wind is around 60% that is similar to nuclear (~70%), not way higher. However the price of nuclear (in Germany) is 3x that of renewables, so it just does not make economic sense to build nuclear.
Gravityloss 4y ago
Wind turbines strive to be as big as they can, and they have grown a lot. Yet they are limited by physics and transport issues. Now you need to install thousands of turbines. Engineering With Rosie has a truly excellent video that analyzes many of the scaling laws: https://www.youtube.com/watch?v=Ze-zaW3au9Q https://www.youtube.com/watch?v=Ze-zaW3au9Q GE gas turbines for example are 35 to 570 MW. https://www.ge.com/gas-power https://www.ge.com/gas-power. They have stopped making smaller ones. There probably are even 100 kW gas turbines made by some companies but that's not used for major power generation (maybe as an airplane APU). You probably won't have these small reactors in towns of 5000 people run by some local operators, because nuclear technology requires so much special training and is so risky because of the potential radiation hazard. You might have 20 in one powerplant in a city, to provide 100 MW, as part of the energy mix (it's always good to have multiple sources). There is a certain threshold for nuclear technology. It's not the same as a diesel generator that anyone can put in their back yard. The risks are too high. Yet, the current reactors like the Olkiluoto 3 EPR in Finland at 1600 MW electrical power are too big and unwieldy and risky. When it turns on or off, it causes some problems to the rest of the grid. One reason for such a huge plant was there was a legal process to provide permission for one reactor. So if you can only build one, of course you try to make it as big as possible. This doesn't make sense from engineering sense - it probably would make more sense to build something like power plants of 4x400 MW reactors (the seventies plants are 2x400 MW reactors). So all in all, probably more optimal size for "small" reactors would be 20 to 200 MW. They're big enough that the radiation protection doesn't eat all the budget, yet they're small enough that you get to build many and can build a production line.

masklinn 4y ago

Seriously, 5MWe is what, a few thousand homes? Low thousand if you need to plug in local commons and you’ve got lots of EVs around maybe. Alongside a few MWt to shed into district heating, that seems pretty nice in a distributed grid context. > Just like wind turbines, a typical design includes more than one. Wind farms are a thing because location is an issue, and there’s a lot of nimby-ism, so if you can plop down turbines you plop down a bunch. Though I guess nimby would also affect SMRs, location is way less of an issue, if you have space for a farm you might as well use a classical nuclear plant. Plus the capacity factor of nukes is way higher than turbines. Assuming SMRs follow the nuclear norm you don’t need to overbuild to compensate.

pencilguin 4y ago
Wind farms are a thing because a wind turbine can only be so big: for more power, you put up more of them. They are so cheap because all the costs are transparent, there is noplace to bury wholly-legal graft. A big farm amortizes fixed project management cost. Capacity factor of nukes is not so much more than of wind turbines, though if you have a bunch of nukes, it would be rare to have many of the nukes down at once other than for urgent retrofits. Steam turbines are down a lot, so nukes are always built with two or more. But the main thing is that nukes cost far, far more than the wind farm that produces as much; or, a wind farm at the same price produces many times the power, with near zero lead time and possibly negative decommissioning cost. After their contribution to the grid gets large enough, you build out storage, which incrementally reduces the fraction of time you spend burning NG or, later, ammonia. A farm of small nukes would cost quite a bit more to build than a big nuke of the same capacity, because all the systems are duplicated throughout. On the up side, the farm might be built incrementally with much less of the graft always attached to monster public works; you might save 75% vs a big nuke just on that basis. If you could get the first one going early, its revenue might help pay for subsequent units. But whatever the heat source, anything with a steam turbine is just not competitive anymore. That is another reason why fusion is a dead end: it is just very hard to compete with zero opex.
mcbits 4y ago
Speaking of farms, 5 MW is enough to power LED grow lights equivalent to 5-10 acres of sunlight (napkin/google math) that could be packed in small-footprint building with hundreds of layers of hydroponics. It still wouldn't be economical in the short term due to construction, water, nutrients, etc. But it's something solar can't possibly provide because there's only so much sunlight per acre. Long term, we could stop trying to farm every square inch of arable land on the planet, of which we're already farming about half.
- acjohnson55 4y ago
  The idea of reducing the farm footprint is pretty exciting to me.
- titzer 4y ago
  > we could stop trying to farm every square inch of arable land on the planet, It'll still be cheaper, thus it will still be done. Mark my words, we're giving nothing back to nature.
  - midoridensha 4y ago
    >It'll still be cheaper, No, it won't. One problem with arable land (i.e., land that's really good for growing crops) is that it's also usually land where people really want to live. Non-arable land is places like deserts and tundra, and almost no one wants to live there, for obvious reasons. So farmers are in competition with developers (and eventually property buyers) for using the best land.
    - titzer 4y ago
      I see you have not been to Iowa.
      - midoridensha 4y ago
        Iowa, like that whole part of the continent, has brutal winters. There's a reason people don't want to live in the interior of the country: the weather on the coasts is much better overall. However, it is really good for growing certain crops, and that's why it's used for that, and also why America has historically had a huge advantage by being the "breadbasket for the world".
derefr 4y ago
Compare/contrast this question: electric car batteries are just big volumetric arrays of 18650 cells. If you know you need that much wattage — and you're manufacturing them yourself anyway — then why not make bigger cells, to reduce per-cell fixed-cost overheads and inefficiencies? I assume there is a good answer to "why not" here; and it's one that's probably related to the "why" for SMR.
- XorNot 4y ago
  Cooling is one reason. Bigger batteries increase the surface area to volume ratio: heat produced in the active part of the battery has to be lost through the casing and into whatever cooling system you're system. Bigger have less surface area. You also have packing issues: cylindrical cells are basically optimal, because they distribute any internal pressure equally. If you play with something like the prismatic Prius batteries, then despite being larger you have far less options to pack them because you need to counter-pressure them horizontally or they swell and then fail.
c2h5oh 4y ago
> Seriously, 5MWe is what, a few thousand homes? Charging 20 teslas at maximum charge rate. Or 1k houses, provided it's general use and not electric heating. 5MW is 43.8GWh/year or an average annual power consumption of 8-12k people in the west (per capita consumption - so includes industry use). Accounting for peak vs average this is likely enough for 3-5k people.
- CHY872 4y ago
  Charging 20 Teslas at maximum rate sure, but that could also be viewed as fully charging 1600 Teslas per day, or steady state providing the energy for about 12k Teslas (assuming 10-15k miles per year per car). Likewise, based on my own electricity bills, 1k houses is closer to 3000-5000. Obviously, peak load vs average load is very important so I wouldn’t expect the energy to go that far, but connected to a big battery… probably, right?
stubish 4y ago
One of the use cases for SMRs is to install them in decommissioned coal and gas power plants. They have a roof, and are already connected to the grid and roads, and near enough people to supply workers but not so close to supply protesters. The locals are much more supportive, because some of the jobs remain but the pollution they have first hand experience with will go. One of the major reasons for wind farms rather than isolated turbines is the economic and environmental cost of grid connections and roads needed for installation and maintenance.
- masklinn 4y ago
  There are no jobs, one goal of SMR is to be completely enclosed and self-safe. When the fuel runs out, you swap the SMR.
azinman2 4y ago
The use case for these nuclear batteries isn’t to power NYC. It’s to be able to replace industrial needs for energy and heat at the source. A glass or cement factory could have its own power source that’s carbon free. It also means that hydrogen production can be considered green. It’s also great for rural communities that might otherwise have expensive/dirty electricity. The goal is for them to be autonomous for this reason: install it at some industrial site without any nuclear expertise. Have it shipped in fueled, and then shipped out to maintain or refuel. These are absolutely the future.
cycomanic 4y ago
Actually the capacity factor of offshore wind is around 60% that is similar to nuclear (~70%), not way higher. However the price of nuclear (in Germany) is 3x that of renewables, so it just does not make economic sense to build nuclear.

Gravityloss 4y ago

Wind turbines strive to be as big as they can, and they have grown a lot. Yet they are limited by physics and transport issues. Now you need to install thousands of turbines. Engineering With Rosie has a truly excellent video that analyzes many of the scaling laws: https://www.youtube.com/watch?v=Ze-zaW3au9Q https://www.youtube.com/watch?v=Ze-zaW3au9Q GE gas turbines for example are 35 to 570 MW. https://www.ge.com/gas-power https://www.ge.com/gas-power. They have stopped making smaller ones. There probably are even 100 kW gas turbines made by some companies but that's not used for major power generation (maybe as an airplane APU). You probably won't have these small reactors in towns of 5000 people run by some local operators, because nuclear technology requires so much special training and is so risky because of the potential radiation hazard. You might have 20 in one powerplant in a city, to provide 100 MW, as part of the energy mix (it's always good to have multiple sources). There is a certain threshold for nuclear technology. It's not the same as a diesel generator that anyone can put in their back yard. The risks are too high. Yet, the current reactors like the Olkiluoto 3 EPR in Finland at 1600 MW electrical power are too big and unwieldy and risky. When it turns on or off, it causes some problems to the rest of the grid. One reason for such a huge plant was there was a legal process to provide permission for one reactor. So if you can only build one, of course you try to make it as big as possible. This doesn't make sense from engineering sense - it probably would make more sense to build something like power plants of 4x400 MW reactors (the seventies plants are 2x400 MW reactors). So all in all, probably more optimal size for "small" reactors would be 20 to 200 MW. They're big enough that the radiation protection doesn't eat all the budget, yet they're small enough that you get to build many and can build a production line.