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I was just thinking about how decentralization is important for building robust systems, but it’s not simply decentralization, also the ability for the nodes to

by rlt 4y ago

I was just thinking about how decentralization is important for building robust systems, but it’s not simply decentralization, also the ability for the nodes to operate isolated from each other. The grid is “decentralized” but still brittle and at risk of cascading failures. A future where the majority of power is provided by onsite solar + storage is much more robust. Similarly not robust are things like tech stacks with complex “cold boot” plans or unexpected cascading failure modes, etc. I don’t know what the right terminology for this subset of decentralization is.

Ygg2 4y ago
Onsite solar and storage is the big issue. That's why most solar plants come with a peaker gas plant. It's cheaper to provide additional demand via fossil fuels than to rely on storage solutions. You need a huge amount of storage.
- Retric 4y ago
  Many solar power plants come with 3-4h of battery simply to time shift output to peak demand. Because solar is DC you effectively skip inefficiency from DC>AC (Solar to grid) and DC>AC (Grid to battery) conversion. On top of this you can use the same DC>AC equipment for both the batteries and solar plus being able to convert DC>AC to charge batteries from the grid becomes optional.
jillesvangurp 4y ago
Parts of Australia have this. They have so much rooftop solar (and reliable access to plenty of sun) and battery there that effectively centralized power is less and less relevant there and quite a few parts of especially southern Australia effectively run on solar and battery for most of the time. It has indeed made the grid there more reliable; not less. Decentralization is mainly bad for centralized power companies as it erodes their monopoly and forces them to deal with the notion that their power is too expensive most of the time. Intermittent scarcity and over supply of energy (both are a thing) also leads to different consumption patterns. People valuing cheap energy when it is scarce invest in batteries that they charge when there's a surplus. Others buy at a premium or simply shift when they consume their energy. Demand shaping is also something that can be incentivized financially. Of course that works great in Australia but other parts of the world have other options like wind, geothermal, hydro, nuclear, etc. Which is why places like Norway and parts of Canada are also mostly running on clean energy at this point. The key is actually not isolating but interconnecting. Norway is part of a connected grid that spans most of Europe with a market where you can sell energy and buy energy. Norway is an energy exporter at this point and there are plenty of countries importing their power to supplement their own generation when it falls short. That's why countries like Germany are now predominantly wind and solar powered and yet doesn't have blackouts when there's no wind. Like today (gloomy winter day with barely any wind here in Berlin). But there's still plenty of wind elsewhere. Germany imports almost as much power as that it exports each year.
rocqua 4y ago
Solar and batteries have some challenges about maintaining frequency and syncrhonization. When using spinning magnets (wind/steam turbines) the frequency is related to power draw. As demand spikes, the generators get slowed down. Effectively the rotational inertia works a bit like a buffer. Balancing the grid is hence a matter of 'maintaining frequency'. Which makes the frequency very stable. Solar and batteries are inherently DC. They have converters that take a reference AC signal, and output their energy synchronized to that reference. Incidentally, this makes it difficult to run your house off solar during a black-out, because you lack the reference. Even in smarter converters that don't need a reference to match the frequency, they still need a reference to synchronize the phase. When we move to more batteries and solar for generation, that will put more strain on the spinning-based generation for short-term fluctuations. Less spinning mass means less buffer. At some point, any flaws in behavior of DC converters might start dominating. If they happen to resonate with each other, we might see some weird things.
- jeffrallen 4y ago
  It is categorically untrue that "it is hard to run your house off solar". Thousands of sailboats, and country houses around the world do just that. It is true that if you insist on making the cutover from inverter derived AC to grid AC without an interruption, you will need some subtle circuitry that can automatically "glide" the inverter into synchrony with the grid before cutting over. I don't know if Tesla, Bluetti, and EcoFlow devices do this, or just make a step-change in the phase and frequency of the output. That would be an interesting investigation, maybe Matthias Wander can do it?
  - rocqua 4y ago
    From what I remember the main problem is code requirements around being able to go from 'isolated' back to being connected to the grid. If you are out of phase when the grid gets back, it gets damaging. So it is difficult to get an approved system that can do it.
- Panzer04 4y ago
  I feel like the bigger issue would be lack of feedback, since presumably an inverter can maintain perfect frequency under any load right up until it can supply Lo more power; I suppose voltage measurement might become more relevant than frequency in such cases (or perhaps inverters are programmed to lag a bit under load, though that seems needlessly artificial)
toss1 4y ago
YES! Also, I'm absolutely baffled why there's never been a civil defense initiative to get even a small baseline of solar/wind power at nearly every household. Even having just 1kW in every household would be enough to keep running basic communication, refrigeration, heating systems (i.e.. starters & blowers for gas/oil/etc. not elec furnaces), etc. In a major extended blackout situation, this would enable society to be sustainable for weeks to months or even indefinitely, instead of only days in winter as we have now. Another huge concern is availability of transformers, which hafe a huge lead time. The attack on substations in Moore County NC [0] may be only a very successful test run. I've read reliable reports indicating that not many such attacks in the correct points on the grid could cripple the entire grid, and could also take out many transformers on the way down. Current production rates could take years to replace. Yet it would cost something like $500 million to stockpile them (shelf life is measured in decades), and AFAIK this has not been done. Why? Seems like just ordinary political oversight - it isn't sexy, even though it could be critical. [0] https://www.npr.org/2022/12/05/1140775417/north-carolina-substation-attack-what-we-know https://www.npr.org/2022/12/05/1140775417/north-carolina-sub...

by rlt 4y ago

Ygg2 4y ago

Onsite solar and storage is the big issue. That's why most solar plants come with a peaker gas plant. It's cheaper to provide additional demand via fossil fuels than to rely on storage solutions. You need a huge amount of storage.

Retric 4y ago
Many solar power plants come with 3-4h of battery simply to time shift output to peak demand. Because solar is DC you effectively skip inefficiency from DC>AC (Solar to grid) and DC>AC (Grid to battery) conversion. On top of this you can use the same DC>AC equipment for both the batteries and solar plus being able to convert DC>AC to charge batteries from the grid becomes optional.

jillesvangurp 4y ago

Parts of Australia have this. They have so much rooftop solar (and reliable access to plenty of sun) and battery there that effectively centralized power is less and less relevant there and quite a few parts of especially southern Australia effectively run on solar and battery for most of the time. It has indeed made the grid there more reliable; not less. Decentralization is mainly bad for centralized power companies as it erodes their monopoly and forces them to deal with the notion that their power is too expensive most of the time. Intermittent scarcity and over supply of energy (both are a thing) also leads to different consumption patterns. People valuing cheap energy when it is scarce invest in batteries that they charge when there's a surplus. Others buy at a premium or simply shift when they consume their energy. Demand shaping is also something that can be incentivized financially. Of course that works great in Australia but other parts of the world have other options like wind, geothermal, hydro, nuclear, etc. Which is why places like Norway and parts of Canada are also mostly running on clean energy at this point. The key is actually not isolating but interconnecting. Norway is part of a connected grid that spans most of Europe with a market where you can sell energy and buy energy. Norway is an energy exporter at this point and there are plenty of countries importing their power to supplement their own generation when it falls short. That's why countries like Germany are now predominantly wind and solar powered and yet doesn't have blackouts when there's no wind. Like today (gloomy winter day with barely any wind here in Berlin). But there's still plenty of wind elsewhere. Germany imports almost as much power as that it exports each year.

rocqua 4y ago

Solar and batteries have some challenges about maintaining frequency and syncrhonization. When using spinning magnets (wind/steam turbines) the frequency is related to power draw. As demand spikes, the generators get slowed down. Effectively the rotational inertia works a bit like a buffer. Balancing the grid is hence a matter of 'maintaining frequency'. Which makes the frequency very stable. Solar and batteries are inherently DC. They have converters that take a reference AC signal, and output their energy synchronized to that reference. Incidentally, this makes it difficult to run your house off solar during a black-out, because you lack the reference. Even in smarter converters that don't need a reference to match the frequency, they still need a reference to synchronize the phase. When we move to more batteries and solar for generation, that will put more strain on the spinning-based generation for short-term fluctuations. Less spinning mass means less buffer. At some point, any flaws in behavior of DC converters might start dominating. If they happen to resonate with each other, we might see some weird things.

jeffrallen 4y ago
It is categorically untrue that "it is hard to run your house off solar". Thousands of sailboats, and country houses around the world do just that. It is true that if you insist on making the cutover from inverter derived AC to grid AC without an interruption, you will need some subtle circuitry that can automatically "glide" the inverter into synchrony with the grid before cutting over. I don't know if Tesla, Bluetti, and EcoFlow devices do this, or just make a step-change in the phase and frequency of the output. That would be an interesting investigation, maybe Matthias Wander can do it?
- rocqua 4y ago
  From what I remember the main problem is code requirements around being able to go from 'isolated' back to being connected to the grid. If you are out of phase when the grid gets back, it gets damaging. So it is difficult to get an approved system that can do it.
Panzer04 4y ago
I feel like the bigger issue would be lack of feedback, since presumably an inverter can maintain perfect frequency under any load right up until it can supply Lo more power; I suppose voltage measurement might become more relevant than frequency in such cases (or perhaps inverters are programmed to lag a bit under load, though that seems needlessly artificial)

toss1 4y ago

YES! Also, I'm absolutely baffled why there's never been a civil defense initiative to get even a small baseline of solar/wind power at nearly every household. Even having just 1kW in every household would be enough to keep running basic communication, refrigeration, heating systems (i.e.. starters & blowers for gas/oil/etc. not elec furnaces), etc. In a major extended blackout situation, this would enable society to be sustainable for weeks to months or even indefinitely, instead of only days in winter as we have now. Another huge concern is availability of transformers, which hafe a huge lead time. The attack on substations in Moore County NC [0] may be only a very successful test run. I've read reliable reports indicating that not many such attacks in the correct points on the grid could cripple the entire grid, and could also take out many transformers on the way down. Current production rates could take years to replace. Yet it would cost something like $500 million to stockpile them (shelf life is measured in decades), and AFAIK this has not been done. Why? Seems like just ordinary political oversight - it isn't sexy, even though it could be critical. [0] https://www.npr.org/2022/12/05/1140775417/north-carolina-substation-attack-what-we-know https://www.npr.org/2022/12/05/1140775417/north-carolina-sub...