6 ms·

There is a lot of discussion here about renewables. I recommend a recent paper published in Nature Communications titled "Geophysical constraints on the reliabi

by todd8 4y ago

There is a lot of discussion here about renewables. I recommend a recent paper published in Nature Communications titled "Geophysical constraints on the reliability of solar and wind power worldwide"[1]. It considers mixes of Solar and Wind, with or without excess capacity, and storage facilities zero, 3, or 12 hours. The paper's model (it looks like the code is available on GitHub) makes optimist assumptions (e.g. no transmission losses within a single country and feasibility of 12hrs of storage for the whole country). Nevertheless, the results are interesting. Figure 3 (see[1]) indicates how much power outage must be tolerated across the entire country for different mixes renewable capacity and storage depending on the country: US -- Generation 1.5 times the capacity needed, 12 hours of storage, wind and solar have a power supply gap of 15% when the goal is to tolerate 10 hours of power outage. Germany -- Generation 3 times the capacity needed, 12 hours of storage, wind and solar have a power supply gap of 60% when the goal is to tolerate 10 hours of power outage. The larger the power supply gap, the more additional dispatchable power that must be provided. [1] https://www.nature.com/articles/s41467-021-26355-z https://www.nature.com/articles/s41467-021-26355-z

melling 4y ago
[flagged]
- einpoklum 4y ago
  > In other news, it’s too late to limit the temperature increase to 1.5 C And you would argue that is due to preferring solar and wind over nuclear? Perhaps that is why you get downvoted. (I have not downvoted you though.)
- dang 4y ago
  Please don't post in the flamewar style and please don't break the site guidelines with complaints about downvotes, tendentious generalizations about the community, etc. All of this noticeably lowers discussion quality. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
DiogenesKynikos 4y ago
Considering Germany alone doesn't make much sense. Any realistic solution would be European.
- lazide 4y ago
  Until folks in Europe stop liking each other again. You think it’s bad when Russia plays with Gas supplies, wait until France/Germany/North/South start using power (literal) plays to mess with each other.
  - moloch-hai 4y ago
    Let me tell you about an entity called the EU.
walnutclosefarm 4y ago
I don't object to using nuclear for grid power, but it's really not a great complement for solar and wind. What you want to complement those variable sources is something that ramps up and down easily, when you hit extended reduced production periods in the variable sources. Something like nuclear, which is inherently a baseline source, which has basically no storage utility, and which is already far more expensive per unit of energy produced, even when run at high utilization, misses the boat.
- timerol 4y ago
  Nuclear is very bad at ramping all of the way off, but NuScale's reactors can go from full power to 25% of output power in 1 hour. https://www.youtube.com/watch?v=h--FAVoAQvk&t=59s https://www.youtube.com/watch?v=h--FAVoAQvk&t=59s Nuclear power is used as base load because of economics, not physics or regulations. France's nuclear fleet is used for load-following. See "Load-following with PWR nuclear plants" in https://www.world-nuclear.org/information-library/country-profiles/countries-a-f/france.aspx https://www.world-nuclear.org/information-library/country-pr.... (SMRs are easier to use for load-following, since you enable and disable reactors, as opposed to using the "grey control rods" mentioned in the linked article.)
  - pfdietz 4y ago
    Technical ability to ramp is not the issue, it's the economic cost of ramping. A nuclear plant must operate with as high a capacity factor as possible or else the cost per kWh inflates. Almost all the costs are fixed.
    - walnutclosefarm 4y ago
      Exactly. To be useful to fill the dips in renewal production, you have to run your the baseline contribution of nuclear at a low power, so you've got headroom to expand into when needed. That makes nuclear kwh, already inherently expensive, prohibitively so.
- loeg 4y ago
_yb2s 4y ago
Your post mentions "hours of power outage" without a context of which interval this is within. I think it is annually from looking at your citation, so "hours of power outage per year"
- Gwypaas 4y ago
  Also what is the shortfall? How many watts are missing? Taking in mind for example demand response which I do not see mentioned in the paper, and of course would be a critical part of a renewable grid. Another central missing word is "sector coupling".
Gwypaas 4y ago
That study is useless from a system standpoint. Sure it is a bit interesting to look at the basic facts, but all energy systems are more complicated. For example it only mentions the world "sector coupling" once in the discussion, while it is central in any renewable system. HVDC connections are being strung up across Europe. Sweden and Norway can together in an hour vary their hydro output by 15 GW, that is 15 nuclear reactors worth of balancing power backed by tens of TWh stored. The research on 100% renewable systems have long embraced the thought of holistic approaches. > The majority of studies show that a global transition to 100% renewable energy across all sectors – power, heat, transport and desalination – is feasible and economically viable.[5][6][7][8] A cross-sectoral, holistic approach is seen as an important feature of 100% renewable energy systems and is based on the assumption "that the best solutions can be found only if one focuses on the synergies between the sectors" of the energy system such as electricity, heat, transport or industry.[9] https://en.wikipedia.org/wiki/100%25_renewable_energy https://en.wikipedia.org/wiki/100%25_renewable_energy Here is a meta study on everything 100% renewable for the interested. The consensus is that it is possible without a doubt. https://ieeexplore.ieee.org/document/9837910 https://ieeexplore.ieee.org/document/9837910
- guywhocodes 4y ago
  Fusion is also possible
- jillesvangurp 4y ago
  Yep, doable and already getting done in lots of places. Discussions like this usually devolve into alarmist what ifs and vague assertions about needing something called "base load" which is a surprising poorly defined notion. There are now several places in the world that regularly have hours/days/weeks of being exclusively powered by renewables. And it's fine. When that happens the cost is low. When it doesn't they pay more to import power from elsewhere or they switch on some peaker plants. Typically, without any outages or downtime. Applying some system thinking is indeed key. If you look at each solution in isolation, they indeed each have issues but they are different issues. If you take them altogether, you end up with a resilient grid network with much less issues. Wind by itself has issues. But together with solar and some short term storage, it gets a lot more resilient. There are still some issues left when you do that because cold gloomy winter days with no wind are a thing and those conditions can last for days or weeks in some places. We don't (yet) have storage to bridge such gaps. Months is actually unusual but weeks is fairly common in places like Germany in the winter. So, you can't obviously rely on that mix exclusively. Which is something nuclear proponents love to point out forgetting that turning nuclear plants on and off is really expensive and slow and generally not something that is done regularly. They kind of suck for backup power. Nuclear peaker plants are not a thing. Hence they like to talk about base load because that means leaving them on permanently to provide that base load. The alarmist view to this is that without this base load we need to have enormous amounts of storage to survive these horrendous apocalyptic spells of gloomy days (i.e. winters). Exaggerating here but this goes to the core of what nuclear proponents advocate: yes it is stupendously expensive but we have to have it because we need the "base load". The fallacy in that argument is pretending that nuclear is the only option for this and ignoring the cost aspect. Also, nobody ever specifies how much of this base load is actually needed (in gwh). They just assume that we need lots of it. The system thinking pragmatic real world solution to this is realizing that these gloomy conditions are typically localized, seasonal, predictable, etc. and that running some cables across the continent adds a lot of resilience. Like Scandinavian hydro power, or solar power imported from places like Spain or Morocco (both of which are a thing). Moving power around with cables means you can shape and shift demand around as well. Mostly we're not talking about 100% collapses in generation but supply and demand variations of more reasonable percentages. And of course the reality is that we have all these legacy plants still providing much more base load than is actually needed right now. We don't actually need more of that right now. It's not an urgent problem (aside from getting rid of emissions). And they aren't going to be switched off overnight and will be around for quite some time. The mix is gradually shifting to more and more renewables, all sorts of storage solutions. It's going to asymptotically converge on 100%.
einpoklum 4y ago
Let me do some cocktail-napkin math here. US generation capacity in Feb 2022 was 1.2e12 Watts [1] (let's take that as the value for 2021 as well) US electricity consumption in 2021 was 3.93e15 Watt-Hours. [2] Now, 1 Watt over a 365.25-day year is 8766 Watt-Hours. So, US capacity for 2021 under our assumption was 8766 * 1.2e12 = 1.05e16 . That's 3x capacity over need. So, those doom-and-gloom descriptions of inadequacy of solar and wind seem to rely on a low capacity/need rate. [1] - https://www.publicpower.org/resource/americas-electricity-generating-capacity https://www.publicpower.org/resource/americas-electricity-ge... [2] - https://www.eia.gov/energyexplained/electricity/use-of-electricity.php https://www.eia.gov/energyexplained/electricity/use-of-elect...

by todd8 4y ago

melling 4y ago

[flagged]

einpoklum 4y ago
> In other news, it’s too late to limit the temperature increase to 1.5 C And you would argue that is due to preferring solar and wind over nuclear? Perhaps that is why you get downvoted. (I have not downvoted you though.)
dang 4y ago
Please don't post in the flamewar style and please don't break the site guidelines with complaints about downvotes, tendentious generalizations about the community, etc. All of this noticeably lowers discussion quality. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

DiogenesKynikos 4y ago

Considering Germany alone doesn't make much sense. Any realistic solution would be European.

lazide 4y ago
Until folks in Europe stop liking each other again. You think it’s bad when Russia plays with Gas supplies, wait until France/Germany/North/South start using power (literal) plays to mess with each other.
- moloch-hai 4y ago
  Let me tell you about an entity called the EU.

walnutclosefarm 4y ago

I don't object to using nuclear for grid power, but it's really not a great complement for solar and wind. What you want to complement those variable sources is something that ramps up and down easily, when you hit extended reduced production periods in the variable sources. Something like nuclear, which is inherently a baseline source, which has basically no storage utility, and which is already far more expensive per unit of energy produced, even when run at high utilization, misses the boat.

timerol 4y ago
Nuclear is very bad at ramping all of the way off, but NuScale's reactors can go from full power to 25% of output power in 1 hour. https://www.youtube.com/watch?v=h--FAVoAQvk&t=59s https://www.youtube.com/watch?v=h--FAVoAQvk&t=59s Nuclear power is used as base load because of economics, not physics or regulations. France's nuclear fleet is used for load-following. See "Load-following with PWR nuclear plants" in https://www.world-nuclear.org/information-library/country-profiles/countries-a-f/france.aspx https://www.world-nuclear.org/information-library/country-pr.... (SMRs are easier to use for load-following, since you enable and disable reactors, as opposed to using the "grey control rods" mentioned in the linked article.)
- pfdietz 4y ago
  Technical ability to ramp is not the issue, it's the economic cost of ramping. A nuclear plant must operate with as high a capacity factor as possible or else the cost per kWh inflates. Almost all the costs are fixed.
  - walnutclosefarm 4y ago
    Exactly. To be useful to fill the dips in renewal production, you have to run your the baseline contribution of nuclear at a low power, so you've got headroom to expand into when needed. That makes nuclear kwh, already inherently expensive, prohibitively so.
loeg 4y ago

_yb2s 4y ago

Your post mentions "hours of power outage" without a context of which interval this is within. I think it is annually from looking at your citation, so "hours of power outage per year"

Gwypaas 4y ago
Also what is the shortfall? How many watts are missing? Taking in mind for example demand response which I do not see mentioned in the paper, and of course would be a critical part of a renewable grid. Another central missing word is "sector coupling".

Gwypaas 4y ago

That study is useless from a system standpoint. Sure it is a bit interesting to look at the basic facts, but all energy systems are more complicated. For example it only mentions the world "sector coupling" once in the discussion, while it is central in any renewable system. HVDC connections are being strung up across Europe. Sweden and Norway can together in an hour vary their hydro output by 15 GW, that is 15 nuclear reactors worth of balancing power backed by tens of TWh stored. The research on 100% renewable systems have long embraced the thought of holistic approaches. > The majority of studies show that a global transition to 100% renewable energy across all sectors – power, heat, transport and desalination – is feasible and economically viable.[5][6][7][8] A cross-sectoral, holistic approach is seen as an important feature of 100% renewable energy systems and is based on the assumption "that the best solutions can be found only if one focuses on the synergies between the sectors" of the energy system such as electricity, heat, transport or industry.[9] https://en.wikipedia.org/wiki/100%25_renewable_energy https://en.wikipedia.org/wiki/100%25_renewable_energy Here is a meta study on everything 100% renewable for the interested. The consensus is that it is possible without a doubt. https://ieeexplore.ieee.org/document/9837910 https://ieeexplore.ieee.org/document/9837910

guywhocodes 4y ago
Fusion is also possible
jillesvangurp 4y ago
Yep, doable and already getting done in lots of places. Discussions like this usually devolve into alarmist what ifs and vague assertions about needing something called "base load" which is a surprising poorly defined notion. There are now several places in the world that regularly have hours/days/weeks of being exclusively powered by renewables. And it's fine. When that happens the cost is low. When it doesn't they pay more to import power from elsewhere or they switch on some peaker plants. Typically, without any outages or downtime. Applying some system thinking is indeed key. If you look at each solution in isolation, they indeed each have issues but they are different issues. If you take them altogether, you end up with a resilient grid network with much less issues. Wind by itself has issues. But together with solar and some short term storage, it gets a lot more resilient. There are still some issues left when you do that because cold gloomy winter days with no wind are a thing and those conditions can last for days or weeks in some places. We don't (yet) have storage to bridge such gaps. Months is actually unusual but weeks is fairly common in places like Germany in the winter. So, you can't obviously rely on that mix exclusively. Which is something nuclear proponents love to point out forgetting that turning nuclear plants on and off is really expensive and slow and generally not something that is done regularly. They kind of suck for backup power. Nuclear peaker plants are not a thing. Hence they like to talk about base load because that means leaving them on permanently to provide that base load. The alarmist view to this is that without this base load we need to have enormous amounts of storage to survive these horrendous apocalyptic spells of gloomy days (i.e. winters). Exaggerating here but this goes to the core of what nuclear proponents advocate: yes it is stupendously expensive but we have to have it because we need the "base load". The fallacy in that argument is pretending that nuclear is the only option for this and ignoring the cost aspect. Also, nobody ever specifies how much of this base load is actually needed (in gwh). They just assume that we need lots of it. The system thinking pragmatic real world solution to this is realizing that these gloomy conditions are typically localized, seasonal, predictable, etc. and that running some cables across the continent adds a lot of resilience. Like Scandinavian hydro power, or solar power imported from places like Spain or Morocco (both of which are a thing). Moving power around with cables means you can shape and shift demand around as well. Mostly we're not talking about 100% collapses in generation but supply and demand variations of more reasonable percentages. And of course the reality is that we have all these legacy plants still providing much more base load than is actually needed right now. We don't actually need more of that right now. It's not an urgent problem (aside from getting rid of emissions). And they aren't going to be switched off overnight and will be around for quite some time. The mix is gradually shifting to more and more renewables, all sorts of storage solutions. It's going to asymptotically converge on 100%.

einpoklum 4y ago

Let me do some cocktail-napkin math here. US generation capacity in Feb 2022 was 1.2e12 Watts [1] (let's take that as the value for 2021 as well) US electricity consumption in 2021 was 3.93e15 Watt-Hours. [2] Now, 1 Watt over a 365.25-day year is 8766 Watt-Hours. So, US capacity for 2021 under our assumption was 8766 * 1.2e12 = 1.05e16 . That's 3x capacity over need. So, those doom-and-gloom descriptions of inadequacy of solar and wind seem to rely on a low capacity/need rate. [1] - https://www.publicpower.org/resource/americas-electricity-generating-capacity https://www.publicpower.org/resource/americas-electricity-ge... [2] - https://www.eia.gov/energyexplained/electricity/use-of-electricity.php https://www.eia.gov/energyexplained/electricity/use-of-elect...