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That could be the difference between "near 100%" and 100%. Or it could be because Australia has good renewable resources. This paper is a similar analysis but

That could be the difference between "near 100%" and 100%. Or it could be because Australia has good renewable resources. This paper is a similar analysis but for the US, check Fig. 3. As you go from 97% to 100% renewables, the overbuilding requirements blow up. https://sci-hub.se/10.1039/c7ee03029k https://sci-hub.se/10.1039/c7ee03029k

pfdietz 3y ago
That conclusion assumes no long term storage. Including hydrogen drastically reduces the overbuilding required. Put another way: if you overbuilt that much, you can make hydrogen for basically the cost of the electrolysers, since the input power is often free.
- gwright 3y ago
  You are correct that you can't create a stable, resilient grid just with intermittent renewables, you need storage. But I don't think anyone has demonstrated long-term storage at grid scale, capable of storing power across seasons, which is needed in many areas. To be feasible the storage system has to be cheaper than maintaining some fossil fuel plants. I haven't seen much about promising hydrogen storage systems.
  - pfdietz 3y ago
    > But I don't think anyone has demonstrated Arguments like this really annoy me, if it's clear there's not a serious obstacle. It's just a "nothing can be done for the first time" argument.
    - gwright 3y ago
      I'm not saying it can't be done. I'm saying it hasn't been done yet. How about we try it before pretending that we can shift to 100% renewables or before legislating transitions that we don't know how to accomplish. Hawaii is trying hard, but it doesn't seem to be going well with the grid becoming less reliable. BTW, this video is a solid overview of the power situation in Hawaii: https://www.youtube.com/watch?v=bbECmVdyWlQ&themeRefresh=1 https://www.youtube.com/watch?v=bbECmVdyWlQ&themeRefresh=1 I believe parts of the Azores have tried, but have not been successful. I would be very interested in pointers to successful projects in this area.
      - hackerlight 3y ago
        I don't like how we talk about 100% renewables as if failing that means failure. I'm happy with 90% renewables, a much easier goal, while we figure out the diminishing marginal returns later as technology breakthroughs and cost curves do the work for us. Our objective is to minimize the area under the curve of future emissions. It's not "net-zero" in the abstract. Net-zero is just a proxy for the true objective. Getting to 90% renewables soon means less emissions (while being cheaper) than waiting an extra 10-15 years for 100% nuclear.
        gwright 3y ago
        I'm not entirely sure what you mean by 90%. 90% of what? You can't just have 90% of power generated by renewables and 10% by fossil fuels because there are times when you get 0% from renewables and so your fossil fuel plants need to provide 100% of the power. So you spent all that money on renewable infrastructure and didn't even get the benefit of shuttering your fossil fuel plants.
        hackerlight 3y ago
        90% of power generation on average. What you've written here isn't persuasive. Are you trying to say that keeping gas peaker plants as a backup will mean renewables are more expensive than nuclear? Where is your analysis that fleshes that out?
        pfdietz 3y ago
        Especially when a simply cycle turbine plant has a capital cost per kW maybe 5% that of a nuclear plant.
      - bryanlarsen 3y ago
        It's harder to do it on islands with only a single weather system than on continents which have diverse weather systems.
        3y ago
    - troupo 3y ago
      > it's clear there's not a serious obstacle However, building grid-level storage is a serious obstacle > It's just a "nothing can be done for the first time" argument. No. The "it's easy, just build a lot of storage" argument is magical thinking.
      - adrianN 3y ago
        How is it magical thinking? The plan is very explicit and all the parts are available: We build gas peakers that are H2 compatible; we build electrolizers; we upgrade the existing methane storage to be H2 compatible; we store hydrogen and burn it when needed. There is no "magic" there. Hydrogen is needed anyway to decarbonize industrial processes, so the cost for the infrastructure has to be paid.
        troupo 3y ago
        You're omitting one tiny detail: we just have to build that at scales never attempted before. Also, omitting the tiny detail of how complex it is to store hydrogen which you assume is the way to store energy.
        adrianN 3y ago
        We literally have the infrastructure to store TWh of methane, so we have already built at the necessary scale in the past. It is also not terribly complex to store hydrogen if you're okay with losing a few percent per year. You might be thinking of cryogenic hydrogen storage, which is definitely not the plan.
        troupo 3y ago
        Everything is simple if you ignore everything. Because in the mind of renewable proponents all that grid-level storage is either already available or can be easily and cheaply built, no biggie. "We have existing infra" ignores that this infra took decades to build. "We know how to build" ignores that the storage costs can vary between 7 EUR/kg and 1040 EUR/kg [1] and so on and so forth. The capability for wishful thinking in renewable space is staggering. Note: no one is saying it is impossible BTW. [1] Great article: https://www.sciencedirect.com/science/article/pii/S0360319923032482 https://www.sciencedirect.com/science/article/pii/S036031992...
- pjc50 3y ago
  > basically the cost of the electrolysers Yes, that's the expensive bit. The reason you don't get much of this already is exactly that the capital cost of electrolysers is very high because of the requirement for platinum electrodes. And big capital investments are not free.
  - pfdietz 3y ago
    Platinum isn't required for alkaline electrolysis.
  - adrianN 3y ago
    The reason we don't have a lot of hydrogen right know is because we don't have a lot of surplus energy right now. It makes no sense to buy expensive equipment and run in only a few hundred hours a year.
    - pfdietz 3y ago
      We have huge amounts of hydrogen right now. At standard temperature and pressure, the amount of hydrogen made globally each year would occupy 700 cubic kilometers of volume. It's just that it's made overwhelmingly from fossil fuels, mostly natural gas (6% of global gas production goes to making hydrogen). That this is being done instead of making green hydrogen is because CO2 from the fossil fuel process is not being taxed or otherwise forced to account for the negative externalities. This also illustrates that producing hydrogen without CO2 release is not an optionally solvable problem. Without the ammonia made from hydrogen (which is where most of it is going) billions will starve.

pfdietz 3y ago

That conclusion assumes no long term storage. Including hydrogen drastically reduces the overbuilding required. Put another way: if you overbuilt that much, you can make hydrogen for basically the cost of the electrolysers, since the input power is often free.

gwright 3y ago
You are correct that you can't create a stable, resilient grid just with intermittent renewables, you need storage. But I don't think anyone has demonstrated long-term storage at grid scale, capable of storing power across seasons, which is needed in many areas. To be feasible the storage system has to be cheaper than maintaining some fossil fuel plants. I haven't seen much about promising hydrogen storage systems.
- pfdietz 3y ago
  > But I don't think anyone has demonstrated Arguments like this really annoy me, if it's clear there's not a serious obstacle. It's just a "nothing can be done for the first time" argument.
  - gwright 3y ago
    I'm not saying it can't be done. I'm saying it hasn't been done yet. How about we try it before pretending that we can shift to 100% renewables or before legislating transitions that we don't know how to accomplish. Hawaii is trying hard, but it doesn't seem to be going well with the grid becoming less reliable. BTW, this video is a solid overview of the power situation in Hawaii: https://www.youtube.com/watch?v=bbECmVdyWlQ&themeRefresh=1 https://www.youtube.com/watch?v=bbECmVdyWlQ&themeRefresh=1 I believe parts of the Azores have tried, but have not been successful. I would be very interested in pointers to successful projects in this area.
    - hackerlight 3y ago
      I don't like how we talk about 100% renewables as if failing that means failure. I'm happy with 90% renewables, a much easier goal, while we figure out the diminishing marginal returns later as technology breakthroughs and cost curves do the work for us. Our objective is to minimize the area under the curve of future emissions. It's not "net-zero" in the abstract. Net-zero is just a proxy for the true objective. Getting to 90% renewables soon means less emissions (while being cheaper) than waiting an extra 10-15 years for 100% nuclear.
      - gwright 3y ago
        I'm not entirely sure what you mean by 90%. 90% of what? You can't just have 90% of power generated by renewables and 10% by fossil fuels because there are times when you get 0% from renewables and so your fossil fuel plants need to provide 100% of the power. So you spent all that money on renewable infrastructure and didn't even get the benefit of shuttering your fossil fuel plants.
        hackerlight 3y ago
        90% of power generation on average. What you've written here isn't persuasive. Are you trying to say that keeping gas peaker plants as a backup will mean renewables are more expensive than nuclear? Where is your analysis that fleshes that out?
        pfdietz 3y ago
        Especially when a simply cycle turbine plant has a capital cost per kW maybe 5% that of a nuclear plant.
    - bryanlarsen 3y ago
      It's harder to do it on islands with only a single weather system than on continents which have diverse weather systems.
      - 3y ago
  - troupo 3y ago
    > it's clear there's not a serious obstacle However, building grid-level storage is a serious obstacle > It's just a "nothing can be done for the first time" argument. No. The "it's easy, just build a lot of storage" argument is magical thinking.
    - adrianN 3y ago
      How is it magical thinking? The plan is very explicit and all the parts are available: We build gas peakers that are H2 compatible; we build electrolizers; we upgrade the existing methane storage to be H2 compatible; we store hydrogen and burn it when needed. There is no "magic" there. Hydrogen is needed anyway to decarbonize industrial processes, so the cost for the infrastructure has to be paid.
      - troupo 3y ago
        You're omitting one tiny detail: we just have to build that at scales never attempted before. Also, omitting the tiny detail of how complex it is to store hydrogen which you assume is the way to store energy.
        adrianN 3y ago
        We literally have the infrastructure to store TWh of methane, so we have already built at the necessary scale in the past. It is also not terribly complex to store hydrogen if you're okay with losing a few percent per year. You might be thinking of cryogenic hydrogen storage, which is definitely not the plan.
        troupo 3y ago
        Everything is simple if you ignore everything. Because in the mind of renewable proponents all that grid-level storage is either already available or can be easily and cheaply built, no biggie. "We have existing infra" ignores that this infra took decades to build. "We know how to build" ignores that the storage costs can vary between 7 EUR/kg and 1040 EUR/kg [1] and so on and so forth. The capability for wishful thinking in renewable space is staggering. Note: no one is saying it is impossible BTW. [1] Great article: https://www.sciencedirect.com/science/article/pii/S0360319923032482 https://www.sciencedirect.com/science/article/pii/S036031992...
pjc50 3y ago
> basically the cost of the electrolysers Yes, that's the expensive bit. The reason you don't get much of this already is exactly that the capital cost of electrolysers is very high because of the requirement for platinum electrodes. And big capital investments are not free.
- pfdietz 3y ago
  Platinum isn't required for alkaline electrolysis.
- adrianN 3y ago
  The reason we don't have a lot of hydrogen right know is because we don't have a lot of surplus energy right now. It makes no sense to buy expensive equipment and run in only a few hundred hours a year.
  - pfdietz 3y ago
    We have huge amounts of hydrogen right now. At standard temperature and pressure, the amount of hydrogen made globally each year would occupy 700 cubic kilometers of volume. It's just that it's made overwhelmingly from fossil fuels, mostly natural gas (6% of global gas production goes to making hydrogen). That this is being done instead of making green hydrogen is because CO2 from the fossil fuel process is not being taxed or otherwise forced to account for the negative externalities. This also illustrates that producing hydrogen without CO2 release is not an optionally solvable problem. Without the ammonia made from hydrogen (which is where most of it is going) billions will starve.