• @[email protected]
    2•1 year ago

    This is a very interesting rabit hole you sent me into. Thanks for that!
    Btw. I don’t get why you’re beeing downvoted. This is a civilised discussion and your comments are fair and well presented!

    I started searching a bit about steering nuclear.

    So as usual it doesn’t seem to be quite so simple. I found a paper from 2017 (in German https://publikationen.bibliothek.kit.edu/1000102277/121070976 ). interesting parts translated through deepl/chatGPT:

    "The operating manuals of the NPPs show that they [nuclear power plants] exhibit considerable flexibility:
    In the range close to full load (above 80/90% of the nominal Power), the output can be increased or decreased by up to 10% of the nominal output per minute. In the upper load range (above 50/60 % PNenn), the power plants can be regulated at 3.8-5.2 %/min (for some reactor types, this is reduced to around 1 %/min if individual fuel rods are defective).

    For comparison: In lignite-fired power plants, this value is around 3 %/min, 4 %/min for hard coal-fired power plants and 6 %/min for natural gas steam or combined power plants 6 %/min. Only gas turbines, at 12 %/min, are significantly faster.

    The lower load range (between 20 and 60%) is also possible, but in discussions with power plant operators it became clear that this has not yet been used in regular operation (apart from start-up and shutdown operations) and is not used in regular operation."

    Also it seems that changing output puts stress on the whole systen. As well cited from the paper:
    “Another factor is the number of cycles that the plants can undergo. Each load cycle stresses the material and, with frequent repetition, leads to signs of material fatigue. Nuclear power plants were designed for a specific maximum number of cycles during their construction. In the upper load range – for example, a reduction in power from 100% rated power to 80% and back (100-80-100) – coolant temperature and pressure hardly change. Therefore, the power plants are designed for up to 100,000 cycles of such nature. However, in the lower load range, the alternating stress on the components increases, and the maximum cycle count decreases significantly. The cycle 100-40-100, for instance, is allowed only 12,000 repetitions. For the cycle rated load-zero load-hot-rated load (100-0-100), a maximum of 400 cycles is specified. Assuming a plant lifespan of 40 years, this would correspond to 10 of these events per year.”

    So there seems to be considerable flexibility but you don’t want to shut it off completely or run below say 50% of nominal power. Also start-up times from 0 seem to be very long (1-2 days). This might not be the perfect match for running together with renewables, but there are definitively possibilities. Even when it’s windy and the sun shines, renewables would need to be shut down and the more expensive nuclear plant would run and burn fuel.
    Therefore, my opinion still stands: the ultimate goal should still be 0 burning stuff, 0 nuclear.

    • @[email protected]
      3•1 year ago

      Hey, likewise, thanks for a sensible debate.

      I definitely think 0 nuclear is possible, just a lot expensive than “mostly renewable with some nuclear.”

      I’ve commented extensively on this before here on Lemmy, let me copy pasta here:

      Here’s a couple of good papers and articles on the topic:

      A systematic review of the costs and impacts of integrating variable renewables into power grids - a large meta-study from Nature Energy showing that the externalised additional cost of integrating 1 MW of renewable production hits £40/MWh between 75% to 85% renewable penetration. Beyond that no studies have been done, but already at this level, renewable would be more expensive than nuclear (at auctioned build-prices today).

      Real-World Challenges with a Rapid Transition to 100% Renewable Power Systems - finds that even if you set the Value of Lost Load to £40,000/MWh in a 100% renewable grid, you’ll still get power outages after 2030. It’s not equivalent to externalised cost of renewable integration, but is a heavy indicator that without forcing massive fines on renewable providers, the reserve capacity won’t be provided (it’ll be cheaper for them to just pay the fine). The study finds that a fine of £4 million (!) per required-but-not-fulfilled MWh is needed to encourage providers build the reserve capacity (through distribution, storage etc.).

      How much can nuclear power reduce climate mitigation cost? - shows that nuclear will lower the cost of getting to zero carbon electricity product by 40%+, compared to refusing to use nuclear energy production.

      Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems - shows some of the challenges of the assumptions that people make in thinking renewables will get us all the way there.

      Projected Costs of Generating Electricity - shows that, all costs considered, nuclear remains an extremely cheap way to create energy, even up against renewables.

      Local Complementarity of Wind and Solar Energy Resources over Europe: An Assessment Study from a Meteorological Perspective - shows that at least in Europe, wind and sun don’t anti-correlate (in other words, we’re not going to get energy from the sun on non-windy days and energy from the wind on cloudy days. Also shows there are many periods (days long) in Europe where we have don’t get neither sun nor wind. So storage will have to last us days across Europe.

      Many of these articles refer to many other articles you may find interesting.

      Overall, my point is that it does us (collective “us”, not just “you and me”) no good to argue that “it’ll be alright if we just commit to renewables”. One has to argue against these peer reviewed studies, done by experts in the field, many collecting and meta-reviewing many other studies, to argue that “renewables will be enough”.

      And these are not “cooky studies” in “cooky journals”. Nature, Cell, Joule are some of the most respected journals, with the highest impact ratings and the authors & their reviewers have studied these topics for years.

      I’m all for more renewables! But it won’t be enough!