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Comment by doikor | Hacker News Reader

The kind of storage we would need in the Nordics is around 1 week of total consumption. That is roughly how long the longest really cold windless periods last in the winter (basically a large high pressure zone parking itself over the area and they can be big enough to cover pretty much all of Sweden) and sun is kinda bad during the winter this far north.

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In the north thermal energy storage is a viable solution, and those can store energy for months. You can dump heat into them in summer and still pull from it in winter.

Since heating is by far the biggest consumer of energy in winter, just taking care of that with stored thermal energy will deal with a big fraction of the energy storage needs.

We need more districting heating systems.

There's several projects ongoing to store heat from district heating systems, for example in Västerås [1] and Linköping [2]

[1] https://www.malarenergi.se/om-malarenergi/framtidens-samhall... [2] https://www.svt.se/nyheter/lokalt/ost/de-lagrar-varme-i-berg...

We are talking about 2 to 3 million MWh for Sweden alone (~120 million MWh yearly consumption so in reality probably a bit more then that as the consumption is higher in the winter).

The largest battery based energy storage in the world is 3000 MWh so we just need to build thousand of those (or a 1000x larger one). Good luck with that.

The largest heat storage under construction is 90000 MWh so that is a step in the right direction but still falls short by around 35x and even more if we have to turn that heat into electricity (While a lot of this consumption is district heating it is not all of it. And a large chunk of new district heating is just massive heat pumps)

And now that you have built these tools to make wind/solar work you have to factor the price of these into the price of wind/solar and suddenly they do not look that cheap when compared to nuclear. This is why the government and Vattenfall in Sweden want to build more nuclear.

Realistically the only cost effective energy storage on this scale we have available is hydro and pretty much all the places where it is cheap in Sweden have already been built.

In general I think Sweden is on the right track. They have a lot of wind and are building a lot more of it. They can also build more nuclear at the same time.

Though Sweden (just like here in Finland) are slowly reaching the point that when it is windy the wind farms don't really make much money as the price on the spot markets is very close to 0 so we also need a lot of new intermittent energy consumption (industrial processes that can be slowed down/ramped up cost effectively, make hydrogen, fill the heat storages with heat pumps, etc). This is the place where batteries can play a big role by being able to "move" this electricity into the future to a moment where there is more consumption/less production.

I don’t think solar is as bad as you think it is during winter. During a stationary high pressure, you’ll have clear skies. Solar cells are more efficient when cold, and in fact in warmer countries the heat of midday can make them so inefficient that solar panels generate the most power in the morning and late afternoon.

It is bad due to the short days and low angle of the sun.

For example in Stockholm you get around 6h of daylight. Malmö (can’t really get further south than that) a bit over 7h.

Basically the northern most point of mainland US is a lot further south than the most southern place in Sweden. Thinking about how good solar panels are in the winter in Anchorage gives you some idea (which has slightly slightly shorter days then Stockholm at around 5h30min at their shortest)

6 hours of daylight, then you need to over-provision the solar so you can charge 18 hours worth of batteries in that time. This is still cost competitive with nuclear

It is way worse than “6 hours of daylight” due to the lower angle of the sun.

I don’t know the numbers for southern Sweden but for Stockholm level you get maybe 5% to 10% of the production you get in the summer.

Here in Finland we have it even worse but I know where to find the numbers.

https://www.fingrid.fi/en/electricity-market-information/sol...

Basically if we are lucky we hit 5% of a typical summer day for an hour maybe two. As the days are less then half as long you end up with ~1% the production vs summer.

But in reverse the panels are really good during the summer as the days are very long. This is why people bother installing solar here.

Is it really? Including the batteries?

And we're still ignoring the fact that many days you'll get barely any direct sunlight during those 6 hours of "daylight"

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