Solar and wind produce more than enough electricity for household demand (on average, that is)

If there is one tweet that shows the problems with intermittent energy sources then it is this one (translated from Dutch):

In 2021, the Netherlands produced more than enough electricity from solar and wind for all households. On an annual basis. There are deviations per hour, per day and per month. In June we had a considerable surplus; this month there is a shortage.

Tweet BM_Visser 2021-12-29

It is accompanied by this graph comparing household electricity demand and solar+wind generation in June and the first 28 days of December (the graph was apparently made on December 29, 2021):

Household demand vs production solar wind June December 2021 - The Netherlands

I think that I can somehow understand what he wants to explain. The share of solar and wind in the Netherlands is about 20%, so if on average 20% of total electricity is used by households, then solar and wind deliver on average enough electricity to satisfy electricity demand of households. The core problem is that those households don’t use their power on average and that solar and wind don’t produce electricity on average, what we can see in those graphs.

There is a lot of information in those two graphs. Looking at the demand side, there is a pretty regular pattern day after day. There are however differences over the months. The demand curve is much higher in December than in June. Not only the lowest points are higher, the highest points are much higher, the amplitude is much larger.

Household electricity demand is clearly higher in December (start of winter) than in June (start of summer). This has to do with the length of the days (much shorter in December than in June) and the temperature (December is much colder than June). Meaning that people are more indoors in winter than in summer, therefor using more electricity.

The production side looks also different. At first glance, solar and wind production seems fairly regular in June, but that regularity is nowhere to be found in December. The regularity in June is the influence of solar, but in December this has diminished substantially because of the shorter days. Then it depends mostly on wind to generate electricity and, although there is on average more wind in December, wind is intermittent in December too. There is still no guarantee that there is always more wind in December or that there is more wind when it is needed.

It is also clear that demand and production are inversely proportional: demand is the lowest and production highest in June and demand is the highest and production lowest in December.

As explained above, production by solar and wind is the most irregular in December. To compare that irregularity, I need more data. Because I don’t have the demand/production data of the Netherlands, let alone household demand, I thoughtlessly digitized those two charts. This is the result after the digitization process:

Chart16a: household demand vs production solar wind June December 2021 (original data)

Let’s now express the y-axis in a metric that shows how meaningless the claim is that solar and wind provide more than enough for household demand. In the assumption that those two months are representative for the rest of the year (which is likely, there is a sinusoidal wave over the year with those two months near the extremes), when I change the y-axis from MW to average households demand, then I get this:

Chart16a: household demand vs production solar wind June and December 2021 (per annual households demand)

Meaning that the production of solar and wind in the Netherlands delivers roughly between 0 and 4 times the average annual households demand. So, luckily those households don’t get their electricity exclusively from solar and wind, otherwise they would get way more than what they can handle in summer and experience prolonged shortages in winter. There is an obvious mismatch between solar & wind production and household demand.

The difference will be greater when we consider the monthly average:

Chart16a: household demand vs production solar wind June December 2021 (per monthly households demand)

Solar and wind provide between roughly 0 and more than 4 times the average monthly demand in June and between roughly 0 and more than 2 times monthly demand in December (but mostly below 1).

When I sum both solar & wind production and demand, then I find that solar & wind produced 1.5 times household demand in June while demand is 1.4 times the production of solar & wind in December. That is roughly the reverse, with slightly more surplus in June than deficit in December.

But then, couldn’t the Dutch save that surplus from summer and use it in December? There is more surplus in June than deficit in December, so that maybe even could account for storage losses. That might be theoretically possible, but I don’t think that would be a bright idea. There was an surplus of roughly 850 GWh in June, storing that in for example grid-sized batteries would require about 6,600 original Hornsdale Power Reserve sized batteries. That could get really expensive, especially when those batteries are mostly changed and discharged only once per year. Battery storage is cheap for short-term storage. It would not that much of a problem to bridge small shortages during the month of June, but we are now talking about seasonal storage. Not only is there an surplus in June, there will also be a comparable surplus in August and probably even more in July. All that has to be stored for use during the period December until March.

You might object that this is not a exactly at hand, that surplus in June (and July and August) will also serve for the other 80% of electricity demand and then you are surely right. That surplus in June will be also be consumed by for example industry, but that also means that the deficit in December will become even more dire and that is a different story.

Concluding, the claim that solar and wind produce enough energy for households is not wrong in itself, but it is rather misleading. On average that is correct. Solar and wind produce annually enough to meet the yearly household demand. It however ignores what is happening per hour/day/week/month/season, and that is exactly the problem with intermittent power sources.

2 thoughts on “Solar and wind produce more than enough electricity for household demand (on average, that is)

    1. trustyetverify Post author

      These are indeed interesting graphs and one of these graph may become inspiration for a post in the future.
      Definitely a lot of that gas will be Russian gas. Belgium has only a low dependence on Russian gas (about 5%), yet prices are skyrocketing here too. This might lead to some unexpected outcomes, for example towards our nuclear exit. Politicians are now slowly coming to the realization that replacing a huge share of cheap nuclear energy by high priced natural gas may be a recipe for disaster (nuclear is currently our cheapest form of electricity generation with a share of about half of our demand). It seems that the Greens are increasingly becoming isolated on the issue. Decision will probably be taken on March 18 (unless they decide not to decide, like previous decision moments).

      Like

      Reply

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