Too much green power

Too much power

We had a holiday yesterday in Belgium. The weather was nice. Sunny, although somewhat cold, and windy. Good weather for a long walk.
But in those first Spring days, Windmills and solar cells were producing a lot of energy and the consumption of energy was very low because of the holiday. There was an enormous overproduction of electricity on Monday. The grid operator had to export electricity to France and had to power down some plants to prevent overloading the grid.

I remember a similar situation before. Almost one year ago (the end of May last year) we had exactly the same problem. We also had a sunny and windy extended weekend which brought our power grid almost to its knees. Last year it was probably worse than it was now and back then a collapse of the grid was only just averted by exporting electricity to France.

But, in the end, is more energy not a good thing? Doesn’t this mean that wind and solar can produce a lot of energy in our country? I think there are more things to consider. This situation is not a good thing. Let me explain.

Wind and solar are intermittent energy sources. Wind mills only produces energy when there is wind. When there is not enough wind or too much wind, nothing will be produced. Between these two borders, the more wind, the more energy.
The same with solar. At night nothing will be produced. In the morning, the evening and on very cloudy days only little. When there is a lot of sun, a lot of energy is produced.
This seems very simple and straight forward, but it is important to realize this.

On the other hand we have the consumption of electricity. Throughout the day different consumption patterns exist. In the morning there will be increasing consumption and a small peak, as will be at noon and at early evening. After this, consumption will decrease rapidly and during the night there isn’t much consumption. To have a workable situation there will be somewhat more energy produced than what is needed in order to accommodate those peaks. Electricity has the property that it is fast available, but the downside is that it is difficult to store. The power grid operator will have to balance the production according to the consumption. Too little production or too much consumption and we will risk a brownout (not sufficient power) of a blackout (no power at all). Too much production or too little consumption and there will be a waste of energy (it is difficult to store) or can overload the grid (with a possible blackout).

Different energy sources (nuclear, oil, gas, coal, renewables) will have different capacity to increase or decrease output on demand. For example nuclear and coal don’t have much flexibility, it is very slow in powering down or up. It is mostly used as base load (the minimum amount of power that has to be made available in order to meet minimum demand based on reasonable expectations). Gas is more responsive and it can be used to increase or decrease according to demand (depending on the type, more or less rapidly).

Wind and solar are a different breed. They are intermittent energy sources. They produce energy, but this is not always predictable and not necessarily in accordance with the consumption pattern of that moment. The more intermittent energy sources in the power grid, the more challenging it will be for the power grid operator to balance the output against the consumption.

So what happened yesterday in Belgium? At first glance it seems a bit counter intuitive. Wind and solar in Belgium are only a few percent of the output. How can that small amount overload our power grid?
There are several reasons for this and they all came together yesterday:

  • It was very sunny and windy. Therefor wind and solar, which normally produce suboptimal, suddenly produces (more) optimal in a very short time frame.
  • Less power will be consumed during a holiday than during a working day. In both cases we had an extended weekend (the weekend plus the Monday that followed was a holiday).
  • We do have a peak shaver at Coo that can pump up water and release it later to produce electricity when again power is needed. But this system only has a very limited capacity of a few hours.
  • Belgium has older conventional power plants that are not that flexible in powering up or down. They kept producing energy while wind and solar also performed very well.

The power grid operator had to balance this overproduction. France was willing to absorb our surplus power. Saved.
Last year it was the same story. Too much production in too short time frame. The Netherlands and Germany were contacted, but they apparently had the same problem. At the last minute, France agreed to import surplus power, saving our grid in the meanwhile.

And yes, Belgium paid to be able to export that energy (there was no demand for it). But now comes the sad part. Belgium imports a lot of energy from abroad. This time we should have more than enough wind and solar to keep up for the demand. No? No, although there was an overproduction during some parts of the day, in the morning and evening there wasn’t much wind or sun. Apparently, that day we paid both ways. We paid to import electricity because we didn’t have enough of it at the beginning and the end. And on the peak output we paid to export it because we had too much of it and needed to protect our grid.

How do you call this…free wind…free solar…or something? And another thing, at this moment wind and solar are minor energy sources in our country. We escaped fairly unharmed this time. But what if we increase our renewables to let’s say 20% (the goal imposed by Europe)? If we don’t drastically change our grid by then, I don’t dare to think about what could happen.

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2 thoughts on “Too much green power

  1. eSell

    Wow, that’s interesting! I didn’t realize that an overproduction would shut down a grid. It is very unfortunate you had to pay to export it, and so lost it for the time you needed it later.

    Hmmm…I think it might be time someone figured out some kind of awesome new battery technology.

    Reply
  2. trustyetverify Post author

    Indeed, the problem is that it is difficult to store electricity when there is plenty of it and release it when needed. This is a necessity when using intermittent energy sources.

    Reply

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