“Installed capacity” versus “electricity produced”

One thing that I notice in the media is how easy it is to confuse “installed capacity” and “electricity produced”. An example is an article in the printed edition of “Het Laatste Nieuws” (a Belgian newspaper) about our looming shortage of electricity next winter. The journalist made the following calculation:

Wind and water 1,800 MW
Fossil fuels 5,500 MW
Nuclear power 1,912 MW
Import from abroad 3,500 MW (?)

In a very cold winter we need about 14,000 MW at peak moments. With the remark that we still have no idea if we can trust having the much needed 3,500 MW import from abroad. Even if we could trust having this imported electricity, we fall short about 1,300 MW according to these numbers.

The problem is the 1,800 MW number for “wind and water”. As it is used, one would think that this 1,800 MW is something to count on. It is assumed it is as reliable as the other numbers. Yet that is not the case. Meaning that the journalist is lowballing the shortage.

That 1,800 MW seems familiar to me. 1,778.95 MW to be exact, is the current nameplate capacity of wind energy, not the real output that we would expect. It doesn’t mean we get that much electricity from wind. It is the number that we expect when the wind blows optimal across the whole country and only for that long. This hasn’t happened before.

Let’s look at the real number of the production of electricity by wind and water in Belgium. It can be found on the Elia website I started making screenshots the day I started to write this post:

Source: Elia

Source: Elia

The water-part of this is probably from the pumped storage power station of Coo that is pumping water to a higher basin (therefor the negative production at some moments) and later producing power when it is needed by letting the water flow in the lower basin again.

It is obvious from these graphs that nowhere in this period there was a production of 1,800 MW by wind and water. Not even close. The first day there was a peak of about 800 MW for a few hours. The second day around 400 MW for some brief moments. The third day there was a peak of somewhat more than 1,000 MW but only for a very, very brief moment. If we ignore the fact that the water-part sometimes uses electricity, the wind/water power source goes from about 10 MW to about 1,000 MW. And those peaks were only for a very short short time. Far from being 1,800 MW continuously.

This also clearly shows the intermittent nature of wind power. In those three days there were several periods that there was hardly any electricity production by wind. For example on the 20th the generation of electricity was extremely low, also at peak hours. The same with the production on the 21th before noon. Suppose this was winter and suppose we would solely rely on wind (and solar) as some think is plausible, at that time we would need as much capacity from conventional sources as there is consumption to fill in that gap. If that conventional power would not available, we would experience a blackout. That is the Achilles heel of wind and solar power. Backup is needed for those times that there is little wind and solar. Like at peak hours in winter.

People often confuse between installed capacity and actual production. Even journalists and politicians alike. Proven by this article in the newspaper. They assume that renewable energy is the same as its conventional counterpart. But renewables are a completely other beast with specific properties, such as intermittency.

It is not because 1,800 MW is installed that 1,800 MW is produced continuously.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s