Last Thursday, a Flemish newspaper brought the story that “the lights will go out in 2020”. We heard that many times before in the past. This time the statement was made by Andries Gryffroy, who was called the “energy expert” of N-VA (Flemish political party on the center right). He rightfully questioned the “energy plan” of current Flemish Minister of Energy, which is solely based on extra solar and wind energy. Even with those extra windmills and solar panels, we will not be able to produce enough energy to meet our demand in a few years and could face power shortages by 2020. More, several old conventional plants will need to be decommissioned in the next years and the new solar panels and wind mills need backup. He gave the example that in winter only 3% of nameplate power of solar energy is produced, while we use most energy in winter.
Okay, I dig that. Solar and wind provide less energy in the winter when we need most energy. Just adding more intermittent energy sources without backup and additionally decommissioning older conventional power plants, makes a good recipe for energy shortages. Especially in winter at peak demand. Especially with our aging power plants. Our politicians are talking about energy security for years now, but in the end go for extra windmills and solar panels. Probably to meet the EU goals.
Although I agree with what was being said, there were some things that seemed rather odd. For example, it was calculated that in winter we will have a shortage of 1,414 MWh and explained that this is the equivalent of 1.5 Belgian nuclear power plants. Which doesn’t make much sense. 1,414 MWh is the electricity that 1.5 nuclear power plants will produce in one hour. My guess was he was confused between “megawatt” (power) and “megawatt hours” (energy). Or was it the journalist that brought in the confusion?
Also the calculated number was puzzling. At first glance, it seems rather unrealistic. Apparently, we would be able to decommission older gas power plants PLUS arrange backup for a doubling of our capacity of intermittent energy sources, yet only need 1.5 conventional power plant to compensate for all that!?
Luckily, the paper version of the news paper mentioned how the calculation was actually done:
|Energy production||Capacity in winter (MW)||Capacity in summer (MW)|
|Nuclear power plants||6,000||4,000|
|Other thermal plants (in 2018)||3,500||3,500|
|On-shore wind energy (in 2020)||600||400|
|Off-shore wind energy (in 2020)||1,016||710|
|Solar energy (in 2020)||180||1,440|
|Small bio gas plants and trash incinerators||1,140||1,140|
|Biomass plant in Langerlo or alternative||400||400|
The calculation was done in MW this time and then the statement “equivalent of” made sense.
The 180 MW probably comes from 3% of the estimates for 2020. In that case it is calculated on an estimate of 6,000 MW, which seems rather steep. We are now almost at 3,000 MW, so in that case we need to double in 3.5 years to reach that level.
The 1,016 and 600 MW for wind are probably done in a similar way. According to wind scenarios of EWEA, the highest target is 3,250 MW onshore and 1,800 MW offshore. Meaning 18% and 56% of nameplate capacity (which seems rather high to me or he starts from an even higher estimate for 2020).
I did recognize that 14,250 MW number. It is the maximum capacity that is needed to be able to provide enough electricity in a harsh winter. As also seen in the table, this required capacity is higher in winter than in summer. In winter days are shorter, it is colder, we stay more in-doors, we are less likely on vacation and so on. But this maximum is not needed over the complete day, there are two peak moments:
There is a peak in the morning, roughly from 7 until 9 am and another peak in the evening, roughly from 5 until 8 pm. The morning peak is due to people getting up from bed, switching on the lights, the coffee machine, the toaster, then public transportation (trains, metro,…) drawing power from the power grid to get people to work, machines in the factory get switched on, and so on.
The higher and wider evening peak comes from public transportation bringing people back to their homes, people switching lights on, switching on ovens/microwaves/cooking plates and so on to prepare supper (which is the most important meal in our country), switching on the television and so on. In winter we should be able to produce 14,025 MW to accommodate this peak. If there would be a shortage, chances are that it will be in the evening peak on a working day.
The problem that I have with this calculation is that the expert seem to rely on the production of 180 MW for solar and 1,616 MW for wind energy, ignoring that there is no guarantee that the sun is shining or the wind is blowing at peak hours. Those two numbers are AVERAGES over a winter, but electricity consumption is NOT ON AVERAGE. It depends on the time of the day, the day of the week/year. The 14,025 MW is necessary to accommodate for the peaks, especially the evening peak, not over the whole day.
He seem to consider intermittent, non-dispatchable energy sources as if these were dispatchable… It is not. If there is no/little sun or wind at the peak, then it is not possible to rely on that 180 MW (solar) and 1,016 MW (wind). It will only be a fraction of that or maybe even nothing at all.
The elephant in the room is that at our latitude, days are shorter and nights are longer in winter. Last winter (December 1, 2015 → February 29, 2016), the sun rose between 07:28 and 08:45 am. In the worst case the sun starts to shine when the morning peak almost ended, in the best case just before the peak (when it is not really powerful yet and production of electricity is very low).
According to the same source, the sun had set between 16:37 and 18:23 pm during these months. In the worst case, this is well before the peak. In the best case, it is in the second half of the peak when demand is going back down. Also here, sun light will be rather faint just before setting and electricity production will be very low anyway.
When I look at the production of solar energy (data via Elia) last winter there was no solar production at the evening peak from December 1 (2015) until February 16 (2016). That means that there was only a (tiny) production in the last 14 days of that period…
When I make the sum of the production of solar electricity during the morning peak, I end up with 0.45% of nameplate capacity, not even close to that magical 3%. In the evening peak it is even worse: there was only 0.17% of the nameplate capacity in the period. That is very, very far from the average of 3%. Which is not surprising knowing that in most days in winter the sun is already gone when the evening peak arrives. The contribution of solar energy to reach the 14,250 MW will be insignificant.
Therefor this 3% average over 3 months has no meaning when it comes to calculating how much extra capacity we need to come to the required 14,250 MW. We need to look at the situation at peak, preferably the evening peak.
Wind energy (data via Elia) did much better on average (it doesn’t depend on the length of the day): there was an average of 46% of nameplate power (it was unusual windy back then), but there were lows of 0,45%. For example, the equivalent of only a 8.82 MW plant on January 19, 2016 (which coincided with zero production of solar). The absolute lowest of the winter was 4.19 MW on February 24, 2016.
Of the 1.606 MW + 180 MW that was counted on in the calculation, not much is guaranteed. If he wanted to use a number, he should use the minimum of wind and solar (8.86 MW) instead of 1,786 MW. Although it is possible that 4.19 MW could also coincide with low or absent solar energy. In theory, but less likely, maybe even nothing at all. It are intermittent, non-dispatchable energy sources.
Concluding, not only were there two different things compared (capacity of dispatchable power versus average capacity over three months of intermittent power), but also this average number is used in a time frame that is different from when maximum capacity is required (over three months versus at peak).