By Prof. Alwin Burgholte
(Translated, edited by P. Gosselin)
A secure power supply is the prerequisite for health, prosperity and work worldwide. An everyday life without electricity is unimaginable, would cause enormous costs, and there would be many deaths. The most important aspect of power supply is the power (in kW) secured in every second, which has been guaranteed by conventional nuclear, coal and natural gas power plants so far. Summed up energy yields (in kWh) over weeks, months or a whole year say nothing about supply quality.
Renewable energy producers are hydroelectric and biogas power plants, geothermal energy and, above all, wind and solar plants, all of which have been subsidized under the Renewable Energy Sources Act (EEG) for 20 years with a fixed feed-in tariff and whose output has to be fed into the grid as a matter of priority.
However, wind and solar plants can only generate power depending on the weather. Without wind and solar, no power is available. Low and fluctuating wind and solar supplies must be augmented accordingly by storage or regulated power plants. Also, wind and solar plants cannot build their own 50 Hz grid. Approx. 25% to 35% of the required power must be supplied by conventional power plants as minimum power, regardless of how large the power supply of the regenerative plants is. .
On July 5, 2020, in the period from 12:00 to 16:00, almost the entire power demand between 57 GW to 44 GW could be covered by renewable generators, only 5 GW were missing. The conventional power plants had to supply 15 GW, which corresponds to about 20% of the required power. This was the only way to ensure grid stability with this required minimum output (Lit.1, report page 57; minimum output 37%). The additional 10 GW were exported. Fig. 1 shows the power and electricity price ratios. .
Figure 1: Negative electricity prices through excess generation On July 5 and 6, 2020
Buyers were only found when additional money was paid for the purchase. The electricity price dropped to negative 65 €/MWh for 4 hours. This resulted in costs for 40 GWh x 65 €/MWh = 2.6 million euros, which the electricity consumers then had to help pay. It would have been cheaper to simply shut down wind farms. However, this is not permitted under the EEG feed in act, although even then the wind farm operator would receive the remuneration that would theoretically have been generated under the existing wind conditions. The term “ghost power” has become established for this. In the event of shutdown, electricity consumers would not have to pay the “disposal costs” of 2.86 million euros.
Any further expansion of wind and solar plants, if the existing subsidies under the EEG are maintained, will increasingly lead to periods of negative electricity prices. With the planned amendment of the EEG, the situation will become even worse. Because wind and solar plants will then be in the public interest and are supposed to serve public safety, prevention by citizen protests will hardly be possible. In 2020, there were 298 hours with negative electricity prices . Every addition of wind and solar plants also reduces the operating hours of all power plants that do not receive EEG subsidies and thus worsens their economic efficiency.
Doubling the number of renewable energy plants will also have little effect, but would generate more surplus power, some of which would then have to be disposed of at even more negative electricity prices. In Figure 2, the March 2022 contributions from wind and solar were extrapolated to Figure 3 if installed capacity was doubled to 400 GW (Economic Minister Robert Habeck’s package). Power would then have to be imported on 23 days and disposed of at negative prices on 9 days up to a maximum of 130 GW. The required long-term storage is currently not available and technically hardly economically feasible to develop.
Figure 3: Electricity generation and consumption in terms of installed capacity Wind: 56 GW, Solar: 58.7 GW 
What needs to be done?
Public clarification and verified scientific findings describing the true facts should be demanded and presented in parliaments, the media and in interviews.
Critical conditions in the power grids need to be pointed out publicly.
Experts and consultants should be chosen according to their professional qualifications and not according to their ideological attitudes.
The “surplus electricity” generated should no longer be purchased. Wind and solar park operators should produce hydrogen from their surplus electricity to make their plants economically viable.
Wind and solar plants should only be expanded to the same extent as electrolyzers and storage facilities are added.
To reduce dependence on Russian natural gas, no further nuclear and coal-fired power plants should be shut down. Some of the nuclear and coal-fired power plants that are shut down must be brought back on line.
Electricity generation with gas-fired power plants should first be massively reduced and instead be provided by coal-fired and nuclear power plants so that the gas supply for the chemical, glass, paper and automotive industries as well as for food and consumer goods can be maintained.
Only long-term imports of natural gas and hydrogen can secure this supply in the long term. Politicians would also have to be able to answer for their decisions and be held accountable.
Prof. Alwin Burgholte, Wilhelmshaven, Germany, June 2022
Prof. Alwin Burgholte is an electrical engineering expert and was responsible for the field of electrical equipment and electromagnetic compatibility (EMC) at the Jade University of Applied Sciences in Wilhelmshaven.