energy transition

Challenges of the energy transition

Will renewable energies be available in the future at the right time and, above all, in sufficient quantities for us if large parts of the industry and private transportation  are electrified as part of the forthcoming mobility transition? Are we on the right track to support the reduction of global CO2 emissions?

There are few topics that are currently being discussed more emotionally and with greater zeal by proponents of electromobility, such as the CEO of Volkswagen AG, Herbert Diess. Do we run the risk that a fair, fact-based exchange of ideas in the interests of the climate becomes more and more difficult because political decisions and ideology replace physical laws which in the end leads to the oppression open-mindedness towards pragmatic technology?

Dr. Daniel Stelter, columnist in various political and business journals as well as operator of STELTERS PODCASTS who is also responsible for articles on the website

THE PIONEER Beyond the Obvious ”, which was discussed on October 25th, 2020 in an interview with Prof. Dr.-Ing. HOLGER WATTER who gave questions and answers regarding the energy-transition .


This interview helps to classify this topic based on Prof. Watter´s experience at the University of Flensburg. Prof. Watter was kind enough to approve the publication of the interview on We probably would not have been able to explain the issue in the same way.

We would like to take the opportunity to thank Prof. Dr. Watter!



All articles and interviews with Prof. Dr. Watter can be found on his website:

Classification support for the energy transition


Question 1

Is it true that the cost of renewable energy is lower than that of fossil fuels and nuclear power?


Answer 1

20 years ago the slogan was clear: “Sun and wind don't send invoices”, which of course was extremely questionable, because you have to distinguish between investment costs and operating costs. Germany has the highest electricity prices in Europe today, so reality shows that something is wrong here.

 From an engineer's point of view, you may try to answer the question with an analogy: If I urgently need a bike, privately or for professional purposes and it is only available temporarily (because my spouse needs it too), then I might think about a second bike or other alternatives. We have a similar situation e.g. in the photovoltaic systems. The sun doesn´t shine at night, therefore no solar energy can be generated .


In contrast, the sun shines most intensely around noon. which may generate an oversupply. Thus the price drops, and even negative prices arise. We pay someone else to take that excess energy off us. If, on the one hand, the operator of the solar system is legally guaranteed a price, someone has to pay the difference. This is the reason why Germany has the highest energy prices and the most fragile network. The more photovoltaic systems are set up, the sooner (especially in summer) their output needs to be regulated or an “energy destroyer” be paid for its service. On average, however, non-availability tends to dominate.

There are similar effects with wind turbines. The more systems that are set up, the sooner they are regulated and the higher the subsidy expenditure. The “remuneration system” for “the windmillers” drives up the costs for citizens and industry. International competitiveness suffers. The CO2 targets are achieved through the de-industrialization and unemployment of an industrialized nation with “hidden costs”.

Despite the clearly noticeable decrease in German CO2 emissions, the question arises whether there are not more intelligent solutions which tackle the problem better and more sensible priorities, e.g. through energy policy cooperation with Africa . In particular, potentials can be seen here for solar energy as well as for hydrogen generation and the solution of the transport problem (through methanation, ammonia, etc.). In the vicinity i.e. of the oceans, technically treated and conditioned water can easily be made available in sufficient quantities from sea water by means of reverse osmosis. However, this increases the water requirement again by a factor of 3 in order to avoid deposits (“scaling”) in the membranes (e.g.approx. 9 x 3 = 27 kilograms of seawater would have to be taken per kilogram of hydrogen, so that 9 kilograms of water would be available for the conversion process The difference of 18 kilograms is returned to the sea as “concentrated lye”).


So the specific answer is:

The prices on the Leipzig energy exchange, which can be viewed daily i.e. via the EEX TRANSPARENCY platform, are therefore not representative. There are no stand-by costs and redundancies. To come back to the question: As an engineer, I find it difficult to give an answer. The fact remains that “apples are often compared with oranges and unfair methods are used”. The fact that GRETA THUNBERG  now also considers nuclear power a possible  option requires a re-evaluation of the impact- and risk assessment of the different systems.



An obvious disadvantage of the so-called “renewables” is that the lack of availability and the fluctuating supply make “back-up” solutions and storage necessary. This will increase energy costs but further reduce security of supply and competitiveness. Due to the physical limits, it is - from my perspective - widely recognized that Germany can never be self-sufficient and therefore international solutions will become necessary.


Fig. 1: Load profile in Germany, updated daily data under

Fig. 2: Basics of electrolysis

Question 2

What are the main challenges for the transition to renewable energies?


Answer 2

The main challenge is the ability to debate this topic in society, as large parts of the population and the majority of the (supposed-to-be) experts cannot differentiate between “kW” and “kWh” and simplify the challenges with gross negligence. This enables political and economic business models that represent lobbying interests, privatize profits, socialize risks and do not contribute to solving problems.

In the case of photovoltaic systems, the installed capacity is always given as an example, although the average yield amounts only to around 10 percent (in other words, 90 percent is not available). An onshore wind turbine, even in good locations, only produces about 25 percent. This is hidden behind clauses that nobody understands (full load hours, capacity factor ...). On average, only 25 percent of the installed capacity is available - even less if there is no wind ... up to 0 percent. Here lobby representatives usually demand more research and more funding for storage, although numerous research results and experiences from pilot plants are available.


We just have to interpret these findings honestly:

Storage is expensive and inefficient - so it increases production requirements and costs again, although it is already evident that the needs of an industrial nation cannot be met with so-called “renewable energies”.

The constant repetition of the thesis that “renewables” are sufficient does not make it  any more correct. Numerous studies such as the DENA or KALTSCHMITT support this statement. As an industrialized nation, we will have to continue to import energy. Based on a CHURCHILL quote, I can only warn against so-called studies by the lobby associations (e.g. the Federal Accociation Wind Energy/ Bundesverband Windenergie or GREENPEACE): Do not trust any website that you have not faked yourself. Due to the lack of energy density, the lack of reliability and the lack of availability, the question is more complex than is often presented. Here is a  quote from the Bible that fits into the context: "Lord forgive them for they do not know what they are doing."



By comparing the meter of a photovoltaic system regarding generation and consumption at the end of the month in believe it is self-sufficient, basic, physical rules were not understood. Please compare to:


  1. Two to three muesli bars (1000 kcal = 1.16 kWh) do not necessarily help when cycling (at 20 km / h approx. 80 W = 0.08 kW of power are consumed and required). It is of no use that the theoretical energy requirement for 1.16 kWh / 0.08 kW = 14.5 hours is completely covered

  2. The following example concerning the coffee machine:
    A photovoltaic system with a peak of 1 kW can perhaps drive a coffee machine at noon. The yield in “kWh” is completely irrelevant and provokes wrong conclusions. There is also no point in “paving” all roofs or the whole country with photovoltaic systems.

  3. The discussion of so-called “surplus electricity” in the Federal Republic of Germany may serve as a social example of misinterpretation: the “regulated surplus electricity ” in Germany in 2017 was around 5,300 GWh [STATISTA] .



1,000,000 kWh = 1,000 MWh = 1 GWh

1000 GWh = 1 TWh

This amount of energy corresponds to an average output of 5,300 GWh / 24 hx 365 d = 0.605 GW = 605 MW.


If you compare this value with the daily cycle from Fig. 1 (between 60 to 80 GW), this corresponds to an average of 0.605 / 70 = 0.8 percent of the daily power requirement. Alternatively: 5300 GWh / 70 GW = approx. 75 hours - ie the surplus production corresponds to approx. 3 days of full load in national consumption.

Fig. 3: Regulated surplus electricity 2017 or “a drop in the ocean”

Fig. 4: Exchange balance with other countries - here too “surpluses hardly recognizable”.

Question 3

Can't we solve the problem of availability?


Answer 3

This is where the discussion about storage comes into play. In order to make the dimensions clear, the example of a simple coffee machine helps to explain the situation: The power consumption of a coffee machine is approx. 1000 W or 1 kW. If you let this coffee machine run for one hour, 1 kW x 1 hour = 1 kWh of energy will be consumed - depending on your personal tariff, 20 to 30 cents per kWh. If you operate this coffee machine with 100 W for 10 hours, you also consume 1 kWh of energy, but you will not get any coffee under normal circumstances.

NOTE: 1 kWh is not the same as 1 kWh.

Back to the storage problem: It is known from pumped storage power plants or pendulum clocks that one can store potential energy with relatively little loss “by raising it”. In this respect, it would be necessary to check for the purpose of classifying how high you would have to lift 10 kg of water to store for example 1 kWh of energy. [...]The result is an altitude of 36 km. This underlines that the storage task is not trivial and that it may be almost impossible for longer periods of time.


For the purpose of comparison, here the chemical energy stored in one kilogram of fuel and in a car battery (15 kg of weight!):

  • Petrol / diesel approx. 10 kWh / kg

  • Car battery approx. 1 kWh / 15 kg = 0.067 kWh / kg

  • 9V Ni-Cd battery approx. 1 Wh / 40 g = 1 kWh / 40 kg = 0.025 kWh / kg

  • Li-ion battery approx. 12 Wh / 60 g = 12 kWh / 60 kg ... 31 kWh / 350 kg = 0.2 ... 0.08 kWh / kg


Note the energy density of the chemical storage (petrol / diesel) i.e. in comparison to hydrogen 33 kWh / kg. Hydrogen is a very good and high-energy storage medium! Battery storage systems, on the other hand, can be scaled to any extent, but with higher outputs they  are economically limited to hours or days. (see the following chart)


The best-known and until recently largest battery storage system in the world is the Hornsdale Power Reserve in Australia with a capacity of 194 MWh (for approx. € 100 million). Let us assume that this storage facility should carry Germany through a windless night, with a low load of approx. 50 GW - that would mean 194 MWh / 50,000 MW = 3.88 x 10-3 hours = 14 seconds!


Batteries are only widely used in small mobile devices with little power consumption (in the milliwatt range).  - This leads us to the next topic:

Who can explain the difference between “MW” and “mW”?  The factor between those two values is ten to the power of nine.: 1 MW = 1000 kW = 1000 x 1000 W = 1000 x 1000 x 1000 mW!

Fig. 5: Energy versus power using the example of a coffee machine

Fig. 6: Does it make sense to operate a coffee machine with 100 W?

Fig. 7: How high do you have to lift 10 kg to store 1 kWh of energy?

Fig. 8: Comparison of storage types (schematic).

Question 4

Currently hydrogen is hyped as THE alternative?  Is that feasible?  

How does it work technically and what would be the requirements?

Answer 4

In the case of hydrogen as a storage medium, curse and blessing are close to each other, as around 55 kWh of energy and 9 kg of treated water are required to generate 1 kg of hydrogen.


A small medium range car with 55 kW (75 PS) has to “drive” about 1 hour at full power to generate approx. 1 kg of hydrogen with an electrolyzer. The energy content is then around 33 kWh. With a fuel cell or a gas engine roughly 15 kW of 33 kWh will then be available. The conversion losses should not be neglected and thus increase the primary energy demand extraordinarily – and that in a country which depends on energy imports and evidently does not produce sufficient energy itself.

Here, too, the problem remains that neither the wind blows, nor the sun shines steadily. The required full load hours for the electrolyser are lacking. Here the classic methods of generating hydrogen by means of the steam reformer process or petroleum pyrolysis  show definite cost advantages (see also SHELL study). Alternatively it is much easier for a French nuclear power plant to generate “green hydrogen” than for the wind or solar systems with their fluctuating supply.

I will refer to the conversion losses, their justification and limitations again down.

Fig. 9: Conversion losses using the example of electrolysis - methanation - reconversion

Question 5

Wouldn´t it work as an international solution?


Answer 5

Supporting hydrogen generation by means of photovoltaics, e.g. in the Sahara Desert, because of the vast supply of solar energy there, must not underestimate the water requirement: 9 kg of treated water are required for each kg of hydrogen. The contradiction “desert vs. water” should not be forgotten. The water still has to be treated because otherwise it will cause deposits and damage (as in the case of the coffee machine)


The above mentioned example (generating “green hydrogen” with electrolysis technology and French nuclear power) shows clear advantages in this case as well. The weak point is clearly the “poor performance” of the wind and solar systems. If you take the missing power from the grid, on the basis of  the current German energy mix, more coal-fired power is required and emissions rise (see load profile). The current  Real-World Laboratories use precisely this option. In this respect, the path taken here must be questioned.

In summary:

The claim for more research with regards to storage is also a lobbying demand by universities and research institutes in order to drive government research funding up - or at least into the "right" direction. The results are known either way: qualitatively and quantitatively. The warning about “the professional simplifiers” can only be repeated again.



Fig. 10: Average yield forecast of an onshore wind turbine for electrolysis.

Question 6

Why is it still common belief  that Germany can work wonders ? is "miracle" is working in Germany?


Answer 6

Unfortunately, I can't give an answer to this - or simply this answer: Because scientific physics is not understood and lobby interests have a chance to privatize profits and socialize risks. It is then argued that one must look at developments in the digital world and hope for similar effects in the energy industry. Fundamental physical limits are ignored here:

  1. In photovoltaics, sunlight “knocks an electron off the track”, thereby releasing a fixed energy potential. The result is known (1.1 eV), the effectiveness can be increased, but the physical limits cannot be exceeded.

  2. The so-called BETZ factor has been known in wind power plants for around 100 years. The efficiency of a wind turbine is limited  to a maximum of 59.3%. Modern wind turbines have almost reached this limit. Further increases are not expected

  3. For thermal processes (geothermal energy, solar power plants ...) the limit efficiency is known as the CARNOT factor. Here, too, modern engines and power plants have come relatively close to this limit curve, the overall potential has largely been exhausted

  4. Water is a very stable compound that “doesn't like” to be split up into its components. Theoretically, at least 33 kWh are required per kilogram of hydrogen - but actually it comes to 55 kWh, because (as i.e. when accelerating a vehicle) “inertia” has to be overcome. There is potential for improvement here, but it will never reach 100% (currently at around 70 to 80%).


Using the method of limit-value oriented key figures according to SANKOL and VOLTA,as provided by DIN ISO 50,000 or VDI 4663, has not been taken into consideration here,. That means, we do not look at the theoretical potential, but rather at what is possible in reality and taking into account the limits of scientific physics. Unfortunately, we know the limits, but ignore them out of naivety, ignorance or lobbying interests.

Our European neighbours therefore have difficulties understanding our position and call it the “German problem”.

On the other hand, imperial tendencies like “the world should improve by going the German way” (Germ. "Am deutschen Wesen soll die Welt genesen") seem to be receiving an unexpected renaissance.


Question 7

Since we see both dangers of the climate change, what would you do to achieve the goal of reducing CO2?


Answer 7

Unfortunately, I have to admit that I can´t provide THE SOLUTION and it probably doesn't exist either. Every contribution made by the so-called “renewables” is important and a progress, but they will not meet the demands of an industrialized nation. It is my job as a university lecturer to point out the risks and misinterpretations so that an appropriate risk assessment can be put in place. I regret that many colleagues mistake the scientific “search for truth” for their own agenda mission.

Maybe the solution is  a realistic mix of “renewable” energy, climate-neutral nuclear power, import (in alternative forms) and renunciation. “Saving is renouncing consumption” and “never against the market and never against physical laws” seem to me to be reasonable guidelines for this process. It is the task of science to accompany this process critically  and with an open mind. Roughly qoting the famous German TV-host HANNS-JOACHIM FRIEDRICHS:

You can recognize a good scientist by the fact that he does not take on a certain cause - not even a good one! He remains aloof.




The colleagues (m / f / d) in the involved fields of sciences may excuse a few simplifications.

As an interim conclusion this might be a suggestion:

  1. Renewable energies pay an important contribution to the task of minimizing CO2, but are NOT sufficient for the needs of an industrialized nation.

  2. Current theses and plans for the energy transition ignore essential boundary conditions and experience. An interim balance in terms of quality management or energy and environmental management according to current industrial standards would be necessary. “Gut feeling” and “wishful thinking” displace an appropriate and reliable analysis of opportunities vs. risks. More expertise in physical laws, critical self-reflection and quality controls with regards to the energy transition would not only be helpful but necessary!

  3. The university's task remains: “Enlightenment is man's release from his self-incurred immaturity. Immaturity is man's inability to make use of his understanding without direction from another. This immaturity is self-imposed when its cause lies not in lack of reason but in lack of resolution and courage to use it without direction from another." Sapere aude! "Have courage to use your own reason!" -- that is the motto of enlightenment," is therefore the motto of the enlightenment. ”- Immanuel Kant, answering the question: What is Enlightenment? 1784. (, jan. 22, 2021)

  4. As a university professor, I feel committed to this “physical discussion hygiene” - it does not seem to me to exist at the moment - the discussion culture appears “toxically poisoned”. It is my job to warn against the “professional simplifiers” (m / f / d) and to demand a reliable risk analysis.

  5. It is my job to examine and critically question the concepts presented according to DIN ISO 9001 or 50.001 for their practical use. Concepts without a balanced pro/con analysis or a strengths/weaknesses analysis, which does not pay attention to the holistic realities, are unsuitable and promote undesired side effects.

Link to the podcast "beyond the obvious" (German version)

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