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Writer's picturemariealixdalle

"In the energy jungle"


Contribution to CELL's Transition Days in Luxembourg, in collaboration with Frédéric Conrotte and Thomas Gibon


Imagine yourself as an adventurer in the heart of an immense tropical rainforest, walking for several days without coming across a drop of water. Thirsty, you come across a stagnant pond populated by gesticulating larvae, and fed by an almost dry stream. Do you wait patiently for the stream to fill your gourd, or do you dive headlong into the pond, to hell with the larvae, it will make protein?



Soon after, it rains, finally! You will be able to store water. But the neck of your gourd is very narrow, you only collect a little... Empty coconut shells around you allow you to collect more, but you would need much more to collect all the water you will need until the next rain ! If it rained continuously, opening your mouth would be enough to drink...


By rushing to save time, you are tired, thirsty and hungry... And the berries around you are rarer and smaller: it will take more work to satisfy your hunger... Will your harvest compensate for the calories spent? When the berries were bigger, you had time to rest after harvesting and eating, before leaving... "Why are you telling us all this anyway? What does this have to do with energy?"



And yet... Imagine yourself, an adventurer in the heart of an immense dense boreal forest, walking for several days without seeing a ray of sunlight. Chilled, you come across a pile of coal, lit by a thin beam of sunlight. Do you wait patiently for the beam to warm your back, or do you hurriedly light a bonfire, to hell with the fine particles and CO2, that will do more for the photosynthesis of the plants ?


Soon after, a sunny clearing, finally! You will be able to recharge your portable battery. But your solar panel is tiny, you only collect a little energy... With the materials around (and your skills as a photovoltaic engineer) you manage to build other panels and batteries, but you would need many more to collect all the energy you will need until the next day! If the sun shone continuously, we wouldn't be cold anymore...


To get warm quickly earlier, you made a big fire, using all your wood at once, whereas a smaller fire would have lasted longer... And the dry wood branches are rarer and smaller: it will take more work to get enough to warm you... Will you collect enough before you are frozen? When the branches were bigger, you had time to rest after making the fire and warming up, before leaving again...

This is how in a few words we explored the main issues of energy.

The stagnant pool of water represents fossil energy sources (oil, coal, gas), carbonaceous, polluting, and available in limited quantities, but dense (containing a lot of energy in a small volume), stored and transportable, and available on demand.

The light rain or the low flowing water represent the so-called "renewable" energy sources (solar, wind...), flowing in an inexhaustible way, intermittent, and not very dense (it takes a lot of surface to collect a sufficient quantity), and thus requiring more collectors and storage means (gourd), themselves requiring more raw materials (coconut shells). 1

We also discussed the notion of loss of useful energy in the form of heat when actions are faster (running vs. walking): this illustrates the need to slow down, anticipate, and organize to save energy.



Finally, the last concept that this story has allowed us to evoke, through the smaller berries requiring more work to harvest, is the Energy Rate of Return (EROI) which compares the energy invested (work to harvest the berries) to the energy recovered (calories provided by the berries). This notion explains why some energy sources are more used than others, because it is the energy sources with a high EROI, i.e. the energy sources that provide us with a lot of energy without us having to spend too much to harvest them, that allow us to have the lifestyle we have today, with vacations, paid vacations, a pension... It is thanks to the discovery of very dense energy sources (i.e. allowing to recover a lot of energy while spending little to collect it) such as coal, oil or nuclear energy that our societies have been able to free up free time to educate themselves and develop. 2

And perhaps most fundamentally, this little comparison highlighted the vital nature of energy, just like water. "Vital? I can live very well without energy! All the adventurer has to do is put on more sweaters!"



It's true that energy is used for a number of nice things that we could do without, like charging our phone to watch cat videos, or heating our home to 23°C in winter. But energy is not only that: energy is also everything that allows us to transform the world around us, to create objects, clothes, houses, and especially, it is what feeds us! Without the energy of the sun reaching the earth, which heats the atmosphere, feeds the water cycle, generates the winds, and above all feeds the photosynthesis of the plants, which we feed on, no life!

"Yes, okay, I was talking about electricity, coal, oil, gas and everything else! All this, we can do without, we only have to live naked in the rainforest, like the adventurer!"



Certainly, although it is not sure that everyone agrees with you... That said, your remark is interesting: it illustrates well the difference between the energy that a human uses directly, and the one that is necessary to power the machines he uses to do the work for him. The difference between a world with little dependence on energy, and the one we live in is mainly... all the activities that use machines, that is to say all the economic activities. And yes, as we have seen, energy is what allows us to transform the world around us, so the more industrial, economic, urban, digital activities there are, the more energy we use.

By the way, to bring back to its starting point a car that would have run with 1L of gasoline, a human would have to push it for 30 days! 3




"It's true that energy is essential to our way of life. But I have a green contract. So I can maintain my standard of living without feeling guilty, climate change is not my fault!"



This is a very good thing! Speaking of adventure, the green contract offer is also a jungle: there are different levels of "quality" of green electricity.


Since power plants cannot move, and electrons are impossible to trace in the European network, the market of what is called "guarantees of origin" allows any consumer to ensure that a renewable MWh (unit of energy) will have been injected in the year in which he consumes a MWh.

"What about those who didn't buy guarantees?"



They end up with unlabeled electricity, too bad for them! The majority of green electricity consumed in Luxembourg comes from Norway (40% in 2018), and Iceland (21%) 4. Ah Iceland, its volcanic landscapes, its black pebble beaches, its hydroelectricity, its geothermal power plants, and... its total lack of electrical interconnection with Europe. While it is undeniable that Scandinavia has one of the lowest carbon electricity production in the world, how is it that we can also benefit from it? The only constraint is that at the end of a year, the sum of MWh sold as "green" must correspond to the sum of consumption linked to green contracts.

"But there is still a problem: if we buy electricity from Iceland, does that mean that the Icelanders consume coal and gas?"



Yes, at least according to this system of guarantees of origin, called the European Energy Certificate System (EECS). Too bad for them, they didn't have to sell their hydroelectricity after all. More realistically, your electricity probably comes from power plants much closer to you, lignite or gas-fired plants - far from green. So what can you do to reduce your carbon footprint? There are contracts that guarantee investment in low-carbon power plants, for example Enovos offers "nova naturstroum", which is stricter than "naturstroum" (which "uses" mostly Scandinavian hydroelectricity, paid for by Norwegian and Icelandic taxes, and depreciated a long time ago), which ensures that your money is redirected to solar and wind farms.

"Is it really effective?"



Studies exploring the topic have shown that this guarantee system is (still) far from encouraging the development of renewables (except in specific cases, such as Dutch offshore wind, which regularly breaks price records) 5. State subsidies for the installation of renewables are much more effective for this development. With a time step of one year, the guarantee system also avoids the daily and seasonal variations inherent to intermittent renewable production. This time step should be reduced to a week, a day or even an hour to increase the reliability of this system and its efficiency. Finally, since we are talking about intermittency, it is also proven that the more renewable electricity there is in the grid, the more gas-fired power plants there are... 6 Difficult to get rid of fossils. If you want more information, we recommend this excellent video to learn all about green electricity: https://youtu.be/goceQuwWwKA.

Now let's get our heads out of the sand. We have focused on electricity, not energy. The majority of Europeans drive a combustion car, fly, and do not heat with electricity. Road transport by trucks but also heavy industry, such as steel production, cement production for buildings, use a lot of fossil fuels (oil, gas, coal). Electricity accounts for only 26% of the final energy consumed in OECD 7.

"Yes, but we will find a new source of energy, clean, dense and with little impact on the environment!



If it exists, we must find it quickly because climate change leaves us little time.

There is one thing that my little fable at the beginning did not explain, and that is that energy is neither created nor destroyed: it simply changes form. As described earlier, the sun is the source of solar, wind and water energy, and feeds plants (biomass). The plants that are not consumed are compressed and condensed under the effect of the high pressures and temperatures that prevail there, and are transformed after a very long time into oil, gas and coal. It is because of this slow natural process that these fossil fuels are so concentrated in energy. So of all the energy sources we know of on earth, most originate from solar energy reaching the earth, and fossil fuels are just the condensed and stored natural form of solar energy.

Nuclear energy is the energy contained in the bonds of the nuclei of matter: it is the densest source of energy, but the elements from which this energy is most easily extracted are also in limited quantity on earth. Finally, there is also a flow of gravitational energy reaching the earth, at the origin of the tides, as well as a flow of thermal energy within the earth, at the origin of geothermal energy, but these flows are tiny in comparison to the other flows. 8

Everything else, electricity, hydrogen, compressed air.... are not new sources of energy, because they do not exist in their natural state, or are difficult to capture in the environment: they are simply energy vectors, more practical to store or transform.

"Ok so in summary, energy is everywhere and shapes our comfort, helping us transform the world. Since there is no perfect energy source, to save energy and reduce our impact on the environment, we need to do fewer things, and slower!"



That's right! Possess less, do less, to create more social connections and savor life (:

Authors: Marie-Alix Dalle, Thomas Gibon, Frederic Conrotte


  1. Quadrennial technology review concepts in integrated analysis, September 2015 []

  2. Energy, EROI and quality of life, Jessica G.Lambert, Charles.S.Hall, Stephen Balogh, Ajay []

  3. https://jancovici.com/transition-energetique/l-energie-et-nous/combien-suis-je-un-esclavagiste/ []

  4. Rapport Biannuel de l’institut luxembourgeois de régulation sur le système d’étiquetage, Graphique 5, accessible à https://assets.ilr.lu/energie/Documents/ILRLU-1685561960-737.pdf []

  5. Jansen, Jaap, Does the EU Renewable Energy Sector Still Need a Guarantees of Origin Market? (July 7, 2017). CEPS Policy Insights No. 2017-27, Available at SSRN: https://ssrn.com/abstract=3055638 []

  6. Alova, G. (2020). A global analysis of the progress and failure of electric utilities to adapt their portfolios of power-generation assets to the energy transition. Nature Energy, 1-8. []

  7. https://www.iea.org/sankey/#?c=OECD%20Total&s=Balance []

  8. W. Hermann, Quantifying Global Eyergy Resources. Energy 2006;31(12):1349-1366 []

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