Emerging Sustainable Technologies

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Erik Orsenna

Elodie, you have a very interesting pathway because you went down one road, then decided in favour of another. You were an engineer in agronomics, and then were with the French Institute of Petroleum.

From agronomics to oil... It begs the question: “What happened to Elodie?” 

Elodie Le Cadre

I have always been driven by two passions: living organisms and energy. I decided to start out by understanding living organisms, by earning a degree in agronomic engineering. I always wanted to work on solutions that are aimed at preventing or reducing pollution, so I started out by working on the transformation of biomass into energy, through biofuels.

That experience opened the doors to the fascinating field of energy that is driving our economy. My work on economics enabled me to bridge the gap between my initial training in agronomics and the French Institute of Petroleum, where I ultimately went back to square one, starting with a Master's degree, then PhD on a technology that is a bit more innovative than first-generation biofuels, in which biomass is converted to make fuel for aviation.

Then, finally, I joined ENGIE to work on the electricity-gas sector.

Erik Orsenna

The energy transition integrates different systems, rather than leaving them to operate in their traditional silos. You are more competent than I am in oil, but as I see it, oil was simple, gas was simple, coal was simple: it was simple, efficient, and very good.

Nowadays, it doesn’t work that way. The transition means that everything is interconnected, as it is in life. So we're going to take a main character, and that’s the soil. Fossil fuels came from the soil, from the subsoil, and renewables will also come from the soil or they will be trapped in the soil.

Can you explain to us the constraints specific to the soil? The soil, the great underdog, is now going to be back in the spotlight.

Elodie Le Cadre

Fossil fuels were already in the soil and when we wanted to tap them, all we had to do was extract them and drive them through networks to the end point of use. Today, we need to replace them and find a way to reproduce them, using our understanding of how these molecules are formed.  To reproduce them, we now need to come up with new systems, and these systems will need space, or will need soil, to produce the material that will be used to make this substitute.

So in either case, the soil is key. 

Erik Orsenna

Soil as a material is a source of conflict, in that there is competition between the different uses for it.

Elodie Le Cadre

This is what I try to work on through renewable energies, which, as you correctly stated, need to gain acceptance and make a place for themselves.

We have the space needed: it could be on the oceans or in the deserts, where we also have a lot of solar energy and a lot of wind. Biomass production, though, has to be done on land, and if we want to remove CO2 from the atmosphere at the same time, we will also need forests that have very high potential for CO2 elimination. So, there too, we will be tapping the soil for resources, such that I think the competition to achieve our various uses will become even greater.

Erik Orsenna

The second question about the soil is this: compared to the old ways of generating power, in extremely large power plants spread across the country in established locations, power generation is now decentralised. We've all seen the biogas digesters more or less everywhere, and they're completely transforming the way we relate to the land around us. There are no more places dedicated only to energy. In a way, it is the entirety of the soil that will produce energy. 

Elodie Le Cadre

And that's why, now, we're going to have systems integrated into systems. That is how we picture the energy transition. My education and my background in agronomics are helpful to me because a good systemic vision also enables you to really understand how a good energy transition needs to look, and really understand the interactions between the different players vying for the same “input”, as we say in economics, which is the soil.

Erik Orsenna

Now that we have talked about land, i.e. the battle for the soil, and the return of the soil to its place of choice, the second issue is that of materials.

Elodie Le Cadre

Absolutely. So here, we are moving to the sub-soil. We had, and still have fossil fuels coming from the sub-soil. We went there to find fuel. Now, we will go, as we were already doing, but now stepping up our efforts, to look for metals.

Renewable energies have a particularity in that they need metals, notably for conductivity. We go looking for these metals in mines concentrated in certain places on the planet. And that is going to create some tensions because demand is not necessarily always in the same place as supply.

Tensions are also on the horizon over the use of these materials. 

Erik Orsenna

The very impressive order of magnitude that you have indicated is that the production of photovoltaic panels will increase sixfold by 2050.

 This means that the metal requirements for producing these panels are going to be absolutely enormous. What are the critical metals involved in these panels?

Elodie Le Cadre

In 2022, 1 terawatt of photovoltaic panels has been installed. And to achieve the carbon neutrality targets, we will need to keep installing, at frenetic pace. This necessarily requires a lot of materials. 

For a material to be termed as critical, there have to be geopolitical and quantitative analyses backing this up, i.e. the quantity that is available. The main critical materials are silicon, borate and germanium. However, that is the European definition of criticality. Some think there are definitions, based on availability over time.

Erik Orsenna

So how do we manage with these critical materials and this huge need?

Elodie Le Cadre

It’s important not to be overly pessimistic, that being said, because otherwise we won't get anywhere. That's another reason why I like research and innovation, which I’ve been immersed in for several years.

If I use the healthcare sector as an example, when we needed a vaccine to protect ourselves from Covid, we were able to speed up research to find a fit-for-purpose vaccine in due course. Energy also has this ability and there are a variety of solutions for meeting this huge international need for materials, for instance, reducing the amount of materials needed. You come to realise that there is a lot of waste, even in the everyday, in a lot of things. You can produce the same quantity with less: that’s about reducing the quantity of materials, and it’s key.

For example, as concerns silver, which speed up conductivity, there has been an 80% reduction in the consumption of silver since 2008. That’s a lot. We can also use substitute materials, i.e. shift from one material to another. 

Nature offers some very interesting examples because certain molecules in living organisms have this same property of conductivity and thus metal materials can be replaced by natural materials.

The third point is recycling. There is a lot of talk about it, but we need to move faster. Recycling is a key component in this, because a quantity of the materials we are all looking for is already around us

And the last point is, yes, to look for ways to relocate the production of these metals, since geopolitics is also a key component of the competition on materials.

Erik Orsenna

To sum up: reducing, substituting, recycling and relocating. So the possibilities are there.

Elodie Le Cadre

We believe so, yes, that the possibilities are there, and innovation and research are, in my opinion, our best allies in the face of this challenge.

Erik Orsenna

There is another broad direction for research, though it has something of the sorcerer’s apprentice about it. It is referred to as geo-engineering, i.e. the Creation all over again. What are you suggesting? Because I, as an author, want to write Volume 2 of the Bible, which is the first best-seller ever written. So, in 7 new days, what are you going to offer us?

Elodie Le Cadre

Geo-engineering is a family of solutions intended to limit the impacts of climate change stemming from the quantity of greenhouse gases present in the atmosphere. There is consensus, albeit criticised, in the literature that geo-engineering includes two families. 

One aims to manage the light radiation that reaches the Earth, which makes the planet warm enough for us to live on it, but at the same time, because of the CO2 that is overabundant in the atmosphere, warms us too much, and is thus a problem. 

Some “sorcerer’s apprentices”, as you say, are looking into solutions such as mirrors that would send these light rays back into space or artificially-created clouds to reduce the heat generated by this light radiation.

It’s true that, here, I too am doubtful because we don’t have enough results and data to qualify the safety of these solutions.

Erik Orsenna

So we agree, it is pretty crazy! I have seen solutions that I would call more modest, for instance, repainting all the roofs in white, which would reflect the light thanks to the Albedo mechanism. Putting up a big mirror to reflect and return to the sun what it sends us, or putting on huge sunglasses to protect us from radiation or create clouds: but we still don’t know what the counter-effect would be, do we? 

Elodie Le Cadre

Exactly. This is a subject that is emerging though, and on which attention is focused. Given how difficult it is proving to significantly reduce our greenhouse gas emissions, some people think that in order to limit global warming to a certain number of degrees, we need to starting thinking up a plan B. And plan B includes solutions that scare people. 

But we have to face the facts. I think that, yes, these solutions could contribute to reducing global warming. But is that what we want? This is the question that needs to be asked.

Erik Orsenna

It’s funny because we are not afraid of that which is certain, but we are afraid of an answer to the uncertain.

Elodie Le Cadre

There is another family of solutions, referred to as “negative emission technologies”, CO2 elimination technologies. Today, the oceans and forests, nature and the soil also have the capacity to absorb this gas at a certain pace. We will try to speed up the elimination of surplus greenhouse gases already stored in the atmosphere.

This category includes a variety of solutions, including solutions that are based on nature, called “natural-based solutions” like the forests. However, the forest means reforestation or afforestation: land that was not originally intended for the forest is replanted into a forest and other land, where the trees have been cut or burned down, is replanted to reconstitute a forest system.

Erik Orsenna

That still goes against the whole trend toward deforesting in order to free up land for solar panels or to increase production capacity. 

Elodie Le Cadre

Or for biofuels that have generated allocation changes.

Erik Orsenna

Which brings us back to big question of the battle for land.

Elodie Le Cadre

Exactly. The issue of land is also going to become evident because the world’s population is growing and needs are increasing. That much is obvious, but it reminds us that with finite resources, there is going to be intense competition.

Erik Orsenna

Could you talk to us a little about another solution? What's all this about biochar? Because what I learned is that coal is the enemy. And yet all of the sudden, it's looking like coal can be nice too.

Elodie Le Cadre

Living organisms are made up of bacteria that have the ability to break down organic matter: this is the process known as digestion. There is aerobic digestion and anaerobic digestion, so with or without oxygen.

If biomass results, it absorbs CO2 from the atmosphere through photosynthesis. Photosynthesis, and this is like magic to me, is something we are also trying to reproduce to be able to capture CO2. If we let the biomass degrade -- this is the carbon cycle -- it naturally re-emits its CO2 into the air, in a gaseous state and then another plant will re-absorb it.

Except that we don't want it to return to the atmosphere, as our challenge is precisely to empty a significant part of this surplus CO2.

So we will look for systems and technologies that will stabilise this CO2, which will prevent it from returning to the gaseous state. Pyrolysis is one solution: it is a technology where we heat up to about 200 degrees, but avoiding combustion and avoiding burning, and we reach a material called biochar, because it looks like a charcoal that, spread over the ground, has agronomic properties and leaves carbon in the mineral state.

So, in conclusion, once the plant has absorbed this CO2, either it is stored in the tree, in the wood and then we make boards with the wood, we make sure that it is not burned because otherwise the CO2 will shift into the gaseous state, or we put it back on the ground through a solution called biochar.

Erik Orsenna

And that’s excellent, because as you made very clear, it's when it's gas that it can be dangerous. When it's solid, it's all good. 

Elodie Le Cadre

Right. We empty our carbon savings account into the air.

Erik Orsenna

So basically, we have too much carbon in a gaseous state. So we are going to try to leave it in a solid state because carbon is life, we know that. So either it goes into the tree and we leave it in the tree, or we find a way to spread it over the ground.

Then, there is hydrogen. Hydrogen is everywhere and we hear people saying that hydrogen is the solution.  Is it really the solution? And if it is, how does it work? 

Elodie Le Cadre

To understand why hydrogen is considered one of the solutions, we have to look at its formula: H2. There are only two H's and no C, no carbon, the thing we are trying to sequester somewhere. So it’s true, hydrogen does seem to be a very promising energy vector for our fight in the energy transition and carbon neutrality. 

Erik Orsenna

It's very rare, isn't it, that a natural element has no C?

Elodie Le Cadre

Yes, because in fact things like to recombine with carbon for the stability of the molecule.

Erik Orsenna

Because carbon is always ready for some swinger action.

Elodie Le Cadre

Right. It enjoys being in combination. That way, it carries more energy. 

We shined the spotlight on two technologies that are other means of producing hydrogen.

The reason why people refer to hydrogen as a low-carbon fuel is that hydrogen is currently based mainly on the reforming of natural gas. Natural gas is CH4, one carbon and four hydrogens. We take the carbon out of CH4 and recover four hydrogens, so that's great, but it pollutes because the CO2 goes back into the atmosphere. 

For turquoise hydrogen we continue to use the same input, i.e. natural gas, CH4. However, instead of returning to the gaseous state, it is in a solid state. So this is a technology that is capable of recovering the four hydrogens in our natural gas molecule, which is a very interesting molecule for many practical reasons, and we end up with carbon in a solid state, which works for us because we don't want it to return to a gaseous state.

The question, when it comes to the market and the economy, is what are we going to do with this solid carbon? For every 1 kg of hydrogen, you get 3 kg of solid carbon. So what to do with this mound of solid carbon?

Let's recap: with turquoise hydrogen, you’ve got the same input, and an environmental balance better than methane reforming. But you have to ask yourself the question: what do we do with this product?

The focus has been put on another technology based on a known system, photosynthesis, capturing light energy and converting it directly into molecules of interest. Today, to produce electricity, you use a photovoltaic panel, you produce electricity and then, with that electricity, you electrolyse water, and all of this is what is commonly known as green hydrogen.

However, you can also do this directly, like plants do. Because they contain chlorophyll, plants capture light rays and, with water and minerals, are able to transform these light rays into molecules of interest for growth.

We try to reproduce the same thing, and this is what we call artificial photosynthesis. Why are we trying to reproduce this, rather than letting nature do its thing? 

Well, nature is very interesting, but it has a limiting factor, and that is its yield. It moves slowly but surely, with photosynthesis posting a yield rate between 0.5% and 1%. That rate can be as high as 4% with some very nice plants such as miscanthus or maize, called monocotyledons, which grow swiftly, but overall, aside from those, it is slow.

What we are trying to do with artificial photosynthesis is to reproduce nature, but in a quicker version, and thus to manufacture hydrogen directly using these light rays, without having to use a photovoltaic panel.

Erik Orsenna

In conclusion, what strikes me is that we are trying to come back to nature, but with the requirements of humans. Nature has its rites, in particular, paces that are inherently slow. Yet we, considering that there are so many of us, need to accelerate. So the question arises: “Will these solutions not pose new problems? ”. We're not playing with fire, we're playing with life.

Thank you, thank you, Elodie.  It's quite exciting, dizzying. And when I look at my own life, during which I studied only economics and waited until a very old age to look into agronomics, I think that, for the most part, I may be looking after myself, but I've wasted my life. Thank you Elodie for bringing that to my attention.

Have a good day. 

Elodie Le Cadre

Have a good day.

Listen to the podcast (in French)

Elodie Le Cadre Loret is an agronomic engineer by training, with a PhD in the economics of energy from IFPEN, INRAE and the University of Nanterre Paris La Défense on the conditions for the emergence of new bioenergy sectors. 

She has been working in industry for over 14 years, where she has held a number of complementary positions, from biomass market analyst in an investment fund to gas and electricity analyst in ENGIE's Strategy Department, not to mention at ENGIE's Research Centre working on the economics of the environment and biomethane production technologies.

Elodie has always had a passion for biomass and the environment, and enjoys sharing her knowledge. She lectures on bioenergy at various Masters courses in Paris and Lyon and publishes the "Emerging Sustainable Technologies" document every year.