Nuclear energy: outsourcing issues

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Since the end of the 20th century, the practice of outsourcing has increased in France. This phenomenon has included strategic sectors, such as the nuclear power industry. Stéphanie Tillement, a researcher in Sociology at IMT Atlantique, has worked on the relationship between safety and subcontracting in the nuclear industry.

“Since the 1970s, we have witnessed an increase in outsourcing in many industrial sectors, particularly for maintenance activities,” says Stéphanie Tillement, a researcher in Sociology at IMT Atlantique. In the book Contracting and Safety, she and other French and international researchers offer a balanced, open-minded analysis of the practice of subcontracting. The book first addresses the nuclear power context. “We wanted to show the diversity of the relationships that exist between nuclear power operators and subcontractors, and in the links between subcontracting and safety,” says Stéphanie Tillement.

“Contrary to popular belief, the term “subcontracting” does not refer to a uniform reality: subcontracting situations vary in terms of the size of the provider company and the duration of the service provider’s presence on-site, for example,” she says. In addition to cases of “nuclear nomads,” who are often associated with subcontracting in the nuclear industry, some subcontracted staff have been working for years, even decades, at the same site, for the same contracting party. While the so-called nuclear nomads perform ad hoc interventions, which cause some to denounce forms of job insecurity, this is not the case for all external providers.  The working conditions and social interactions between the contracting authority and service provider therefore vary significantly depending on the type of subcontracting.

High-risk occupations

Outsourcing in the nuclear industry and its effects on the safety and security of the facilities and workers has received increased attention in both the political sphere (with the “Pompili” parliamentary committee in 2018) and academia. Annie Thébaud-Mony, the honorary research director of the Inserm Scientific Interest Group on Occupational Cancers demonstrated that “at French nuclear sites, employees of subcontracting companies were exposed to 80% of the collective ionizing radiation dose during maintenance activities,” Stéphanie Tillement says. In other words, subcontracted employees are more exposed to ionizing radiation than others. 

This is linked more to the nature of the outsourced tasks, which are often dangerous because they require intervention in high-risk areas, than it is to the type of protection used or follow-up with subcontracted employees.  In addition, the operators of typical nuclear facilities —such as nuclear reactors or radioactive waste treatment plants— are legally responsible for the safety of their facilities under the terms of the law of June 13, 2006 on transparency and safety in the nuclear sector. This also applies to outsourced activities. In the event of an incident or accident, the operator still remains responsible.

One of the major questions posed by the use of subcontracting is that of the monitoring of activities performed by external service providers. In order to ensure that the tasks are carried out in accordance with safety requirements, the operator is required to monitor subcontracted staff. True supervision by contracting authorities implies that they have maintained their industrial technical mastery of the outsourced activities and have allocated the necessary resources (time, human resources) to this supervision. “A major issue for monitoring pertains to the skills of the person performing the monitoring: if they do not master the technique, there is a risk that the monitoring will be reduced to formal checks without take into account the reality of the activity,” the sociologist explains. In the case of specialty subcontracting, this issue is all the more important since operators hire subcontracted staff who have specific skills which they do not have in-house. 

Complex relationships

In the nuclear sector, one example of specific skills that are both scarce and highly sought after are those of welders, whose role is fundamental in maintaining the safety of the equipment. Their work requires a high level of expertise. In the case of specialty subcontracting, the balance of power can therefore be in favor of the service providers, since the operator is dependent on them. They can therefore negotiate more favorable contracts (with less pressure on costs and deadlines, for example).

“Outsourcing poses a more general problem related to the fragmentation of work and organizations, which is more complex due to the multiple interfaces and interdependencies to be managed,” said Stéphanie Tillage. “We often see that companies that choose to outsource part of their activities are primarily concerned with short-term gain,” she explains. “In doing so, they omit an entire series of hidden long-term costs, including the need for the contracting authority to restructure the internal organization in order to ensure the long-term coordination and monitoring of the activities,” the scientist explains. This restructuring can be costly and require significant training in order to ensure the safety and security of workers in the long-term.

Rémy Fauvel

IN-TRACKS: tracking energy consumption

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Nowadays, companies are encouraged to track their energy consumption, specifically to limit their greenhouse gas emissions. IN-TRACKS, a start-up created last November, has developed a smart dashboard to visualize energy usage.

“With rising energy costs, these days it is useful for companies and individuals to identify their excessive uses of energy,” says Léo-Paul Keyser, co-founder of In-Tracks.  In November 2021, the IMT Nord Europe graduate created the start-up with Stéphane Flandre, former Enedis executive. The young company, incubated at IMT Nord Europe, provides monitoring solutions to companies to track their energy consumption via a digital dashboard. The software, which can be accessed via computer, smartphone or tablet, displays a range of information pertaining to energy usage.

Typically, graphics show consumption according to peak and off-peak times, depending on the surface area of a room, house or building. “A company may have several premises for which it wishes to track energy consumption,” says Keyser. “The dashboard provides maps and filters that make it possible to select regions, sites, or kinds of equipment for which the customer wishes to compare energy performance,” he adds.

For advice and clarification, “clients can request a videocall so we can help them interpret and understand their data, with our engineers’ expertise,” continues the start-up’s co-founder. The young company also wishes to develop a system of recommendations based on artificial intelligence, analyzing consumption data and sending advice on the dashboard.

The load curve: a tool for analysis

The specificities of clients’ energy use are defined based on load curves: graphics generated by smart electricity and gas meters, which show evolutions in energy consumption over a set period. To obtain access to these curves, In-Tracks has created an agreement with EDF and Enedis. “With the data from the meters received every hour or five minutes, we can try to track the client’s consumption in real-time,” explains the young entrepreneur.

The shorter the intervals at which data is received from the meter, typically every few seconds rather than every few minutes, the more detailed the load curve will be and the more relevant the analysis in diagnosing energy use. By comparing a place’s load curve values to its expected energy consumption threshold, excessive uses can be identified.

Thanks to the dashboard, clients can identify sub-optimal zones and equipment. They can therefore not only reduce their energy bills but also their carbon footprint, i.e. their greenhouse gas emissions, which are also evaluated by the start-up. To do so, the company bases itself on the quantity of fossil energies used, for instance, with natural gas or biodiesel. “We plan to use programs that make it possible to track variations in the energy mix in real-time, in order to get our results as close as possible to reality,” Keyser remarks.

An application accessible to individuals

The young company plans to make an application available to individuals, allowing them to visualize consumption data from smart meters. The software will display the same data as for companies, specifically, energy consumption over time, according to the surface area. In-Tracks also wishes to add a fun side to its application.

“For example, we would like to set up challenges between friends and family members, for everyone to reduce their energy consumption,” explains Keyser. “The aim is to make the subject of energy consumption something that’s fun rather than a source of restrictions,” he adds. To develop this aspect, the start-up is working with students from IMT Nord Europe. The young company is also undertaking research into the Internet of Things, in order to create data analysis methods that make it possible to identify energy issues even more specifically.

Rémy Fauvel

Déchets plastiques, plastic waste

Plastic waste: transforming a problem into energy

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The linear life cycle of plastics, too rarely recycled, exerts a heightened pressure on the environment. The process of gasification makes it possible to reduce this impact by transforming more waste – currently incinerated or left in landfill – into useful resources like hydrogen or biomethane. Javier Escudero, process engineering researcher at IMT Mines Albi, aims to perfect this approach to make it easier to implement locally.

Plastic waste is so abundant, it is practically like rain. While we know well that it is piling up in landfills and oceans, an American study published in the journal Science has also shown that plastic particles are even in the air we breathe. Despite increased levels of pollution, international plastic production continues its explosive growth. However, at the end of the chain, the recycling industry has never managed to keep up with consumption. In France, the average recycling rate for all plastics is 28%, a percentage mainly obtained from bottle recycling (54.5% of the total). The vast majority of these materials is therefore incinerated or sent to landfill.

In order to respond efficiently to the plastic crisis, other forms of reuse or recycling must be developed. “Gasification means we can transform this waste into useful energy vectors, while losing as little material as possible”, explains Javier Escudero, Process Engineering Researcher at IMT Mines Albi. It is an alternative that contributes to a circular economy approach.

Some plastics not so fantastic

Rigid plastics used for bottles are generally made from a single material, which makes it easier to recycle them. For plastic films, which represent 40% of waste deposits, this is not the case. They are made from a multilayer combination of various plastics, such as polyethylene, polyurethane, and so on, sometimes joined with other materials like cardboard. The complex configuration of chemicals makes recycling such packaging too expensive. This means that in recycling centers, these products are overwhelmingly used for solid recovered fuel (SRF) – non-hazardous waste used for energy production. They are incinerated to feed turbines and generate electricity.

Another kind of waste that is ineligible for recycling is packaging from chemical products (industrial and mass market), considered hazardous. Some of the toxic compounds (chorine, sulfur, metals, etc.) are removed from the surface by pre-washing. However, certain atoms are absorbed into the material and cannot be removed by prewashing. This is where the advantages of gasification come in. “It makes it possible to process all plastics – SRF and contaminated ones – with less prewashing beforehand, as well,” emphasizes Escudero.

Moreover, this process has greater capacity for recycling plastic waste than incineration, as it produces chemical compounds that can be reused by industry, The synthesis gases can be burnt to generate energy (heat, electricity) with better yield than combustion. They can also be reprocessed and stored in the form of gas to be used as fuel (biomethane, hydrogen). To achieve this, one of the challenges of research is to observe the influence of pollutants, and therefore the composition of plastics, on products obtained from gasification.

Transforming materials down to the last crumb

Ground-up waste is compacted in the form of pellets, all the same size, to facilitate their transformation into gas in the gasifier. But if you want to recycle as much waste as possible, you need to adapt the gasification operating parameters, depending on the types of plastics contained in the pellets. For example, processing at a low temperature will break the long chains of polymers in plastic films. The molecules are then broken up again in the next step, as is done in petrochemistry. This produces a wide variety of products: hydrogen, methane, acetylene, and heavier molecules as well.

Processing at a higher temperature will produce more synthesis gas. However, it also produces more aromatic molecules like benzene and naphthalene. These compounds have a very stable structure and are very difficult to break into useful molecules. They may turn into soot – solids that build up in pipes – representing a significant loss of materials. The objective of Escudero’s research into gasification is therefore to combine the advantages of these two methods of processing, to avoid solid residue forming while producing as much gas as possible.

To do so, the researcher and his team are mainly focusing on gas injection, which breaks the molecular bonds of the materials being processed. Where and at which point in the process should injection take place? In connection to what? How does the material react? These questions, and many others, must be answered to improve the process.  The gasifier at the Valthera technological platform, located at IMT Mines Albi and used for the tests, can process around 20 kilograms of material per hour. The process recycles not only the materials but also their energy. “Gasification reactions require energy to occur. This means that we use the energy stored in the materials to power their transformation,” explains the researcher.

Use less, convert more

Hydrogen and biomethane obtained through gasification directly power the goals of the French energy transition. Gasification therefore transforms materials made from fossil fuels into renewable energy. However, this process remains restricted to the context of research. “There are still many small aspects to study in designing gasifiers, to make them higher-performing and more mature for a certain amount of material. We are also going to concentrate on purifying synthesis gases with the aim of finding even cheaper solutions,” concludes Escudero. Gasification could supplement waste management channels at a local level. However, cost remains the greatest obstacle to small industrial actors adopting this method.

Anaïs Culot

Antoine Fécant

Antoine Fécant, winner of the 2021 IMT-Académie des Sciences Young Scientist Prize

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Antoine Fécant, new energy materials researcher at IFP Energies Nouvelles, has worked on many projects relating to solar and biosourced fuel production and petrol refining. His work has relevance for the energy transition and, this year, was recognized by the IMT-Académie des Science Young Scientist Prize.

“Energy is a central part of our lifestyles,” affirms Antoine Fécant, new energy materials researcher at IFP Energies Nouvelles. “When I was younger, I wanted to work in this area and my interest in chemistry convinced me to pursue this field. I have always been attracted by the beauty of science, and I find even greater satisfaction in directing my work so that it is concretely useful for our society.” His research since 2004 has mainly focused on materials that speed up chemical processes, known as catalysts.

Antoine Fécant’s initial research was based on a class of catalysts called zeolites. Zeolites are materials mainly made of silicon, aluminum and oxygen. They are found naturally, but it is also possible and often preferable to synthesize them. These minerals contain networks of porosity that can be used to limit the quantity of by-products generated. Zeolites are useful for optimizing the yield of chemical reactions and energy consumption, and thus limiting the CO2 and waste produced.

The main idea of Antoine Fécant’s thesis, undertaken between 2004 and 2007, was to develop a unique methodology to generate new zeolites. For this, he used a multidisciplinary approach and chose to pair combinatorial chemistry with molecular modeling to “identify ways to synthesize zeolites depending on the kind of porous structure desired,” he describes. “This methodology allowed us to define streamlining criteria and therefore very significantly speed up research and development work in this area,” Antoine Fécant continues.

15 years ago, this approach was completely innovative and won him the “Yves Chauvin” thesis prize in 2008. Now, however, it is widespread in the fields of chemistry, biochemistry and genomics, showing the trailblazing nature of the researcher’s approach.

Improving solar energy production and recycling CO2

After completing his PhD, Antoine Fécant took the post of research engineer at IFP Énergies Nouvelles. Continuing to pursue his goal of offering technical solutions to contain greenhouse gas emissions, in 2011, the researcher began a project aiming to develop materials and processes to recycle CO2 using solar energy. This work won him the 2012 Young Researcher Award from the City of Lyon. The initiative stems from the intermittent nature of solar power. It is based on the idea that a phase directly converting/storing this energy flow as an easily usable energy source would allow it to be better exploited.

Further reading on I’MTech: What is renewable energy storage?

“To get around this disadvantage, we wanted to find a way to store solar energy as a fuel,” states Antoine Fécant. “This would make it possible to create energy reserves in a form that is already known and usable in various common applications, such as heating, vehicles or in the industrial and transport sectors,” he adds. To achieve this goal, the researcher based his research work on the principle of natural photosynthesis: capturing light energy to convert CO2 and water to more complex carbon molecules that can be used as energy.

In order to artificially transform solar energy into chemical energy, Antoine Fécant and his team, in collaboration with academic actors, developed several families of specific materials. Known as photocatalysts, these materials have been optimized by researchers in terms of their characteristics and structures on a nanometric scale. One of the compounds developed is a family of monolithic materials made from silicon and titanium dioxide, allowing for better use of incident photons through a “nano-mirror” effect. Other families of materials with composite architecture are able to reproduce the energetic processes in multiple complex phases of natural photosynthesis. Lastly, entirely new crystalline structures give greater mobility to the electrical charges needed to convert CO2.

According to Antoine Fécant, “these materials are interesting, but at present, they only allow us to overcome a single obstacle at a time, out of many. Now, we have to work on creating synergy between these new catalyst systems to efficiently perform CO2 photoconversion and reach an energy yield threshold of at least 10% for this means of energy production to be considered viable.” The researcher believes it will still be several decades before this process can be deployed on an industrial scale.

Catalyzing the production of biosourced and fossil fuels

Antoine Fécant has also undertaken research to reduce the environmental impact of the use of conventional fuels and their manufacturing processes. For this, he designed higher-performing catalysts that help to improve the energy efficiency of processes and thereby limit related CO2 emissions. The researcher has also participated in discovering catalysts that increase yields in the Fischer-Tropsch process, a key phase in transforming lignocellulosic biomass to produce advanced biofuels. Furthermore, these fuels could contribute to limiting the aviation sector’s carbon footprint.

By winning the IMT-Académie des Sciences Young Scientist Award, Antoine Fécant hopes to shine a light on research into solar fuel and hopes that “this area will be more highly valued”. Such fuels could truly represent a promising avenue to make better use of solar energy, by controlling its intermittent nature. “Research into these topics needs to be supported in the long term in order to contribute to the paradigm shifts needed for our energy consumption,” concludes the prizewinner.

Rémy Fauvel

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From energy to tires

During his career, Antoine Fécant has also participated in a collaborative project on the production of biosourced compounds. The aim of this project was to design a process to manufacture butadiene, a key molecule in the composition of tires, using non-food plant resources. It is commonly produced using fossil fuels, but researchers have found a way to generate it using lignocellulosic compounds. Project teams have managed to refine a process and associated catalysts, making it possible to transform ethanol into butadiene using condensation. This 10-year-old project is now in its final phases.

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fission spin, nucléaire

Nuclear fission reveals new secrets

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Almost 80 years after the discovery of nuclear fission, it continues to unveil its mysteries. The latest to date: an international collaboration has discovered what makes the fragments of nuclei spin after fission. This offers insights into how atom nuclei work and into improving our future nuclear power plants.

Take the nuclei of uranium-238 (the ones used in nuclear power plants), bombard them with neutrons, and watch how they break down into two nuclei of different sizes. Or, more precisely, observe how these fragments spin. This is, in short, the experiment conducted by researchers from 37 institutes in 16 countries, led by the Irène Joliot-Curie Laboratory in Orsay, in the Essonne department. Their findings, which offer insights into nuclear fission, have been published in the journal Nature. Several French teams took part in this discovery.  

The mystery of spinning nuclei

But why is there a need to conduct this kind of experiment? Don’t we understand fission perfectly, since the phenomenon was discovered in the late 1930s by German chemists Otto Hahn and Fritz Strassmann, and Austrian physicist Lise Meitner? Aren’t there hundreds of nuclear fission reactors around the world, that allow us to understand everything? In a word – no. Some mysteries still remain, and among them is the spin of nucleus fragments.  The spin is the equivalent, in the quantum world, of angular momentum. This is more or less how the nucleus spins like a top.

Even when the original nucleus is not spinning, the nuclei resulting from fission still spin. How do they acquire this angular momentum? What generates this rotation? Up to now, there had been two competing hypotheses. The first, supported by the majority of physicists, was that this spin is created before fission. In this case, there must be a correlation between the spins of the two fragments. The second was that the spin of the fragments is caused after fission, and that these spins are therefore independent of each other. The findings by the 37 teams are decisive: the second hypothesis is correct.

184 detectors and 1,200 hours of radiation

“We have to think of the nucleus like a liquid drop,” explains Muriel Fallot, a researcher at Subatech (a joint laboratory affiliated to IMT Atlantique, CNRS and University of Nantes), who took part in the experiment. “When it is struck by the neutron, it splits and each fragment is deformed, like a drop if it received an impact. It is when the fragment attempts to return to its spherical shape to acquire greater stability that the energy released is converted into heat and rotational energy.”

To achieve these results, the teams irradiated not only uranium-238, but also thorium-232, two nuclei that can split when they collide with a neutron (this is referred to as fissile nuclei). And this was carried out over 1,200 hours, between February and June 2018. These fragments dissipate the energy accumulated in the form of gamma radiation.  This is detected using 184 detectors placed around the bombarded nuclei.  Yet, depending on the fragments’ spin, the photons do not arrive at the same angle. An analysis of the radiation therefore makes it possible to trace the fragments’ spin. These experiments were conducted at the ALTO accelerator located in Orsay.  

Better understanding the strong interaction

These findings, which offer important insights into the fundamental physics of nuclear fission, will now be analyzed by theoretical physicists from around the world. Certain theoretical models will have to be abandoned, while others will incorporate this data to explain fission quantitatively. They should physicists to better predict the stability of radioactive nuclei.

“Today, we are able to predict the lifetime of some heavy nuclei, but not all of them,” says Muriel Fallot. “The more unstable they are, the less we are able to predict them. This research will help us better understand the strong interaction, that which binds the protons and neutrons within the nuclei. Because this strong interaction depends on the spin.”

Applications for reactors of the future

This new knowledge will help researchers working on producing nuclei that are “exotic,”  very heavy,  or with a large excess of protons compared to neutrons (or the reverse). Will these findings lead to the production of new, even heavier nuclei? They would provide food for thought for theorists to further understand nuclear interactions within nuclei.

In addition to being of interest at the fundamental level, these findings have important applications for the nuclear industry.  In a nuclear power plant, a nucleus obtained from fission and which “spins quickly” gives off a lot of energy in the form of gamma radiation.  This can damage certain materials such as fuel sheaths. Yet, “We don’t know how to accurately predict this energy dissipation. There is up to a 30% gap between the calculations and the experiments,” says Muriel Fallot. “That has an impact on the design of these materials.”  While current reactors are managed well based on the experience acquired, these findings will be especially useful for more innovative future reactors.

Cécile Michaut

Thermiup

ThermiUp: a new heat recovery device

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ThermiUP helps meet the challenge of energy-saving in buildings. This start-up, incubated at IMT Atlantique, is set to market a device that transfers heat from grey water to fresh water. Its director, Philippe Barbry, gives us an overview of the system.

What challenges does the start-up ThermiUp help meet?

Philippe Barbry: Saving energy is an important challenge from a societal point of view, but also in terms of regulations. In the building industry, there are increasingly strict thermal regulations. The previous regulations were established in 2012, while the next ones will come into effect in 2022 and will include CO2 emissions related to energy consumption. New buildings must meet current regulations. Our device reduces energy needs for heating domestic water, and therefore helps real estate developers and social housing authorities comply with regulations.

What is the principle behind ThermiUP?

PB: It’s a device that exchanges energy between grey water, meaning little-polluted waste water from domestic use, and fresh water. The exchanger is placed as close as possible to the domestic water outlet so that this water loses a minimum of heat energy. The exchanger connects the water outlet pipe with that of the fresh water supply.

On average, water from a shower is at 37°C and cools down slightly at the outlet: it is around 32°C when it arrives in our device. Cold water is at 14°C on average. Our exchanger preheats it to 25°C. Showers represent approximately 80% of the demand for domestic hot water and the exchanger makes it possible to save a third of the energy required for the total domestic hot water production.

Is grey water heat recovery an important energy issue in the building sector?

PB: Historically, most efforts have focused on heating and insulation for buildings. But great strides have been made in this sector and these aspects now account for only 30% of energy consumption in new housing units. As a result, domestic hot water now accounts for 50% of these buildings’ energy consumption.  

What is the device’s life expectancy?

PB: That’s one of the advantages of our exchanger: its life expectancy is equivalent to that of a building, which is considered to be 50 years. It’s a passive system, which doesn’t require electronics,  moving parts or a motor. It is based simply on the laws of gravity and energy transformation. It can’t break down, which represents a significant advantage for real estate developers. ThermiUP reduces energy demand and can also be compatible with other systems such as solar.  

How does your exchanger work?

PB: It is not a traditional heat plate exchanger, since that would get dirty too quickly. Our research and development was based on other types of exchangers. It is a device made of copper, which is an easily recycled material. We optimized the prototype for exchange and its geometry along with its industrial manufacturing technique for two years at IMT Atlantique. But I can’t say more about that until it becomes available on the market in the next few months.

Do you plan to implement this device in other types of housing than new buildings?

PB: For now, with our device, we only plan to target the new building market which is a big market since there are approximately 250,000 multiple dwelling housing units a year in France. In the future, we’ll work on prototypes for individual houses as well as for the renovation sector.

Learn more about ThermiUp

By Antonin Counillon

fonds industrie

Eclore and ThermiUp, new beneficiaries of the IMT “Industry & Energy 4.0” honor loans

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After the IMT Digital Fund, Institut Mines-Télécom (IMT) and the Fondation Mines-Télécom launched a second fund last October, dedicated to the sciences of energy, materials and processes: “Industry & Energy 4.0”. Its committee, made up of experts from the major partners of the Fondation Mines-Télécom (Orange, BNP Paribas, Accenture, Airbus, Dassault Systèmes and Sopra Steria) met on March 18. Eclore and ThermiUp were granted honor loans for a total amount of €80,000. They are both incubated at IMT Atlantique.

L’attribut alt de cette image est vide, son nom de fichier est Logo_ECLORE-300x119-1.jpg.

Eclore Actuators offers a bio-inspired pneumatic and hydraulic actuator solution which is highly energy efficient, 100% recyclable, and based on unique and patented industrial bending processes. Eclore actuators are less expensive, lighter, less bulky and require less maintenance than traditional actuators. There are many sectors of application, such as industrial automation, robotics, IOT and home appliances. Find out more

L’attribut alt de cette image est vide, son nom de fichier est Logo_thermiUP-300x188-1.jpeg.

ThermiUp has developed a heat exchanger that recovers heat from the gray water of buildings to preheat domestic water. It allows builders to save up to 1/3 of the energy needed to produce domestic hot water, which represents half of the energy needs in new housing. This renewable energy device reduces greenhouse gas emissions by 1/3. Find out more

In search of a future for fast neutron reactors

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In August 2019, it was announced that the Astrid project for sodium fast reactors (SFR) was to be abandoned. In late 2020, Stéphanie Tillement, a researcher at IMT Atlantique, analyzed the rationale behind this abandonment in an article for I’MTech. But what is the global situation? Does this technology still have a future? Stéphanie Tillement and her colleague Frédéric Garcias analyze the prospects for this industry.

In 2000, fast neutron reactors returned to center stage, after years of being forgotten. The United States Department of Energy (DOE) organized a very important event for the nuclear industry at the global level, the “Generation IV International Forum” (GIF). This forum sought to help the nuclear industry recover by kick-starting research and innovation based on what were described as “revolutionary” reactors, which had to fulfill a number of very general objectives: safer, more cost-effective, reduce the risks of proliferation, save natural resources and minimize waste. And sodium fast reactors (SFR) fulfill these five criteria.

It was during this forum that this notion of generations of nuclear reactors was first defined. Those currently in operation in France – all of which are Pressurized Water Reactors (PWR) – are referred to as generation II. The European Pressurized Reactor (EPR) being built in Flamanville is referred to as a generation III – as are those being built in England and in Finland and the two EPRs in operation in Taishan in China. Generation IV reactors refer to reactors that are able to fulfill the previously-mentioned objectives. The members of the Generation IV forum agreed on six concepts of reactors referred to as generation IV, three of which are SFR. Among them, one is lead-cooled, another is gas-cooled, and the third is sodium-cooled, like the Astrid prototype introduced by France.

Saving uranium

“We have to put ourselves in the context of the 2000s,” says Frédéric Garcias, a researcher in organizational management at the University of Lille. “The nuclear industry was going through a lull in the construction of new reactors, in particular in the wake of the Chernobyl accident, but many believed that it remained a solution for the future. In what form, and within what timeframe? Growth was anticipated in China and in emerging countries, which could give rise to a high level of uranium consumption. Thus the interest in seeking uranium-efficient sectors.” Fast neutron reactors are able to consume depleted uranium and plutonium, which are waste products of previous generations of reactors.  

Today, Russia and China are at the forefront of the SFR sector. Russia has two (BN-600 and BN-800, respectively 560 and 820 megawatts of electricity) that are based on an earlier design, which are not considered generation IV. China started out in 2011 with an experimental generation IV low-power sodium-cooled fast reactor (20 megawatts of electricity). France, which had also been at the forefront, has fallen behind since the Astrid project was abandoned in 2019. As for the United States, after kick-starting research efforts through the Generation IV Forum, it abandoned nuclear energy for a while, enticed by the prospects of shale gas and oil. But the prospects of a controllable, zero-carbon energy offered by nuclear power has led the country to turn its attention to this industry once again. While many start-ups are working in this area, there are no plans to build reactors at this time.

Towards small, modular reactors

If nuclear energy is struggling to revive itself, especially in countries like France and the United States, it may be that the prevailing approach to development throughout the second half of the 20th century is now outdated. It focused on building ever-bigger, more powerful, more complex reactors. This meant that they were more expensive and harder to fund. This race to build giant reactors may have reached its limitations with the EPR. “Big reactors are, or were, developed in highly-centralized countries like Russia or China, or like France was in some ways in the 1980s,” observes Stéphanie Tillement, a researcher in industrial sociology at IMT Atlantique. “It’s clear that historically, nuclear energy has been less successful in decentralized countries. With the rise of decentralized methods of governance, stakeholders wondered, ‘Why not consider smaller, modular reactors built to respond to needs – in short, decentralized?'” This is precisely the principle of Small Modular Reactors (SMR), which are anywhere from three to one hundred times less powerful than Generation III reactors. They do not have the same business model or organization: smaller reactors require less funding, and seem to be easier to deploy when there is less long-term visibility. SMR concepts are extremely varied: some are inspired by known tried and tested technologies while others are more “exotic.” They all use fission, and can be pressurized water (like generations II and III) or fast neutron reactors.

Read more on I’MTech: Nuclear: A Multitude of Scenarios to Help Imagine the Future of the Industry

Will we see a resurgence of nuclear power in France, whether through SMR or otherwise? “So far, the French government has been quiet on these issues,” says Stéphanie Tillement. “Neither the decision to launch (and then stop) a project to build a reactor like Astrid, or the launch of new projects have been debated or voted on in Parliament. There is no real industrial strategy for nuclear power in the multiannual energy program, a tool designed to steer France’s energy policy.” Clearly, no government, current or previous, seems to want to discuss these issues, as they are deemed to be too risky from a political viewpoint. And yet, nuclear energy is built over time, requiring long-term strategies and public investment. Without this, there is a risk that there will be a massive loss of skills, which will have definite consequences on the industry.

Loss of skills

“The French project to build EPR was started in 2007, after ten years without any building in France,” explains Frédéric Garcias. “The longer we go between projects, the more skills we lose, along with the entire industrial fabric. Industrial capacity requires upkeep! But politicians are unaware of this question of skills – they think that we can stop for twenty years and then just flip a switch to start up again.” Moreover, when there are few construction projects, and few prospects, the nuclear industry becomes less attractive, which impacts recruitment.

Politicians and the nuclear industry do not operate on the same timeframe. A presidential term lasts five years, while nuclear power take decades to develop. Could SMRs be an answer to this short-term vision? “We don’t yet know the answer to this question,” say the two researchers. SMRs would certainly be better- suited to a more volatile, less centralized world, with more participatory democracy. But we would also lose some of the advantages of the sector, such as its small physical footprint. And there would still be safety issues. France currently counts 18 nuclear power plants (56 reactors) – far more SMRs would be needed to produce the same amount of energy. This is unlikely to gain wide public acceptance!

Learning to innovate again

The nuclear industry is struggling due to its difficulty to plan for the future as it awaits government decisions that never come. Perhaps it should also reconsider the way it works. “The abandonment of the Astrid project raises questions about opportunities for innovation in the French nuclear sector,” says Stéphanie Tillement. “The French nuclear sector depends on a very small group of players, primarily EDF/Framatome for operations and design, the French Atomic and Alternative Energy Commission (CEA) and regulators — the Nuclear Safety Authority (ASN) with technical support from the French Institute for Radiation Protection and Nuclear Safety (IRSN). This provides stability, but also a certain inertia. The system has a hard time innovating and breaking away from pre-established models and modes of operation. This was seen in the work on Generation IV: only CNRS dared to develop a concept that was truly a radical breakthrough from previously-developed technologies, a concept for a molten salt reactor, which had never been built in France.” A debate has therefore been set in motion within the nuclear sector: is it still capable of innovating and changing?

By Cécile Michaut.

hydrogène décarboné carbon-free hydrogen

Carbon-free hydrogen: how to go from gray to green?

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The industrial roll-out of hydrogen production only makes sense if it emits little or no carbon dioxide. Researchers at IMT schools are working on various alternatives to the use of fossil fuels, such as electrolysis and photocatalysis of water, plasma pyrolysis of methane, and pyrolysis and gasification of biomass.

Currently, the production of one ton of hydrogen results in 12 tons of CO2 emissions and 95% of the world’s hydrogen is produced from fossil resources. This is what we call gray hydrogen. A situation that is incompatible with the long-term roll-out of the hydrogen industry. Especially since, even if the CO2 emitted by current processes can be captured in a controlled environment, fossil resources will not be able to meet the government’s ambitions for this energy. It is therefore essential to develop other modes of “carbon-free hydrogen” production. Within the Carnot H2Mines network, researchers from the different IMT schools are working on processes that could turn the color palette of today’s hydrogen to green.

From blue to green

One process in line with the French government’s plan published last September is water electrolysis. This consists in separating an H2O molecule into hydrogen and oxygen using an electricity supply. This is a carbon-free solution, provided the electricity comes from a renewable source. But why turn an already clean energy into gas? “Hydrogen enables the storage of large amounts of energy over the long term, which batteries cannot do on a large scale to power an entire network,” explains Christian Beauger,  a researcher in materials science at Mines ParisTech. Gas therefore partly responds to the problem of intermittent renewable energies.

Researchers therefore want to improve the performance of electrolyzers in order to make them more competitive on the market. The goal is to find the best possible balance between yield, lifespan and reduced costs. Electrolyzers are made up of several electrochemical cells containing two electrodes and an electrolyte, as in the case of fuel cells. There are three main families: alkaline solutions with liquid electrolyte, polymer membrane technologies (PEM) and high-temperature systems based on ceramic solid oxide (SOC). Each presents its own problems.

At Mines ParisTech, Christian Beauger’s team is seeking to increase the lifespan of PEM electrolyzers by focusing on the materials used at the anode. “We are developing new catalyst supports in the form of metal oxide aerogels which must be electronically conductive and capable of resisting corrosion in a humid environment, at a temperature of 80°C and subjected to potentials often higher than 2 volts“, says the researcher. Another major problem also affects the materials: the cost of an electrolyzer. The catalyst present on PEM electrodes is iridium oxide, a compound that is too expensive to encourage widespread use of future high-power electrolyzers. For this reason, researchers are working on catalysts based on iridium oxide nanoparticles. This reduces the amount of material and thus the potential cost of the system.

Shedding light on photocatalysis

In the laboratory, an alternative using solar energy to break water molecules into hydrogen and oxygen is also being considered. This is photocatalysis. The semiconductors used can be immersed in water in powder form. Under the effect of the sun’s rays, the electron-hole pairs created provide the energy needed to dissociate the water molecules. However, the energy levels of these charge carriers must be controlled very precisely to be useful.

“We form defects in materials that introduce energy levels whose position must be compatible with the energy required for the process,” explains Christian Beauger. This ultra-precise work is delicate to carry out and determines the efficiency of photocatalysis. There is still a long way to go for photocatalysts, the most stable of which hardly exceed 1% in efficiency. But this method of hydrogen production should not be dismissed too quickly, as it is cheaper and easier to set up than a system combining a renewable energy source and an electrolyzer.

Turquoise hydrogen using methane pyrolysis

At Mines ParisTech, Laurent Fulcheri’s team, which specializes in plasma processes, is working on the production of hydrogen not from water, but from the pyrolysis of methane. This technique is still little known in France, but has been widely explored by our German and Russian neighbors. “This process requires electricity, as for the electrolysis of water, but its main advantage is that it requires about seven times less electricity than water electrolysis. It can therefore produce more hydrogen from the same amount of electricity,” he says.

In practice, researchers crack molecules of methane (formula CH4) at high temperature. “To do this, we use a gas in the plasma state to provide thermal energy to the system. It is the only alternative to provide energy at a temperature above 1,500°C without CO2 emissions and on an industrial scale,” says Laurent Fulcheri. The reaction thus generates two valuable products: hydrogen (25% by mass) and solid carbon black (75% by mass).  The latter is not to be confused with CO2 and is notably used in tire rubber, batteries, cables and pigments. The carbon is thus stored in the materials and can theoretically be recycled ad infinitum. “The production of one ton of carbon black by this method avoids the emission of 3 tons of CO2 compared to current methods”, adds the researcher.

This process has already proven itself across the Atlantic. Since 2012, researchers at Mines ParisTech have been collaborating with the American start-up Monolith Materials, which has developed a technology directly inspired by their work. Its location in Nebraska is not insignificant, as it gives it direct access to wind energy in the heart of the corn belt, a major agricultural area in the United States. The hydrogen produced is then transformed into ammonia to fertilize the surrounding corn farms.

Although the machine is working, the research of Laurent Fulcheri’s team, a major player in the start-up’s R&D, is far from over. “Hydrogen production is the simplest task, because the gas purification processes are fairly mature. On the other hand, the carbon black produced can have drastically different market values depending on its nano-structure. The objective is now to optimize our process in order to be able to generate the different qualities of carbon black that meet the demands of consumer industries,” says the researcher. Indeed, the future of this technology lies in the short-term valorization capacities of the two co-products.

Biomass processing: a local alternative

At IMT Mines Albi, Javier Escudero‘s team is working on thermochemical processes for the transformation of biomass by pyrolysis and gasification. Organic waste is heated to high temperatures in a reactor and converted into small molecules of synthesis gas. The hydrogen, carbon monoxide, methane and CO2 thus produced are captured and then recombined or separated. For example, the CO2 and hydrogen can be used to form synthetic methane for use in natural gas networks.

However, a scientific issue has yet to be solved: “The synthesis gas produced is always accompanied by inorganic molecules and large organic molecules called tars. Although their concentration is low, we still require an additional gas purification stage,” explains Javier Escudero. The result is an increase in processing costs that makes it more difficult to implement this solution on a small scale. The researcher is therefore working on several solutions. For example, the exploration of different catalyst materials that could accelerate certain reactions to separate molecules from waste, while eliminating tars.

This approach could be envisaged as a form of local energy recovery from waste. Indeed, these technologies would enable a small and medium-scale territorial network with reactor sizes adapted to those of the collection centers for green waste, non-recovered agricultural residues, etc. However, there is also a need to clarify the regulations governing this type of facility. “For the moment, the law is not clear on the environmental constraints imposed on such structures, which slows down their development and discourages some manufacturers from really investing in the method,” says the researcher.

There is no shortage of solutions for the production of carbon-free hydrogen. Nevertheless, the economic reality is that in order to be truly competitive, these processes will have to produce hydrogen cheaper than hydrogen from fossil fuels.

By Anaïs Culot

Power-to-gas, when hydrogen electrifies research

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Hydrogen is presented as an energy vector of the future. In a power-to-gas system, it serves as an intermediary for the transformation of electricity into synthetic methane. The success of this energy solution depends heavily on its production cost, so IMT researchers are working on optimizing the different processes for a more competitive power-to-gas solution.

Increasing production of renewable energy and reducing greenhouse gas emissions. What if the solution to these two ambitions were to come from a single technology: power-to-gas? In other words, the conversion of electricity into gas. But why? This method allows the storage of surplus electricity produced by intermittent renewable sources that cannot be injected into the grid. The energy is then used to produce hydrogen by electrolysis of water. The gas can then be consumed on site, stored, or used to power hydrogen vehicles. But these applications are still limited. This is why researchers are looking at transforming it into other useful products such as methane (CH4) to supply natural gas networks. What is the potential of this technology?

Costly hydrogen?

“The main issue with the development of power-to-gas today is its cost,” says Rodrigo Rivera Tinoco, a researcher in energy systems modeling at Mines ParisTech. If we take into account the cost of producing hydrogen using a low-temperature electrolyzer (PEM), the technology envisaged in power-to-gas installations, a 1 GW hydrogen reactor (almost the power equivalent of a nuclear reactor) would today cost €3 billion.” In September, the French government allocated a budget of €7 billion in aid for the development of the national hydrogen industry. A reduction in the production cost of this gas is therefore necessary. All the more so since power-to-gas technologies are destined to compete with other energy modes on the market.

France wants to reach a cost of €50 per megawatt-hour in 2030. However, a low-cost but short-lasting technology would not be suitable. “To be cost-effective, systems must have a minimum 60,000 to 90,000 hour operating guarantee,” adds Rodrigo Rivera Tinoco. Currently, low-temperature electrolyzers (PEMs) have an operating life of between 30,000 and 40,000 hours. This is where research comes in. The objective is to optimize the energy efficiency of low-cost technology.

Which technology for which use?

Digital modeling enables the identification of the strengths and weaknesses of technologies prior to their installation. “We carry out technical and economic studies on the various water electrolysis processes in order to increase their efficiency and reduce their cost,” says Chakib Bouallou, an expert in digital modeling and energy storage at Mines ParisTech. Several technologies exist, but which one is the most suitable for storing renewable energy? On an industrial scale, low-temperature electrolyzers are mature and seem to respond to the intermittent nature of these energy sources.

However, in the evaluation phase, no technology is being ruled out. As part of the ANR MCEC project and in collaboration with Chimie ParisTech, Chakib Bouallou’s team is currently working on a solution based on molten carbonates that relies on the co-electrolysis of water and CO2. “Using performance curves of materials depending on the current, we estimate the efficiency of the systems under different usage scenarios. The overall analysis of this technology will then be compared to other existing techniques”, says the researcher. Indeed, the adaptability of a system will depend above all on the intended use. To complete these studies, however, experiments are essential.

Minerve: a demonstrator for research purposes

In order to gain the knowledge needed to make the transition to power-to-gas, the Minerve demonstrator was installed in 2018 on the Chantrerie campus north of Nantes. “The platform is first and foremost a research tool that meets the needs of experimentation and data collection. The results are intended to help develop simulation models for power-to-gas technologies,” explains Pascaline Pré, a process engineering researcher at IMT Atlantique. Equipped with solar panels and a wind turbine, Minerve also has an electrolyzer dedicated to the production of hydrogen converted, with CO2 in cylinders, into methane. This is then redistributed to a fuel distribution station for natural gas vehicles (CNG) and used for mobility.  The next step is to integrate CO2 capture technology from the combustion fumes of the site’s heating network boilers to replace the cylinders.

Carbon dioxide is very stable in the air. Turning it into useful products is therefore difficult. Pascaline Pré’s team is developing a new process to capture this gas by absorption using a solvent. The gas collected is purified, dried, compressed and sent to the methane plant. However, some hurdles need to be overcome in order to optimize this approach: “Solvent regeneration consumes a lot of heat. It would be possible to improve the energy efficiency of the device by developing an electrified microwave heating system,” explains the researcher. This concept would also reduce the size of the facilities needed for this process for a future industrial installation.

In the long term, Minerve should also serve as a basis for the study of many issues in the Carnot HyTrend project, which brings together part of the French scientific community to look at hydrogen. Within three years, initial recommendations on the different technologies (electrolysis, methanation, CO2 capture, etc.) will be published to improve the existing situation, as well as studies on the risks and environmental impacts of power-to-gas.

What about power-to-gas-to-power?

It is possible to go beyond current power-to-gas techniques by adding an oxycombustion step. As part of the ANR project FluidStory, Chakib Bouallou’s team focused on modeling a device based on three advanced technologies: low-temperature PEM electrolysis, methanation (allowing the storage of electricity in the form of gas) and oxycombustion power plants for the destocking stages. The first two steps are therefore the same as in a classical power-to-gas infrastructure as mentioned above. The difference here is that oxygen and CH4, obtained respectively by electrolysis of water and methanation, are stored in caves for an indefinite period of time. Thus, when the price of electricity rises, the oxy-fuel combustion process reuses these gases to produce electricity. The CO2 also emitted during this reaction will be reused by the methanation process in the next cycle.

This closed-cycle design therefore allows autonomous operation with regard to the required reagents, which is not possible in conventional power-to-gas setups. However, analyses aimed at better understanding its mechanics and the nature of the interactions between its components have yet to be conducted.

Looking towards power-to-X

The methanation at the heart of the processes mentioned so far is only one example of the transformation of hydrogen in contact with CO2. Indeed, these reactions, called hydrogenation reactions, are used to synthesize many chemicals usually obtained from fossil resources. At IMT Albi Mines, Doan Pham Minh’s team is working on the optimization of these processes. As well as methane production, researchers are targeting the synthesis of liquid biofuels, methanol, ethanol and other carbon-based chemicals. All these “X” compounds are therefore obtained from hydrogen and CO2. Two factors determine the nature of the result: the operating conditions (temperature, pressure, residence time, etc.) and the catalyst used. “This is what drives the reaction to a target product. Thus, by developing active, selective and stable catalytic materials, we will improve yields in synthesizing the desired product,” the researcher explains.

Methanol is of particular interest to industries. Indeed, this compound is everywhere around us and is used in particular for the surface materials of furniture, in paints, plastics for cars, etc. The same is true for ethanol, biofuels or chemical intermediates of renewable origin. Beyond the role of hydrogen in the national energy mix, the researcher therefore insists on its use by other high-consumption sectors: “It is widely used by the chemical industry and we must be ready to develop competitive and high-performance processes by anticipating future uses of hydrogen and power-to-X.”

By Anaïs Culot