The history of the Odeillo solar oven in Font-Romeu: A masterpiece of science and technology


The Odeillo solar furnace in Font-Romeu is not just a large scientific facility hidden away in the south of France. It is the symbol of a quest to harness one of our planet's most abundant and cleanest resources: solar energy. Erected in the majestic Pyrenees-Orientales, this masterpiece of engineering bears witness to decades of research, scientific curiosity and vision for a sustainable future.

Designed to concentrate sunlight at an incredibly intense point, the Odeillo solar oven is capable of generating extreme temperatures, opening the door to experiments that were previously unimaginable. Beyond its technical prowess, this solar oven is also a beacon of innovation, attracting researchers from all over the world keen to push back the boundaries of science and technology.

But what makes this solar oven so special? Why was it built in the first place, and how does it work? What is its importance in the vast field of renewable energy, and what challenges and opportunities does it present? This article sets out to answer these questions by exploring the fascinating history of the Odeillo solar furnace, its innovative operation and its significant impact on science and society.

The Pioneers of the Sun: Origin and Vision by Félix Trombe and André Roux

The idea for the Odeillo solar cooker was the brainchild of French physicist Félix Trombe, who had been fascinated by the potential of solar energy since the 1940s. In 1946, he initiated feasibility studies with the support of his colleague, the engineer André Roux. Together, they began to sketch out the outline of what would later become the Odeillo solar furnace.

During the 1950s, Félix Trombe obtained the support of the CNRS (Centre national de la recherche scientifique) in France and was able to start making small-scale prototypes. It wasn't until 1962, after receiving additional funding from the French government, that the project to build the oven at Font-Romeu was officially launched. The construction of this gigantic solar oven required a wide range of technical skills, and Trombe enlisted the help of experts such as optical engineer Jean Bernard to design the mirrors and focusing systems.

The Font-Romeu region was chosen not only for its exceptional sunshine but also because of its strategic location in the Pyrénées-Orientales, which offered an advantage in terms of reducing atmospheric effects on solar concentration. Construction began in 1964 and was completed in 1968, under the supervision of project engineer Marc Foing.

Construction and Improvements

The construction of the Odeillo solar cooker in Font-Romeu was a monumental undertaking, involving an orchestra of scientists, engineers and politicians who worked together to transform a bold vision into a tangible reality. Inaugurated in 1968, this technological colossus was the fruit of the labour and ingenuity of such luminaries as project engineer Marc Foing and optician Jean Bernard. The inauguration was a grandiose ceremony, marked by the presence of François-Xavier Ortoli, the Minister for Research at the time, confirming the national and international importance of the project. With an initial budget of around 1.2 million dollars, the construction of this solar oven was a significant investment, testifying to the confidence and optimism placed in this innovative project.

But the story of the solar cooker doesn't end there; it has continued to evolve over the years thanks to substantial technological improvements. In 1980, an ambitious project to modernise the heliostats was initiated by the management of the French National Centre for Scientific Research (CNRS). Under the aegis of engineer René Barthélémy, the solar furnace underwent a major upgrade, which was completed in 1985. This modernisation had a major impact on the efficiency and precision of the concentration of sunlight, opening the door to a new range of experiments and applications.

The turn of the millennium brought another significant advance: the addition of a new experimental chamber in 2002. Led by researcher Clara Latour, this extension was made possible by European funding and has broadened the range of test conditions that can be achieved, thereby enriching the possibilities for research and innovation.

So the Odeillo solar cooker is not a static monument, but a living organism in constant evolution, adapting and improving its functions to stay at the cutting edge of scientific and technological research.

At every stage of its transformation, the Odeillo solar furnace has benefited from interdisciplinary partnerships, ranging from research institutions to companies specialising in advanced technologies. For example, collaboration with Thales Alenia Space was an important milestone in incorporating space technologies into the heliostat pointing and tracking mechanism.

Not only has the solar furnace undergone structural improvements, but it has also been the site of several unique experiments, such as tests on the purification of extraterrestrial materials for future space missions. These successive developments have enabled the furnace to maintain its pioneering status in research into renewable energies, advanced materials and space applications.

In short, the Odeillo solar furnace in Font-Romeu is far from being a relic of the past. It embodies a tradition of excellence and continuous innovation, adapting and evolving to meet the scientific and environmental challenges of today and tomorrow. Through its various phases of construction and improvement, it remains a powerful symbol of interdisciplinary collaboration and the relentless quest for knowledge and progress.

After this rich history of development and evolution, it is crucial to note that the Odeillo solar furnace is not resting on its laurels. Researchers and engineers are continuing to explore new methods to further optimise its energy efficiency and precision. New modernisation projects are under discussion, in particular to incorporate even more sensitive sensors and materials resistant to high temperatures, all with a view to maximising the diversity of possible scientific experiments.

Partnerships with academic institutions and high-tech companies are also underway to extend the impact of the solar cooker far beyond France's borders. In a world increasingly aware of the need for sustainable energy solutions, the Odeillo solar cooker in Font-Romeu is a flagship example of how a decades-old installation can remain relevant and forward-thinking.

This journey of constant innovation makes the solar cooker not only an impressive technical achievement, but also a living illustration of the power of human collaboration and ingenuity to solve some of the most pressing problems of our time.

How it works

Basic principle

The Odeillo solar cooker in Font-Romeu is an engineering marvel based on fascinating scientific principles, first developed by French physicist Félix Trombe and his engineering colleague André Roux in the 1950s. The basic system is based on the principle of concentrating sunlight, using an ingenious combination of two types of mirror: heliostats and parabolic mirrors.

Heliostats are flat mirrors mounted on motorised structures that allow great freedom of movement. These mirrors are strategically positioned on a vast expanse of flat land around the main parabolic mirror. The precise positioning of the heliostats is the result of complex calculations designed to maximise the capture of sunlight throughout the day. Thanks to ultra-precise electric motors and temperature and luminosity sensors, each heliostat can adjust its orientation in real time to follow the path of the sun across the sky. This solar tracking is essential to maximise the reflection of light towards the parabolic mirror.

The parabolic mirror is at the heart of the system. It collects the light reflected by the heliostats and concentrates it at a focal point. This point can reach extremely high temperatures, providing an ideal environment for experiments that require a large amount of energy at a very precise point.

The Odeillo solar oven would not be what it is without the complex synergy between the heliostats and the parabolic mirror, orchestrated by a series of precise calculations and mechanisms, the legacy of decades of research and innovation.

The role of heliostats

The Odeillo solar furnace in Font-Romeu is notable for its impressive assembly of 63 heliostats, covering a total surface area of almost 2,000 square metres. These heliostats, which are the silent sentinels of the system, play a crucial role in the concentration of sunlight. Not only do they capture the sun's rays, but they also redirect them with extraordinary precision towards the parabolic mirrors, which are the heart of the system.

What makes this orchestration possible is a set of state-of-the-art electric motors built into each heliostat. These motors, coupled with temperature and luminosity sensors, enable the heliostats to adjust their orientation in real time according to the position of the sun. The adjustment is so precise that it optimises the reflection of light towards the parabolic mirror at every moment of the day.

The integration of these advanced technologies would not be possible without a dedicated team of engineers and scientists, constantly working to maintain and optimise the system. As a result, each heliostat is like a piece of a larger jigsaw, part of a remarkably complex system that results in an ultra-efficient concentration of sunlight.

It's these seemingly minor but crucial details that make this solar cooker not just a technical achievement, but also a marvel of precision and efficiency.

Concentration and focus

After being captured and redirected by the heliostats, the sunlight begins the second phase of its fascinating journey in the Odeillo solar furnace. It is concentrated by a set of carefully calibrated parabolic mirrors. It's no coincidence that these mirrors are parabolic in shape. The unique geometry of these mirrors enables the sun's rays that strike them to be focused on a single point, known as the "focal point".

The power concentrated in this focal point is phenomenal. Thanks to the precision of the parabolic mirrors and the efficiency of the heliostats, this focal point can reach dizzying temperatures of up to 3,500 degrees Celsius. That's almost twice the temperature of the sun's surface!

This extreme temperature is not simply a scientific curiosity. It has important practical applications, enabling experiments and research that would not be possible with other sources of heat. These range from melting materials to carrying out chemical reactions that would otherwise be impractical.

The ingenuity of the engineers and scientists who designed and refined this system makes this formidable concentration of energy not only possible but also efficient and, above all, controllable. It's not just a demonstration of the power of solar energy, but also a remarkable example of how human intelligence can combine with natural forces to achieve extraordinary things.

The focal point and its applications

The focal point of the Odeillo solar furnace is not just the site of intense heat; it is the very heart of the facility, where all the experiments and research applications take place. The stability of this focal point is crucial to the success of these experiments. This is why a highly sophisticated solar tracking system has been developed. The innovation of this system dates back to 1972 and was designed under the direction of engineer Jean-Claude Dupuy.

The solar tracking system uses advanced algorithms and ultra-sensitive sensors to track the sun's movements across the sky. Thanks to this system, the focal point is kept in a stable position throughout the experiments. This means that even as the sun moves, the system adjusts the parabolic mirrors and heliostats to ensure that the maximum concentration of sunlight remains focused. In this way, the temperature at the focal point remains constant, which is essential for guaranteeing the accuracy and reliability of the scientific data collected.

In short, the stability of the focal point is not just a technical feat, but absolutely essential if the solar furnace is to fulfil its role as an advanced research platform. The sophistication of the solar tracking system makes it a key part of this exceptional facility, ensuring that the intense heat generated can be used as efficiently and accurately as possible to advance science.

Technological advances

In addition to the solar tracking system, various improvements have been made to the Odeillo solar furnace to optimise its efficiency and versatility as a research tool. One of the most notable additions was the introduction of a more advanced cooling system in 1995. This innovative project was led by Clara Latour, a well-known researcher in the field of renewable energy and thermal systems.

The new cooling system was designed to solve a key problem that is often overlooked in solar concentration systems: how to effectively dissipate excess heat that does not contribute to experimentation? Thanks to more efficient liquid cooling techniques and cutting-edge materials, the solar furnace was able to achieve unprecedented control conditions during experiments. This improved system made it possible not only to maintain a high temperature at the focal point, but also to ensure that this temperature could be maintained more stably and over longer periods.

The introduction of this more efficient cooling system has opened the door to new research possibilities, particularly in areas requiring extremely stable temperature conditions. It has also improved the safety of the installation, by reducing the risks associated with overheating or temperature fluctuations. All in all, this innovation has been a key step in the evolution of the Odeillo solar furnace, strengthening its position as one of the world's leading research facilities.

Safety and control

It is also worth noting the importance of safety measures in the operation of the furnace. High-tech sensors and monitoring systems ensure that conditions remain optimal and safe during the experiments. All this is controlled from a control room, where a team of engineers and researchers monitor every stage of the process.


Solar tracking system

One of the most crucial technological elements of the solar cooker is its solar tracking system. This system is equipped with advanced artificial intelligence that calculates in real time the optimal position of the heliostats and parabolic mirrors according to the position of the sun. This was made possible by years of research under the direction of Michel Armand, a specialist in robotics and artificial intelligence, who joined the team in 1988.


Heliostats use ultra-precise electric motors to adjust to the sun's movements. Each heliostat is fitted with temperature and luminosity sensors to adjust its position and angle. This cutting-edge mechanism was designed in collaboration with Thales Alenia Space, a company specialising in advanced technologies.

Parabolic mirrors

The parabolic mirrors, which focus the sun's rays on the focal point, are made from an alloy of aluminium and silicon to maximise reflectivity and minimise wear. The mirror coating has been specially developed to withstand extreme conditions, such as high temperatures and bad weather.

Experimental chamber

The experimental chamber where the focal point is located is a masterpiece of engineering. It is designed to withstand extreme temperatures and is equipped with a number of safety features, such as pressure relief valves and emergency ventilation systems.

IMAGEA technical diagram showing the experimental chamber and its various components.

Control systems

The entire solar cooker is managed by an integrated software platform that provides real-time control of the various components. The software was developed in-house and is constantly updated to incorporate the latest advances in automated control.


The heliostats at the Odeillo solar furnace are at the heart of its operation, and their technology is extremely advanced. Each heliostat is equipped with ultra-precise electric motors that can adjust the position of the mirror to within a few millimetres. These motors are powered by advanced electronic systems, guaranteeing their reliability and durability. In addition to the motors, the heliostats contain temperature and luminosity sensors. These sensors are essential for adjusting the position and angle of the mirrors in real time, depending on the surface temperature and the amount of sunlight available.

One of the highlights in the development of these heliostats was the collaboration with Thales Alenia Space. This company, which specialises in space and defence technologies, contributed its expertise in guidance, command and control systems, enabling the creation of a robust and precise heliostat system. All these technological elements are coordinated by an integrated control system that manages the orientation of each heliostat in real time. This system uses complex algorithms to determine the optimum orientation of the mirrors, based on the data supplied by the sensors and according to the needs of the scientific experiment in progress.

IMAGEA detailed diagram of a heliostat, showing the motors, sensors and other key technological components.

Scientific importance

The Odeillo solar furnace is much more than just a technological marvel or an object of curiosity. It is a platform for fundamental research in key sectors for the future of humanity. The complex enables advances to be made in fields as varied as advanced materials, energy storage techniques and environmental clean-up methods. Researchers can use the intense heat generated by the furnace to test new materials and compounds that would be difficult, if not impossible, to achieve using other methods. In addition, the furnace is also a playground for studies into thermal energy, including how it can be captured and stored for future use.

Not only has the Odeillo solar furnace helped to push back the frontiers of knowledge in these areas, it has also had a considerable impact on the global development of research into solar energy and sustainable technologies. Its construction and success have encouraged other countries and institutions to invest in similar technologies. It is no exaggeration to say that the Odeillo solar furnace has paved the way for a new generation of solar furnaces and concentrating solar power technologies, fuelling global progress in the transition to more sustainable energy sources.

IMAGEA graph showing the significant increase in research and publications in the field of solar energy since the construction of the Odeillo solar furnace.

The solar furnace has also proved to be a versatile platform for interdisciplinary research, involving experts in physics, chemistry, engineering and environmental sciences. This multidisciplinary collaboration has led to discoveries and innovations that have had an impact far beyond the simple framework of solar energy. For example, studies into the durability of materials at high temperatures have direct applications in the aerospace industry and in the design of nuclear reactors. Similarly, research into thermal energy storage can revolutionise the way we manage energy in our homes and businesses, making energy systems more efficient and sustainable.

In addition to its scientific value, the Odeillo solar furnace also has an educational impact. It serves as a training site for science and engineering students, offering them a unique opportunity to learn the fundamentals of solar concentration and renewable energy in a practical and stimulating environment. It is also an invaluable resource for public awareness and education programmes on renewable energy, helping to inform and engage a new generation of scientists, engineers and environmentally conscious citizens.

In short, the importance of the Odeillo solar furnace transcends academic and geographical boundaries. It is not only a powerful tool for advanced scientific research, but also a symbol of international collaboration and innovation in the pursuit of solutions to the most pressing challenges of our time.

A Beacon of Innovation: Towards a Sustainable and Enlightened Future

The Odeillo solar cooker in Font-Romeu is not only a monument to the power of engineering; it is also a vibrant tribute to the human capacity to innovate, collaborate and overcome technical obstacles for a greater good. This technology complex follows in the footsteps of great human achievements that not only advance science and technology, but also have the power to inspire us and remind us of what is possible when human ingenuity is harnessed to achieve noble goals.

Behind its construction and operation lie decades of research and dedication on the part of scientists, engineers and technicians. Their collective work has resulted in a facility that is helping us to better understand and exploit our planet's energy resources in a sustainable way. The furnace is therefore a perfect illustration of how fundamental research can be transformed into practical applications that benefit humanity as a whole.

In short, the Odeillo solar cooker in Font-Romeu is an achievement that transcends its status as a simple research tool or technical demonstration. It embodies our collective aspiration for a better understanding of our world and the responsible and innovative use of the resources that the Earth has to offer. It is a living reminder of what human will, combined with rigorous scientific research and technical creativity, can achieve to forge a more sustainable and equitable future for all.

In addition to its scientific and technological function, the Odeillo solar furnace in Font-Romeu has become a symbol, reminding present and future generations of the importance of international collaboration in the pursuit of progress. It is the product of teamwork involving a variety of experts from different disciplines and countries, all united in a common goal: to harness the sun's energy in a sustainable way for the benefit of mankind. It is living proof that, even in the face of the complex and interconnected challenges of our time, solutions are possible when people come together to share their knowledge and resources.

The complexity and scope of the Odeillo solar furnace also reminds us that the path to a sustainable future requires a long-term vision and investment in fundamental research. While quick, short-term solutions can be tempting, it's essential to understand that truly revolutionary discoveries and significant breakthroughs take time and require sustained focus and dedication. This solar oven is an inspiring example of what we can achieve when we invest in a future that goes beyond our immediate horizon.

So the Odeillo solar cooker in Font-Romeu remains not only a testament to human ingenuity, but also a manifesto for our relentless quest for knowledge, our need to explore beyond established limits, and our ambition to make ethical and sustainable use of our planet's natural resources. It is not simply a tool, but a beacon guiding our path towards a more enlightened and sustainable future.

Summary: The Solar Furnace, from French Invention to Global Clean Energy Tool

The solar cooker, a French invention dating back to 1946, was created by chemist Félix Trombe. The world's first solar oven, located at Mont-Louis in Languedoc-Roussillon, is still in operation and is used for scientific research by the CNRS. It can produce up to 50 kW of energy. Another furnace, at Odeillo, is even more powerful, with a maximum capacity of one megawatt. These solar furnaces are not only technological feats, they also represent a promising future for clean energy. They are becoming indispensable tools, particularly in developing countries, where they are used for cooking and sterilisation.

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