École Polytechnique is actively involved in sustainable development in both its research and teaching. Ten of the units that make up its research center are participating in the TREND-X program on the issues around the energy transition: some thirty researchers and PhD students are working on energy storage, smart buildings and smart cities. X's scientists are looking to improve photovoltaic cells by new manufacturing processes and to develop innovative systems for recovering power from motion. Other initiatives concern pollution-related issues, such as the use of plasmas to recycle CO2 to produce fuel or the diagnosis of water pollution. Green chemistry is another area that several laboratories are working on, through the development of sustainable phosphorus chemistry, the creation of efficient, non-polluting processes such as electrosynthesis, or modeling-assisted design to develop catalysts to limit the production of chemical waste. On the training side, the students on the engineering course are made aware of the issues through specialization modules in Year 3 - "Science and Environmental Challenges' and "21st Century Energies". Two master's courses are also offered to students wishing to get specialized training in these issues: "Water, Air, Pollution and Energy" on the environment and "Renewable Energy Science & Technology" on renewable energies. Since 2016, Polytechnique's training offer has expanded internationally with two new Science and Technology Master's courses, "Science and Technology for Environment and Energy Management" and "Smart Cities".