The negative effects of climate change and their consequences have been the subject of debate for many years. Since the energy sector is responsible for most of the greenhouse gas emissions, an energy transition is necessary. Switching from fossil fuels to renewable energy is an impractical and expensive option, so there is a need to decarbonize the gas system using low-carbon and renewable gases, ie biomethane and hydrogen. The European Union is introducing a variety of measures to encourage decarbonisation, ranging from the European Green Deal through the EU Strategy for energy system integration and the Hydrogen Strategy for climate neutral Europe to the Fit for 55% and REPowerEU. In order to achieve the desired climate and energy goals, the European Union emphasizes in the legislative framework the importance of using new gases and repurposing and/or building new hydrogen infrastructure. The European Union sees hydrogen as an important energy source for the future energy mix, so several European transport system operators have participated in the development of European Hydrogen Backbone. Although the injection of biomethane into the existing gas network is not a problem, the injection of hydrogen has not been fully researched. However, by investing in science, research, innovation and development, the knowledge about the possibilities of hydrogen injection in the natural gas grid and repurposing of gas pipelines for hydrogen transport is expanded. Reducing the cost of producing green hydrogen from renewable energy sources in Europe will encourage further development of the hydrogen market and its infrastructure.