The transition to renewable energy sources is vital to mitigate global warming and achieve the climate targets set by the EU. The availability of natural gas in Europe is challenged due to the Russian invasion of Ukraine, leading to a shift towards fossil-free alternatives. In collaboration with Siemens Energy, this thesis investigates the availability of green fuels for gas turbines in Europe, specifically in Germany, Poland, and the UK. The methodology includes analysing literature, internal and official documents, and conducting a customer survey.  The fuel availability outlook indicates an upcoming expansion of hydrogen infrastructure, with Germany and the UK expected to have operational hydrogen infrastructure within the next 5-10 years. While green ammonia and e-methanol may have limited roles in the energy transition, ammonia's capacity to transport hydrogen makes it a potential energy carrier, and the existing distribution network could facilitate the early adoption of large-scale ammonia transportation. Biofuel availability varies across regions, feedstocks, and production methods, with biogas, biomethane and HVO showing significant potential. Natural gas remains the most cost-effective fuel until 2040, with blue hydrogen and ammonia, along with carbon capture, utilisation, and storage (CCUS), identified as the best alternative green fuels. After 2035, green hydrogen will emerge as the most cost-effective green option. The customer survey highlights the preference for hydrogen and ammonia, driven by governmental requirements and environmental responsibility. This study emphasises the promising transition fuels and the need to explore CCUS technologies' impact on fossil-based fuel prices.