Abstract. Energy security is a key component of economic growth and sustainable development. Russian invasion of Ukraine in February 2022 and following energy crisis over Europe revealed significant dependence of European states, including Ukraine from Russian energy resources. Current strategy of the EU on total replacement of Russian energy supplies and accelerated implementation of renewables, being challenging now, lead to energy security of Europe in long term. Ukraine currently are meeting all burdens of the war, including thousands killed people and millions of refugees, ruined infrastructure and occupied territories. National energy security is one of many challenges for the country. Strong international support, national integrity and determination are key elements for both Ukrainian victory and postwar rebuilding of the country.  Following the EU strategy, Ukraine needs urgent transformation of its energy sector in sustainable way, e.g., Ukraine has a huge potential in bioresources, including biogas / biomethane production being one of the largest producers of agricultural crops in the world.