The collective monograph is devoted to the development of independent and sustainable energy production. Sustainability of energy sources is determined by various factors. The main factors are energy efficiency and use of renewable energy sources. The emphasis is put on implementation of climate technologies, as well as reduction of environmental impact at source. Several types of renewable energy sources, e.g. biomass combustion and gasification, heat pump technologies, hybrid systems, as well as improvement of district heating system efficiency have been considered. Several aspects like technological, environmental, political, economic, as well as socio-economic have been discussed in the monograph. The results can be used by scientists, industry experts and entrepreneurs when looking for the necessary, environmentally sustainable and most energy efficient technology. The government and municipalities can use the results of policy analysis to improve transition to low-carbon economy.