The work refers to studies carried out on the social functions that can be used as urban green forest on the example of City Forest in Olsztyn. Forests located within the city limits are often spontaneously used as a place of recreation and sports. However, as demonstrated by research on the indicated object, green forests could also be an important place for the inhabitants, fulfilling tasks such: the educational, cultural or landscape. Proper definition areas of particular functions in the urban forest, will allow for the optimal proper use and disposal in accordance with specifications and expectations of society. The paper summarizes the methods of biogas production and management as the one of waste management and energy requirements. Some biogas utilization investments based on sustainable development were characterized.
