Recently, the practice, reclaiming the manure resulting from animal wastes, has been gaining ground with biomass energy systems in large-capacity central biogas plants. These plants enable the use of a renewable source of energy in an efficient way and make a significant contribution to the sustainability in the environment. This study was performed on a total of 929 dairy farms which were members of a cooperative in 43 villages in Tire, in the Izmir province, in Turkey. The aim of the study was to estimate the methane emissions through manure management applications, to plan the optimum capacity and location for plants to produce biogas from the manure, and to evaluate the environmental effects of biogas production. An emission factor of 2.05 kg head(-1) year(-1), and methane gas emission value of 0.036 Gg year(-1), were estimated for local conditions. An optimization model was developed to minimize plant investment and manure transport costs for optimum biogas production. The model was chosen to include the approximate total of 1600 tonnes day(-1) produced in the area. A 400-tonne day(-1) capacity biogas plant was planned for each of the 4 villages and it was determined that 35.10(6) m(3) year(-1) of biogas could be produced. It was calculated that total plant investment would be $9.497.680 and manure transport costs would be $432.525 per year. This biomass-energy conversion would also provide socio-economic benefits to the area, and help to form a clean environment by preventing methane gas emissions from animal production.