An evaluation of the green energy potential generated from biogas and solar power, using agricultural manure waste and a photovoltaic (PV) system, was conducted in a large geographical area of a rural county with low population density and low pollution. The studied area, Shoufeng Township in Hualien County, is located in eastern Taiwan, where a large amount of manure waste is generated from pig farms that are scattered throughout the county. The objective of the study is to assess the possibility of establishing an integrated manure waste treatment plant by using the generated biogas incorporated with the PV system to produce renewable energy and then feed it back to the incorporated farms. A filed investigation, geographic information system (GIS) application, empirical equations development, and RETScreen modeling were conducted in the study. The results indicate that Shoufeng Township has the highest priority in setting up an integrated treatment and renewable energy plant by using GIS mapping within a 10-km radius of the transportation range. Two scenarios were plotted in assessing the renewable energy plant and the estimated electricity generation, plus the greenhouse gas (GHG) reduction was evaluated. Under the current governmental green energy scheme and from a long-term perspective, the assessment shows great potential in establishing the plant, especially in reducing environmental pollution problems, waste treatment, and developing suitable renewable energy.