The Estimated Impact of Photovoltaic Power Systems on Varieties of Japanese Forest Vegetation

Abstract

Objective. Photovoltaic (PV) power systems are considered an essential component of environmental friendly society. However, the land area required for generating unit amount of power by PV system is larger than that for an equivalent coal-fired power system. In Japan there has been some instances of PV power systems being installed in forest areas. Therefore, the purpose of this study is to explore the impact of PV power systems on Japanese forests. Forest vegetation is classified into the 13 types used in the “Life cycle Impact assessment Method based on Endpoint modeling 2 (LIME2)” methodology. This will allow us to establish the relationship between the reduced CO₂ emissions of a PV power system and the system’s impact on forest by way of land use, compared with those of coal-fired power system.
Results and Discussion. The environmental impact of a PV power system installed on a roof was calculated as 6.3% of the impact of a coal-fired power system. In contrast, placing the PV power system in oak or pine forest had a substantially greater environmental impacts, of 76.7% and 99.9% respectively. Following sensitivity analysis, it became apparent that the area required by a PV power system per generated unit of power is the most important factor. For example, with regard to the oak forest, the environmental impact of the PV power system can be reduced from 99.9% to 74.2% by decreasing the area required per generated unit of power from 15,200m²/MW to 11,000m²/MW. A further improvement of 5.8% can be achieved by planting grass under PV panels.
Conclusions. LIME2 damage factors were used to classify land use impact for 13 vegetational types of Japanese forest. From the calculated results, it is clear that the environmental impact of PV power system land use on a forest should not be disregarded; however, the level of that impact will depend on the vegetational classification. Furthermore, reducing the utilization rate of the PV power system is an effective way to lessen the impact of land use.