Shades of Green: Life Cycle Assessment of a Novel Small-Scale Vertical Axis Wind Turbine Tree

Abstract

Are small-scale wind turbines green? In this study, we perform a ‘cradle to grave’ life cycle assessment of a novel domestic-scale 10 kW vertical axis wind turbine tree which uses combined Savonius and H-Darrieus blades. Situated at a test site in Surat Thani, Thailand, SimaPro software was used to evaluate the environmental impact profile of the tree. Comparisons to the Thai grid mix were made, using both with and without end-of-life treatments. Impact profiles were calculated using wind data collected over two years at Surat Thani, and from wind data from a higher capacity factor (CF) site at Chiang Mai, Thailand. Energy and greenhouse gas payback times were estimated for both locations. The relative magnitudes of impacts were compared with environmental prices protocol, and we investigated reductions in impacts using three mitigative scenarios: changes to design, transportation and materials. The results showed that Chiang Mai had a CF = 7.58% and Surat Thani had a CF = 1.68%. A total of 9 out of 11 impacts were less than the grid values at Chiang Mai, but at Surat Thani, 9 of 11 impacts were more than the grid values. End-of-life treatments reduced impacts by an average of 11%. The tower and generator were majority contributors to impacts (average 69%). Greenhouse gas and energy payback times were 28.61 and 54.77 years, and 6.50 and 12.50 years for Surat Thani and Chiang Mai, respectively, with only the Chiang Mai times being less than the turbine’s estimated lifetime. Location changes mitigated impacts most, followed by design, transportation, and then materials. We make recommendations to further improve the environmental impact profile of this turbine tree.