Meteorological assessment of vertical axis wind turbine energy generation potentials across two Swiss cities in complex terrain

Abstract: Wind energy is the most mature renewable energy technology, however, its exploitation in cities is often met with skepticism. Thanks to their ability to operate effectively at low wind from any direction, vertical axis wind turbines (VAWTs) offer an attractive opportunity for wind energy harvesting in cities, but limited evidence exists on their potential in complex urban environments, and the role of different geographical settings, local meteorological conditions, and urban characteristics remains unclear. Here we use realistic Weather Research and Forecast model high-resolution wind speed simulations alongside representative VAWT power curves to quantify the range of micro-generation potentials at the annual, seasonal, and diurnal scale across two Swiss cities (Lausanne and Geneva) residing in complex terrain. Our results show that Lausanne generally experiences higher (+24%) wind speed than Geneva. Both cities present the greatest micro-generation potential during the summer months, although Lausanne shows non-negligible potential also during the wintertime. Wind speed is higher during the nighttime in Lausanne and during the daytime in Geneva, due to the different interaction between the local lake-breeze circulation and the synoptic flow. Simulated performance of case-study VAWTs is dominated by cut-in wind speed and power curve inflection point. On average, in 2022, an individual VAWT would have produced 2665 kWh of total annual electricity, equivalent to 16.5 square meters of photovoltaic panels. These results highlight the need for research on urban wind energy featuring detailed city-scale assessments that account for urban heterogeneities and regional circulation patters, to inform future planning investment and engineering development.