The Recalculation and Evaluation of CO₂ Basic Unit of 2MW Domestic Wind Turbine: A Case Study in the Choshi Area, Chiba Prefecture, Japan

Abstract

Objective. Many wind turbines have been constructed in the Choshi area, Chiba prefecture, Japan, as the Choshi area is rich in good wind supply for wind power generation. Wind turbines generate sustainable energy, however CO₂ is emitted during the various processes in the life cycle of a wind turbine. Therefore, it is important to estimate the environmental impact in the megawatt scale wind turbines by the method of LCA using the latest data of the environmental impact.
Method. The functional unit is selected as 1kWh electricity delivered to consumers. In this study, the lifetime of turbines is set to be 20 years and the life cycle includes manufacturing, construction, transportation and operation and maintenance processes. The investigated turbine is a J82-2MW manufactured by Japan Steel Works (JSW), Ltd. in Muroran factory, Hokkaido, Japan.
Results and Discussion. The LCA result shows that 1kWh electricity generated by a domestic turbine under the condition that the average wind speed is equal to 6m/s, the CO₂ emission from operation and maintenance processes which are calculated at the rate of 0.5%/year to 2.0%/year of total emission of CO₂ from manufacturing and transportation processes and the losses of transmission grid are set to 5 and 10%, has impact ranging from 10.1 to 12.9g-CO₂ in its life cycle. When the result is compared to the amount of CO₂ emission of 29.5g/kWh by 300kW turbine, it is clear that the environmental burdens of MW wind turbine are significantly lower.
Conclusions. The recalculation result of the domestic 2MW wind turbine constructed in the Choshi area shows 10.8g-CO₂/kWh under the condition that the average wind speed is equal to 6m/s, the CO₂ emission from operation and maintenance process which are calculated at the rate of 1.0%/year of total emission of CO₂ from manufacturing and transportation processes and the loss of transmission grid is set to 5 % in its life cycle. The important points of electricity produced by wind turbines are finding locations with good wind supply and application of large scale wind turbines. And the “product category rule” should be established for the standardized calculation of the Japanese CO₂ basic unit (g-CO₂/kWh) of the wind generator.