Determining the upper economic limit of wind fleets

Abstract

Wind fleets have become significant energy sources within national grids. However, future expansion of wind fleet capacity may result in little incremental benefit due to the inability of present grid architectures to absorb high levels of excess generation. Determining the upper economic limit is a topical issue but its solution is complicated by variations in energy system architectures and local weather conditions, making energy models essential to system planning. This paper outlines a simplified methodology, referred to as the histogram model, to calculate the upper economic limit for wind fleets, based on annual data for energy generation, recorded at hourly intervals, and the system’s headroom, defined as the difference between base load and demand. The amount of ‘useful energy’ is derived from the wind energy frequency table, the total installed wind fleet capacity, and the headroom. The calculations lead to values for the incremental decarbonisation cost, which can be directly compared to the cost of decarbonisation for gas-based energy generation. The results indicate that the upper economic limit is a wind fleet capacity of 3 times the headroom, where 78% of the required energy is derived from wind and the wind fleet efficiency is 82% (18%of the available wind energy is shed). The development of the model has implications for energy planners, who can now more easily simulate the performance of energy systems as a function of various input parameters.