Micro, midi or macro? Onshore wind turbine economics for Scotland

This article investigates the feasibility of the application of wind turbine as a means of offsetting the electricity demand for public buildings within Scotland. A number of case studies are presented with respect to currently operational micro-, midi- and macro wind turbines within England and Scotland. Presently, the micro-, midi- and macro wind turbines have been categorised as those that have their nominal output within 0-2 kW, 2-20 kW and Gt20 kW power bands. Their electrical energy generation data have been critically analysed. In particular the turbinespsila capacity factor, the annual energy output and payback period are presented. It has been found that within urban settings micro-turbines perform poorly and hence they are uneconomical. The payback period for midi-turbines located at rural, high-altitude locations with clear horizons are of much shorter order. However, the sitting of such turbines is critical. For large public sector organisations, such as universities and institutions of higher education with a high electrical energy demand and base load, large, megawatt machines provide a sustainable and economic solution. It has been shown that for one Scottish university, presently under discussion, two 1.25 MW wind turbines provide the economical option with a payback period of 7.4 years. The capacity factor for the latter machine, to be located 35 km west of university campus will be around 0.14. The machine will be able to offset 84% of the total electrical load for Napier Universitypsilas Merchiston campus.