Limits to Wind Power Penetration
Limiting factors to large scale wind power penetration were identified. These limiting factors can be related or unrelated to other factors and they can be specific to various levels of penetration. The factors can be classed as either 'hard' or 'soft'. A hard limit being characteristically definitive (e.g. limit to availability of sites), whereas a soft limit can be applicable to one situation and not to another depending on the circumstances, for example, the limit of lack of spinning reserve can be overcome by new generation plant.
Identified Limiting Factors
Availability of Sites
Scottish wind farm developments, proposed developments and applications for developments are almost entirely for onshore sites. This is in direct contrast to England, where the availablity of onshore sites is severely restricted and therefore most applications are for offshore.
It has been stated that the issue of land availability is not likely to pose a significant problem to wind farm development in Scotland, this has been sited as a reason for the lack of interest in offshore developments in Scotland (and as onshore development is 25% cheaper than for offshore, the developers should be attracted north).
An indepth study looking in to the accurate assessment of site availability was not possible given the time frame for the project. For this reason an assumption was made (based on wind industry past studies) that Scotland has ample site availability.
Conventional Backup Generation
The availability of backup generation is seen as one of the main limiting factors to increased wind power penetration. This is based on the fact that with large penetration levels and an intermittent source there is likely to be periods of no generation. Backup generation is therefore required to cover for calm days.
Presently the available conventional generators combined have enough reserve capacity to cover for penetration levels up to around 15%, this is based on thermal generating stations having an available 'flex' of around 4% of their peak capacity.
This therefore can be thought of as a soft limit, in that, without additional conventional generation the limit of wind power penetration stands at 10-15%.
Transmission/Distribution Network Availability and Connectability
The availability of grid connectability is of upmost importance to developers. There is little spare capacity available on the transmission network for extra capacity. This means wind developments are restricted to areas of the network which can acommodate extra generation.
Availability of Storage Sites
The preferred choice of storage being Pumped Hydro means that there is a limiting factor in terms of potential water storage sites (reservoirs/lochs). However, our research has highlighted that there is sufficient resource in Scotland. The cost of pumped hydro is the real limiting factor.
The financial aspect of wind power and wind power penetration is well known to be the prime mover, it is without doubt the biggest barrier facing the greater uptake of wind power. However, the financial incentives of recent have made it more attractive to capital investors, which means that the balance of limiting factors has changed.