Scotland has some of the best wind renewable energy resources in the world. The importance of wind energy to Scotland’s energy mix is evident from the dramatic increase in the last decade in both onshore and offshore wind farm construction projects and the decision by a number of global manufacturers to establish Scottish manufacturing and research and development facilities.

The overall aim of the industry is quite understandably to be able to build and install the most cost effective systems that it can. In the case of offshore wind in particular this could mean much larger turbines with all that implies in terms of the design of their components and structure.

Exploiting internationally leading wind energy research capability derived from more than twenty years’ experience, Scotland’s universities are being mobilised to support the wind industry. Already, the universities are directly engaged with the industry in several aspects of the technology.

Generators and speed drives

The design of generators and variable speed drives that eliminate the need for gearboxes is being pursued as gearboxes are commonly believed to be prone to failure and so a potential cause of reduced availability for offshore sited wind turbines. One university team has developed a new direct-drive generator design that reduces the weight by up to 50%, simplifies assembly and, thereby, reduces their cost. Commercial demonstrators of this design are now being produced.

Important to the efficiency and survivability of the proposed larger offshore turbines is the structural and aerodynamic design of the turbine blades. One approach under investigation is the use of lighter, more durable materials making blade assemblies easier to install and replace as well as increasing their life expectancy by reducing erosion and structural issues.

As the size of the wind turbines increase, the control system’s role in reducing the loads on the turbine becomes increasingly important. Unequalled expertise on the design of control systems arising from twenty years of research experience and practice is available.

Offshore wind turbines

Onshore wind turbines are easy to access and, therefore, fairly straightforward to service and maintain. However, offshore, where access can be limited, the operations and maintenance costs contribute increasingly to the cost of energy. Efficient and effective maintenance routines will become critical to avoid damaging and costly failures. These will evolve as experience is gained of the offshore environment and offshore turbine reliability. The routines will depend on failure rate analysis and the increased use of advanced condition monitoring systems.

The universities are heavily involved in the Wind Energy development of these including the use of new techniques such as vibration and acoustic monitoring. The layout of a wind farm has to be optimised with regards to maximising energy capture and reducing infrastructure costs. The development of computer design tools to assist with this task is on-going, in particular, to increase their accuracy. This issue applies both to onshore and offshore wind farms as indeed does the issue of reducing radar interference to a minimum.

With offshore wind farms, the sub-sea structure, that supports the turbine, will be an important cost element. Its design has to take into account a range of issues. These will include the use of soil mechanics to determine the conditions of the seabed and the near subsurface so that an appropriate foundation design is selected. Similarly it is important to analyse and model the loads on the turbine support structure.

Integrating wind power into the national grid

As the number of offshore wind farms grows, the development of offshore power grids is likely. The development of new design rules on how to manage high voltage AC and DC networks will be required as will research into power electronics for rapidly switching and balancing these networks.

The integration of large and variable amounts of wind power into the national grid will inevitably have an impact on its stability and so will require careful monitoring and the development of sophisticated management systems.

The issue of “excess generation” will also need to be addressed. To do so may involve energy storage perhaps using so called flow cells which are essentially large capacity batteries or using excess electricity for producing hydrogen or sea water desalination. Appropriate solutions still need to be developed.

Environmental impact

The impact of wind farms on the environment both on and offshore is also important and some ground rules need to be developed which can be applied during planning and when obtaining public support. Consideration also needs to be given to the impact on the economy and how society can benefit generally from the growing wind turbine industry.

Domestic wind turbines designs

It is important to point out that there is also a burgeoning market in medium size and small domestic wind turbines which are subject to similar pressures towards reducing cost. The universities are also supporting this sector. The improvement in energy yield at low wind speed through the redesign of the rotor has been explored in conjunction with a small turbine manufacturer.