By Andrew Garrad
Thursday, January 31 2013
Updated: Monday, November 04 2013
Many so-called pundits, myself included, made predictions about the maximum size of turbines that in retrospect were ridiculously conservative. We have now stopped making such predictions and are happy to be amazed by the engineering achievements of the present.
One useful “back of the envelope” limit is that a turbine blade longer than about 1km would probably buckle under its own weight, so there is still plenty of scope for growth!
Offshore, we are just starting something big. On land, turbine designs are constrained by having to be good neighbours to humans. There are no humans living near offshore turbines, and the constraints for the design engineer are purely technical. He or she has a free hand to design the most cost-effective turbine, limited only by engineering imagination.
Offshore wind farms today consist of standard turbines and towers, connected to separately designed substructures, with standard turbine electrical and control systems connected to separately designed electrical infrastructure. They should be integrated into a single design for each site. These projects are big enough to warrant site-specific design, and the benefits will be large.
The next stage is the design of an offshore-wind power station. Integrated design will be the key — not only integrated structure and electrical systems, but installation logistics, operation and maintenance, life extension and decommissioning. We also need to rethink the standard onshore design life assumption of 20 years — that’s not long enough offshore.
So, we should let our imaginations soar. We should be painting on a broad canvas. We should not restrict ourselves with the constraints of the onshore wind industry.
Initial offshore activity has been centred on the North Sea and the Baltic, where waters are fairly shallow. What about the deeper waters of the Aegean and the Mediterranean, and, more immediately, the sea around Japan? To exploit these deeper waters we need still more imagination to design and build floating turbines and floating substations.
Nowhere offers a better opportunity for this adventure than Japan, a country with few indigenous resources, where energy security is a high priority and there is almost no shallow water.
GL Garrad Hassan’s analysis suggests that most of the country’s 600GW potential offshore resource is in water deeper than 100 metres. In the wake of the 2011 Fukushima nuclear disaster, renewables have taken centre stage in Japan, and policy is developing rapidly.
Even five years ago, floating wind turbines seemed to be pie in the sky. Now we are helping to design three large, real-life, commercial floating turbine designs. We have developed sophisticated dynamic analysis tools and we now understand the behaviour of these devices.
With our help, two companies have deployed full-size prototype floating turbines; a further six scale-model projects are under way in Japan alone, with many industrial giants getting involved. Large floating wind turbines are a physical reality and could soon be a commercial one as well.
The past 30 years have taught me not to underestimate the dynamism of the wind industry or the imagination of its engineers.
The offshore business is not just about adapting onshore turbines for the sea. It is something much bigger: it is a new industry. To support that new industry and to realise the engineers’ ideas, we will need forward-thinking policies and consistent support. Even more so for floating turbines.
Post-Fukushima Japan needs new renewable sources of energy. It has deep waters and it has industrial might — it therefore has a unique opportunity to lead the development of this new phase of wind energy. It should be congratulated for its encouragement of early floating turbine prototypes.
What the country needs now is a stable regulatory regime and patient policymakers to allow the engineering to shine and its industrial heavyweights to challenge Norwegian trailblazers for the technical lead.
If Japan creates the right conditions, the future of floating wind power will be shaped there, and the engineering profession can demonstrate its flair again. History shows that we can expect to be amazed.
Andrew Garrad is chairman of GL Garrad Hassan, the global renewables consultancy
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