The wind sector has been growing spectacularly over the past decade. However, to sustain these impressive growth figures over the next twenty years in Europe and North America, business-as-usual will not be enough. In several European countries, the number of remaining onshore sites for building new wind farms is already declining (see interview with François and Benoît Henriet, 'Barriers for wind projects', on this blog). Maintaining current growth will require going off-hore, or at least off the beaten track.
Given its target of 20% renewables by 2020, the EU sees offshore wind as a major power source for the future. EU Energy Commissioner Andris Piebalgs declared at the European Wind Energy Conference in March that he is counting on the potential of offshore wind energy to 'ensure that the growth trend in wind energy continues'. He indicated that he would develop an Action Plan by the end of this year outlining the means by which the EU can facilitate the development of offshore wind energy.
Piebalgs also clearly stated that 'a maritime grid infrastructure is needed for the development of offshore wind energy. As this is not yet in place, it must be developed fairly quickly and a central question is how it should be financed.'
In the meantime, the US has yet to see its first offshore wind project even begin construction. Surprisingly enough, it could very well be a group of commercial fishermen and dock operators who will lead the way. I say surprisingly because the commercial fishing industry has almost universally opposed offshore developments as a dual threat to fishing grounds and navigation. The state of New Jersey wants to become the home of the first offshore wind farm in the US and is providing a grant for the best project proposal. One of the leading contenders is the Fishermen’s Energy of New Jersey group. This group has apparently concluded that offshore wind farms are inevitable and that its members will be in a much more powerful position by joining rather than fighting it. If wind turbines are going to limit access to some of their traditional trawling grounds, they want to make sure that they can at least harvest the wind instead.
The active participation of commercial fishermen will enhance the chances of overall success. They are intimately familiar with the local weather, ocean currents, and continental shelf topography. Faced with ever-declining fish stocks worldwide, they are a group of experienced people ready and willing to work offshore. Fishermen’s Energy of New Jersey hopes to install its first pilot of 20 MW by 2011 and to expand it to 320 MW by 2013.
Another group equally well acquainted with working offshore is the Norwegian oil and gas company StatOilHydro. In May of this year, they decided to build the world’s first full scale floating wind turbine. The 2.3 MW wind turbine will be attached to the top of a spar-buoy, a design already being used for some oil and gas production platforms and for various oceanographic instrumentation systems. It will be located approximately 10 kilometres from the coast near the city of Stavanger, Norway. The floating element of this pilot installation will have a draft at some 100 meters below sea level, providing it with the required stability in the often-turbulent North Sea storms.
Floating wind turbines, if they are able to reach technical and economic maturity, have the potential to give a significant boost to the wind sector. It would enable the location of wind farms not only in shallow near-coastal waters, but also at locations with sea depths of 120 to 700 metres, where wind speeds are favourable and the visual impact minimal.
The StatOilHydro project combines known technologies in an innovative way. The California-based Selsam Superturbine(TM) company, on the contrary, has developed a radical new concept for offshore floating wind turbines. It consists of a long shaft bending in the wind like a reed and containing several rotors at different heights. The shaft connects to a buoy carrying the generator. The Superturbine website enumerates many potential advantages of this concept:
This is, of course, strictly the current promotional position of the company as they try to sell the concept. The bottom line will be the cost per kWh that this new type of turbine will be able to produce. Moreover, the technology will first have to prove itself in rigorous field tests before it can be regarded as a viable option for the future. In a comment on the Physics Forum, Fred Garvin fears that the rotor dynamics of this concept could be a nightmare.
Probably closer to realisation are the Jet Engine wind turbines by FloDesign, a Massachusetts-based company. The Jet Engine channels the wind into a vortex that spins the small, high speed rotor blades. This makes them at least twice as efficient as traditional rotor blade turbines. Moreover, they are capable of operating both at lower and at higher wind speeds than traditional turbines, enhancing the capacity factor of the unit (see blog post 'The capacity factor of wind power'). FloDesign turbines are easier to install since they have much smaller blades — they fit into a single standard size long haul truck — and are inherently safer. A no less important advantage is that they can be placed closer together on a site, optimising land use. If all those arguments prove out and this technology is cost-efficient, it could boost the yield of onshore wind farms.
A new domain for expanding wind energy is building-integrated wind turbines. Like any new idea, it has its sceptics. They point out that wind passing around buildings generally shows a high level of turbulence that can affect the efficiency of the turbines. Nevertheless, proponents can point to the Bahrain World Trade Center in Manama, Bahrain, inaugurated last April, to prove that this barrier can be overcome. It is the first building integrating utility-scale wind turbines into its design. The turbines are mounted on the three bridges that span the gap between two sail-shaped buildings, and not on the rooftop. The architecture of the building shape is designed to funnel wind through the gap between the two buildings to provide the maximum amount of wind passing through the turbines. The turbines have a capacity of 225 kWp each and provide 11 to 15% of the buildings energy needs. They are expected to operate 50% of the time.
Will we all have our own personal wind turbine on our house one day? I have my doubts and, frankly, I hope we will not. Many can still recall the sea of television aerials that once created an urban visual pollution all of it own before the advent of cable. Nevertheless, it appears that residential wind turbines are getting cheaper. The E2D Windmaster of the California-based company Freetricity’s is probably the first affordable roof-mounted residential wind turbine. It is small enough to be used in residential areas and powerful enough to provide 25% to 50% of the electricity needed by the average household. The system connects via an inverter, rather like a photovoltaic system. A unique feature is that it comes with a battery and can be used as a backup system during electrical blackouts. It is probably also an appropriate solution for off-grid houses in remote, windy regions.