Energy capture squeezes extra output from wind farms

Paul Boughton

The latest generation of wind turbines are capable of much greater energy capture. Eugene McCarthy reports.

Novel technologies, particularly to do with increased energy capture, have led to a raft of new and prototype wind generators coming on to the market in 2014.

Vestas is leading the way with the launch of its first V164-8.0 MW prototype wind turbine. This, says the company, is the world's most powerful turbine in operation (Fig. 1).

"We have now completed the production, testing, and installation of the V164-8.0MW as planned, thanks to the team's intense effort during a time when Vestas has reduced its investments and lowered fixed costs. We now look forward to evaluating the turbine's performance on site," says chief technology officer Anders Vedel.

The turbine, installed at the Danish National Test Centre for Large Wind Turbines in Østerild, will be closely monitored in the coming months to further validate reliability and energy output.

The turbine's installation is a key milestone towards ensuring maximum business case certainty for customers investing in offshore wind.

The V164-8.0MW will be the flagship product for the offshore joint venture between Vestas and Mitsubishi Heavy Industries.

One of the new units is capable of supplying electricity for 7500 average European households. With a 140-metre tower, the turbine at Østerild has a tip height of 220metres.

Increased energy capture

The swept area of more than 21,000m2, equal to three football pitches, increases the amount of energy captured, while reducing operational and maintenance costs by enabling customers to run fewer, larger turbines, with fewer service visits.

Depending on the number of orders, commercial production is expected to begin in 2015.

Meanwhile, at the European Wind Energy Association's annual conference in Barcelona, Spain, GE launched its smarter, more powerful 2.75-120 wind turbine. The new model is capable of five percent more annual energy production than the company's existing 2.5-120 model and is available with various tower technologies, ranging between 85-139 metres, and optional energy storage.

"As we accelerate our platform's growth in Europe, we will continue to invest in technology such as the 2.75-120's flexible tower and other energy storage options, making GE's wind turbines more customisable for developers and operators," said Cliff Harris, general manager of GE's renewable energy business in Europe.

Short-term or long-term energy storage is available with the 2.75-120, making wind power more predictable, flexible and fast responding through battery software applications. Short-term storage is integrated at the turbine level and long-term storage is centralised for the wind farm.

Performance-optimised blade design

For its part, ENERCON has just finished installing a new Wind Class IIA machine in northern Germany The prototype is perched on a precast concrete tower at a hub height of 135 metres, but is also available with hub heights ranging from 92 to 149 metres.

The company says that thanks to its performance-optimised blade design and a rotor diameter of 115metres, the E-115 generates high yield even in the partial load range making the new series a profitable choice also for inland sites with slightly less wind.

Up to now, ENERCON's top selling product was the E-101/3 MW machine with a rotor diameter of 101 metres. "The demand for this category of wind turbine is high. And customers now have yet another state-of-the-art turbine to choose from featuring technical innovations such as the divided rotor blade concept for optimised logistics," said sales director Stefan Lütkemeyer.

At a typical inland site with average wind speeds of 6.5m/s at 149 metres hub height, the E-115 can generate an annual output of roughly 9.3 million kW hours - an increase of 14 per cent compared to the E-101. The E-115 will be available from mid-2014.

Low power density

Finally, the G114-2.0MW wind turbine from Gamesa is designed for low power density and to contribute to significantly cutting the cost of energy of products designed for medium and low wind speed sites.

With a rotor spanning 114 metres, the new turbine's swept area is 38 per cent greater than that of the G97-2.0MW and it produces up to 20 per cent more energy a year.

Meanwhile the company's G128-5.0MW is designed to position Gamesa as one of the leading players in the multi-megawatt market. The 5MW turbine has evolved from the 4.5MW platform and caters to the most complex wind farm developments in terms of competitiveness and cost of energy.

The company says its innovative modular design and technology ensure reliability while complying with the most stringent international grid-connection codes and environmental standards.

The first prototype, already generating power off the Canary Islands coast, has a 128 metre diameter rotor, a total height of 154 metres and 62.5 metre-long blades. It will produce enough power to supply 5000 households every year.

Wind power dominates Spain's electricity production

Red Eléctrica de España (REE) Spain's grid operator, has released a report on the country's power system showing that, for the first time ever, wind power contributed most to meeting the country's annual electricity demand. The report says that wind turbines met 21.1 per cent of the Spanish peninsula's electricity demand last year, with nuclear just behind at 21 per cent.

Wind farms are estimated to have increased generation 12 per cent to 53,926GWh while heavy rainfall pushed hydroelectric power output up by 16 per cent to 32,205GWh.

"Throughout 2013, the all-time highs of wind power production were exceeded. On 6 February, wind power recorded a new maximum of instantaneous power with 17,056MW at 3.49 pm (2.5 per cent up on the previous record registered in April 2012), and that same day the all-time maximum for hourly energy was also exceeded reaching 16,918MWh. Similarly, in January, February, March and November wind power generation was the technology that made the largest contribution towards the total energy production of the system," notes the report.

Overall, renewables contributed 49.1 percent of installed power capacity on the Spanish peninsula, benefiting from a 173MW increase in wind power capacity, a 140MW increase in solar photovoltaic capacity and rise of 300MW in solar thermal capacity.

The figures also show a 34.2 per cent year-on-year fall in output from combined cycle gas plants, a 27.3 per cent fall in coal-fired generation and a drop of 8.3 per cent in nuclear output.

Recent Issues