Low wind speeds 'may deter offshore growth' in China

China's plentiful offshore wind resources may be relatively expensive to tap without substantial government support, an EU-funded study has concluded.

Researchers modelled the wind resources along 1,000km of coast from Fujian to Shandong province. They also ran a feasibility study for a 100-megawatt (MW) offshore wind farm off the Jiangsu coast, a location popular with local developers.

The results — still being drawn up — show that along much of the coast, China's average wind speeds are significantly lower than in Europe, at around seven metres per second, compared with a European average of around nine.

"That makes a huge difference to the energy yield. You could get roughly 50% more energy with the European wind speeds," says Richard Boddington, wind analysis manager at SgurrEnergy, the consultancy leading the project. Despite reasonably low installation and operational costs, the internal rate of return (IRR) predicted for the wind farm in the study was only 4.25%, largely because of the low wind speeds. A project of this type typically seeks an IRR higher than 8%.

"Jiangsu isn't the windiest area on the Chinese coast. You may need to move further south. Or else you would need to raise the feed-in tariff to around 1.4 yuan [$0.20] per kilowatt hour [kWh]," says Boddington.

China's first offshore project, a 102MW wind farm near Shanghai, will get a feed-in tariff of 0.97 yuan per kWh.

The study findings are important for the development of China's offshore wind industry . The country still has plenty of space to tap onshore wind, but many of the sites are a long way from population hubs. An estimated third of the wind energy being generated is not getting onto the grid or reaching the country's load centres. Offshore resources, closer to the industrialised east coast, may therefore be more useful. Yet Boddington says that developing and maintaining offshore wind farms in China will be challenging. Its coastline has highly varied wind conditions, with modest speeds in the north picking up further south. The area around Fujian province, near Taiwan, is prone to typhoons and tropical storms.

"The problem is getting the balance between fairly low average wind speeds and occasional extreme winds. You don't have this technical challenge in the UK," Boddington explains.

Chinese developers will also need to carefully consider where they build. Many seem to be focusing on the area of mobile sandbanks off the coast of Jiangsu province, says Boddington. "We have concerns about the depth of the sand, installation access and also the fact that these sandbanks are quite mobile, moving up to 0.25km per year. This would create problems for foundations and cabling."

At the proposed feed-in tariff, Chinese offshore wind farms will be unable to afford costly maintenance. "There is potential here, but it really depends on how much China is willing to pay for clean energy. Offshore wind will be relatively expensive because of the low wind resources."

Potential difficulties have not stopped turbine-makers and developers from exploring the market. Lars Andersen, China president at Vestas, says his firm is seeing "a lot of interest" from Chinese customers relating to offshore projects.

Siemens is also eyeing the market. "We're already number one in the world market for offshore. We also expect to achieve a leading position in China," says Andreas Dupuis, manager of Siemens wind-power sales in Asia.