Nissens supplied its first cooling systems for wind turbines in 1988, when wind turbines were named windmills. Since then, the company has been supplying to all the leading producers in the world, including Vestas, Siemens and General Electric.

Although the company began developing its coolers for onshore wind turbines, such as those operated by farmers, Nissens has grown adept at producing systems which can meet the tough requirements for offshore turbines. Handling corrosion resistance when cooling wind turbines installed at sea is one of the technical challenges the company takes into consideration when designing and manufacturing one of its advanced cooling solutions.

The Nissens Group is a family-owned business headed by Alan Nissen, whose great-grandfather established the company in 1921. It is headquartered in Horsens, Denmark, and has production facilities in Denmark, Slovakia and China, in addition to a network of sales subsidiaries in Europe, Asia and the Americas.

"I am a technician," says Alan Nissen. "When I was younger, my free time and my working time were always spent on radiators and technology. That is my personal and professional interest."

Best in the market

Arne Bojesen of Hydro points out that Nissen is also the head of production in his company. "Alan knows technology," he says. "We talk with him when we look at new things. He challenges us and we challenge him."

Bojesen is responsible for Hydro's European sales of aluminium tubing for industrial heat exchange applications. The two companies have been doing business together since 1985.

Nissen explains: "We moved from copper and brass to aluminium in the early 1980s and we became successful with our aluminium radiator. I tried to find not the cheapest supplier, but the best in the market. I wanted a supplier to give the best support. This is still my philosophy today."

In its oil coolers, Nissens uses an extruded aluminium spacer bar/plate concept because of its flexibility and high-pressure capabilities, and the corrosion-resistant qualities of the alloys. "I have always recognized Hydro as an innovative company that is continually offering new ideas and solutions," Alan Nissen says.

Bigger is more challenging

Off-road machinery, like earth-moving machines, represents the biggest part of the business for Nissens. But the business of cooling wind turbines is no less important, regardless of whether it is in Denmark, where wind is one of the five largest industries, or in China, where the wind industry is growing rapidly.

"Our company made the first coolers for the wind industry," says Nissen. "It was not big, but then neither was the windmill."

Since then, the company's systems have grown in step with the size of the turbine and the development of the industry, which has moved from a business for farmers with a small plot of land to a business for power companies with vast offshore wind farms.

Today's typical turbine uses three or four cooling systems, says Alan Nissen.

"The technical steering of our systems has become more sophisticated. And when it comes to size, the largest cooling surface in one piece that we deliver is three-by-three meters," he says. "Currently, we are developing the cooling units for a 6 MW turbine in close cooperation between the turbine manufacturer and our engineers.

"That process simply fascinates me, and we are proud to add value to the design and development of the customized cooling system needed by our customers."

He adds that the increase in offshore wind farms has created challenges for Nissens and its competitors. "Factors like humidity and salt play a much larger role in offshore installations, so we have developed systems with more wall thickness and different alloys for water. The Hydro products are serving us well here," he says.

"The offshore environment is also challenging because of the cold. Oil is so heavy that when we experience temperatures e.g. 40 degrees below zero, we need heaters and not coolers."