History of Danish Wind Power - Wind Power for the World: The Rise of Modern Wind Energy - page 76

In the meantime, a pair of other Danish firms entered the wind
turbine market. The first one—Nordtank—originally produced
mostly road tankers for the oil companies, but the oil crisis has
nearly eliminated this market. In the search for a new product,
wind turbines were the choice. Here, Nordtank could also use its
knowledge of rolling and welding steel tank sections and introduced
the tubular steel tower—built by cylindrical and conical sections—
which became the trade mark of Nordtank and soon were adopted
by other producers.

Figure 3.35 Nordtank—with their background in oil tanker vehicles—was

the first to introduce. in 1980, the tubular steel tower, which in
various designs substituted the traditional steel lattice tower
on most Danish wind turbines during the following years
(Photo: Jan Vium Nielsen, DVS) (left); Bonus adapted the
tubular tower from the start. The first Bonus 30 kW turbine,
sold in September 1981, was still in use, as seen in the photo,
in the summer 2010 (Photo: Erik Grove-Nielsen, www.
windsofchange.dk) (right).

Danregn was the other Danish firm entering the market in
1981.

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It was specialised in mobile water irrigation machines and
pipes for farms. As the market for this product had an obvious
seasonal character, there was a need for a product to “fill up” the

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See chapter From Danregn to Bonus by Egon Kristensen.