Not long ago, the Nordic country of Denmark became the first place in the world where the ubiquitous lattice transmission tower is no longer accepted for any power line construction. While relatively small and with a population of only some 5.6 million, what made this development noteworthy on the international stage is that Denmark is the frontrunner in a trend that is impacting a growing list of countries – public opposition to new overhead lines. Fortunately, resistance to added power infrastructure by affected communities across the globe seems to relate more to appearance than function. Rightly or wrongly, the lattice tower has become a symbol of the blemish that overhead lines sometimes impose on natural landscapes. That suggests that if power companies can find alternative, more aesthetic structures, there is reason to expect that the public will object less, if at all. Of course, leaving behind the steadfast lattice tower is something that would probably never be driven only by economics: time has demonstrated that these towers are cost effective and offer outstanding performance and service life. Indeed, that explains why they have remained in use, basically unchanged, for decades. In 2014, INMR visited one of the world’s most recent alternatives to lattice towers and met with the industrial designers who developed the concept as well as the transmission system operator who made use of it. Apart from valuable information on how to make new transmission lines more accepted by an increasingly wary public, this article also offered insight into the specification and application of insulators for these types of projects.
The origins of the new double circuit 400 kV Kassø-Tejle line that runs northward along the Jutland Peninsula lie in the longstanding goal of strengthening the interconnection between Germany and Denmark, and from there to Norway and Sweden. However, realizing this goal by means of another overhead line required overcoming strong objections by those who lived in this flat region of mostly small farms and historic towns.
Energinet, the Danish grid operator, first began planning the line back in March 2009 with an environmental impact assessment, as required by regional planning authorities. This document proposed that the initial route for the new line would be aligned as much as possible with an existing transmission line between the two points. The first public planning then took place in June that year and Energinet was asked to study different routes in terms of their expected effect on people, buildings as well as local wildlife and vegetation. Within 3 months, these alternatives were set out, each with a 400 meter wide planning zone.
A second pubic hearing for the project took place between March and May of 2010 during which the environmental impact assessment was published and the public was given a time frame to express their views as well as any proposals for adjustments. By the autumn of that year, the final environmental impact assessment and detailed route planning were both reviewed and within 6 months negotiations began in regard to compensating affected landowners. Construction of the line began around the start of 2013, with the project scheduled to be complete by November 2014.
The firm who developed the design of the stylistic structures used along this line – dubbed Eagle Pylons – is a Copenhagen-based firm of industrial designers whose background lay more in public works than energy. However, back in 2001, the founder, Erik Bystrup, was intrigued by a competition aimed at finding new tower designs for another sensitive transmission line in Jutland. Until then, like most of the public, he found himself driving along motorways looking out at what he refers to as “the vast amount of gear and steel elements that comprise modern power lines” and wondering why these were not yet being replaced by more aesthetic designs. Says Bystrup, “it seemed clear to me that these structures were not being designed by people who cared all that much about the sky. Then, in 2001, when we were awarded not only 1st but also 2nd and 3rd prizes in the competition in Jutland, it made me realize that applying our design ideas to the power sector might prove an attractive proposition.”
Bystrup talks about some of the initial concepts developed to make power structures better blend into their environments. For example, one of his earliest proposals, called the Sky Pylon, involved polished stainless steel monoliths that reflect light in every direction and therefore appear almost invisible. However, this design ran into concerns that motorists might be blinded by reflected headlights and therefore never actively pursued.