Advances in high temperature superconductors (HTS) for wind turbines (also applicable to small hydro) will soon be able to reduce the size of the generator to about a quarter of the size and weight of that of a conventional system, while at the same time significantly increasing efficiency and reducing maintenance requirements. This could transform the economics of offshore wind by opening up the possibility of turbines with much bigger unit capacity, but of manageable size and weight.

A comparison between an HTS machine and a conventional system is shown in the table above.

UK based power conversion specialist Converteam says it hopes to have a “full scale product available by 2010.” It expects that within the next four years it will be possible to increase the output of superconductor based generators to 12 MW from a current level of around 4 MW.

The company is currently leading a UK Department of Trade and Industry funded project to design an 8 MW direct drive superconducting wind generator, capable of achieving major cost savings. Converteam is using HTS technology developed by Zenergy, with whom it has recently signed a five-year exclusive co-operation agreement covering wind and small-hydropower applications. The agreement provides for the joint development, manufacture, marketing and selling of HTS generators into these markets. Under the agreement Zenergy becomes the exclusive supplier of HTS wires and coils for all Converteam’s commercial activities in wind and small hydro. The companies believe “offshore wind power to be potentially the largest and most commercially viable market for HTS technology.” The purpose of the agreement is to “maximise penetration of Converteam HTS generators into the renewable energy markets”, conferring a “substantial competitive advantage in a market where barriers to entry are high and first mover advantages are significant.”

The agreement, announced in March, follows a long working association between Converteam and Zenergy.

The two companies have already made good progress in the small hydropower sector. In October 2006 the European Commission funded the installation of the world’s first HTS hydro generator – developed by Zenergy and Converteam – into an E.ON Wasserkraft GmbH hydro facility at Hirschaid, Bavaria, Germany. This was a 1.25 MW machine.

HTS conductor and conventional copper