Jan De Nul Group has completed the installation of four medium-voltage export cables for Taiwan Power's 109MW Changhua demo offshore wind farm off the coast of the Asian island.

Cable-laying vessel Willem de Vlamingh installed the four subsea export cables from the project site, 10km off the coast, to landfall near Fangyuan.

Jan De Nul Group teamed up with Taiwanese partner Hung Hua Construction, which provided essential marine equipment including a jack-up barge, for the beach pull-in operations such as passing over a shallow water sandbank.

The wires had to be pulled through 1km-long underground ducts, which had previously been installed by horizontal directional drilling (HDD) up to 21 metres below the seabed, due to the presence of a nearshore oyster farm and an important shipping lane for fishermen on the cables route.

Willem de Vlamingh also acted as a trenching support vessel for the offshore work, while the nearshore trenching works, Jan De Nul’s Starfish excavators used an in-house developed plough-skid and jet-skid.

Jan De Nul Group project director Jan Kop said: “Originally, the HDD’s were stipulated in the contract to be 300 meters long, but Jan De Nul decided to extend them in order to prevent any damage to the sensitive coastal zone and fish farms.

“As such, we demonstrate once more Jan De Nul’s global care for the environment.

“Our offshore cable team did an amazing job, as did our onshore civil construction team who worked on the HDD together with Taiwanese companies Hung Hua and Magitech.”

The work also included an upgrade to the onshore substation in Changhua County, Jan De Nul said.

Together with its Taiwanese subcontractor Chung-Hsien Chen, Jan De Nul completed the installation and commissioning of new electrical equipment, including HV transformers, HV and MV switchgear, a new SCADA control room and emergency power supply, inside the onshore substation in Da Cheng.

The upgraded substation has been connected to the national grid for the first time in this new configuration, following a 24-hour energisation test.

Jan De Nul added that foundation installation of 84 pin piles and 21 jackets is making steady progress, with its consortium partner Hitachi continuing to prepare the turbines in the Taichung marshalling port.

The turbine installation campaign, due to start this month, will feature Jan De Nul’s jack-up Taillevent.

Jan De Nul Group is responsible for the full balance of plant, including design, fabrication and installation of the foundations, and the provision of the offshore vessel for the installation of the wind turbines.

Hitachi is in charge of manufacturing, assembly, installation and other works related to the 21 Typhoon certified turbines using a downwind rotor, each with a capacity of 5.2MW.

The Jan De Nul–Hitachi consortium is responsible for the first five years operation and maintenance of the TPC Changhua offshore wind farm phase 1.