Clean energy must be the source of 70 % of Hawaii's electricity by 2030 and, according to State law, 40 % of this has to be produced locally from renewable sources.
To help meet these targets, Buckner Companies of Graham, North Carolina, USA installed wind turbines at two farms in Oahu and Maui, Hawaii, using a 600 tonne capacity Terex CC 2800-1 NT (narrow track) lattice boom crawler crane.
The two wind farms are the Kawailoa Wind project on Oahu’s North Shore and the Kaheawa Wind II project in Maui. At the Kawailoa Wind project 30 turbines have been erected, wit ha capacity of 69 MW, while at the second site, the Kaheawa Wind II project, 14 turbines have been added to an existing wind farm. The additional turbines in Maui have increased the energy output to 51 MW, which is enough to power 18,700 homes.
Project owner of the two sites is First Wind of Boston, Massachusetts, USA. The work was carried out by Buckner for renewable energy service provider RMT, based in Wisconsin, USA.
Challenges during the projects included small set up spaces, narrow roads, steep terrain and strict installation guidelines due to a habitat conservation plan to protect the surrounding environment. "Because of the challenging site conditions [in Oahu], we had to assemble and disassemble the crane three times," explains Jay Lusso, technical services representative for Hayden Murphy Equipment Company, a Terex Cranes distributor who was on site to assist with rigging and derigging the crane.
"The total disassembly and reassembly process took two to three days," adds Kevin Long, Buckner heavy lift project manager. "If we had needed the superlift derrick, this would have added another full day to the process."
Problems such as the narrow access routes were overcome thanks to the small foot print and narrow (5.3 metre) track width of the Terex CC 2800-1 NT. Crawlers in the 600 tonne capacity class measure up to 9.9 m wide to the tracks’ outside edges. Buckner considered using a 400 tonner on the Maui project to navigate the tight roads. In the end, however, "we wanted the higher capacity crane to deal with wind challenges, and we had the narrow track crane on the island," Long says. Other challenges included increasing wind speeds, which, on several occasions, reached 17 mph (27 km/h). "We faced consistently high wind speeds on the project, and the CC 2800-1 NT efficiently and effectively handled the wind," Long says. "Having the higher capacity crane gave us more working days on the project."
If the narrow roads weren't challenging enough, the steep grades of the mountainous terrain added to the project’s difficulties. "We were travelling unusually high grades of up to 17.5%," explains Long.
At the Kawailoa Wind project in Oahu, the Terex crawler was used to build 30 additional 2.3 MW turbines. To complete the task, the crawler was configured with full counterweight, 102 m of main boom and a 12 m fixed jib offering a 10 degree offset, a company spokesperson said. The lifts required the crawler’s maximum capacity in that configuration of 95.2 tonnes.
For the construction of the 1.5 MW turbines in Maui, the crawler was configured with 84 m of main boom and a 12 m fixed jib. The crane’s upper structure was fitted with 180 tonnes of counterweight.
Now completed, the two wind farms in Oahu and Maui generate enough energy to power more than 40,000 businesses and homes. Buckner will keep the Terex CC 2800-1 NT on Oahu for five years to carry out maintenance work.