Renewable-energy business and project developer Red Cap was announced as one of the preferred bidders in round three of the Renewable Energy Independent Power Producer Procurement Programme (REIPPPP) last month for its Gibson Bay wind farm project in the Kouga local muni- cipality, in the Eastern Cape.

Construction on the project is scheduled to start in August 2014 and it is expected to start generating electricity in the first quarter of 2017. The Gibson Bay wind farm will have thirty-seven 3 MW wind turbines, each of which will be 91 m high, with 117-m-diameter rotors, explains Red Cap MD Mark Tanton.

Red Cap has a full engineering, procure- ment and construction contract with Germany-based wind turbine design, manufacturing and supply company Nordex. The 3 MW wind turbines, including the nacelles and blades, are manufactured by Nordex and will be imported from Germany. However, the towers will be manufactured locally by internationally recognised manufacturing and engineering company DCD, he explains.

“In the first round of the REIPPPP, there were no local original-equipment manufacturers for wind turbine components,” he notes. This changed in March, when DCD began construction of its Wind Towers subsidiary, which is expected to start manufacturing wind towers in January 2014.

Red Cap is also undertaking construction at its Kouga wind farm in Oyster Bay, in the Eastern Cape, where the company will erect thirty-two 2.5 MW wind turbines, which will have an installed capacity of 80 MW. Each of the 80-m-high wind turbines will be anchored by 20-m-diameter concrete foundations, of which 22 have been cast to date.

Nordex has subcontracted South Africa-based civil engineering firm Power Group to carry out all the civil engineering work, which includes the casting of the concrete foundations. The blades of these wind turbines have a diameter of 90 m.

Tanton notes that the final wind turbines are planned to be erected before the wind farm is connected to the grid of State-owned power utility Eskom. The Kouga wind farm is expected to have all turbines erected by June 2014, as well as access to the national grid.

He adds that, once installation and grid connection are completed, Nordex will begin testing and commissioning the wind turbines until December 2014 to ensure performance meets specifications.

He explains that the windy conditions at the wind farm sites resulted in the lengthy installation process, which can make operating the cranes to erect the wind towers dangerous and, therefore, downtime needs to be planned into the programme.

“The wind turbines for both projects will be shipped to the Port of Ngqura, in the Eastern Cape, and then transported to site on specialised flatbed vehicles, which have low clearance to allow for the transportation of the nacelles. The trailers of the flatbed vehicles are split to allow for manoeuvrability around corners while carrying the blades of the wind turbines,” says Tanton.

He notes that the location of the Kouga and Gibson Bay wind farms are in some of the best wind resource areas of South Africa, owing to consistent high wind speeds throughout the day.

Tanton explains that there are two popular ways in which wind energy industry members determine the probable energy output of a wind farm.

“A P90 assessment calculates a 90% probability of the amount of energy a wind farm will generate. The calculation includes data, such as wind measurements in the area of the proposed wind farm, over a minimum of 12 months and the topo- graphy of the surrounding area, as nearby mountain ranges, for example, will cause turbulence and, therefore, affect wind speed. Banks require P90 assessments to approve financing for a wind energy project, as banks need certainty that the debt can be serviced and repaid.

“Generally, P50 assessments are used from an equity perspective. It is more reflective of predicted actual performance than the conservative P90 assessment. P50 assessments provide an average prediction of what energy output a wind farm will generate,” he explains.

The Kouga wind farm is expected to produce on average 309 GWh/y. This figure takes into account electricity losses owing to low wind speeds. The Gibson Bay project is expected to generate about 424 GWh/y, he adds.

Tanton notes that the documentation needed for a successful bid for the REIPPPP includes a detailed financial model and the P50 and P90 assessments, which are then audited by an independent third party, with a duty of care to government and the lenders. Also included as part of the documentation is any past wind energy project experience and technical documentation, which includes a detailed assessment from a third-party wind resource technical expert.