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Arup conducted risk assessments for the lender considering all technical aspects of the project, from engineering analysis of the equipment and facility design, through to transaction advice and engineering expertise in optimizing the construction. In addition technical reviews of the Engineering Procurement and Construction (EPC) and the Operations & Maintenance contracts were required for financial close of the project.
Arup provided key technical advice from the pre-bid stage resulting in the project successfully reaching financial close and Commercial Operation Date (COD) on schedule. This project required significant technical support in the contract negotiation phases to ensure best value to the developer and the lender. Specific foundation design engineering advice was also required during the detailed design stage.
On behalf of the borrower, Arup provided basic guidance with respect to maintaining environmental and social compliance at the outset of the construction and operation phase.
Site description
Noblesfontein Wind Farm is located on Farm Noblesfontein, approximately 35km south of the town of Victoria West in the Northern Cape region of South Africa. It lies east of the N12 national road and west of the N1 national road.
The Noblesfontein Wind site comprises approximately 11,000 hectares requiring 42km of road and is at an elevation of 1,370m. The northern end of the site is relatively flat with an elevation of 1350m above sea level (asl). The southern end of the site is characterised by ridges and hills and the elevation ranges from 1250m to 1550m asl.
Climate and site conditions
The site falls within the Northern Cape which experiences high temperatures in summer and low temperatures in winter. Rainfall is scarce but when it rains the storms are generally short but intense, resulting in flash flooding.
Foundation design
The foundation consists of two parts, foundation slab and pedestal. The foundation slab is circular (15.3m diameter) with a variable thickness from 0.9 at the edges to 1.9m at the pedestal base. The pedestal is circular with a 5.5m diameter.
Each foundation base required 280 m³ of concrete and 44 tons of high-tensile steel reinforcement bars.
Up to four pipes Ø200 and one Ø100 are embedded within the concrete under the foundations for power cables, optical fibre and copper cables.
Wind turbines
Noblesfontein Wind Farm consists of 41 wind turbines generators Vestas V100 (80m hub height) rated 1.8 MW each, totalling an installed capacity of 73.8 MW, nevertheless each wind turbine generator can produce up to 2.0 MW.
Construction period
The EPC contract commenced on the 10th December 2012 and commercial operation was reached on the 11th July 2014. This represents an overall contract period of 19 months. Construction mobilisation works commenced on the 6th March 2013, representing a construction period of 16 months.
