4.0 Project Description. 4.1 Renewable Energy in the Mauritian Context

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1 4.0 Project Description 4.1 Renewable Energy in the Mauritian Context The vision of the government is to make Mauritius a sustainable island Maurice Ile Durable which emphasizes on the exploitation of renewable energy resources. The wind power sector is rapidly being developed and several wind farm projects have already been announced. 4.2 Wind Power Wind turbines convert the kinetic energy in wind into electricity. A wind farm consists of several such turbines which are in turn connected to the electric power transmission network. Individual turbines are interconnected with a medium voltage power connection system and communication networks. At the substation, the medium-voltage electric current stepped up with a transformer for connection to the high voltage electric power transmission system. As of 2011, 83 countries in the world were using wind power on a commercial basis in one form or another. 4.3 Wind Power Potential in Mauritius Studies carried out in the early eighties, namely the Batelle Report, indicated that Mauritius and Rodrigues islands, being exposed for the major part of the year (mainly in winter) to the South East Trade Winds, have a good wind regime for installation of wind turbines. The average annual wind speed varies over Mauritius. The wind speed is more significant in the South and Coastal region of the island, and less significant in the West. In winter, the island is most favorable for wind energy exploitation. Wind turbines were installed on a pilot basis at Trefles (Rodrigues) and Grand Bassin (Mauritius) respectively. However, the turbines had to be decommissioned later on since they were not designed to operate in cyclonic conditions and problems were encountered during the procurement of spare parts of the WTGs. In 2008, a wind farm pilot project in Rodrigues, comprising 3 wind turbines each having a capacity of 60 kw proved to be successful. In view of this success and the considerable progress in the design technology of the turbines, Government of Mauritius is now reconsidering the use of wind energy on a larger scale in the island. The Government of Mauritius has sought and obtained assistance of the Government of India with respect to the application of the wind technology in Mauritius. Sustainable Resource Management Ltd Page 23

2 4.4 The Proposed Suzlon S MW Wind Turbine Generator (WTG) to be used for the Wind Farm at Plaine Sophie The Suzlon S MW WTG (see Figure 4.1) comprises a nacelle, 3 blades, a tower and a foundation. The detailed technical specifications of the Suzlon S MW Wind Turbine are found in Annex 8. Figure 4.1: Suzlon S MW WTG The nacelle The nacelle contains the main components of the WTG. It is designed in such a way that the internal components are fully protected against ambient conditions. The nacelle cover is made up of Glass-Fiber Reinforced Plastic (GRP). It is mounted to the tower with a torque adjustable friction type yaw bearing consisting of polyamide slide bearings, which transmit the loads from the nacelle to the tower Rotor and blades Rotor cone angle Rotor speed at rated power Tip speed at rated power Rotor orientation 5 o rpm 78.7 m/s Upwind The rotor consists of a high strength cast iron hub supporting three pitch rotor blades. The blades are connected to the hub via ball bearings. The hub is housed in a nose cone Sustainable Resource Management Ltd Page 24

3 which covers the hub cabinet. The rotor blades are aerodynamically optimized to provide high lifting forces and low air resistant values to produce high performance The Tower Tower type: Tubular Tower (4 sections) Corrosion Protection: Epoxy/PU coated The WTG also consists of a tubular steel tower having a height of 87.6 m (Foundation top equal to ground level). The tower is connected to the foundation by bolts which are set into concrete at the foundation. There are various working platforms inside the tower. The bottom cabinets arranged on the lowest tower platform are connected to the generator and the top cabinet inside the nacelle via power and control cables Braking System Aerodynamic brake Mechanical brake 3 independent systems with blade pitching mechanism Hydraulic fail-safe disk, brake system Gearbox Type 3 stages (One planetary & Two Helical) Ratio 1:98.8 (±0.5) Mechanical power MW Yaw System Type Bearings Driven by 3 electrical driven planetary drives Polyamide slide Certifications Design Standards GL 2003 Quality ISO 9001:2000; ISO 9001:2008, ISO 14001:2004 & OHSAS 18001: Materials of Construction 1. Cast Iron 2. Glass-Fiber Reinforced Plastic 3. High Grade Steel 4. Epoxy/Polyurethane coating 5. Epoxy bounded fiber glass Sustainable Resource Management Ltd Page 25

4 4.5.9 Technical Characteristics of the Suzlon S MW Wind Turbine Generator Operating data Rated Power Rotor speed Cut in wind speed Cut out wind speed Hub height Wind Class 2.1 MW 12.1 to 17.6 rpm 3.5 m/s (30-second average) 25 m/s (10-minute average) 34 m/s (3-second average) 90 m (Foundation top equal to ground level) IIa Rotor Diameter 95 m Swept Area 7085 m 2 Generator Type Rated frequency Synchronous speed Rated generator speed Power factor (compensated) Asynchronous 3-phase induction generator 50 Hz 1500rpm 1568 rpm 0.94 lagging to 0.94 leading Suitability of the Suzlon S MW Wind Turbine Generator for the Plaine Sophie Wind Farm A turbine generator for a wind farm project is chosen based on the following considerations: Wind resource (the class wind speed of the proposed site); Worst conditions for mechanical specifications (Insurability); Maintainability over 20 years Transportability on site and availability of crane for erection; Grid integration (supply of system services and fault-ride through capability); Land usage; Noise legislation; Market positioning The Plaine Sophie site has a wind speed regime in the range of Class 3 wind regime (annual wind average of less than 7.5 m/s as per IEC ) as per the wind measurement done for the met mast location of Curepipe Point (see Annex 6). The Sustainable Resource Management Ltd Page 26

5 proposed wind turbine generator (Suzlon S MW) is designed to withstand medium wind with an annual average wind speed of less than 8.5 m/s or 30.6 km/h and, it is therefore considered ideal for usage onsite. The wind turbine concept is based on robust design with pitch regulated blade operation, a three stage gearbox with MW mechanical power and flexible coupling to the asynchronous induction generator. The Suzlon flexi-slip system provides efficient control of the load and power control and the turbine operation is effectively controlled. Mauritius is a cyclone-prone area with Cat 5 cyclones (Maximum wind speeds over 280 km/h). The selected wind turbines must therefore be able to sustain such wind speeds, or else the wind farm will not uphold the cyclonic conditions and might be partly or totally destroyed in case the designed maximum wind speed is exceeded. The S MW WTG is designed to withstand extreme conditions and operate effectively with low maintenance costs. Besides, the design philosophy of the gearbox is based on years of experience with wind turbines in harsh environments. The turbine towers are cyclone resistant and can withstand wind gust of up to 252 km/hr. Suzlon has a team of trained wind farm technicians around the globe who focus on excellence in service, maintenance and monitoring. The service technicians aim to maximize energy production from wind, and ensure the turbines operate reliably and with minimal maintenance costs during their life span. A Suzlon team of engineers and technicians will be present for a warranty period so as to ensure proper operation and maintenance of the wind turbines. They will also be responsible to train local technicians and engineers who will in turn ensure proper operation and maintenance of the turbines. Consortium Suzlon-Padgreen Co Ltd will hire a special crane for the erection of the wind turbines. Large items like blades, towers and hubs will be transported by open flat rack lorries with relative sizes varying with respect to length, width and weights of the components. The grid connection point at 66 kv level will be at Henrietta which was decided in consultation with the Central Electricity Board (CEB). A pooling Sub Station (SS) has been envisaged within the wind farm (see Annex 3) at 33 kv level. The transmission lines in the wind farm will also be of 33 kv. Each turbine foundation will cover an area of 100 m 2 each. The total area covered by the 14 Suzlon S MW Wind Turbines will therefore be around 1400 m 2. The wind farm will cover a total land extent of 433,000 m 2. Sustainable Resource Management Ltd Page 27

6 As per the Environmental Standards for Noise (Amendment) Regulations 2003, in any other area apart from residential area, at any time, the noise level should be less than 70 db(a)l eq. According to Annex 9, the noise level of Suzlon WTGs is from points A and B are db(a)l eq and db(a)l eq respectively. Hence, the noise produced by the WTGs installed on site will be in compliance with the regulations in Mauritius. Suzlon is one of the leading wind turbine manufacturing groups in the world. Born in India, Suzlon operates across Asia, Australia, Europe, Africa and North and South America. It is the world s 5 th largest and fastest growing integrated wind turbine manufacturer with a workforce of over 13,000 people in 33 countries. It is a market leader in Asia with a Suzlon Market Share (Combined with Repower) of 6.9%. Sustainable Resource Management Ltd Page 28