Wind is a developing resource in the South Pacific. Some island nations like Fiji have already adopted wind power, while others like Samoa are committed to proving the resource and assessing the feasibility of wind-based generation.

Assessing Ulopu’s wind energy

The Government of Samoa, the power utility Electric Power Corporation (EPC), the Secretariat of the Pacific Islands Applied Geoscience Commission (SOPAC) and the United Nations Development Program (UNDP) are undertaking a wind resource assessment project for Upolu Island, Samoa.

Previous studies by Risoe – the National Laboratory for Sustainable Energy at the Technical University of Denmark – and others have identified potentially economically viable wind resources on the islands of Samoa. Following the recommendations of these initial studies, Clay Engineering of Fiji established two NRG Systems wind monitoring stations on the island.

With over a year of data available from the wind monitoring stations, GHD was engaged by UNDP in November 2008 to complete the next stage in the wind resource assessment. The company reviewed the data already collected and undertook the extrapolation of that data through wind flow modelling to all parts of Upolu Island and neighbouring Savaii Island.

To analyse the data GHD used the latest version of industry standard wind flow modelling software, the Wind Atlas and Analysis Program (WAsP), in conjunction with WindPro and in-house software. Following site visits by UNDP and EPC personnel, a preferred site was selected.

Turbine selection

GHD reviewed a previous study of wind turbines in the 250 kilowatt (kW) to 1 megawatt (MW) range and contacted the turbine suppliers to determine interest in supplying turbines to Samoa.

Vergnet was the only turbine manufacturer, supplying turbines in the size range considered, that expressed interest in supplying turbines to Samoa. The company’s 275kW and 1 MW turbines are both designed for use in remote and cyclonic areas, able to be lowered to the ground for servicing and for protection during cyclones.

Energy predictions

Layouts for a 2 MW and a 5 MW wind farm were prepared for the preferred site and preliminary energy production estimates made for a single turbine model.

The energy predictions are based on the GEV 275 MP turbine – Vergnet’s preferred turbine for use in Samoa. For the 2 MW wind farm, annual generation is estimated at 3.6 gigawatt hours (GWh) and for the 5 MW wind farm, 8.6 GWh. Predicted annual CO2 savings have been estimated in the order of 2,900 tonnes of CO2 equivalent (CO2e) and 6,900 tonnes of CO2e.

To identify the point at which wind energy generation becomes cost effective for the model projects, the energy estimation for the two wind farm sizes was used with preliminary cost estimates to provide an energy cost curve. This was then compared against the long-run cost of energy from diesel generation. The results were encouraging.

“There is real potential for Samoa to reduce its dependence on imported fuel by using the wind,” said GHD Senior Engineer of Renewable Energy, Nic Jacobson.

GHD has provided advice to advance the next stage of the wind resource assessment for Upolu and Samoa more generally. EPC is moving ahead, with resource assessment and data collection underway. There are also plans to install new monitoring stations on Savaii Island and to relocate the monitoring station from Afulilo to the potential wind farm site located near the centre of the island, and on top of the main ridge.