Modern grid connected wind turbine technology has been developed over the last twenty years. The typical capacity of a modern grid connected wind turbine is in the range of one to five MW. Wind turbines designs can accommodate high wind or low wind conditions.
Wind turbines designed for low wind conditions are characterised by a large swept rotor area in relation to the capacity, and an increased hub height. Low wind turbines are suitable for wind conditions in Oman. Modern wind turbines are equipped with cooling systems enabling operation under extreme environmental conditions such as the high air temperatures which occur in Oman.
Utilisation of the wind energy resources in the southern part of Oman should be further investigated. We recommend a detailed wind resource survey and further analysis of the potential connection of wind farm to the Salalah Power System.
The use of wind turbine capacity in a grid system is generally limited by technical considerations. If wind turbines account for a high percentage of total generating capacity, fluctuations in the energy output of wind turbines may adversely affect power quality in terms of frequency and voltage fluctuations, unless special measures are implemented to regulate wind turbine output.
The present technical potential for grid connected wind turbines in Oman is approximately up to 50 MW, corresponding to 20 % of the present installed capacity of the Salalah Power System (251 MW). In 2014 commissioning of the new Salalah IWPP will increase the amount of generating capacity connected to the Salalah Power System to 580 MW and the potential wind turbine capacity will increase to around 120 MW.
The interconnection of the Main Interconnected System and the Salalah Power System would further increase the potential for wind turbine capacity to at least 750 MW. This corresponds to an estimated net annual energy output of at least 2300 GWh/year.
The potential for grid connected wind turbines would be even higher if the interconnected system had the capacity to transmit electricity to all load centres in Oman from the southern part of the country where wind energy resources appear to be abundant. Wind energy resources are highest during the summer period which coincides with the period of peak electricity demand.
Wind energy, off-grid wind turbines
The study finds the potential for off grid wind turbine applications to be limited. These types of applications may be relevant for electricity supply to consumers in rural areas where wind speeds are high e.g. along the coast in the southern part of Oman and where no grid connection is possible.
The forecast of electricity generation capacity is 5691 MW in 2014. A scenario where 5% of the capacity (285 MW) is covered by renewable energy could e.g. consist of a combination of 125 MW wind farm capacity, 100 MW solar thermal power capacity and the remaining capacity of 50 MW large and 10 MW small solar PV.
The investment costs for this scenario would be in the order of 900 Mill USD based on the present market price of renewable energy technologies and corresponds to 3 USD/MW. In comparison the specific investment costs for a gas turbine plant is 0.3 USD/MW and for a coal steam plant 1.6 USD/MW.
We also recommend the implementation of a wind power monitoring programme in south Oman along the coast and in the mountains north of Salalah to verify and map wind energy resources. This programme should also include detailed grid analysis to determine the amount of wind turbines capacity that could be connected to the Salalah Power System (noting that for technical reasons wind turbine capacity should normally not exceed 15% to 20% of total system capacity).
We expect the wind monitoring programme to support the early implementation of a wind farm project: 10 MW Grid Connected Wind Farm; Purposes: Demonstrate the technology and obtain experience of operating the technology under Omani conditions. Technology: 10 MW Wind farm consisting of 5 x 2 MW wind turbines. Location: Dhofar, Thumrait/Quiroon Hariti area. Annual energy output: 25-30 GWh/year. Budget: USD 20 – 22 mill. (tentative). Energy production cost: 65 USD/MWh.
This project is potentially very significant, as it could provide the basis for a larger scale wind farm of between 500 to 750 MW (assuming interconnection of the Main Interconnected System and the Salalah Power System).
The total population of Oman is 2.6 mill including 0.7 mill non-nationals. Industrial development in Oman has traditionally focused on relatively smallscale manufacturing. However, with the discovery in the early 1990s of large deposits of non-associated natural gas, the focus of government efforts has shifted to attracting large investment in capital-intensive gas-based industries.
Solar energy is the sole renewable energy resource which presently is utilised in Oman. Solar energy is primarily used for house hold water heating by heating water in tanks located on the roofs at private houses. Solar energy is also utilised by the oil production industry (PDO). Electricity generation by Photovoltaic cells is used for powering small remote located equipment and solar energy is used for steam production which is used for extraction of oil from the oil fields in the dessert.
Oman’s economy is heavily reliant on oil and gas revenues, which account for about 84.2% in 2005 of the country’s export earnings and 48.8% of its gross domestic product (GDP). All of Oman’s domestic energy consumption is supplied by natural gas and oil, reflecting the country’s relative abundance of oil and natural gas reserves.
The assessment of the wind energy resources is based on the wind data measured at twenty one stations in Oman under the responsibility of DGCAM. The wind data is measured at 10 m above ground level. Five stations with the highest wind speeds (in 2005) were identified. For these stations the hourly wind speed data for 2006 was received from DGCAM. The annual mean wind speed in 2005 and in 2006 was almost identical.
The wind conditions at 80 m above ground level were estimated which is equal is to the hub height of a modern large wind turbine, having a capacity in the order of 2-3 MW. The calculation is based on the hourly wind speed data for 2006 received from DGCAM.
The high wind speeds are found along the coast from Masirah to Salalah. The highest wind speeds are in the Dhofar Mountain Chain north of Salalah. The low wind speed areas are in the north and western part of Oman.
The highest wind energy speeds are observed during the summer period. The summer period is also the period with the highest electricity demand in Oman.
Potential capacity for grid connected wind turbines
As a general rule based on experiences the maximum wind power capacity should not exceed approximately 15 % – 20 % of the existing conventional power capacity of the system in order to avoid disturbances in the power quality due to the fluctuating power generation by the wind turbines. In case of sufficient grid capacity a higher percentage of wind turbine capacity can be connected to the grid.
In Oman the future power system will have a total capacity of 5000 MW (2015) and the power system in the north and in the south will be interconnected. The technical future potential for installation of wind turbine capacity in Oman will be at least 750 MW.
Another technical limitation for installation of wind power capacity is the availability of open land without obstacles for erection of the wind turbines.
The space required for installation of wind farms with a total capacity of 750 MW is available in the mountains north of Salalah where the highest wind speeds in Oman are measured. Another possibility for installation of wind turbines is at Sur where the third highest wind energy resources are observed. The estimated required land area for a 750 MW wind farm is in the order of 100 km2 assuming 375 wind turbines with a capacity of 2 MW each.
The wind conditions at Thumrait and at Quiroon Hariti and a 2MW reference wind turbine with a hub height of 80 m has been used as a n example for estimation of the technical potential for electricity generation by wind turbines. The location at Masirah is not considered suitable for installation of large scale wind power capacity as the present power system is an isolated system and the energy consumption on the island is relatively small. In the power system connects to the main system via sea cables Masirah may be relevant for installation of wind turbines.
Joba and Sur could be potential sites for wind turbines, however the annual output at these locations is more than 25 % lower than at Quiroon Hariti.
The tentative estimated annual net energy output from a 2 MW wind turbine at Thumrait is 5820 MWh/year and at Quiroon Hariti the net output is 6470 MWh/year. If half of the capacity equal to 375 MW is installed at wind conditions corresponding to the wind conditions at Thumrait and the other half of the capacity is installed at wind conditions similar to the conditions at Quiroon Hariti the total annual net output of 750 MW wind turbine capacity will be in the order of 2300 GWh/year. This corresponds to 20 % of the total electricity generation in Oman in 2005.
Wind Energy cost varies according the wind speed at the site. The most efficient production site is Qairoon with average cost of 67.2 USD/MWh, while Joba is the most expensive production site with 88.7 USD/MWh.
The economic effects by replacing a minor part of the planned capacity by wind turbine capacity are illustrated by the following example. It is assumed that 40 MW wind power plant replaces 40 MW gas power plant.
The establishment of 40 MW wind farm will have the following main effects on the Omani power system:
-The electricity generation from the wind farm will reduce electricity generation (GWh) at other plants in the system, and thereby lead to decreased fuel costs, variable O&M costs, and emissions.
-The wind farm will contribute to the installed capacity in the system (MW). Due to wind speed variation the net capacity contribution by wind turbines is less than the installed capacity.
The system effects by a wind farm connected to a power system can be analysed by a system modelling tool (e.g. WASP), which can estimate the effects in the form of substituted electricity (MWh), and in the form of substituted capacity (MW) assuming that the level of security of supply is the same as in the basecase situation. The system effects can also be estimated from the base-case situation by doing some assumptions/considerations on what conventional units that may be substituted. The second approach is used for an evaluation of the system effect of establishing the wind farm in the power system.
It is assumed that the 40 MW installed wind power capacity can substitute 40 MW gas turbine capacity. In the calculation it is assumed that a 140 MW GT (natural gas fired) is replaced by a 100 MW GT and a 40 MW Wind Farm erected in the Quiroon and Thumrait areas. It is assumed that the wind farm can be ready for operation in 2011 and one of the 140 MW gas turbines in 2009 will be replaced by a 100 MW gas turbine and 40 MW wind farm.
It is furthermore assumed that the electricity generation from the wind farm substitutes the electricity generation from the planned gas turbine corresponding to the production by 40 MW. By this assumption the annual savings in fuel cost and variable O&M costs can be calculated.