Offshore wind energy has recently attracted some serious commercial attention from stakeholders in India with various positive developments in the sector. The ministry of new and renewable energy (MNRE) plan to establish a National Offshore Wind Energy Agency (NOWA) has uplifted the market sentiment and made the sector lucrative for investors. India has so far fared well on onshore wind energy front with installed capacity of over 19,000 MW and it occupies fifth position in the world after the US, Germany, China and Spain. With the first National Wind Energy Mission (NWEM) expected to be announced by mid 2014, India plans to achieve 100 GW of wind power by 2022. The Centre for Wind Energy Technology (CWET) has estimated India’s onshore wind potential at 102,778 MW at 80 meters height with 2 per cent land availability assumption.
Europe is the global leader in offshore wind installations with 4995 MW, followed by China (390 MW) and Japan (25 MW). Overall global installation has reached 5 GW and is expected to reach 80 GW by 2015. This growth is being fueled by strong R&D as well as deployment activities carried out by major turbine manufactures. These turbine companies have now recognized offshore wind generation as new potential growth market with tremendous opportunity. Subsequently, the high cost associated with offshore wind installations is expected to come down owing to technological progress and this shall help in sustaining healthy growth for the sector.
India has vast coastline running into approximately 7600 km, making it a preferred destination for offshore installations, in spite of wind speed being lower when compared to Europe. So far majority of work has been limited to preliminary investigative and resource assessment studies. These studies will be required to be conducted for two-three more years to arrive at some definite conclusion regarding wind speed and potential. Total offshore potential for India is expected to be around 350 GW. Preliminary studies suggest Tamil Nadu, Gujarat and Maharashtra as potential sites for offshore wind energy development. According to a study, the potential of Tamil Nadu alone is estimated to be 127 GW at 80 meters height but this estimation needs further validation. Preliminary assessment conducted by Scottish Development International in Tamil Nadu has found potential of 1 GW in north of Rameshwaram and 1 GW in south of Kanyakumari.
Government initiatives are providing the much required thrust to propel the sector towards commercial viability. However, a lot still remains to be done. Offshore Wind Energy Steering Committee (OWESC), being constituted to oversee policy framework and inter-agency coordination. A draft National offshore Wind Energy Policy has already been released last year. Through this policy MNRE aims to promote deployment of offshore wind farms up to 12 nautical miles from the coast where the sea is relatively shallow (territorial waters).
From a technical point of view, onshore and offshore wind turbines are based on the same technology and have similar operational life span of approximately 20 years. The rated capacity of offshore turbines is higher than that of onshore ones and is in the range of 3 MW-5 MW. Offshore wind farms witness higher power density and high plant load factor (PLF) compared to land. However the capital expenditure of offshore wind farms is almost 1.5-3 times than that of onshore farms. Development cost for offshore wind farms is $4.5 million to $5.5 million per MW. Nevertheless, there are several other factors associated with offshore wind farms that score over onshore ones.
Onshore wind farms are often opposed owing to their negative visual impact. Also, wind turbines tend to emit slight whirring noise which is said to affect humans as well as animals. Since offshore wind turbines are located far off the coast they do away with problems like noise and negative visual impact. Moreover, offshore wind turbines are not restricted by obstacles such as limited land availability, sanctions related to land use and other topographical restrictions affecting the wind speed. Offshore farms have the advantage of higher and more consistent wind speeds in absence of topographical hindrances and thus result in higher efficiency. Not to forget that land availability/acquisition has become a major roadblock for majority of infrastructure and power projects in India plus environmental clearances are becoming increasingly difficult for wind power projects. Industry is also witnessing technological shift towards development of very large turbines to achieve higher efficiency at lower wind speeds, and this is going to favour offshore wind installations.
There are also few challenges associated with offshore wind installations, high cost being one. Not only the turbine cost but the operational costs are also relatively higher in case of offshore wind farms. Offshore wind installations will require creation of robust support services, infrastructure such as specialized turbine installation vessels, under-sea electricity transmission and additional evacuation infrastructure at the coast. Hence harnessing territorial waters (shallow sea) in initial phases would be most prudent decision to save cost as well as time.
There has been some industry interest in offshore sector but nothing very recent. Oil and Natural gas Corporation (ONGC), announced its plans to enter offshore wind energy space way back in April 2009. The company set up its first 50 MW plant in Gujarat with initial investment of 600 crore in first phase and plans to tap offshore wind potential in big way. In another instance, Tata Power has submitted a formal request to the government of Gujarat for approval of an offshore project in the year 2010.
India should focus on setting few demonstration projects to gather reliable potential and wind speed data. Offshore masts must be erected in adequate numbers to measure wind speed data for two-three years and analyze seabed quality to support foundation of wind turbines. Thorough studies must be conducted to mitigate risks associated with natural calamities such as tsunami and cyclones. Results of these studies need to be carefully collaborated in order to validate wind speed, wind direction, sea temperature as well as resource assessment data.
Infraline Energy Renewable Knowledgebase Team