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A novel modelling approach to the identification of optimum sites for the placement of OTEC power plant: application to the tropical island climate of Mauritius

The Small Island Developing State (SIDS) of Mauritius, situated near the subtropical latitude of the south-west Indian Ocean, benefits from a wealth of renewable energy resources. The necessity of developing the renewable energy sector in SIDS stems from the impediment brought by the reliance on imported fossil fuels to satisfy the energy needs of the population. The fluctuations of fossil fuel prices on the international market bears economic repercussions on the financial structure felt by the small island economies. The installation of innovative renewable energy technologies in the offshore region of the island can help in the energy transition towards greener alternatives. One such technology is the Ocean Thermal Energy Conversion (OTEC) system which operates on the principles governing the laws of thermodynamics. The ocean is the world’s largest solar collector, where tropical and subtropical regions possess high sea surface temperatures.

One of the priorities of the Government is to achieve self-sufficiency in terms of electricity generation, with a long-term target of attaining 35 % electricity generation from renewable energy systems by 2025. The benefits of promoting the OTEC project in Mauritius are numerous. Deep, cool water pumped to the surface may be used to cool buildings. Additionally, seawater pumped from depths of 1000 meters is rich in nutrients and when pumped to the surface, encourages the growth of algae. The latter in turn are food sources for other marine organisms higher up in the food chain, thereby providing a basis for commercial fish farming.

The MOI has investigated the most suitable region in the EEZ of Mauritius for the installation of an OTEC power plant. A model has been designed and implemented based on the underlying principle of thermal stratification of seawater, whereby the warm surface seawater has the tendency to rise above the colder, deeper seawater. About 2 billion of data values have been assimilated by the developed model and integrated in the proposed OTEC power generation model, which resulted in the production of GIS maps describing the distribution of OTEC resources around the island. From the maps, the appropriateness of the south-western region of the island is revealed and is attributed to higher sea surface temperatures and deep cold water availability at a proximity of less than 5 km from the coastline.

The installation of a 100 mega-watts OTEC power plant in the southern region of the country is believed to have the capacity to supply 20% of the electricity demand of Mauritius. A cost–benefit analysis performed suggests that cost estimates for setting up the farm is around $410 million, with annual operational and maintenance cost of about $6.15 million. Further analysis reveals that the initial cost of investment can be recovered within the first 7 years of the plant operation, while during the 30 years plant lifetime, profits of the order of about $1920 million can be generated. The project is, therefore, found to be profitable in the long run.

 

Seismicity around Mauritius and Rodrigues article published in l’Express Tuesday 6 March 2018  Read Article

 

MOI Exploiting Wave Energy Potential in Mauritius

Mauritius faces the common challenge of small islands developing states (SIDS) which comprise of a highly volatile economical structure, with heavy dependence on international markets to satisfy the energy needs of its population. About 85% of the total primary energy requirement of the island stems from imported fossil fuels, mostly from the Middle-East. With the objective of phasing out progressively the reliance on petroleum products and coal, the Government of Mauritius is encouraging the gradual penetration of renewable energy technologies in the electricity distribution network of the island. Consequently, a number of solar, wind and hydro-electricity schemes are being promoted by local authorities. In an attempt to sustain power system decarbonisation and improve energy security, a capital share has been allocated in the recent 2017 socio-economic budget of the island to increase grid absorption capacity from intermittent renewable energy resources.

Despite the vested interest of the Government in the promotion of sustainable energy development in Mauritius, wave energy technology is inexistent in the coastal and offshore waters of the tropical microcosm. A study undertaken by the Mauritius Oceanography Institute, reveals that the geographical location of the island near the Tropic of Capricorn ensures tremendous wave energy potential, which can be successfully converted into electricity through the deployment of wave energy converters. The research carried out highlights the favourable wave energy climate of the eastern region of Roches Noires for tapping into the less variable and high energy potential surface waves, as compared to western sites which are more variable with significantly lower wave energy potential for electricity generation. The optimum configurations of wave energy converters as well as maintenance operations that need to be carried out on wave energy farms in order not to disrupt the peak performance conditions for electricity production has been delved.

The attractiveness of wave energy as compared to other renewable energy sources such as solar and wind, lies in its predictability. The fluctuations in solar and wind energy harnessed are mainly attributed to the heterogeneity in the sky and surface wind conditions. The ability to forecast with better accuracy the electricity production from wave energy systems is of paramount importance to grid operators to better manage the electricity dispatch in the network of the island. Additionally, unlike solar which operates only in daylight hours, wave energy can be harnessed 24/7. A feasibility study carried out by the institute estimates that a 50 MW wave power plant constructed on about 200 square meters of open sea can contribute to a net electricity generation of 20 MW in the energy grid, representing about 4.3% of the peak power demand in 2016 in Mauritius. This would imply an eventual return of roughly about 2.4 billion MUR over a certain timeframe through savings in fossil fuel imports.

Our generation has the moral obligation to develop and integrate renewable energy technologies, especially considering the finiteness of fossil fuels and its implications on the environment through the effects of global warming and climate change. Wave energy appears to be the best choice, which would bring Mauritius to another level in terms of energetic requirements. As rightly said by James Cameron: “The nation that leads in renewable energy will be the nation that leads the world.”