Mauritius has seen significant hydro developments in recent years, but more use should be made of its hydro resources if it is to meet growing power demand, says I M Sahai

6 R UMAX PowerLook 3000 V1.6 [3]

Ferney power station

MAURITIUS is known the world over for its silvery beaches, coral reefs and clean air. Apart from the 1865km2 main isle, the country also comprises the isles of Rodrigues to the east, and Agalega to the north.

It gained political independence in the year 1968. However, electricity came to the country in 1899, with the commissioning of a 40kW turbine set at Reduit. In 1903, the first hydro station was made operational at Tamarind Falls in the west, with a 250kW turbine. The station, with a current installed capacity of 11MW, celebrated its centenary last year.

Since those early days, nine more hydro stations have been established (including two captive stations), giving Mauritius an aggregate installed hydroelectric capacity of about 60MW. In 2002, these generated around 85.60GWh of hydro (Table 1).

Hydro development began in 1903, when the first big hydro power station was established at Tamarind Falls. In 1906 private company General Electric Supply Co Ltd. (GES) was given the licence to run the electricity operations in the country. It took over the existing stations and set up new ones between 1906-1956.

In 1956, the newly-established Central Electricity Board (CEB) took over the ownership and operations of these stations, bringing the power-sector under the direct control of Government. Since then, CEB has also upgraded some of the existing stations. It established the 30MW Champagne hydroelectric station in 1984.

Hydro commands a mere 6% share of the total generation in the country. It is to go down further as greater reliance is placed on thermal sources (Table 2). CEB owns and operates four oil-fired stations in Mauritius and one in Rodrigues, with a total installed capacity of around 354MW. It also purchases power from 11 captive thermal stations owned by private sugar companies. Of these, three fired by bagasse/coal and having an installed capacity of 131.2MW operate all year. The other eight (82.6MW), operate only on bagasse and thus run during the sugar season. More thermal stations are being planned to meet the growing electricity demand.

Hydro operations

At present there are eight hydro stations owned and operated by CEB, with installed capacity ranging between 0.94MW–30MW. Four are dam-based, while the remaining are run-of-river. In addition, there are two privately-owned stations of capacities 100kW and 200kW, from which CEB buys power.

Champagne (30MW)

The Champagne hydro plant gets its water from Diamamouve dam, which was completed over Grande Riviere Sud Est in 1984, the same year in which the power station was commissioned. Water from the dam, which has a storage capacity of 4.3Mm3, is brought to the station by a 3km long tunnel and 80m long penstock, generating a gross head of 220m. The power house has two Francis turbines (600rpm) of 15MW each. Apart from being the newest hydro station, Champagne is also the largest, having more than half the total effective hydro capacity in the country.

Tamarind Falls (11MW)

The station was established with a 250kW turbine, way back in the year 1903, in the western part of the country. The dam has a capacity of 2.25Mm3. Its water is brought through two 1.4km long penstocks, generating a gross head of 290m. The power house operates four turbines, the two oldest being 2MW Turgo turbines installed in 1945-46. A 3MW Turgo turbine was installed in 1953, and a 4MW Pelton turbine in 1987.

Magenta (0.94MW)

Located near Tamarind, the dam-based Magenta station was established in 1960, with the installation of a Francis turbine of 0.94MW (600rpm).

Leval (4MW)

Commissioned in 1961, Leval is the fourth dam-based station. The station gets it water from Eau Bleue reservoir, which has a
storage capacity of 4.1Mm3. Two Turgo turbines of 2MW each (600rpm) at the power station utilise a gross head of 183m.

Reduit (1.2MW)

Established in 1906, Reduit’s last transformation was in 1984, when a Francis turbine of 1.2MW was installed to operate on a 50m gross head.

Ferney (10MW)

Located south of Champagne in the eastern region, Ferney operates two Francis turbines of 5MW each (600 rpm), which were installed in 1971. They utilise a gross head of 123m, from the waters of Riviere des Creoles.

Cascade Cecile (1MW)

Located in the southern highlands, Cascade Cecile utilises the water of Riviere des Anguilles, made available at 76m head, to operate a single Francis turbine installed in 1963.

La Ferme (1.2MW)

Established in 1959, La Ferme was revamped in 1988 with the installation of a Francis turbine of 1.2MW (1000 rpm), utilising a gross head of 127m.

Private hydro stations

Apart from the eight CEB-owned stations, there are two private stations, Riche en Eau (200kW) and Bois Cherie (100kW). They are presently selling power to CEB.

As the information above suggests, no new hydro stations have been established in the country since 1984. Even the repairs carried out on some stations were completed on an ad hoc basic, rather than as part of any prior comprehensive study of hydro potential.

Central Electricity Board

Following the pattern of other British colonies, a single public utility, owned and controlled by Government – the CEB – was introduced on 8 December 1952. From its introduction, it took over the assets of some of the power units being operated directly by Government. Over the next ten years, it acquired all the plants and power lines in the country, including those run by private companies (except the captive plants). It thus became a vertically-integrated company, owning and operating the various assets in the electric power sector.

After Mauritius gained independence from colonial rule in 1968, a national programme of rural electrification was progressively implemented, thereby increasing the coverage of the population and leading to enhanced power demand. By the end of 2003, CEB had 0.33M customers on its rolls, covering the entire country. Electricity sales had reached almost 1500GWh in 2002 and peak demand had risen to more than 320MW. CEB estimates that its sales would register a 6% growth, rising to 1990GWh by the year 2007, and by a further 4.1% to 2436GWh by 2012.

On the generation side, CEB by now owns an aggregate installed capacity of about 408MW, with an effective capacity of about 362MW. During 2002, CEB’s own generated supply was about 926GWh, with purchases of another 747GWh.CEB estimates that from the year 2006, it will need extra installed capacity and, over a seven-year period, around 228MW of such extra capacity will have to be put in place. Most of it would come from thermal sources – coal, oil, bagasse. Hydro and other renewable sources may make only marginal additions, depending on their techno-
economic feasibility.

Restructuring

In line with many developing countries, Mauritius has looked at the possibility of undertaking sectoral reforms. A study was initiated in 2000 by consultants led by Arthur Andersen. The report was submitted to the Government in 2002.

As mentioned in CEB’s Integrated Electricity Plan, 2003-12, ‘Government, after watching the extent of reforms elsewhere, has wisely recognised that Mauritius is neither ready for, nor in need of, large-scale electricity reform’, because of the small size of its power market. Instead, it has set out on a ‘cautious road to reform’, under which:

• CEB would continue as a vertically-integrated utility but would be corporatised as a Government company. Efficiency-improvement programmes would be initiated.

• An independent regulator would be appointed to oversee sectoral development and set tariffs for power (along with the water and wastewater sectors).

• Legislations for (a) and (b) above are likely to be passed by the National Assembly before mid-2004.

• Private participation would be actively encouraged in the generation sector, and ‘transparent and competitive’ processes would be undertaken to encourage this.

• There would be a gradual movement towards the practice of least-cost despatch based on the marginal cost of generation.

• Development, expansion and operation of the transmission and distribution network in the country would remain with CEB.

Hydro situation

Discussions with the concerned officers in CEB revealed that the negligible resort to hydro power in recent years has been due to a variety of reasons: limited water resources, competing demand from other usages such as irrigation and drinking water, high cost of development, lack of investment, and increasing use of thermal sources.

Mauritius has 25 major and 21 minor river-basins. Over the years 11 reservoirs have been constructed, four of which support power projects. Their aggregate capacity is about 93Mm3.

The country depends on annual rainfall, including the cyclones that often hit Mauritius during the summer season (December-March). Rains are needed both to fill the storages and recharge the groundwater. The average annual rainfall in the country is 21cm, ranging from 10.5cm in the west to 28.6cm in the Central plateau.

Due to the obvious limitations of water resources, the latter needs to be optimally utilised. No survey of hydro power potential has been carried out in recent years. On the basis of an evaluation in the 1980s, it was presumed that the country had utilised all its potential. However, it has been recognised that there is still scope at least for micro and mini-hydro schemes.

For example, the Midlands dam, inaugurated in March 2003, has been constructed primarily for irrigation of the water-scarce northern region (see IWP&DC December 2002, p.30). The dam has a height of 38.4m and a length of 88m, giving a storage capacity of 25.5Mm3. Its power potential, about 1MW as stated in the Integrated Plan, has not been developed. Another new dam, Bagatelle, being developed in the north, is also for non-power usage. The planning and construction of dams in the country is the responsibility of the Ministry of Public Utilities, which decides whether a dam is also to have a power component. CEB is only involved if the projected dam were to have a power unit. Extra hydroelectric capacity could also come out of modernisation and uprating of the existing stations.

In recent months, two significant developments have taken place on the hydro front. During the Mauritius Prime Minister’s visit to India in November 2003, a protocol was signed on the development of renewable energy in Mauritius. Earlier that year, an Indian team comprising officials of the Small Hydro Division of India’s Ministry of Non-Conventional Energy Sources, visited Mauritius and held talks about a possible Indian assistance in this regard.

Future plans

As the Integrated Electricity Plan of 2003-12 suggests, CEB intends to rely mostly on non-hydro sources to increase its generation capacity. However, the need to produce extra peaking power, the creation of new reservoirs and a greater stress on the environmental factors may induce Mauritius to take a second look at hydro, together with other sources of renewable energy.This could include:• ï„·A comprehensive study of the hydro potential in the country, using the various modern techniques. This could be funded by bilateral country assistance or multilateral credit.

• Preparation of detailed project reports for any new hydro sites.

• Fixation of an appropriate tariff structure, to act as an incentive to the prospective hydro IPPs.

• Uprating and refurbishment, on a planned basis, of existing hydro stations, owned both by the CEB and captive producers.

• Better coordination between the Water Resources Unit and the CEB (both of which come under Mauritius Ministry of Public Utilities), so that the competing needs of both irrigation and power could be given due consideration.


Author Info:

I M Sahai is an independent consultant in hydro power

Tables

Table 1
Table 2