Malawi: Aquatic Weeds and Silt Lead to Power Deficiency

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George Mhango
May 18, 2012

Two things are clear in Malawi, especially at night: blackouts and the sound of generators in various workplaces. Power interruptions continue to affect both private and public sectors including people. These blackouts are also attributed to effects of weeds and silt.

Latest findings by Malawi Business Climate Survey (MBCS) cuts in power transmission have contributed to losses beyond the minimum acceptable level of seven percent.

The growth of water weeds has a significant impact on rivers and hydropower generation in many countries in Africa

The Millennium Challenge Account-Malawi (MCA-M) estimates that the country is losing 215.6 million dollars a year due to the power outages.

With transmission and distribution losses pegged at about 20 percent, according to Escom, the Consumers Association of Malawi says poor Malawians bear the cost of losses through hiked tariffs.

Tedzani Hydro Power Station is one of the affected apart from Nkula and Kapichira.

Visits to Tedzani which generates close to 90 megawatts of power proved that in recent years there has been a dramatic increase in the onset of floating aquatic weeds on the river so much so that electricity generation has been greatly affected especially during the rainy seasons.

However, the intake was previously provided with a course-screen that runs across the pond to catch and divert any oncoming trash and weeds. The equipment suffered damage at its base foundations and some screens got washed away during the 2001 similar operation.

For Escom power stations operated without any major environmental problems until 1990s when there was an increase of floating aquatic weeds and debris in addition to silt deposition at the intake ponds.

Knowing that they already use equipment to deal with weeds and silt, Escom officials think it is high time they engaged communities in sensitization meetings at Tedzani so they stop cultivating along the river banks.

Public relations manager, Kitty Chingota confirmed this to media practitioners during a recent tour to the site that communities are crucial since farming along the river has side effects on their head-ponds.

“Soils that are being eroded are full of soil nutrients, in addition to this, almost all farmers use artificial fertilizers which are eroded together with top soils before finding their way into the river,” she says.

The awareness is expected to involve the agricultural officials and the forestry department.

Shire River Bridge, Mangochi Malawi

In a paper presented during the International Conference on Hydro Power in Malawi held in Sri Lanka three years ago, Escom officials alluded that when these soils and their nutrients are deposited into the river they provide necessary nutrients to the aquatic plants and they then grow and multiply.

The paper states that the weeds among others comprise of water hyacinth (eichhornia crassipes) known as Namasupuni, Red water fern (Salvinia molesta), water lettuce (Pistia stratiotes) and elephant grass

Engineers say that as aquatic weeds float, the river currents then cuts them off from the main firm grounds of the river banks and they are carried away downstream which affects power generation.

She states that Escom’s priority is to ensure that Malawians have power hence the decision to work on the machines. “Silt and aquatic weeds are a major threat to power generation because most of the equipment cannot pump water as a result of the two problems,” says Chingota.

Rex Muhome, head of Tedzani Hydro Power Station shares his input saying that through flooding, crops are washed away and as such weeds are emptied into the river while forming silt.

During the tour it was observed that the screens are cleaned by trash rakes but at certain instances the trash rakes have been overcome by the inflow of the weeds so much so that the whole power station could be shut down to allow for the weeds to be cleared out at the intake.

It is against this background that during the Easter Holiday, Escom repairs equipment from the head-ponds. “We lose revenue once we halt operations but such repair works on Easter Holidays are crucial to us as Escom. Just this year, we first closed Tedzani on Friday and Sunday and then Nkula later to ensure that most parts still have power,” said Chingota.

Muhome, head of the power station hints that the shutting of production at the site is routine considering that on the Easter Holiday, not many companies are in production.

“In this project of maintaining and removing weeds and silt we always target all Hydro Power Stations but in phase. However, communities have got to be sensitised having observed serious repercussions on our machines,” Muhome says.

He says the civic education for communities not to cultivate along the river banks is likely to start soon. “We are working on modalities for the whole project for it to be a success,” Muhome says.

Such decisions by Escom to involve communities would ensure that power generations projections by the (MCA-M) for 2010, 2015 and 2020 estimated at 408MW, 603MW and 829MW are achieved inclusive of new power plants establishments.

Statistics by the power utility company and economists vindicate that the concealed demand for power in Malawi for about 180 000 clients is about 300MW. However, the available power generation capacity as at now is 266MW not in line with the overgrowing demand of power.

Up to 98 percent of electricity is obtained from power plants located on the Shire River in Chikhwawa South of Malawi, except for Wovwe mini hydro plant in Karonga situated. Escom authorities point out that the country’s hydro potential is estimated at over 1,000MW.

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