Autor: Roland Gruber , 22.06.2016

The charitable work of the Benedictine Sisters of St. Agnes in Tanzania had made a big impression on hydropower plant operator and private investor Albert Koch.

In fact, he was so impressed that a couple of years ago he decided to support the Sisters. He initiated a new and modern hydropower plant in the little developed, rural region of Ruvuma in the Southwest of the country and set up the financial plan. In cooperation with experienced hydropower companies, such as the Austrian  hydropower specialist Kössler and the Swiss planning agency AF-ITECO, a high-capacity run-of-the-river power plant was created along the Ruvuma River near the village of Tulila. The plant has a capacity of 5 MW, but is expandable to up to 7.5 MW. It will not only replace numerous diesel generators and secure the electricity supply of the remote region, but will also guarantee a solid and sustainable economic basis for the charity work of the Benedictine Sisters in the long run.

The electricity supply in the East African state of Tanzania is far from offering nation-wide coverage. However, the last 10 years have seen rapid developments that give hope for new progress. A study by diploma engineer Christian Matyelele Msyani shows that in 2003 only 10 percent of the population had access to electricity, but by 2013 the number had already increased to about 20 percent. What the numbers do not show is how the situation changed in the remote parts of the country, far away from the cities. Individual, decentralized plants are the most important sources of electricity in places where electricity supplier Tanesco has not yet established any subsidiaries. One of these regions with insufficient electricity supply is Ruvuma in the Southwest. The region has 66,000 km², which is about the size of Latvia, and is home to about 1.35 million people. Of Tanzania's 30 regions Ruvuma ranks third-lowest for population density. The border with Mozambique in the South runs along the river that has given the region its name.

Ruvuma is the home of the Benedictine Sisters of St. Agnes of the Chipole Convent (“BSSA Convent”). The Order, founded in 1938, is dedicated to the gratuitous support of the locals. Today it has about 370 Sisters, who tend to the health, schooling and education of the local children and operate orphanages and hospitals, to name just a few of their charitable activities. More than ten years ago, the Order received a helping hand from a distant region, Schwyz. Robert Fuchs, from Schindellegi, Switzerland, and his foundation built a small-scale power plant with an output of 400 kW in order to ensure clean electricity for the convent. The plant still serves this purpose today. Until recently, however, the Sisters did not have the possibility to use more than half of the plant's potential. But progress would not stop there and the far-away Swiss canton of Schwyz would again assist in the development. “I knew Mr. Fuchs personally and after his passing, his daughter Mrs. Stockmayer-Fuchs approached me. As the head of the Robert Fuchs Foundation, she asked me to look after the power plant in Chipole and find solutions on how to best use the full potential of the site,” says Albert Koch, who already had decades of experience in the hydropower field. “I sat down and prepared well before traveling to Tanzania half a year later. I had some ideas for galvanization works, mills, juicers and the production of cans in mind. However, when I arrived in the bush, I realized quickly that it was all out of the question: distances were too great, roads were in very bad conditions and, worst of all, there were no potential buyers who would be able to spend money on the goods.” While Albert Koch had been in Switzerland contemplating possible solutions, the Sisters of the Convent had launched their own initiative and had purchased a corn mill in the meantime. From now on the electricity could be used entirely.

When Albert Koch arrived in Chipole he saw the enormous charitable commitment of the Benedictine Sisters. Institutions worked smoothly and about 2000 students were perfectly taken care of. Furthermore he was impressed by the humble and economical way the Sisters lived. That was when he decided to support their cause. “I asked the Prioress if we could obtain further water rights from the state, if we needed them. Her answer was that that would be no problem at all. So we looked for a suitable site,” the entrepreneur from Schwyz recalls. A jeep brought Albert Koch and his ecclesiastical partners to the heads of the villages or their representatives in preselected potential areas. However, the first day ended disappointingly, as the ideal site for a plant had not been found. “Two days later we left again early in the morning for another ex pedition. When we approached the Tulila area we could hear the distant sound of rushing water. To me it was clear: it's here or nowhere,” Albert Koch says. It was the right place and all arrangements regarding water rights, purchase of land, electricity consumers and various licenses were made. “We were lucky that at that time the state-owned electricity supplier Tanesco had planned to issue an agreement to purchase electricity from external power plants for the main grid. That facilitated the whole matter.” For the next 15 years Tanesco will pay a reimbursement for the feeding-in to the amount of 26 US cents per kWh.

After Koch had returned home to Switzerland he began with the construction project, setting up a plan and the financial strategy of the project. The costs were estimated at about 30 million US dollars. The entrepreneur took care of one third of the costs with his own capital, another part was met by the foundation and the rest came from a loan financed by Credit Suisse Bank covered by Swiss Export Risk Insurance SERV. “At the beginning of August 2014 the funding of the project was secured. Until then I had to pay for all costs personally,” adds Albert Koch, who seems to have taken quite a big entrepreneurial risk. The Swiss entrepreneur, who says of himself that he is “infected with the hydropower virus”, is without a question the “father of the powerplant project”. Where there is a “father” there must be a “mother”: Yoela, a very active Sister, devoted all her energy to the realization of the project. “Sister Yoela dedicated all her time to the hydropower project. Today everyone, every institution, every board knows her. She has connections to the highest positions, even to the CEOs of Tanesco and EWURA,” says Albert Koch.

By early 2013 all licenses for the hydropower project had been obtained and the venture could begin. Construction camps and accommodations were set up, a freshwater system was installed and the construction works began. The project was conceived as a run-of-the-river power plant with a combination of an earth-filled dam and a weir. A constant reservoir filling during operation guarantees a reservoir surface of 0.75 km². The area around Tulila is sparsely populated and the backwater has only a minor impact on the settlement area and the local agriculture. The depth of the water at the inlet channel is 7.5 m, resulting in a gross head of 22.40 m, whereas the flow rate is 40 m³/s. The weir and dam systems are designed to withstand a one-thousand-year flood. The process water channel consists of two separate 190-meters-long process water penstocks of the sizes DN2300 and DN2500. The penstocks were chosen in two different dimensions in order to transport one inside the other. In this way the transport costs could be diminished by half. The two penstocks have been installed and a third penstock is planned to be built in as soon as the third machine unit is placed. At the moment two identical double regulated Kaplan turbines from Lower-Austrian hydropower specialist Kössler are in operation in the power house. The two units have a total output of 5 MW. Including the planned third machine unit, the hydropower plant will bring forth an installed capacity of 7.5 MW. Having passed the turbines the process water will be diverted again into the Ruvuma River through a 100-meters-long side channel.

The barrage consists of one non-homogenous earth-filled dam on each side of the river, wing walls between the earth-filled dams and the weir, as well as a fixed weir with 15 identical round-crested overflow sections, which are separated by pillars supporting the concrete bridge above the weir. Furthermore it has one inlet structure including three inlet chambers as well as two bottom outlets identical in construction. The total breadth of the weir plant is 111 m, with weir openings of 6 m each. The concrete building of the power house was erected on solid rock. It houses the turbines, the generators, the control system, the transformers, the medium voltage electric power distribution system, an indoor crane, the drainage system, an emergency power system, as well as the control, supervision and communication equipment. To deliver the electricity to the customers in Songea, the capital of this region, a 90-kilometers-long overhead power line was built.

Basically, the power plant and its entire components correlate with the high European standards. During the realization of the pro ject, however, the people involved had to face some major challenges. Diploma engineer Lothar Groschke of AF-ITECO AG was the manager of the project and was there during the entire construction phase to set the conditions for the operation and to assure a smooth progress. He says: “We had only a limited choice of special products with the building material available, so we had to rearrange some construction works and their sequences. We had to work without any armoring and standard joint armor systems and we constructed the weir with cyclopean concrete because of the construction material available on site.” An important factor was the communication, which wasn't always easy, “First we had to explain the facts to the Sisters in English, but in a way that even people who were no experts on construction would understand. Then the explanation was translated from English into Swahili. The construction entrepreneur, who spoke Swahili rather poorly, then translated the things that he understood into Chinese. Some parts were lost in the translation and it happened quite often that we spoke about two completely different things. We managed by drawing drafts on the ground and gesticulating,” construction manager Åke Aurebekk explains the art of communication.

The access road to the construction site had already existed. The state of the district roads was quite acceptable. It was only necessary to improve the shape, breadth and drainage of the dirt road towards the construction site and make it an all-weather road to guarantee access also during the rainy season. The equipment for the electromechanics by Kössler (Austria), the electrical equipment and control systems by Schubert Elektroanlagen (Austria), the hydraulic steel engineering by Fäh Anlagen- und Maschinenbau (Switzerland) and the penstocks by APR Schweiz were imported from Europe. The Sisters of the Chipole Convent organized the complex transport from Dar es Salaam Port to the construction site. The exposed position of the construction site was a big challenge, says Karl Henninger, project manager of Kössler: “The arrival of people as well as the transport of goods had to be arranged in different stages. All parts were shipped from Hamburg to Dar es Salaam, where they were transported by truck onto the construction site in the Southwest of Tanzania. The installation team also traveled to Dar es Salaam and from there by plane to Songea and from there by Jeep to the site.” Another important aspect of the transport is that the single parts were delivered in various “lots”, to keep the outside storage periods short and guarantee a smooth installation schedule.

The order from summer 2013 wasn't the first order from this part of the world for the hydropower specialist from Lower Austria. Kössler had pursued business in the Sub-Saharan region for many years before. The renowned turbine manufacturer had already equipped power plants in Tanzania, Rwanda and Cameroon. Even the machine unit of the existing plant of the Benedictine Sisters had originally been delivered from the far-away village of St. Georgen, Lower Austria. The unit has been operating reliably for the Sisters of the Chipole Convent for more than a decade now. The entire order for Kössler comprised the two turbine and generator units, the entire electrotechnical equipment consisting of a very complex control system, the indoor crane as well as the connecting pipes to the penstock. The two vertical Z-Kaplan turbines have a runner diameter of 1600 mm and are designed for a net head of 21.70 m and a design flow of 13.30 m³/s. The nominal output of the two turbines is 2581 kW. A special axial arrangement and the specific type of turbine make them perfectly suitable for the conditions of the Tulila site. In general, Kössler turbines are known for their high degree of efficiency through a most modern design and a high overall quality, which guarantees a longer life.

The first delivery of the turbines from Lower Austria to their distant destination, Tanzania,took place at the end of September 2014. One month later the second machine unit would follow. “We started with the installation in January 2015. Again and again small constructional delays led to minor interruptions, but all in all the work continued consistently. The commissioning was executed in two stages: at the end of August and at the beginning of September last year the required dry runs were carried out. In order to connect the plant faster to the grid and start making money off it sooner we decided to put the weir into partial operation. The operation of the entire weir was launched in January this year. All remaining works were carried out after the commissioning of the entire plant, such as building the bridge above the dam.” An essential aspect regarding the operation requirements of the power plant is its capacity for isolated operation. “We had to clarify various details with the state-owned Tanesco beforehand, because for now the plant runs in isolated operation. That is also the reason why we obtained the higher feed-in tariff of 26 US cents per kW. It will sink to one third of the current tariff as soon as the national 132 kV power line reaches the Ruvuma Region and electricity is fed into the state grid. At the moment Tanesco is planning a 300-kilometers-long power line from Makambako to Songea, the capital of Ruvuma,” says Christian Strupp, section head of Hydro at AF-ITECO.

Even on the technical side the isolated operation was a core aspect of the project. The two machine units are responsible for supplying the wide-spread “island”-like grid of the rural surroundings all the way to the city of Songea, a power grid marked by constant oscillations and outages. Kössler's biggest challenge was to make the turbines run in outage situations and keep them going at minimum performance until the grid would be reestablished. “Our constructing engineers have managed to enable the difficult isolated operation by using enormous mechanical centrifugal masses, a very complex control system and an electronic load controller,” says Karl Henninger. He admits that there were enough challenges to be overcome. These could not have been managed without the constructive and respectful teamwork of the building owners, planners and the executing company. The technician from Lower Austria adds that the Europeans were very well taken care of: “It was very nice to have such a beautiful construction camp. The Sisters of the Convent provided the best food and accommodation.” The Benedictine Sisters from Chipole are to a great extent responsible for the success of the project. They were in charge of import and customs formalities, as well as logistical coordination. They even conducted blasting operations as one of the Sisters is a trained explosives engineer. The Sisters were supported by initiator and project sponsor Albert Koch, who supervised the construction progress the entire time, and by the planners of AF-ITECO, who assisted in the many negotiations on various concessions. The planning agency was also involved in the financial talks with banks and in the surveillance of the construction costs.

The top priority of the project was an environmentally friendly realization. From the first outlines of the project Albert Koch and the Benedictine Sisters of Chipole constituted that the construction would not have any negative consequences on the environment. For this reason an unchanging amount of residual flow on various places of the dam structure is being discharged. The total guaranteed flow is 465 l/s minimum; in the rainy season, which runs from July to December, the amount is augmented to 930 l/s minimum. At the moment the power plant - in its first expansion stage - operates two Kössler Kaplan turbines producing a total average output of 36 GWh a year. This number, however, exceeds the grid demand of 20 GWh enormously. This is the reason why the third machine unit has not yet been installed. The unit will be placed as soon as the electricity demand increases. In its final stage the Tulila hydropower plant will have an average output of 44.5 GWh a year.

Until only recently the needed electricity was produced by diesel generators in the power center in the capital city of Songea. They have been taken off the grid one after the other. This means cost savings for the consumers and a striking ecological improvement for the climate. An incredible 36,000 tons of harmful CO2 are being saved with this method. Another important fact is that the degree of electricity available for this remote region with its 300,000 to 400,000 inhabitants will be increased. Until now only 5 percent of all households in the Ruvuma Region were connected to the power grid. The new Tulila power plant will help households without power receive clean hydropower electricity – an aspect crucial to the development of the region. The new power plant is a huge gain for the proactive Sisters of Chipole, as the better part of its proceeds will be dedicated to social and charitable endeavors. As soon as the credit capital is repaid the ownership of the hydropower plant will be passed over to the BSSA Convent. The initiator of the project Albert Koch can now take stock. He achieved his goal to set a long-term economic basis for the Benedictine Sisters' further projects with flying colors. However, this doesn't mean that the Swiss entrepreneur will now sit back. He is already focused on a new hydropower plant project. The new undertaking will help yet another convent. He still sees great potential in combining hydropower and development aid in Africa.

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Two penstocks with a length of 190 m were installed from the water catchment to the power house.

photo credits: Kössler



A Swiss hydropower investor has realized a new run-of-the-river power plant in the far Southwest of Tanzania. In its first expansion stage the Tulila power plant will deliver an average of about 36 GWh per year to the remote region.

photo credits: Kössler



The power house consists of a reinforced concrete frame structure filled with bricks and concrete blocks to achieve good ventilation. The processed water is being diverted back into the Ruvuma River through a 15-meters-wide discharge channel.

photo credits: Kössler



The exposed position of the construction site was a big challenge for all workers involved.

photo credits: Kössler



“Blasting Sister” Sistahili instructs the local construction workers on how to fill the blasting holes correctly.

photo credits: AF-Iteco



The dam was realized in two non-homogenous earth-filled dams. The wing walls were designed as retaining walls with a reinforced concrete structure.

photo credits: Kössler



The weir was constructed using quarry stone masonry and cyclopean concrete. The earth-filled dam consists of a carrier core permeable to only a little water and a waterproof core. It was built in layers, each of which was sealed separately.

photo credits: Kössler



The Sisters of the Chipole Convent took on a significant position in realizing the construction of the power plant. Sister Yoela (third from left), especially, was fully committed to the project. The initiator of the project Albert Koch (second from right) made most of the  arrangements for the hydropower project on his own.

photo credits: Kössler



In its first expansion stage two machine units were installed. The two Z-Kaplan turbines from Kössler have a nominal output of 5 MW.

photo credits: Kössler



The new machine unit was inaugurated by the Benedictine Sisters.

photo credits: Kössler