Mirza Teletović is undoubtedly Bosnia-Herzegovina’s most famous basketball player. He considered it a matter of honor to initiate and fund a project to utilize renewable energy in his home country.

Recently, at a cost of around €7.5 million, he built a small-scale hydropower plant on the River Doljanka – just one kilometer from Jablanica, the town in Central Bosnia in which he was born. In compliance with strict environmental provisions, using the very latest hydropower technology, the ecologically-friendly electricity plant was constructed in line with the latest criteria for hydropower ventures in Europe. Equipped with two differently-sized Francis turbines produced with the small hydro expertise of Voith Hydro, in a regular year the small hydropower plant will generate around 18.4 GWh of green electricity for this picturesque region of Central Bosnia.

Since the energy market was deregulated at the start of 2015 there has been notable activity in the field of renew­able energies in Bosnia-Herzegovina. Currently, renewable energy accounts for about 40 percent of gross end consumption, allow­ing favorable comparisons with most neighboring states. In general, this small Balkan country has a very good record in the production of electricity. The total power output of all electricity plants in the country is around 17 billion kWh, meaning it produces 143 percent of its own consumption requirements and – by definition – has achieved energy autarky. Bosnia and Herzegovina’s most important energy sources are coal and hydropower, although at present coal-sourced electricity accounts for around twice as much power as hydropower. Nevertheless, about one third of the electricity produced in Bosnia-Herzegovina comes from water power. According to official research, the potential would only be exhausted at around 40 percent. The industry organization IHA (International Hydropower Association) estimates the Balkan state’s hydropower potential to be around 8400 MW, so it can be assumed that hydropower will soon become the most important energy provider here.

Hydropower as an economic factor
Hydropower has long been a key force in the mountainous canton of Neretva; certainly since the mid-1950s when Yugoslavia’s then leader Josip Tito implemented the prestigious Jablanica hydroelectric power plant project, involving the construction of an 80 m high dam wall, the country’s second-largest to this day, less than 5 km from the town of Jablanica. The resultant Jablaničko jezero reservoir dams the water of the Doljanka upstream for around 30 km. Revenue from the 165 MW storage power plant remains a key source of economic wealth in Jablanica. However, this is not the scale of project Mirza Teletović has in mind. Having played in the NBA, the best basketball league in the world, the former world-class player has returned home to give something back, and is investing in infrastructural modernization. His intention is to provide decentralized, eco-friendly energy production in the region. In 2013, this culminated in the decision to build a small, modern hydropower plant on the Doljanka, a side arm of the Neretva in the tiny village of Zlate, just 1 km west of Jablanica – in the strictest compliance with all official environmental directives: “Projects of this kind must comply with environmental and water legislation. These two aspects oblige the investor to respect nature, both in the design and construction phases, and when the plant is in operation. The investor is obliged to calculate and adhere to a biological flow known as EPP – the amount of water that must remain in the river to allow the fish population to pass freely through the fish path and, in general, to implement all necessary measures in and around the river with the least possible environmental damage. Regular reports are written, flow data is recorded and submitted to the competent institutions to ensure any possibility of manipulation is minimized”, emphasized the project initiator who founded the operating company ECO-VAT for this purpose.

A long journey down a rocky road
Mirza Teletović recounts the long and arduous journey from the initial idea to the commissioning of the plant: “We have come a long way from the idea itself to obtaining a building permit. That trip lasted a whole 5 years. I came up with the idea in 2013 when I decided to start a company and invest in the BiH energy sector. Building just one such facility requires 7 or 8 different permits; post construction another 3 or 4. Each of these permits involves procedures that sometimes take several months. I have to admit this was quite unexpected for me, and sometimes even tiring. I knew I would have to be patient, but luckily, I had surrounded myself with experienced people who had already worked on several similar projects. These procedures really are long, but in the end, the most important thing is that the work is completed in accordance with all laws and regulations.” In 2018, all the official permits had been issued and construction work finally commenced.

Optimally tailored turbines
Ultimately, due in no small measure to ecological considerations, ECO-VAT chose to implement a conventional run-of-the-river power station, thus omitting any need to dam a local section of the Doljanka. Consequently, the turbines at the heart of the machine room needed to adapt continuously to the prevailing flow conditions. Voith Hydro’s project manager, Zijad Bajramovic (Dipl.-Ing.) noted: “This section of the Doljanka is subject to significant fluctuation in the volumes of water coming through, which had to be reflected in the versatility of the electrical machinery. The result was the choice of a classic 1/3 – 2/3 Francis spiral turbine solution.” Bettina Holzer, Bajramovic’s colleague from the Construction Design and Project Management departments, added: “The turbines were precisely tailored and tuned to the conditions on site, involving the selection of vertical versions to save space. Part of the turbine housing had to be set in concrete to best accommodate the weight of the generators mounted directly on top.” As well as providing the two turbines, Voith Hydro’s Lower Austrian center of excellence in the field of small-scale hydropower infrastructure was responsible for the connecting pipelines, slide valves and outlet pipe, hydraulic units and the cooling water system. Moreover, Voith Hydro’s scope of delivery also included the technical infrastructure for the sump pit. ECO-VAT issued the order to the Lower Austrian company, then still working under the Kössler banner, in 2018. Mirza Teletovic confirms he has never regretted doing so: “From the very beginning I was committed to purchasing only the very highest quality electromechanical equipment; so the choice of Kössler/Voith as our equipment supplier was a logical one. We are pleased with the collaboration so far, and with the cooperation and support Voith is providing. We hope the company continues to justify its reputation – and to convince us that we have made the right choice.”

Custom-designed solutions and expertise
The operators particularly emphasized the importance of the optimal adaption of machinery to the conditions and requirements on site, as was the case with the turbines’ guide vanes – so an off-the-peg solution was never under consideration. Bettina Holzer states: “The guide vane was definitely a non-standard solution. The unfavorable installation conditions on site demanded an answer that allowed installation and maintenance to be conducted on just one side. Ultimately, we managed to develop a solution that was both very practical and low-maintenance.” A further customized technical solution was required to accommodate the situational difficulties posed regarding installation of the slide valves integrated into the spirals. The bypass outlets in the spiral housing serve to reduce pressure, thus contributing significantly to stress reduction for the entire piping conduit system.

Simplified on-site assembly
The Voith Hydro team came up with some excellent responses to the difficulties posed by assembly and installation. The generator was pre-assembled along with the guide vane and runner at the works in Lower Austria. This meant only two large main components per turbine had to be installed on site. Installation required the building of a special lifting device to greatly simplify the task of assembly. Reducing the number of components to be installed ensured the assembly phase could be completed without any hitches. The commissioning work for the plant has been running smoothly since the end of last year, even though integrating the slide valves into the spiral housing proved a major challenge. A special water-driven valve is used to detect the increase in water pressure and activate the slide valve for water hammer reduction. Bettina Holzer recalls: “Ensuring the valve was optimally set up to harmonize with the machine ensemble required a great deal of skill and patience, but in the end our expert commissioning engineers implemented these final steps successfully.”

Ultra-modern hydraulic design
In total, the two new Voith Hydro Francis spiral turbines can accommodate a maximum flow volume of 5.5 m³/s. The smaller unit, also known as the ‘winter turbine’, was designed to process 1.5 m³/s and achieves a nominal output of 1,325 kW from a gross head of 96.30 m. ­ The larger one has an intake capacity of 4 m³/s with a nominal output of 3,540 kW. Working in combination, the two unique turbines generate a maximum reserve output of 4.5 MW. The high efficiency of the machines is due in no small degree to the modern design of the hydraulics. The hydraulic contours of the turbine runner wheels are based on models tested at the Voith Hydro Brunnenmühle research center. In the first weeks of operation it became clear the machine’s performance curve corresponded completely with the guarantees, as did the agreed pressure and rpm levels. Zijad Bajramovic explained: “The customer was concerned about the vibrations such machinery can generate, so we had vibration readings taken by external specialists – all of which were more than satisfactory in this regard.”

Inspirational flagship project
Mirza Teletović has every right to be pleased with achievements so far and has expressed his appreciation for the constructive cooperation with the authorities and all partners involved. He has often emphasized that reaching a consensus was the main objective from the very beginning: “The most important topic for us was ensuring everything complied with all envisageable legal requirements. I can’t stress this often enough. I want to do the right thing for my fellow citizens. I’m only in this to help – and improve things.” The new Zlate power plant in Bosnia-Herzegovina has been commissioned at the beginning of February. The plant is now in regular operation and is expected to supply the grid with around 18.4 GWh of green electricity in an average year. So, as the first EKO-VAT plant is now in operation, the new energy business is already working on a second station – currently in the approval phase. Mirza Teletović explains: “We are working simultaneously on another project called SHPP Pačići, another smaller-scope run-of-river SHPP to operate on the same river, several kilometers upstream. Applications for construction permits are now being inspected for a project that has a planned installed capacity of 1.4 MW and an annual production output of just over 6 GWh.”