Austrian hydropower technology masters all challenges in Transcaucasia

Autor: Roland Gruber , 23.09.2019

Two powerful new diversion-type hydropower plants have been built along the Mestiachala river in the well-known Svaneti ­region of Georgia for a total investment volume of around 65 million US dollars.

The two-plant joint venture, financed by the Georgia Capital Group and Austria’s RP Global Investment, has now almost been completed. The consortium put together a team of expert businesses to ensure optimum implementation throughout the entire project. The Austrian hydropower specialists at Kössler were selected for their expertise in turbine technology. In addition, the know-how of the people at the Braun Maschinenfabrik, also an Austrian company, was brought on board for hydropower steel infrastructure engineering. Shortly, both plants will be going online and are expected to feed 176 GWh of clean power into the Georgian electricity grid on an annual basis.

In order to reduce dependence on foreign energy imports the government of Georgia decided to take advantage of one of the country’s greatest natural assets – water power. Today, Georgia’s water power provides around 80% of all the electricity consumed in the country. At the end of 2015 the country in the Caucasus region boasted around 70 hydroelectric power stations with a total operative power output of 2730 MW. The area’s mountainous topography and abundance of water makes Georgia a typical hydropower country. There are, of course, disadvantages associated. Although excess electricity can be sold to neighbouring countries in the summer months, low water levels in the winter mean the country is still dependant upon foreign fossil-fuel energy. Georgia has been investing time and money in the expansion of its hydropower resources for several years in order to improve the country’s degree of self-sufficiency. After 2004, a new political course was set, which now also permits foreign investment in the expansion of hydropower infrastructure in the Caucasus. The double-plant project, Mestiachala 1 & 2, upon which work commenced in the summer of 2017, is a perfect example of this – Mestiachala 2 is already in operation, Mestiachala 1 will follow soon.

Strategic expansion of hydropower
At the ground breaking ceremony at the beginning of July 2017, Georgia’s Energy Minister Kakha Kaladze announced: “This is another step along the road to energy self-sufficiency”. In the speech he also spoke of the expansion of local infrastructure and the creation of jobs on the power plant site for the people in the region. The project was developed by Svaneti Hydro, a Georgia Capital Group joint venture holding 65% of the shares - and RP Global Investment, in possession of the remaining 35%. The Georgia Capital Group is an investment platform trading on the London Stock Exchange. RP Global Investment is an international strategic investor, project developer and operator from Austria with over 30 years of experience in renewable energy. The two partners have worked out a strategic approach to increase the use of regenerative energy sources in Georgia. Around 500 MW should be accounted for by solar, wind and hydropower. The joint venture acquired the requisite water rights for the double-plant project in an international call for bids. In 2014 and 2015 a declaration of intent was signed with the Georgian government for the implementation of each of the hydropower projects in the Svaneti region. “We received a great  deal of assistance from the Georgian Ministry of Energy, underlining their commitment to the expansion of Georgia’s immense energy production potential”, explained Gerhard Matzinger, CEO of RP Global.

50 MW from 5 turbines
Specifically, the two power plants, Mestiachala 1 & 2, are diversion type stations on the Mestiachala river in the Mestia area. The 207m (+/-) net head will be exploited by two identical 6-nozzled Pelton turbines at the Mestiachala 1 plant. Both have been set up for a flow rate of 6 m³/s and provide a bottleneck capacity of about 23.7 MW. The net head at the Mestiachala 2 station is very similar at 231m. However, the additional water collection channel along the Chalaati river allows the system to take in an extra 6m³/s of flowing water. This enables the three Pelton turbines, each designed for 6m³/s of flow rate, to achieve an overall bottleneck capacity of around 30 MW. In total, the two plants utilize three collection channels, two compensation basins and two power houses. The pipeline system is particularly impressive. Steel pipes were laid along a 1900m above-ground channel and the underground infrastructure required the deployment of 3800m of GRP pipes, plus 3460m of steel piping - for a total piping distance of 7260m.

Challenging delivery deadline
Kössler is a renowned Austrian hydropower technology manufacturer and had already supplied turbines for a Georgian hydroelectric power station, thus being a logical choice as a supplier of electromechanical equipment. The delivery contract was signed for the turbines, the generators, the entire electrotechnical infrastructure, and the medium-voltage system in June 2017. To ensure the electrical technology was installed flawlessly, Kössler chose a proven project partner in Schubert Elektroanlagen. The generators were provided by Nidec/Leroy Somer. The notable similarity of the operating conditions made it possible to send 5 identical turbine sets to the South Caucasus. The scheduling was extremely ambitious, as Kössler’s responsible area sales manager Karl Henninger confirms: “The delivery deadline posed a great challenge. However, flooding and an extreme winter caused con- struction delays that forced the restrictive timetable to be revised slightly.” The turbine housing, the corresponding distribution piping and the closing devices all left the Kössler works in Lower Austria last June. In total, delivery of all the parts to the power station site in the South Caucasus required 52 heavy good vehicle trips. A bottleneck on the road to Mestia and a 60-ton weight limit on a bridge ahead of the site made it necessary to split up the turbine housings and dismantle the generators for the drive, and to reassemble everything on site. “Because we had already inspected the access routes before compiling our bid, we were aware of – and accounted for – the requisite measures very early on. Resultantly, the actual transportation of infrastructure was completed without any major restrictions”, reported Karl Henninger. Assembly work also went smoothly and was completed according to schedule, not least due to the excellent cooperation with the other companies on site.

Robust and efficient
In technical terms there was no need to customise any of the 5 turbines. In principle, since Kössler turbines meet very high technical standards in general, they already fulfil all the requirements placed on modern hydropower operations. “The size of the plant and the weight of the generator made it necessary to build turbines with interior-facing nozzles and to use concrete-embedded distribution pipelines. This also provides better protection from earthquakes; something that can never be ruled out in the Caucuses”, argued Karl Henninger. Kössler turbines are known for their robustness and excellent efficiency. The latter can be attributed in no small measure to the close cooperation enjoyed with the parent company Voith Hydro, and the provision of continually enhanced, ultra-modern runner designs. Kössler’s runners are considered to be among the most sophisticated designs on the market.

250 tons of steel components
Of course, a hydropower project of this magnitude is heavily reliant on robust steel infrastructure. Braun Maschinenfabrik was chosen by the responsible decision-makers as a company that has had a good reputation within the industry for producing supreme quality steel waterwork structures for decades – all over the world. “We were awarded the contract in July 2016 and completed the final designs for all of the components between autumn 2016 and May 2017. We produced all of the components at our workshop within about a year up to last April”, recounted Michael Habring, the Braun Maschinenfabrik project manager. In total, the Vöcklabruck company provided the entire package of mechanical steel structure for the three weir plants, the two storage basins and the powerhouses, including all the hydraulics, electrics and controls. Overall 250 tons of steel structure were sent from Upper Austria to the South Caucasus region. Habring explained: “Around 20 heavy good vehicles made the long trip of around 3300km in total.” The first consignment arrived in June 2017 and altogether included around 15 tons of anchor plates for the two power plants. Subsequently, the steel infrastructure components for the power plant construction site were all delivered last July.

All-inclusive customised solutions
Braun Maschinenfabrik’s scope of delivery was considerable. As well as the 19m-broad weir gates for both water collection channels on the Mestiachala river, the contract also included an additional steel weir gate with a width of 10.5 m on the Chalaati river. It also comprised several sections of stop log fortification, bottom outlets, three large debris rakes for the three channels, and a fine debris rake for each of the storage basins. Braun Maschinenfabrik also fitted each compensation basin with a deicing system and with a cable rake cleaning machine for the grate. Because they are so efficient at cleaning deep water fine-debris rakes, these machines have set the standards for decades and enjoy an excellent reputation. The steel infrastructure package for the weirs was rounded off by supplying the hydraulics, the corresponding electrotechnology and the control units. What makes Braun’s hydro-plant steel engineering so special is the fact that it is the product of immense know-how, and often involves custom-built solutions for specific requirements. Instead of installing conventional intake regulation gates to control flow to the intermediate storage basin, special gates were mounted for both power plants on the Mestiachala river. “The advantage is that they can be closed by a counterweight and protect the storage basin from flooding. If there’s a power outage the gates close automatically, without an external power supply”, explained Braun’s project manager.

Backwater gates halved for transport
Last autumn the main components were installed, such as 19m x 3m weir gates, under the supervision of Braun Maschinenfabrik. The gates were cut down the middle for transportation, due to the lack of space on site, and were re-welded after installation. “We began the overall installation process in July 2018. A number of schedule changes led to some small delays. Nevertheless, we were able to complete the project on time”, stated Habring. The entire fortification and protective side plates were installed before the onset of winter – as were the hydraulics and control infrastructure in the late autumn. To this end a second specialist installation engineer was sent from Vöcklabruck to Mestia to complete the electrics and prepare the infrastructure for commissioning. The weir systems were successfully pre-commissioned at the end of November.

Contract showcase in Georgia
Not only does this contract in the north-western part of Georgia provide proof of the expertise Braun Maschinenfabrik can offer on an international level, it is also the company’s first order from this Caucasian country. The responsible executives for the Upper Austrian specialists are justifiably proud that this hydropower project was an excellent opportunity to put on a broad-based showcase of the company’s immense expertise and consummate quality. Georgia is still considered an emerging market in the hydroelectric industry. Both power plants are connected to the grid already, and with a potential power output of 176 GWh they can be expected to make a significant contribution to Georgia’s energy production strategy. It is understandable that a project of this scale was of great importance, even to established hydropower specialists like Kössler. The Lower Austrian company had already provided turbines for two Georgian power plants, Gudauri in 2012 and Aragvi 2 in 2018, and has now installed a total of 8 turbines in Georgia. Successful completion of the two-plant project on the Mastiachala River by Kössler and Braun Maschinenfabrik has ensured they have left an impressive reference work for other potential customers to admire.

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LKW Stauklappenteil und Schuetze web2

 

The individual components for the weir gates were sent on a 3000 km journey on a low-loader all the way from Vöcklabruck.

photo credits: Braun

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In total five machine units with a bottleneck capacity of more than 50 MW have been installed in the new double hydro power plants Mestiachala 1 & 2 in Georgia.

Photo credits: Svaneti Hydro

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The backwater gates were delivered as separate components and welded together on site under the supervision of the Braun assembly team.

photo credits: Braun

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All shut-off devices have been delivered by Kössler as well.

Photo credits: Svaneti Hydro

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Water from 6 nozzles drive the turbine runner, which is 1350 mm in diameter.

photo credits: Kössler

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Thanks to the close cooperation with the parent company Voith Hydro runners made by Kössler feature an ultra-modern and highly efficient design.

photo credits: Kössler

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The two hydro power plants at Mestiachala River are already connected and operating (M1 in test mode).
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Photo credits: Svaneti Hydro

 

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Two steel weir gates, each 19m in width, were installed in the two water collection channels of the double hydropower plant project Mestiachala 1 & 2. As with all of the steel engineering, they were produced by the Austrian hydropower steel structure specialists at Braun Maschinenfabrik.

photo credits: Braun