A selection of current construction work and studies shows hydropower’s wide range, says Patrick Reynolds.
Numerous hydropower and pumped storage projects are in construction or planning across the globe, and International Water Power & Dam Construction (IWP&DC) briefly notes progress and developments on a selection in Asia, Europe, North America and South America, and also the Middle East.
A major hydropower scheme that is well advanced is the Ulu Jelai project, in Malaysia. Being constructed by Salini Impregilo, the project involves significant surface and underground works.
Both surface and underground works feature in the Foz Tua pumped storage project, in Portugal, and which is also at an advanced stage. The project involves construction of a 108m-high double-curvature arch dam.
Developing hydropower where a new dam is not needed, efforts are pushing ahead in the US to exploit existing lock and dams structures, such as the run-of-river projects being undertaken by power company American Municipal Power (AMP) on the Ohio River. The plants under construction include 72MW Smithland.
Statkraft may give the go-ahead this year for two run-of-river projects in Chile, following an acquisition in 2015. However, following a recent review of its investment programme it has yet to decide what action it will take.
Many further projects are coming, and a few among those include recent awards for consultants MWH Global and ÅF, respectively, in South America, Europe and the Middle East.
Malaysia: Ulu Jelai
Construction of the 383MW Ulu Jelai hydropower project, in Malaysia, has been underway since 2011 and is well advanced, including the recent milestone completion of the Susu roller compacted concrete (RCC) dam.
Ulu Jelai is being developed by Tenaga Nasional Berhad (TNB) in Pahang state, approximately 200km north of the capital Kuala Lumpur. It is one of five hydro projects being built at present to help stabilise the power grid.
The project is located on Bertam River, and involves major dam and tunnel works. The rated net head of the scheme is approximately 360m.
Key features of the project include the Susu reservoir on Bertam River, and to which water is conveyed by transfer tunnels from the Lemoi and Telom rivers, running on opposite sides of the main river. Lemoi and Telom are tributaries of Bertam and naturally join the main river downstream of the project location but are being tapped with offtake weirs at higher elevations. The tunnels have lengths of 7.5km and 8.5km, respectively.
Water flows from Susu reservoir down a 9.5m-diameter unlined headrace tunnel to the underground powerhouse complex, holding a pair of 191MW Francis turbines. Ulu Jelai is expected to generate approximately 326GWh of electricity annually.
Salini Impregilo is main contractor on the scheme, which is nearing completion.
The Susu RCC dam is more than 80m-high with a crest length of 512.5m. Its volume is approximately 750,000m3, the contractor said.
The volume of other concrete works on the project is approximately 190,000m3. Surface excavations and earth moving has involved more than 3M m3 of material.
Underground construction has been performed by both TBM boring and drill and blast excavation. In total, the project has called for excavation of 26km of tunnels and also the powerhouse cavern complex. The TBMs were used to bore 15km of tunnels, and 11km of excavation of undertaken by drill and blast.
Salini Impregilo notes that the total underground rock excavation is approximately 800,000m3.
Works are well advanced at Ulu Jelai HEP, Malaysia. Courtesy Salini Impregilo
Portugal: Foz Tua
Construction of the Foz Tua pumped storage project, in Portugal, has called for building a double-curvature arch concrete dam with a crest length of 275m.
Construction work on the dam started in 2011, and the well-advanced project is scheduled to be complete in 2016.
The project is on the River Tau in the Douro catchment, in northern Portugal near the border with Spain. It has a capacity of 260MW and an expected annual output of almost 670GWh.
Foz Tua is being developed by Energias de Portugal (EDP), which is undertaking project management. The utility designed the scheme in collaboration with COBA, Quadrante, and Architect Souto Moura.
The main contractor on Foz Tua project is Barragem de Foz Tua, A.C.E., which is a consortium of Mota-Engil S.A., Somague S.A and MST S.A. Construction supervision is by FASE and Gibb.
Equipment is being supplied by Andritz, EFACEC and SMM.
Peri has a subcontract to supply formwork for the dam construction, and also has had a project manager on site. It also supplied the steel formwork carriage for tunnel lining works.
The subcontractor said the most challenging aspect of its works on the structure were at the top. At the 5m-wide crest, the formwork had to enable concrete casting for the double-curvature main wall along with the integrated overflow structures.
A combination of Peri's SCS climbing system and its VARIO GT 24 wall formworks was used. The SCS allow single-face load transfer of the wet concrete to the climbing anchor of the prior, set concrete lift. The load is transferred through a bracket to the anchor. The multi-piece brackets are part of modular system of SCS, which allows the system to be adapted to varying geometry. Working platforms were 1.9m-wide.
The project involves two 700m-long tunnels. The formwork carriage system supplied by Peri allowed for tunnel lining works involving placing the steel reinforcement cages in sections with diameters varying from 7.5m down to 5.5m.
Foz Tau dam required complex concreting formwork. Courtesy Peri GmbH
Developed recently on the Ohio River, in Kentucky, the 72MW Smithland has horizontal bulb turbines and generators supplied by Voith Hydro.
The run-of-river project has been developed by AMP to add hydroelectric generation to the existing unpowered lock and dam facility, operated by the US Army Corps of Engineers (USACE). Smithland operates under a gross head of 6.7m and is expected to generate almost 380 GWh/year (gross).
Initial works started in late-2010. Construction began on site before mid-2012 and completed recently.
The power plant structure is just over 78m long by approximately 62m wide and is 32m high, including the intake structure and discharge channel.
Smithland has been built by contractor CJ Mahan Construction. The construction challenge involved a tight schedule to build the large structural elements, including multi-curved surfaces. The curvature challenge involved forming concrete walls and slabs for conduits narrowing from almost 18m to 11.4m diameter over a distance of only 27.5m.
Peri supplied formwork for the concreting works, including fabrication of a number of specially-made 3D formwork units in addition to standard units. The subcontractor undertook planning for the formwork as well as the shoring solution. It also kept a project manager on site to optimise all planning, assembly and delivery activities.
AMP's other run-of-river plants include 44MW Willow Island, 88MW Cannelton and 105MW Meldahl/Greenup.
Smithland is a run-of-river project in US. Courtesy Peri GmbH
Statkraft weighs Chile new build
Statkraft has been planning to build the Osorno and Los Lagos hydropower projects, in Chile, as part of its expanding portfolio of international energy assets but is now considering possibly postponing the two run-of-river schemes following a review of its overall investment plans.
A spokesman for Statkraft said a decision on moving into construction with the two projects is now expected to be made sometime in 2016. Construction on 54MW Osorno has been due to commence around March 2016, approved by the board of directors' investment decision as recently as October 2015.
However, the Norwegian government changed its financial plans related to state-owned Statkraft, requiring higher dividend payouts from the utility. Statkraft, therefore, has had to review its investment programme.
The outcome of the investment review was announced in December 2015, and noted that in its renewables portfolio the company has put a halt on all new offshore wind power projects and that some hydro projects may be postponed.
The spokesman said the affected part of the hydro programme are the two planned Chilean projects only; no other international hydropower schemes under development are affected by the review.
Osorno and Los Lagos are both to be developed on the Pilmaiquen River, and will be located downstream of the existing 55MW Rucatayo facility.
All the stations would be held by Empresa Electrica Pilmaiquen, which is 99% owned by Statkraft, said the spokesman. Statkraft made the strategic acquisition of Empresa Electrica Pilmaiquen in 2015, and in addition to Rucatayo the company has three licenced projects — Osorno, Los Lagos and Trafun, the smallest.
Osorno would be farthest downstream in the proposed cascade with Rucatayo and Los Lagos. Its development is to involve construction of a 39m-high by 220m-long embankment dam with a combined clay core and cut-off wall.
Key structures for Osorno also include a diversion runnel in the right-side river bank, and it may also be used for flood control during the operational life of the station. A gated spillway and powerhouse with a Kaplan turbine will be on the left riverbank.
Net head on the turbine is 32.6m, gross head is 34m, and nominal flow is 180m3/s.
Statkraft’s Rucatayo hydro plant, Chile.
Studies for coming projects
Among many studies underway on coming hydropower and pumped storage projects are a range of recent awards for consultants MWH Global and ÅF, respectively. The companies are working in countries including Argentina, Austria and Saudi Arabia.
MWH won contracts last year to work a number of hydropower projects in South America, including work to be done for the large binational power plant owned with Uruguay — Salto Grande.
The company will work as consultant on the modernisation of the 1,890MW Salto Grande project, which supplies half of the electricity in Uruguay and 8% of Argentina's needs. The study is being managed by the Inter-American Development Bank (IADB) for the joint developer, owner and operator Comision Tecnico Mixta do Salto Grande.
Salto Grande is on the Uruguay River. Construction began in 1974 and the complex was officially inaugurated in 1983 on commissioning of the last of 14 generating units. The complex comprises a number of sections of concrete and earthfill dams, and has 19 spillway sections wit a total discharge capacity of approximately 60,000m3/s. The power plant has 14 Kaplan turbines, each 8.5m diameter with 135MW capacity.
MWH is also working on the new 1,140MW Nestor Kirchner and 600MW Jorge Cepernic hydro projects in Argentina. The two projects are being developed on the Santa Cruz River, about 80km apart, by a joint venture of local firm Grupo Eling S.A. with China's CGGC. The Nestor Kirchner dam is a 75m-high CFRD structure. The projects will boost electrical power in the Santa Cruz province by more than half.
Pumped storage has been the focus of recent contracts awards for ÅF, and includes studies for projects in Austria and Saudi Arabia.
ÅF — along with ILF — signed a contract with Pumpspeicherkraftwerk Koralm GmbH in early 2015 to provide engineering services for the Koralm PS scheme, located in the Styria area of Austria.
Its work on Koralm began with a project review of the 940MW planned scheme, which includes upper and lower reservoirs as well as major underground infrastructure works - headrace, surge tank, penstock, powerhouse caverns, and tailrace. The head is approximately 650m.
The next stages of the services are a feasibility study and then, following the project approval, preparation of the documents for the procurement phase. The company is also to provide site supervision services.
In Saudi Arabia, the Saudi Electricity Company (SEC) is developing a 1,000MW pumped storage scheme at Wadi Baysh. SEC signed a contract in late 2015 to receive consulting services from ÅF for the project.
The services are to focus on concept and feasibility studies, and preparations of tender documents and technical support during contract procurement.
SEC develops and operates the electricity generation and grid systems in Saudi Arabia, and is looking at the pumped storage project to both store energy at off-peak times but also to managing the grid by improving the load curve.
ÅF said that Saudi Arabia is embarking a massive renewable energy programme to diversify its generation mix. A key feature of most renewables is intermittent generation, and therefore the strategy requires extra storage capacity to store excess energy on generation but also support the grid when output is less than demand.
* This is a version of an article that first appeared at International Water Power & Dam Construction.