Iran’s plans to develop its hydropower sector are nothing if not ambitious, but progress is proving slower than the authorities hoped.

Due to open in 2014, the Bakhtiari Dam and Hydroelectric Power Plant in southwest Iran will be the tallest dam in the world at 315 metres, surpassing China’s 305 metre Jinping-I Hydropower Station.

Bakhtiari is planned to be a double-arch concrete dam creating a reservoir with an area of 5,900 hectares. Six 250MW turbines installed in the dam will give it a generating capacity of 1.5GW.

If Bakhtiari is a good indicator of Iran’s grand hydropower ambitions, it is also representative of the long lead times and numerous delays that dog the country’s major projects.

Hydropower project delays

Feasibility studies for the scheme began in 1996, but a series of problems meant that a design team comprising Iranian and Swiss consultancies was only appointed in May 2005. The most notable delay was caused by the 2002 liquidation of the German contractor originally appointed to build the scheme.

A joint venture of China’s Sinohydro and local firm Farab was named contractor for the scheme in 2007, with Chinese banks providing financing for the $2bn project.

However, as late as October 2010 the managing director of the client, Iran Water and Power Resources Development Company (IWPCO), Mohammad Reza Rezazadeh told the Iranian Students News Agency that contract negotiations were still ongoing with the Chinese.

Projects have been pretty much limited to using Chinese manufacturers or trying to make parts locally

Tehran-based consulting engineer

Since being established in 1989, IWPCO has been responsible for the construction of all new hydropower plants in Iran. Progress over the past decade has been steady, if not as dramatic as the country’s Energy Ministry had hoped.

In 2002, there were 14 operational hydroelectric power plants in the country with a combined generating capacity of 2GW. This represents 6 per cent of the country’s total 33GW electricity capacity, which is dominated by gas-fired plants.

Under the Islamic Republic’s third five-year development plan, the share of hydropower was set to rise to 20 per cent of total installed capacity by the end of the fourth development plan, ending in 2009. This target has not been met.

There are now 23 operational hydropower plants in Iran with a combined electricity generating capacity of 8.2GW. This represents 14 per cent of the country’s total generating capacity of 58.5GW. A further 4.8GW of capacity is under construction, 2GW of which, including Bakhtiari, is at an advanced stage of design, while 12.7GW of hydro capacity is either undergoing feasibility study or in the early design stages.

UN sanctions against Iran’s nuclear programme are being blamed for the country’s lack of progress in developing hydropower schemes. Specifically, the most recent UN Security Council Resolution passed against Iran in June 2010, included a list of conditions carefully targeted to impede its nuclear programme. In reality, the conditions hamper progress on any kind of energy project.

“For the past year, with the financial sanctions, it has been difficult to purchase equipment for hydro projects here,” says one Tehran-based consulting engineer. “Projects have been pretty much limited to using Chinese manufacturers or trying to make parts locally. This has slowed down a number of schemes, especially those that have had to change their equipment specifications mid-way through construction. Nonetheless, they are moving forward. Sanctions have just meant that projects won’t necessarily have the best equipment installed and may take longer and cost more.”

Most hydropower plants being built or considered in Iran are dam structures of one type or another – concrete, rockfill or clay – rather than small schemes. This is because the Iranian government views hydropower as strategically important for electricity generation and water supply.

Two-pronged approach to hydropower sector

Annual precipitation in Iran is estimated to be 240mm, one third the global average. Many regions of Iran constantly face drought.

The reservoirs that result from dam construction help to guarantee water supply and the hydroelectric power plant construction programme is part of a wider dam construction programme. According to the Iranian Water Resources Management Company, construction has begun on 17 dams since March 2010, with work due to begin on a further 120 between October 2010 and the end of 2011.

As well as creating reservoirs for water storage and installing turbines for electricity supply, many dams are being built alongside irrigation projects. The most recent example is the Moshampa Dam & Power Plant and Irrigation Network, the contract for which was awarded to Sinohydro in September 2010. This $1.5bn scheme will include a 108MW power plant as well as a vital crop irrigation system.

The US Energy Information Administration said a severe drought during late 2007 and early 2008 adversely affected Iran’s hydroelectric production, leaving water reservoirs emptied during the summer peak demand season. This resulted in a drop of nearly 70 per cent in hydroelectricity generation.

Such a sharp capacity drop brought into question the country’s ability to fulfill its domestic power needs, let alone its export obligations. Iran’s electricity grid currently exports to Afghanistan, Pakistan, Iraq, Turkey, Turkmenistan, Armenia and Azerbaijan.

As a result, many of the dams and hydropower plants either planned or under construction are based on the same river basins as existing facilities. This will help to increase the water-holding capacity of existing reservoirs, while at the same time boosting their hydro-electric output.

Recent additions to hydroelectric capacity

The most recent additions to the country’s hydroelectric generating capacity were the first and second 250MW units of the Karun 4 hydroelectric power plant brought online in December 2010 and January 2011. The plant will have a total generating capacity of 1GW when completed.

Following on from the Karun 3 2GW hydropower plant with 205-metre-tall arch dam further upstream, the Karun 4 dam in Chaharmahal & Bakhtiari Province, southwest Iran, is being built to provide both electricity and flood control.

Lying on the Karun river, which has the highest discharge of Iran’s rivers, the Karun 4 plant comprises a 230-metre-tall concrete double-arch dam that holds a reservoir with a surface area of 2,900 hectares. The dam crest is 440 metres long and the entire structure is 7 metres wide at the crest and 37 to 52 metres wide at the foundation. The dam has a gated spillway with three radial gates and a discharge capacity of 6,150 cubic metres a second.

Construction of this project, estimated at $562m, began in 2001 and was originally forecast to be completed in 2009. It now looks likely it will be fully operational later this year. The main contractor for the scheme is Farab.

Another major project under construction
is the 2GW Upper Gotvand Dam in Khuzestan. A rockfill dam with a clay core, at 180m tall it will be Iran’s tallest earthen dam and reservoir impoundment is expected to open later this year. The hydroelectric power plant will subsequently come online in two 1GW stages, each comprising four 250MW turbines. It is being built by a local joint venture of Farab and Sepasad Engineering, with Mahab Ghodss as consulting engineer.

Other major schemes under way include the 480MW, 180-metre-tall concrete double-arch Seymareh dam; the 450MW, 158-metre-tall Rudbar Lorestan dam, Iran’s tallest roller-compacted concrete structure being built by a joint venture of Farab and Chinese contractor Gezhouba; and the 300MW, 175-metre-tall Khersan 3 double-arch concrete dam.

One of the most strategically significant hydro projects being built in Iran is the Siah Bishe pumped-storage hydropower plant.

The 1GW project in Mazandaran Province is being built by a joint venture of Farab and Kayson Engineering. Originally scheduled to be built by 2008, the plant’s construction is said to be more than 80 per cent complete.

The scheme was described by Energy Minister Majid Namjoo during a site visit late last year as “a source of national pride”. It is Iran’s first pumped storage hydropower plant, with the capability to take in 940MWh of electricity off the grid and store it by pumping water from one dam to another at a higher elevation. The two reservoirs are about 2.8km apart and have a difference in elevation of approximately 500m.

The water will be pumped up during off-peak hours when electricity costs less, and then released from the higher reservoir to the lower reservoir to drive hydroelectric turbines during peak electricity demand.

The need for such a facility becomes clear when looking at how traditional power plants are employed in Iran. Some are used as base-load plants, but many are used as peaking facilities, providing top-up supply when demand is high and on average meeting 6-8 per cent of the country’s electricity demand. However, last summer the plants ran at close to full capacity, meeting 12 per cent of the country’s electricity demand.

Peaks and troughs in electricity demand

There is a large swing between low demand and peak demand for electricity in Iran. Pumped-storage not only provides peak demand supply, but also enables thermal power plants to continue operating during periods of low demand by taking the excess power they generate and providing a stabilising effect for the grid.

At a pumped-storage hydro event in Tehran in November 2010, the managing director of Iran Power Generation, Transmission and Distribution Management Company, Homayoon Hayeri said that when consumption drops, thermal power plants can only operate at 75 per cent of their total capacity.

“The figure for combined cycle and nuclear power stations stands at 80 per cent and 95 per cent respectively,” he said.

“Failure to keep to these standards would mean the power stations should be disconnected from the grid. Reconnection of power plants entails huge costs. But when it comes to pumped-storage power plants, major grid changes can easily be handled thanks to the flexibility of these facilities.”

Plans are already well-advanced for a second pumped-storage facility to be built in Ilam Province, also with a generating capacity of 1GW.

Although considerably behind schedule, Iran’s investment in its hydropower sector forms a central part of its energy policy, providing a diverse and flexible portfolio. In recent years, the sector been vulnerable to drought, but projects being planned today aim to prevent this from happening again in the future.