Bui Dam
Encyclopedia
The Bui Dam is an under construction 400 megawatt hydroelectric project at the Bui Gorge at the southern end of Bui National Park
in Ghana
. The project is a collaboration between the government of Ghana and Sino Hydro, a Chinese construction company. Construction on the main dam began in December 2009, its first generator should be online in 2012 and project completion is expected in 2013.
It will be the third major dam in the country after the Akosombo Dam
and the Kpong Dam
. It would flood about 20% of the Bui National Park
and impact the habitats for the rare Black Hippopotamus as well as a large number of the native wildlife species. It will also require the forcible resettlement of 1,216 people, and affect many more.
when he visited the Bui Gorge. The dam has been on the drawing board since the 1960s, when Ghana’s largest dam, the Akosombo Dam
, was built further downstream on the Volta River. By 1978 planning for the Bui Dam was advanced with support from Australia and the World Bank
. However, four military coups stalled the plans. At the time Ghana began to be plagued by energy rationing
, which has persisted since then. In 1992, the project was revived and a first feasibility study was conducted by the French firm Coyne et Bellier.
In 1997 a team of students from Aberdeen University carried out ecological investigations in the area to be flooded by the reservoir. The Ghanaian environmental journalist Mike Annan, who was included in UNEP’s Global 500 Roll of Honour
for 1998, called the dam an “environmental disaster” and a “text book example of wasted taxpayer money”. In his article he quoted the investigation team, but apparently somewhat exaggerated the environmental impact of the dam. The leader of the investigation team, the zoologist Daniel Bennett, clarified that “the opinions (Anane) attributes to our team are unfair and misleading”. He continued to say that “Contrary to Mr Anane's claims, we are unaware of any globally endangered species in Bui National Park, nor did we claim that the dam would destroy the spawning runs of fish.” Although Daniel Bennett always maintained a neutral stance towards the construction of the dam, in April 2001 the government of Ghana banned him from doing further research on the ecology of the Bui National Park. The government stated that the issue was "very sensitive" and Bennett's "presence in the National Park was no longer in the national interest". One of the journalist who criticized the government for banning Bennett was Mike Anane.
In 1999 the Volta River Authority
, the country’s power utility, signed an agreement with the US firms Halliburton
and Brown and Root to build the dam without issuing a competitive bid. In December 2000 President Jerry Rawlings
, who had ruled the country for the two previous decades, lost elections and was replaced by John Kufuor
. In October 2001 the new government shelved the dam project. According to Charles Wereko-Brobby
, then President of the Volta River Authority, Bui Dam was not considered the least–cost option and could not meet “immediate” energy needs. Instead gas-powered thermal power plants were to be built, producing electricity at what was said to be half the cost of Bui. Furthermore, a severe drought in 1998 exacerbated the energy crisis due to low water levels in Akosombo Dam. As a consequence, the government wanted to reduce its dependence on hydropower at the time.
However, as soon as in 2002 the project was revived. An international call for tender was issued, but only a single company submitted a bid and the tender was cancelled. In 2005 the Chinese company Sinohydro submitted an unsolicited bid for the dam together with funding from the Chinese Exim Bank. The government accepted the bid and the Ministry of Energy signed contracts for an environmental impact assessment in December 2005, as well as for an updated feasibility study in October 2007. In August 2007 the government created the Bui Power Authority to oversee the construction of the dam and the associated resettlement, as well as to operate the dam and power plant. The responsibility for the dam was thus taken away from the Volta River Authority
, which until then had been responsible for the development and operation of all power projects in Ghana.
Field investigations for the dam began in October 2007. In January 2008 preparatory construction began and in May 2008 the first people were resettled. In December 2008 the river was diverted and a year later construction on the main part of the dam began. The filling of the reservoir is expected to begin in 2011. Sinohydro Corporation
is serving as the main contractor while Coyne et Bellier is the consulting engineer.
-type and have a height of 108 m (354 ft) above foundation and 90 m (295 ft) above the riverbed. The crest of the dam will be 492 m (1,614 ft) meters long and sit at an elevation of 185 m (607 ft) above sea level (ASL). The main dam's structural volume will be 1000000 cubic metre. Southwest of the dam there will be two saddle (or auxiliary) dams to maintain pool levels and prevent spillage into other areas of the basin. The first and closest to the main dam is Saddle Dam 1. It is 500 m (1,640 ft) southwest of the main dam and will be a rock-fill embankment dam
. The dam will rise 37 m (121 ft) above ground level and have a crest length of 300 m (984 ft). Being constructed 1 km (0.621372736649807 mi) southwest of the main dam is Saddle Dam 2. This dam will be a zoned earth-fill type and have a height of 7 m (23 ft) ASL and a crest length of 580 m (1,903 ft). Both saddle dams will have a crest elevation of 187 m (614 ft) ASL.
The reservoir
that the main and saddle dams create will have a maximum capacity of 12570000000 cubic metre of which 7720000000 cubic metre is active (or "useful") for power generation and irrigation. The reservoir's maximum operating level will be 185 m (607 ft) ASL and the minimum 167 m (548 ft) ASL. At the maximum level, the reservoir will have a surface area of 440 km² (170 sq mi) while the at minimum it will be 288 km² (111 sq mi). The reservoir's volume at minimum level is 6600000000 cubic metre. The average length of the reservoir will be 40 km (25 mi) with an average depth of 29 m (95 ft) and a maximum 88 m (289 ft).
Just downstream of the dam on the left bank will be the dam's power station
. Just above it and at the top of the dam, the intake will feed water through three penstock
s which in turn will supply water to three separate 133 MW Francis turbine
-generators. The power station will have an installed capacity of 400 MW and an estimated average annual generation of 980 GWh. The power station's switchyard will be located 300 m (984 ft) downstream and will convert the electricity to 161 kV
before it reaches main the transmission lines.
The dam's spillway
will be near the right bank and consist of five radial gates, each 15 m (49 ft) wide. The spillway will sit at an elevation of 169 m (554 ft) and have a maximum discharge of 10450 m3/s which correlates to a 1-in-10,000 year flood. The dam's outlet works
will consist of a single outlet on the right bank converted from one of the diversion tunnels.
will be significantly affected by the Bui Dam. 21% of the park will be submerged. This will affect the only two populations of black hippopotamus in Ghana, whose population is estimated at between 250 and 350 in the park. It is unclear if hippos can be relocated and if there is any suitable habitat near the area to be inundated. Even if there were such a “safe haven”, it is not clear if the country's game and wildlife department has the means to rescue the animals. The Environmental and Social Impact Assessment states that hippos will be vulnerable to hunting during the filling period of the reservoir. It also claims that they would ultimately "benefit from the increased area of littoral habitat provided by the reservoir".
The dam could also have other serious environmental impacts, such as changing the flow regime of the river which could harm downstream habitats. A survey by the University of Aberdeen
has revealed that the Black Volta River abounds with 46 species of fish from 17 families. None of these species is endangered. Nevertheless, these fish communities could be severely impacted by changes to water temperature, turbidity and the blocking of their migration. Waterborne disease could also occur. Schistosomiasis
in particular could become established in the reservoir, with severe health risks for local people.
Bui National Park
The Bui National Park is found in Ghana. It was established in 1971. This site is 1820 km². The reserve is notable for its Hippopotamus population in the Black Volta. The endangered black and white colobus monkey and a variety of antelopes and birds are also present. Part of the park will be...
in Ghana
Ghana
Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...
. The project is a collaboration between the government of Ghana and Sino Hydro, a Chinese construction company. Construction on the main dam began in December 2009, its first generator should be online in 2012 and project completion is expected in 2013.
It will be the third major dam in the country after the Akosombo Dam
Akosombo Dam
The Akosombo Dam , is a hydroelectric dam on the Volta River in southeastern Ghana in the Akosombo gorge and part of the Volta River Authority. The construction of the dam flooded part of the Volta River Basin, and the subsequent creation of Lake Volta...
and the Kpong Dam
Kpong Dam
The Kpong Dam is the second hydroelectric power generating dam in Ghana. It is owned and operated by Volta River Authority. The dam was introduced to supplement power production from Akosombo Dam, especially for the smelting of aluminium at VALCO in Tema....
. It would flood about 20% of the Bui National Park
Bui National Park
The Bui National Park is found in Ghana. It was established in 1971. This site is 1820 km². The reserve is notable for its Hippopotamus population in the Black Volta. The endangered black and white colobus monkey and a variety of antelopes and birds are also present. Part of the park will be...
and impact the habitats for the rare Black Hippopotamus as well as a large number of the native wildlife species. It will also require the forcible resettlement of 1,216 people, and affect many more.
History
The Bui hydro-electric dam has first been envisaged in 1925 by the British-Australian geologist and naturalist Albert Ernest KitsonAlbert Ernest Kitson
Sir Albert Ernest Kitson KBE, CMG was a British/Australian geologist and naturalist, winner of the Lyell Medal in 1927.-Early life:...
when he visited the Bui Gorge. The dam has been on the drawing board since the 1960s, when Ghana’s largest dam, the Akosombo Dam
Akosombo Dam
The Akosombo Dam , is a hydroelectric dam on the Volta River in southeastern Ghana in the Akosombo gorge and part of the Volta River Authority. The construction of the dam flooded part of the Volta River Basin, and the subsequent creation of Lake Volta...
, was built further downstream on the Volta River. By 1978 planning for the Bui Dam was advanced with support from Australia and the World Bank
World Bank
The World Bank is an international financial institution that provides loans to developing countries for capital programmes.The World Bank's official goal is the reduction of poverty...
. However, four military coups stalled the plans. At the time Ghana began to be plagued by energy rationing
Energy rationing
Energy rationing primarily involves measures that are designed to force energy conservation as an alternative to price mechanisms in energy markets...
, which has persisted since then. In 1992, the project was revived and a first feasibility study was conducted by the French firm Coyne et Bellier.
In 1997 a team of students from Aberdeen University carried out ecological investigations in the area to be flooded by the reservoir. The Ghanaian environmental journalist Mike Annan, who was included in UNEP’s Global 500 Roll of Honour
Global 500 Roll of Honour
The United Nations Environment Programme established the Global 500 Roll of Honour in 1987 to recognize the environmental achievements of individuals and organizations around the world.The last Global 500 Roll of Honour awards were made in 2003...
for 1998, called the dam an “environmental disaster” and a “text book example of wasted taxpayer money”. In his article he quoted the investigation team, but apparently somewhat exaggerated the environmental impact of the dam. The leader of the investigation team, the zoologist Daniel Bennett, clarified that “the opinions (Anane) attributes to our team are unfair and misleading”. He continued to say that “Contrary to Mr Anane's claims, we are unaware of any globally endangered species in Bui National Park, nor did we claim that the dam would destroy the spawning runs of fish.” Although Daniel Bennett always maintained a neutral stance towards the construction of the dam, in April 2001 the government of Ghana banned him from doing further research on the ecology of the Bui National Park. The government stated that the issue was "very sensitive" and Bennett's "presence in the National Park was no longer in the national interest". One of the journalist who criticized the government for banning Bennett was Mike Anane.
In 1999 the Volta River Authority
Volta River Authority
The Volta River Authority is the main generator and supplier of electricity in Ghana.-Establishment:The VRA was established by the Volta River Development Act, Act 46 of the Republic of Ghana on April 26, 1961....
, the country’s power utility, signed an agreement with the US firms Halliburton
Halliburton
Halliburton is the world's second largest oilfield services corporation with operations in more than 70 countries. It has hundreds of subsidiaries, affiliates, branches, brands and divisions worldwide and employs over 50,000 people....
and Brown and Root to build the dam without issuing a competitive bid. In December 2000 President Jerry Rawlings
Jerry Rawlings
Jerry John Rawlings is a former leader of the Republic of Ghana and now the African Union envoy to Somalia. Rawlings ruled Ghana as a military dictator in 1979 and from 1981 to 1992 and then as the first elected president of the Fourth Republic from 1993 to 2001...
, who had ruled the country for the two previous decades, lost elections and was replaced by John Kufuor
John Kufuor
John Kofi Agyekum Kufuor was the second president of the 4th Republic of Ghana and Chairperson of the African Union...
. In October 2001 the new government shelved the dam project. According to Charles Wereko-Brobby
Charles Wereko-Brobby
Dr. Charles Wereko-Brobby is a politician, diplomat and businessman in Ghana. He is currently the chief executive of the Ghana@50 secretariat, responsible for planning Ghana's 50th Jubilee in 2007. Werek-Brobby ran for President of Ghana in 2000 as leader of the United Ghana Movement...
, then President of the Volta River Authority, Bui Dam was not considered the least–cost option and could not meet “immediate” energy needs. Instead gas-powered thermal power plants were to be built, producing electricity at what was said to be half the cost of Bui. Furthermore, a severe drought in 1998 exacerbated the energy crisis due to low water levels in Akosombo Dam. As a consequence, the government wanted to reduce its dependence on hydropower at the time.
However, as soon as in 2002 the project was revived. An international call for tender was issued, but only a single company submitted a bid and the tender was cancelled. In 2005 the Chinese company Sinohydro submitted an unsolicited bid for the dam together with funding from the Chinese Exim Bank. The government accepted the bid and the Ministry of Energy signed contracts for an environmental impact assessment in December 2005, as well as for an updated feasibility study in October 2007. In August 2007 the government created the Bui Power Authority to oversee the construction of the dam and the associated resettlement, as well as to operate the dam and power plant. The responsibility for the dam was thus taken away from the Volta River Authority
Volta River Authority
The Volta River Authority is the main generator and supplier of electricity in Ghana.-Establishment:The VRA was established by the Volta River Development Act, Act 46 of the Republic of Ghana on April 26, 1961....
, which until then had been responsible for the development and operation of all power projects in Ghana.
Field investigations for the dam began in October 2007. In January 2008 preparatory construction began and in May 2008 the first people were resettled. In December 2008 the river was diverted and a year later construction on the main part of the dam began. The filling of the reservoir is expected to begin in 2011. Sinohydro Corporation
Sinohydro Corporation
Sinohydro Corporation is a Chinese state-owned hydropower engineering and construction company. It is the world's largest hydroelectric company...
is serving as the main contractor while Coyne et Bellier is the consulting engineer.
Design
The Bui Dam will be a gravity roller-compacted concreteRoller-compacted concrete
Roller-compacted concrete or rolled concrete is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for Portland cement. RCC is a mix of cement/fly ash, water, sand, aggregate...
-type and have a height of 108 m (354 ft) above foundation and 90 m (295 ft) above the riverbed. The crest of the dam will be 492 m (1,614 ft) meters long and sit at an elevation of 185 m (607 ft) above sea level (ASL). The main dam's structural volume will be 1000000 cubic metre. Southwest of the dam there will be two saddle (or auxiliary) dams to maintain pool levels and prevent spillage into other areas of the basin. The first and closest to the main dam is Saddle Dam 1. It is 500 m (1,640 ft) southwest of the main dam and will be a rock-fill embankment dam
Embankment dam
An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi-plastic mound of various compositions of soil, sand, clay and/or rock. It has a semi-permanent waterproof natural covering for its surface, and a dense, waterproof...
. The dam will rise 37 m (121 ft) above ground level and have a crest length of 300 m (984 ft). Being constructed 1 km (0.621372736649807 mi) southwest of the main dam is Saddle Dam 2. This dam will be a zoned earth-fill type and have a height of 7 m (23 ft) ASL and a crest length of 580 m (1,903 ft). Both saddle dams will have a crest elevation of 187 m (614 ft) ASL.
The reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
that the main and saddle dams create will have a maximum capacity of 12570000000 cubic metre of which 7720000000 cubic metre is active (or "useful") for power generation and irrigation. The reservoir's maximum operating level will be 185 m (607 ft) ASL and the minimum 167 m (548 ft) ASL. At the maximum level, the reservoir will have a surface area of 440 km² (170 sq mi) while the at minimum it will be 288 km² (111 sq mi). The reservoir's volume at minimum level is 6600000000 cubic metre. The average length of the reservoir will be 40 km (25 mi) with an average depth of 29 m (95 ft) and a maximum 88 m (289 ft).
Just downstream of the dam on the left bank will be the dam's power station
Power station
A power station is an industrial facility for the generation of electric energy....
. Just above it and at the top of the dam, the intake will feed water through three penstock
Penstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems. It is a term that has been inherited from the technology of wooden watermills....
s which in turn will supply water to three separate 133 MW Francis turbine
Francis turbine
The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts....
-generators. The power station will have an installed capacity of 400 MW and an estimated average annual generation of 980 GWh. The power station's switchyard will be located 300 m (984 ft) downstream and will convert the electricity to 161 kV
KV
-In physics and chemistry:* Voltage-gated potassium channel,a large family of potassium channels* Kilovolts , 1000 volts* The rating of RPMs per volt as used in reference to the rotational speed of brushless motors...
before it reaches main the transmission lines.
The dam's spillway
Spillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...
will be near the right bank and consist of five radial gates, each 15 m (49 ft) wide. The spillway will sit at an elevation of 169 m (554 ft) and have a maximum discharge of 10450 m3/s which correlates to a 1-in-10,000 year flood. The dam's outlet works
Outlet works
A set of outlet works is a device used to release and regulate water flow from a dam. Such devices usually consist of one or more pipes or tunnels through the embankment of the dam, directing water usually under high pressure to the river downstream...
will consist of a single outlet on the right bank converted from one of the diversion tunnels.
Benefits
The Bui hydropower plant will increase the installed electricity generation capacity in Ghana by 22%, up from 1920 MW in 2008 to 2360 MW. Together with three thermal power plants that are being developed at the same time, it will contribute to alleviate power shortages that are common in Ghana. Furthermore, like all any hydropower plants, the project avoids greenhouse gas emissions that would have occurred if thermal power plants had been built instead. An additional expected benefit is the irrigation of high-yield crops on 30,000 hectares of fertile land in an "Economic Free Zone". The current status of the irrigation project is unclear.Cost and financing
The total project costs are estimated to be US$622 million. It is being financed by the government of Ghana's own resources (US$60m) and two credits by the China Exim Bank: a concessional loan of US$270 million at 2% interest and a commercial loan of US$292 million. Both loans have a grace period of five years and an amortization period of 20 years. The proceeds of 30,000 tons per year of Ghanaian cocoa exports to China, which are placed in an escrow account at the Exim Bank, serve as collateral for the loan. Once the dam becomes operational, 85% of the proceeds of electricity sales from the hydropower plant will go to the escrow account. If not all the proceeds are needed to service the loan, the remainder reverts back to the government of Ghana.Environmental and social impact
An Environmental and Social Impact Assessment (ESIA) for the dam was completed in January 2007 by the US consulting firm Environmental Resources Management (ERM). During its preparation hearings were held in Accra and in five localiites near the project area, such as Bamboi. However, no hearings were conducted in the project area itself. Once completed, an independent panel appointed by the Environmental Protection Agency (EPA) of Ghana reviewed the ESIA. The latter was revised in the important aspects, including the following: “compensation” had to be provided for the inundated area of Bui National Park, a “rescue plan” for the hippos was required and it had to be specified how resettlement would be carried out. When the EPA issued the environmental permit for the dam, it required the Bui Power Authority to present within 18 months an Environmental Management Plan based on the revised ESIA. Construction and resettlement began in 2008, but no environmental management plan had been submitted as of July 2010. Oliver Hensengerth:Interaction of Chinese Institutions with Host Governments in Dam Construction:The Bui dam in Ghana, German Development Institute, Discussion Paper 3/2011, p. 22-24, retrieved on May 7, 2011 (full version not available on-line)Environmental impact
The Bui National ParkBui National Park
The Bui National Park is found in Ghana. It was established in 1971. This site is 1820 km². The reserve is notable for its Hippopotamus population in the Black Volta. The endangered black and white colobus monkey and a variety of antelopes and birds are also present. Part of the park will be...
will be significantly affected by the Bui Dam. 21% of the park will be submerged. This will affect the only two populations of black hippopotamus in Ghana, whose population is estimated at between 250 and 350 in the park. It is unclear if hippos can be relocated and if there is any suitable habitat near the area to be inundated. Even if there were such a “safe haven”, it is not clear if the country's game and wildlife department has the means to rescue the animals. The Environmental and Social Impact Assessment states that hippos will be vulnerable to hunting during the filling period of the reservoir. It also claims that they would ultimately "benefit from the increased area of littoral habitat provided by the reservoir".
The dam could also have other serious environmental impacts, such as changing the flow regime of the river which could harm downstream habitats. A survey by the University of Aberdeen
University of Aberdeen
The University of Aberdeen, an ancient university founded in 1495, in Aberdeen, Scotland, is a British university. It is the third oldest university in Scotland, and the fifth oldest in the United Kingdom and wider English-speaking world...
has revealed that the Black Volta River abounds with 46 species of fish from 17 families. None of these species is endangered. Nevertheless, these fish communities could be severely impacted by changes to water temperature, turbidity and the blocking of their migration. Waterborne disease could also occur. Schistosomiasis
Schistosomiasis
Schistosomiasis is a parasitic disease caused by several species of trematodes , a parasitic worm of the genus Schistosoma. Snails often act as an intermediary agent for the infectious diseases until a new human host is found...
in particular could become established in the reservoir, with severe health risks for local people.