Engineering and Environmental Aspects of the Renaissance Dam
Asfaw Beyene, professor of mechanical engineering and director of the Center for Renewable Energy and Energy Efficiency at San Diego State University, published an informative commentary titled “Reflections on the Grand Ethiopian Renaissance Dam.” The focus is on the engineering and environmental aspects of the dam.
On a recent Sunday morning a friend called and asked me to tune-in to an online discussion forum on one of the Ethiopian Paltalk forums. 500 attendants, the maximum allowed per room, packed the voice chatting room. After several attempts, I was able to join the room, which was managed by a postmaster named Aba Mela whose civil tone was pleasing.
The Internet is serving Ethiopia’s version of First Amendment, with unfiltered abuses and insults written as footnotes of the busy site so much that I couldn’t keep up reading and listening in tandem. The anonymity afforded by pseudonyms favors excessive diatribe. The topic that captivated so much emotions and interests among Ethiopians of diaspora was the construction of the hydroelectric dam on the Blue Nile River, the Grand Ethiopian Renaissance Dam (GERD).
The outpouring of emotions was triggered by comments made by Egyptian opposition party leaders during a meeting called by Egypt’s president Dr. Mohamed Morsi to review the impact of Ethiopia’s controversial dam to their country. Unaware that the discussion was transmitted live on Egyptian TV, some of the politicians warmly proposed sabotaging Ethiopia’s plan to build the dam. One party leader suggested helping the Oromo Liberation Front while another surmised spreading rumors about purchase of a refueling airplane to fake preparation of attacking the dam. A gentler politician cautioned that this ‘dangerous’ act neglects the fact that Israel and America are Egypt’s real enemies, not Ethiopia – a trajectory which may be more comforting to Ethiopia but less to Israel and the U.S. Another suggested keeping the discussions confidential; at which time they were told that the event was being transmitted live on Egyptian TV. Laughter followed.
President Morsi’s comment came precipitously after he knew the discussion is certainly headed for an international consumption. He interjected that Egypt will not engage in any aggressive act out of respect for Ethiopia and its people. But he also stated that Egypt would not allow loss of a drop of Nile’s water. A drop will certainly be lost. Unintended exposure of this diplomatic tittle-tattle might have thwarted a real conflict. The coercion could no more intimidate once it was self-exposed, and Ethiopia capitalized on the idle talk summoning the Egyptian Ambassador to Ethiopia and asking for clarification.
Many in the audience at the packed chat room implied that since the Ethiopian government abuses human rights, arrests journalists, distributes land to international corporations, promotes ethnic favoritism, etc., they therefore oppose construction of the dam. Ironically, a journalist named Muluken Tesfaw was detained on May 4 for reporting on the return of thousands of farmers who had been forced from their lands in the Benishangul-Gumuz region – the same region where Ethiopia is construction the multibillion dam. Another journalist was tried for terrorism and sentenced to two years jail for reporting on alleged coercion to force government employees to contribute to the construction of the dam. One can chronicle these facts and set them as conditions that need to be resolved before a dam of this magnitude is built if one believes freedom and construction of the dam are tightly linked.
The reader may indeed decide to object construction of the dam solely based on the regime’s totalitarian governance. I am sympathetic to those who say issues of freedom and human rights shall remain at the forefront of the Ethiopian political discourse, and the rights of the oppressed people must be respected before launching a grand project such as this. Strictly political objections valid but put aside, those who opposed construction of the dam based on its engineering merit did not make their cases. My purpose here is not to debate the political consequences, or speculate on emotional reactions in Egypt or Ethiopia objecting or favoring the project.
I am circumventing altogether issues such as Ethiopian unity, self-determination of the Oromo, warfare in the Ogaden, etc. These are far more important issues than the dam itself, but I prefer not piggy-bagging them with this topic. Instead, I will focus only on the engineering and environmental aspects of the dam to the extent possible, hopefully without the technical jargons, so that the reader will make an informed decision based on facts and a range of views.
Why hydroelectric dam?
Hydroelectric dams are increasingly popular in water-rich countries of Sub-Saharan Africa, especially those less endowed with oil. For example, a 250 MW dam was recently completed on the Nile in Uganda. A 300 MW dam was also built by China and completed in 2009 on the Tekeze River in Ethiopia. A smaller, 120 MW dam was recently completed on the Wele River in Equatorial Guinea, to mention a few.
As a background to any large hydroelectric dam, one has to take into account the growing global energy demand and weigh this demand with sharply increasing fuel prices and air pollution that causes climate change. The global Carbon dioxide (CO2) content of the air in February 2013 was 397 ppm (parts per million by volume), compared to 280 ppm of the preindustrial level. There is an immutable need to slowdown or reverse the global CO2 generation toabate negative consequences of climate change. On the other hand, facing this sharp increase in CO2 concentration which is threatening the human existence, is a well-established knowledge that social development is strictly tied to energy and electricity supply. A well-respected autonomous intergovernmental organization, the International Energy Agency(IEA) produces annual reports on climate change related issues.
The 2003 report discusses the link between energy use and economic welfare measured in gross domestic product (GDP). This well-sited research paper states that above $3,000 per capita GDP (1995), energy demand explodes as industrialization and personal mobility accelerate. But when GDP reaches $15,000, energy demand grows more slowly as services begin to dominate. After $25,000, economic growth can continue without significant increases in energy use. Countries like S. Korea, Malaysia, and China are following this path. In fact, China’s CO2 emissions from power plants and transportation surpassed that of the USA’semissions in 2006 by 8%. Ethiopia, (with a skeptically received rate of growth that resulted in GDP of $1200 by 2012) or any other country is no exception. Recognizing the fact that large hydro dam is less of a threat than nuclear energy, an option cordially discussed recently in countries like Kenya, and also acknowledging the fact that hydroelectric dams have near zero emissions, the World Bank, after years of refusal, has now started funding large dam projects.
The critical question that seems to overwhelm all development strategists seems to be ‘how can a country develop without adding significant air pollution?’ The international mood of the day is such that, this strategic question will be given priority over the next several decades while other environmental concerns such as population displacement or wildlife damage will certainly be reviewed but as secondary. There is no completely benign method of power production; it is a matter of negotiating and accepting adequate penalties of development, and identifying the ones where negative impacts can possibly be mitigated.
In my opinion, hydroelectric dams of any size are better than nuclear power or fossil fuel power plants. The political challenge to build internationally agreeable share of resources is vital, but it is a political matter to be settled by governments that share the resources. But in the end, at least in the case of sub-Saharan Africa, news of building a dam is certainly far better than news of a vexing barren poverty that leads a barely walking skeletal child to death, again and again for decades. The talk of a microclimate change or environmental impact as a result of a hydroelectric dam is a luxury that Ethiopian politicians would relish, the international community would cherish, and most in Ethiopia would ignore.
Challenges and benefits of a large hydro project:
Generally large hydroelectric dams such as the GERD are not considered renewable. An energy resource is considered to be renewable when its impact on the environment is negligible. Wind and solar energy are regarded renewable despite some arguments that these resources also inflict some damage to the environment. For example, wind turbines are blamed for killing migratory birds, and the Altamont Pass Wind Farm in California is shut down for several weeks every winter just for this reason. Noise from the turbines is another issue that keeps their installation away from populated areas. This in turn necessitates laying transmission lines to transport the power to cities where the demand for electricity is abundant. Solar energy too has its share of complains.
In 2011, environmental groups brought a string of lawsuits to stop construction of large solar plants in the Mohave Desert of California, a region said to have demonstrated extreme vulnerability to climate change. Desert that Africans try to wet is protected here. There is a growing objection to interfering with the desert climate, and increasing voices to protect the ambience of flora and fauna of these arid regions. Thus, there is no perfect system that leaves no trace in the environment to recover energy. And energy is a key component of development. The option to build a hydroelectric dam for the development of a society is therefore inherently controversial. The dams displace people and animals, kill vegetation, and may change the microclimate of the region. Most critics of large hydro favor many smaller dam instead, a concept known as distributed generation. Distributed generation may or may not be better for the environment; – the sum of overtaken land and people can be more or less scattered than those overtaken by the mega projects.
Small-scale hydro, which is promoted by many journalistic scholars, requires more trained cadres to man each site. More importantly, it requires construction of extensive transmission networks to pull the lines into urban areas where demand is guaranteed. Electrification of rural areas is a very expensive business since the houses are often scattered, and the farmer may not afford to pay for the installation cost. This can be done with government subsidy in the economy allows, as is the case in several Latin America countries. The telephone industry is an excellent example of failure of infrastructure to network in African rural. In the developing countries, even after several decades, land-based phone lines simply did not penetrate into the rural areas. Phones are today more accessible in rural Africa simply because landlines are made obsolete by wireless technologies.
Cost: Cost and return on investment are critical components of power generation. On installed capacity basis, wind energy costs $2100 per kW, whereas energy from solar – large Photovoltaic (PV) costs about $7000 (2010 California price), more than three times higher. The price of PV cells is dropping gradually, but it will likely remain inaccessible to most African countries for years to come. Besides, solar energy is available only during half of the day, requiring expensive and often-unsafe storage systems. Construction cost of hydroelectric dam on a per kW basis, according to the U.S. Department of Energy, varies from $735 to $4,778, whereas the average capital cost is estimated at about $2,000 per kW. The construction cost of GERD is about $800, which is the result of dividing the $4.7 billion cost by 6000 MW output. For the engineer reader, I realize that comparison based on kW-hr would have been more useful.
The intermittent nature of wind also requires a large backup to cover the base load when wind is not available. This will drive the cost higher. European countries as well as the USA have large base-power supplies from nuclear, natural gas, and coal to mitigate supply discrepancies in the power industry. In fact, the power supply deviation as a result of wind energy is negligible on the US power industry. However, a country such as Denmark that relies on wind for up to 25% of its electricity has to import as much from neighboring countries when the wind dies. The decision to import power is often made as abruptly as the wind disappears, making it vulnerable to on-the-spot market volatilities.
Hydroelectric dams may also be susceptible to seasonal water levels and drought, but the daily or even weekly variation is suppressed by the reservoir, which to some extent serves as mass as well as energy storage. The seasonal variation also gives more time than wind to prepare. Nonetheless, seasonal water level ups and downs are very important parameters in hydroelectric economy. For example, the world’s largest dam, the Three Gorge, has a capacity of 24 GW. The second largest, the Itaipu is 14 GW – just over half of Three Gorge’s capacity. On an annual basis however, Three Gorge produces only about 85 billion kW-hr, whereas Itaipu, with a more consistent water flow, produces about 94 billion kW-hr. Despite such variations, the life cycle of hydroelectric dam is generally assumed to be 100 years, i.e., they remain one of the most stable, and eventually very affordable forms of energy supply. I have visited the Itaipu dam, the Three Gorge dam, as well as the Hoover dam, and I am always impressed by these breathtaking engineering accomplishments.
Searching for published materials, I came across an interesting research paper entitled “Integrated Management of the Blue Nile Basin in Ethiopia” published in 2007 by The International Food Policy Research Institute through University of Colorado Ethiopia. The study indicates that the project would typically produce benefit-cost ratios (the ratio of the benefits of the project relative to its costs, both expressed in monetary terms) from 1.2 – 1.8 under historical climate regimes. The economists may expand on the quality of this numbers.
Selection of the GERD site
Selection of the site was one of the highly debated topics during my visit to the Paltalk site. I too didn’t understand why such a large dam is placed almost on the border. So, I investigated the 2013 Google map attempting to identify why this location was selected. The detailed review of the map (Google allowed reading within a hundreds of meters scale) shows that the dam is between two narrow hills rising to 1200 meters on the far northern bank, and 600 meters on the southern.
The 600-meter southern bank elevation stretches far inland up to the Dabus River, close to 100 km west. The Northern bank also drops to 600 meters quickly and expands to the immediate north where the reservoir will likely extend, and then rejoins the riverbank narrowing the strip as far inland as Western Shewa. Despite its proximity to the border, the reservoir will therefore be contained within Ethiopia, and will not expel over the 600-meter high banks that escorts it for several dozen km inland.
Average slope of the Blue Nile inside Ethiopia drops about 2 meters for every kilometer distance, a huge drop by all accounts. This drop is sure to exert tremendous pressure on the dam. The typical slope of the Nile in Egypt, for example, is about 8 centimeters per km. The location of the dam has to take into account several such factors including the possibility to contain the new reservoir.
I have come across few fairly informative papers related to exploitation of Blue Nile. However, the United States Bureau of Reclamation (USBR) at the request of the Ethiopian government conducted the most comprehensive early study in 1964. This event coincided construction of the Aswan Dam, and also the Fincha dam in Western Wollega. USBR conducted a thorough study of the hydrology of the upper Blue Nile basin with a simple feasibility study that listed some latent projects.
The study recommended four major hydroelectric dam sites along the Blue Nile with accompanying preliminary designs for irrigation and hydroelectric power along the Blue Nile and the Atbara Rivers. The four sites were 1) the Karadobi Dam located just upstream of the Guder River confluence, 2) The Mabil Dam on the Birr River, 3) The Mendaia dam 175 km from the Sudan border, and the 4) the near-border site which is the current location. Of the four sites, only the Mandaja and the near border sites offer some potential for irrigation because of relatively easy access to flat land and lower escarpments than upstream.
Escarpments rising well over 1200 meters that fortify Karadobbi and Mabil sites rendered the two sites less useful for irrigation purposes. Thus, the choice of the current site is legitimate if the parallel development of irrigation and power generation are taken as criteria. The California experience makes it obvious that withdrawals of water from deep reservoirs involve significant pumping costs.
Can it be maintained?
Any mechanical machine requires maintenance, and this is a highly neglected factor of the design process even here in industrialized nations. Soil deposition must be removed continuously, and the turbines need about yearly preventive maintenance. This can be built into the design process. The Itaipu dam, for example, has 12 turbines, producing 2 GW each. At least one turbine is under maintenance most of the time – reducing power output by 2 MW. However, The Three Gorge dam has32 generators, – about 700 MW each. The preventive maintenance at Three Gorge is less disruption to the power output because it will drop only 700 MW for each turbine under maintenance. An Internet site mentions that the GRED will contain 16 x 350 MW generators; a number that positively suggests the system is designed for maintenance.
Why is Egypt worried?
One of the issues that concern down-stream countries, especially Egypt, is the amount of water that will be trapped to fill the 150 meters high dam. Opening the bypass gates, which will allow more water to pass through, can easily regulate the length of time it takes to fill a dam. If for example, more water is needed to supply the downstream countries because of the drop in the flow rate during the Ethiopian dry season, more water can be released to ensure supply. This will drop the reservoir level, and also the power output. Such mode of operation is common for the Hoover dam where a drop in water level is strongly contested by Mexico, although the Colorado water level is impacted more by irrigation than the reservoir for power production. In fact, the US government has a desalination plant near the border with Mexico to clean runoff and waste water, and replenish the Colorado River to supply the minimum amount to Mexico as agreed bilaterally.
The Yangtze river of the Three Gorge dam has a winter flow rate of about 345 million (cubic meters per day jumping to well over 3000 cubic meter per day in summer, less than 9 times the seasonal swell. Iguasu has a swell of just over 7. The water level in China’s Three Gorges dam reached full capacity in October 2010. It began generating power in 2008. Thus, it took merely two years to fill Three Gorge compared to the 17 years it took to fill Lade Meade on Hoover dam of the Colorado River. The Nile River swell is among the highest in the world from about 50-60 million cubic meters per day in April-May, to over 700 million in September, a more than 10 times swell. Countries along the Nile expect a large and destructively excessive flow in the rainy season, the excess of which will also fill the reservoir fairly quickly. Rate of evaporation in the reservoir will probably be less of a concern than that of the existing dams in the Sudan and Egypt.
Legal, Environmental and local use Issues
Legality: The 1959 Agreement allotted 55.5 and 18.5 billion cubic meters to Egypt and the Sudan, respectively, through the Blue and Atbara Rivers. Ethiopia has limited rights to use these resources. In May 2010, upstream states of the Nile signed a Cooperative Framework Agreement pronouncing the 1959 Agreement no longer valid and claiming rights to more water from the River Nile while Egypt and Sudan refused to sign. Thus, there is no mutually accepted water treaty between upstream and downstream countries. Flourishing irrigation projects and dam constructions in the Sudan and Egypt, while these same countries object the use of Nile by upstream countries, will have little convincing power in Africa and the rest of the world, even if it can’t convince Arab countries whose firm solidarity remains with the Sudan.
Environmental impact study: as stated above like any major project of its kind, the GRED should have had environmental impact study to address costs and benefits of the project. Perhaps the greatest weakness of this project is that no environmental study was conducted, or if it was conducted, it was not made public. In the USA, no such project would be allowed without environmental impact analyses. As such, the project was kept highly confidential (code named Project X) perhaps to avoid adverse and premature reactions from Egypt before the dam is started.
In my opinion, the resolution wouldn’t have been much different even if the process was made transparent and the community was involved opening the matter for public debate. In a country where the in-house expertise is very poor – to the extent that even simple model analysis was outsourced to the University of Denver, the tangled petty politics would only render the project another bogus venture of perpetual talk. The 1250 MW dam in the Sudan overtook parts of the historic sites of Merowe, displaced 15,000 families, and flooded a 174 km of fertile land; and the project was not slowed down by these obvious shortcomings. The Bui Gorge dam in Ghana was known to create a reservoir that will flood a quarter of the Bui National Park, but the dam was built anyway. All the talks of looming disasters of the Three Gorge dam that saturated the cyber waves dissipated once the dam became operational. Scary talks of imminent environmental disasters never stopped any of the hydro projects in a developing country.
In fairness, the above-mentioned paper entitled “Integrated Management of theBlue Nile Basin in Ethiopia” covers at least briefly some aspects of environmental study as an impact analysis. The study developed hydrological models to assess transient stages of large-scale reservoirs, relevant flow retention policies and associated downstream ramifications, and the implications of stochastic modeling of variable climate and climate change. Climate change scenarios including historical frequency of El Niño events are included.
Domestic use of the power: The Internet debate also raised several issues. One speaker was concerned that the power will not be used for domestic development. In light of significant talks of power purchase agreements with neighboring countries, there is a legitimate concern that the project is meant for cash than for the people. Ethiopia has set up the ‘Eastern African Power Pool’, an intergovernmental authority promoting the transmission of power across the region. The line links Ethiopia to Kenya, Tanzania, Eritrea, Uganda, and the Sudan. A high-voltage link between Ethiopia and Kenya funded by the World Bank is expected to wind up by 2019. Such decisions are temporal by nature, and future governments can change them, preferably based on the will of the people. They are valid concerns nonetheless.
Lack of transparency: The GERD is being built by Salini Costruttori, the third Italian General Contractor group with turnover cash of € 1.1 billion (FY 2010) and total budget of € 15.7 billion. It has about 14,000 employees worldwide. It is one of the foremost players in the construction of hydroelectric power plants. It has completed a number of projects in Ethiopia, including the Chida Sodo Road Project, the Emergency Dire Dam, parts of Gilgel Gibe I, Gilgel Gibe II, Gibe III, and the Beles Multipurpose Project. At least Gilgel Gibe II and the Nile dam contracts were awarded with non-competitive biding. Lack of transparency has triggered a lot of opposition to the project, its fundraising aspect in particular. Will the money that is collected be used for the dam? Will corrupt officials pocket some of the fund? Can Ethiopia by itself fund the $4.7 billion dollar project? These are questions that remain to be answered.
* The author, Asfaw Beyene, is a Professor of Mechanical Engineering and Director of the Center for Renewable Energy and Energy Efficiency at San Diego State University. He can be reached at email@example.com.