Potential for Ethiopia to Produce and Export Renewable Energy

Jan 19, 2011 - Harry Valentine - EnergyPulse.com

Several years ago the European group called Desertec developed a strategy to generate renewable energy resources across the Middle East and North Africa (the MENA) and export the electric power into Europe. The range of technologies included wind, solar-PV, solar-thermal, hydroelectric, geothermal, ocean wave, ocean tidal currents and biomass sources. The original Desertec plans focused on developing the renewable energy potential of MENA nations located to the north of 15°N, until the South African Eskom Group initiated discussions about beginning development of the hydroelectric power generation potential of Inga Falls on the Congo River. Peak demand for electric power occurs between May and September across Europe, the MENA and South Africa due to electrical heating of buildings during the southern winter.

The South African plans called for HVDC power lines radiating south across Africa to South Africa, northwest through Algeria and Morocco and across the Spain as well as northeast toward Egypt. Then the Congolese government chose to reconsider the prospect of developing a hydroelectric project estimated at average of 40,000MW to 45,000MW output with peak output pf 100,000MW between October and March. While Congo reconsiders their options and Eskom considers the potential for new hydroelectric development on the Zambezi River (peak output between October to March), Ethiopia announced that they might have some 45,000MW possible generating capacity that includes 30,000MW of hydroelectric power between May and September, wind (10,000MW) and geothermal (5,000MW) sources.

Ethiopia's Power Potential:

Some of the tributaries of the headwaters of the Nile River flow through deep valleys located in the Ethiopian Highlands. The width and depth of these valleys allow for the construction of large reservoirs that could store water for hydroelectric power dams. There are also several suitable mountain valleys in the southern Highlands that could also allow for the development of large storage reservoirs that would supply hydroelectric power dams.

Prevailing winds blow across the Ethiopian Highlands in a southwesterly direction during the cool, dry season and in a northern/northwesterly direction during the hot, humid and rainy season. Humid summer winds blow through mountain valleys at substantial velocity, where it may be possible to install wind turbines on high towers that are stabilized from the valley walls. It may also be possible to suspend arrays of transverse-axis wind turbines on cable systems across suitable valleys.
There is potential for geothermal energy in eastern Ethiopia and Eritrea. While it is possible to drive steam turbines using hot geothermal steam, there may be scope to superheat the steam using concentrated solar thermal energy. Geothermal energy from large geothermal wells at some 80°C to 140°C may be used to energize air-based chimney engines and vortex engines rated at 50MW to 300MW. During humid summer weather, the operation of these engines would propel humid air upward into the cooler regions found at higher elevation, where the moisture droplets may coalesce into rain droplets.

Ethiopia's Dilemma:

Ethiopia has in recent years been involved in a military skirmish with their neighbor to the southeast, Somalia as well as with their neighbor to the northeast, the now nominally independent Eritrea. Egypt has warned about hydroelectric power dams upstream along the Nile River in the event that such development reduces the volume of water that Egypt receives. Dams and reservoirs built with a large water surface area have a propensity for increased evaporation and seepage into aquifers that can reduce water flow volumes downstream.

Sudan and Ethiopia need to ensure that Egypt receives enough water should either nation develop additional hydroelectric generating capacity. Ethiopia would need to develop mutually cordial and cooperative diplomatic relations with neighboring states in order to peacefully and productively develop their renewable energy resources.

Increasing Summer Precipitation:

Some of the highest mountains across sub-Sahara Africa occur in Ethiopia with elevations exceeding 7000-ft above sea level. Summer humidity reaches 100% across Ethiopia as prevailing summer winds blow across the Seychelles region of the Indian Ocean and pick up moisture that is then carried over the Ethiopian Highlands. There are numerous technologies that promise to increase the rate of condensation at higher elevations in humid regions.

Some 60-years ago, the head of the South African weather bureau, Dr Theodore Schumann theorized that humidity passing through an electromagnetic field would condense. He proposed to install a demonstration project at the top of Table Mountain near Cape Town. Inventors in Latin America installed fine-meshed fog or dew fences across valleys that faced the Pacific Coast and through which humid wind would blow. The fog or dew fence is now a proven method of extracting water from humid air.

Researchers in China have experimented with using low-frequency sound waves to activate the moisture droplets in humid air, causing them to coalesce into droplets of water. The combination of sound waves and dew fences offers one option by which to increase precipitation in some areas of Ethiopia. The addition of the South African electromagnetic field approach may further increase the amount of water that can be extracted from the stream of humid air.

Wind turbines churn and swirl the air causing warmer air at a lower elevation to mix with cooler air at a higher elevation. Winds blowing from the Irish Sea on to England's northwestern coast have turned to streams of fog after passing through the blades of coastal wind turbines. Horizontal-axis wind turbines mounted on towers quite naturally produce low-frequency sound waves and some refinement to their operation at higher elevations could result in them generating electrical energy while assisting humid air to coalesce into rainfall.

Solar chimneys and vortex engines are relatively recent, experimental air-based, solar thermal power technologies that draft air through turbines that drive electric generators. These engines may be powered by concentrated solar energy focused by an array of mirrors or captured by saline ponds. They may operate on low-grade geothermal energy. The operation of these engines propels warmer humid air from ground level into the cooler atmosphere at higher elevation, where there is greater potential for the moisture droplets in the humid air to coalesce.

The solar thermal air-engines pull air through ducted wind turbines that may be tuned to produce the frequency of sound waves that would cause moisture droplets to coalesce in the cooler air at the higher altitudes. There may be potential to combine all 5-methods of water extraction in various locations across Ethiopia, to increase the amount of liquid water than can be extracted from the humid air streams that blow across that nation. The objective would be to ensure that neighboring nations receive a steady supply of potable water while Ethiopia generates hydroelectric energy.

Pumped Hydraulic Storage:

The Danakil land depression covers some 3800-square miles along the Red Sea coast of Eritrea and stretches into Ethiopia. The region is a source of rock salt with potash mines located around the land depression that measures up to 148-feet below sea level. There is potential to partially flood the Danakil land depression and operate it as a seasonal pumped hydraulic energy storage system. Seawater would flow in during summer to generate up to 3000MW of hydroelectric power as its depth drops from 60-feet below sea level to 80-feet below sea level.

The seawater would be pumped out during the winter months using energy mainly from excess off-peak wind energy from across Ethiopia and the MENA plus future electrical energy from the Inga Falls hydroelectric installation. Future off-peak tidal power from kinetic turbines installed under the Strait of Bab-el-Mandeb may also be transferred into pumped storage at the land depression. During winter, the Equatorial Counter Current flows in the anti-clockwise direction in the northern Indian Ocean and produces a stronger tidal current through the Strait of Bab-el-Mandeb.

Flooded Danakil Land Depression:

Dropping winter water levels in the flooded Danakil land depression would allow for the installation of saltpans around the land depression, to collect salt for market. The flooded land depression will also provide increased evaporative surface for winter winds that blow in from the Red Sea toward the southwest. During winter, the surface area of the lake may drop from 3800-sq.mi to around 2000-sq.mi. The 125-mile wide band of wind that blows across some 25,000-sq.mi of Red Sea surface would also blow across an added 8% of evaporative water surface that would be much shallower than the Red Sea.

The surface elevation of the flooded land depression would be below that of the Red Sea and in a warmer region. Seawater stored in the land depression could increase in salinity and capture more of the infrared solar spectrum, causing the water to heat more rapidly to a higher temperature than the Red Sea. Winter evaporation could increase some 10% to 20% per unit area, adding some 18% to 30% more moisture to the band of wind that blows inland from the Red Sea and over part of the northern Ethiopian Highlands. It may be possible to operate technology in this region that may produce some winter rainfall over the watershed area of the Blue Nile.

The higher salinity of the flooded land depression would divert more solar heat to the lakebed and raise its temperature. That heat could become the source by which to operate air-based solar-thermal chimney engines and vortex engines of 100MW to 300MW output each. The operation of these engines could pump humid air to higher elevations with the potential to produce winter rainfall in areas of Ethiopia that lie to the west of the flooded land depression.

The Somali Question:

Somalia lies to the east and southeast of Ethiopia, with 2-main rivers, the Juba and the Shibeli flowing across the border into Somalia and to the Indian Ocean. Any attempt by Ethiopia to build hydroelectric dams in the large valleys through which the headwaters either of these rivers flow, would require the involvement and cooperation of Somalia. Dams built along the headwaters of these rivers have the potential to increase evaporation and seepage, possibly reducing water flow volumes into Somalia.

One possibility would be to explore methods and install technologies by which to increase precipitation over the watershed areas of the rivers that flow from Ethiopia into Somalia. An alternative approach would be to develop ways to reduce evaporation from the dams, perhaps by installing some form of UV-resistant cover that can float on the water surface.

During winter, prevailing winds blow over the Gulf of Aden toward northern Somalia and southern Ethiopia. During summer, prevailing winds blow from the Indian Ocean toward southern southwestern Somalia and southern Ethiopia. The present social and political situation in Somalia has stalled development of electric power and water resources.

Ethiopia's Challenge:

Ethiopia will need foreign investment to develop their vast capacity for cost-competitive electric power generation, energy storage and to introduce feasible methods by which to increase precipitation. The market for cost-competitive renewable energy will include such nations as Sudan, Egypt, Kenya, parts of Europe and parts of the Middle East along with potential to export electrical energy as far south as South Africa. Ethiopia will need to balance the volume of water it will store in their future reservoirs while ensuring that sufficient volumes of water flow downstream, for the benefit of other nations.

Ethiopia will need to negotiate cooperative agreements with neighboring nations that will include Eritrea, Somalia, Sudan, Kenya and Egypt. There have been serious political tensions between Ethiopia and Eritrea and also between Ethiopia and Somalia. Ethiopia's plans to develop their potential hydroelectric resources have become a cause of concern for neighboring nations downstream along the Nile. A neutral outside mediator could assist in developing mutually cooperate agreements between Ethiopia and several other neighbor nations.

China is assisting Sudan in the development of their oil industry, China has assisted in the development of an automobile factory in Egypt and several other African economies to develop various other manufacturing industries. China, South Africa and several European nations administer a neutral foreign policy across Africa and the Middle East while pursuing mutually cordial diplomatic intergovernmental relations with governments in that region. China and South Africa are in a position to fulfill the role of a neutral mediator with the objective that Ethiopia may generate electric power for local use as well as for export to neighbor nations while assuring that sufficient water volumes flow from Ethiopia into the Nile, Atbara, Juba and Shibeli rivers.

Attracting Foreign Investment:

Ethiopia's economy and population neither has the means by which to fund the development of electric power generation capacity inside their nation, nor does it have the capacity to subsidize the operation of photovoltaic installations or other forms of energy conversion. Economic conditions would restrict a future power industry in Ethiopia to operating unsubsidized, feasible power generation technologies and export a substantial amount of that power to neighboring nations.

The willingness of Ethiopia's government to allow private power generation to operate in their nation over the long term, with property protection rights will determine the future development of potentially feasible renewable power generation technologies across that nation. Such a condition would set the stage for investors from across the Middle East and Asia to consider the option of developing viable renewable energy power generation in Ethiopia.

Conclusions:

There is increasing demand for electric power across Africa, Europe and the Middle East with an evolving preference for feasible power from renewable sources, especially hydroelectric. Africa has much undeveloped potential for seasonal hydroelectric power along the headwaters of rivers that flow from the Ethiopian Highlands, Inga Falls on the Congo River, valleys along the Zambezi River as well as undeveloped hydroelectric power in Nigeria. Investors and developers from India are already exploring the potential to develop the electric generation capacity of Nigeria in exchange for oil from Nigeria.

The development and operation of mainly seasonal hydroelectric power generation would require access to seasonal energy storage, including pumped hydraulic storage in land depressions such as the Danakil, the Qattara Depression and the Dead Sea. The latter 2-land depressions have been the subject of much research related to power generation and energy storage. The advent of high-efficiency, high-capacity HVDC power transmission technology opens the door to future development of renewable energy resources in Ethiopia, along the Congo River, Zambezi River along with seasonal energy storage.

Hydroelectric development in Ethiopia will have to include methods by which to increase rainfall from the humid summer air, to ensure neighbor nations downstream of sufficient water in rivers that flow from Ethiopia. A neutral mediator such as China could assist Ethiopia and neighboring nations to resolve differences and concerns while cooperating to their mutual benefit to develop renewable power generation and a power transmission system across the region. Peak hydroelectric power generation in Ethiopia would coincide with peak demand for electric power in the neighboring nations.