BY ZEKARIAS WOLDEMARIAM
After waiting for more than a decade Ethiopians are now lucky to see the second turbine at the Grand Ethiopian Renaissance Dam (GERD) start generating electric power. Construction of the GERD started in March 2011 with a capacity of generating 6000 megawatts of electricity. Built on River Nile, the longest river in the world and the second largest in its water regime in Africa, the power plant is one of the largest in the continent.
The dam has 16 turbines each with a capacity of producing 375 megawatts of electric power. With the filling of water in the dam for a third year now, two of its turbines have already started generating electricity. It is worth celebrating the starting of power generation as it is in the minds of each Ethiopian who have participated in the construction in different ways.
Some have contributed money while others contributed ideas and moral support. It is a project beyond a power generation plant. All the benefits obtained from it are always in the minds of the people, the owners of the project.
The government and the people expect not only energy but also the economic and political progress that it brings about with it.
Indeed Ethiopia is endowed with vast resources for energy development. It can generate electricity not only from its rivers but also from solar, wind and geothermal power among others.
The government is doing its best to exploit all these resources as much as possible. Yet due attention is given to the development of hydroelectric power. Accordingly, various hydroelectric power plants have been operational in the country for decades. Still, various new projects, including the GERD are underway in the country.
The Ethiopian Herald had a brief stay with Aytenew Kidane, electrical engineer and energy development consultant to find out how worth it is to focus on the development of hydroelectric power compared with solar and wind.
Because our country is a developing country aspiring to industrialize its economy what kind of energy is the
best or prefer to invest in?
For a country like Ethiopia, where there is a rich natural resources, efficiency and Human Resource, hydroelectric power is likely to be more fruitful. Water is available in high quantity and quality in Ethiopia. Many rivers flow around the year in the country. They can generate power throughout the year. The water regime and the water discharge speed of rivers in Ethiopia make hydroelectric power highly preferable.
If we look at solar energy the efficiency is only 21%. Wind farms efficiency is only up to 65%. And their maximum efficiency is achieved after investing a huge sum of money.
The other drawback of wind and solar energy is that the availability of the human resource in the country is not based on solar and wind farm technology. The majority of the human resource in the country at the moment is well versed in the development and management of hydroelectric power plants than solar and wind power plants.
In addition, the maintenance, protection and repair cost of solar and a wind energy plants is extremely difficult. In countries that are rich in finance and technology, such plants can be cleaned by robots. But we cannot deploy robots as we do not afford them financially and technologically.
If we take a wind farm there is a large number of gears, induction motors … etc. This incurs a huge expense and human resources for maintenance. Therefore, since we are endowed with water and human resource and as long as its 98% efficient, it is durable up to 75 years. Hydroelectric power is the most preferable source of on-grid electric power.
Even for off-grid power, it is highly feasible. There are many types of schemes for off-grid plants.
In addition, there is an adequate amount of rainfall in our country the whole year round. It can also be conserved. But no one can conserve sunlight. Hence, there are a lot of costs to store the electricity generated with the small duration of sunlight.
In the same way as the sunlight, people cannot store wind. Therefore they can generate energy only when there is wind. Otherwise, they have to store the energy generated in a storage device, a battery. Along with that, it is important to keep in mind that the battery that is used to store the power generated by the wind or solar power plant is a high environmental pollutant.
The control system for a wind farm is very sophisticated that it is not cost-effective for countries like Ethiopia. The available human resource in the country to handle wind farm is also limited. Therefore we have to continue our focus on hydroelectric power.
In general, you cannot compare solar and wind energy plants with hydroelectric power plant which is 98% efficient, and cost-effective. It can be developed both at mega scale, micro scale, on the grid and off-grid.
How can we know the effectiveness of hydropower plants for off-grid purposes and small-scale uses? Are they tried in our country?
Yes, there are some small-scale hydropower plants in many places in Ethiopia. They are built on small rivers and they generate power up to 10 megawatts.
Hydroelectric power is dependent on geography. Transporting energy to distant places causes loss. So how can we manage the loss of energy during energy transportation to long distances?
One of the limitations of hydroelectric power is that it is dependent on location. Therefore, you have to transport to the place where it demanded. During the transportation of electricity, there is a loss. However, the amount of loss has an international standard. If the amount of loss is beyond standard the system is not acceptable.
The international standard is set by International Electric and Electrical Engineers (IEEE). According to the international standard, up to 12% of loss is tolerable as it is the outcome of resistance. But if the loss exceeds 12% the system needs to be redesigned.
One of the causes of loss is when the cable that used for transportation is highly resistant. When it travels a long distance the resistance increases. We cannot change the resistance nature of the cables. That’s natural. The longer it travels, the resistance increases and so does the loss.
In such cases, we can use various hacks like increasing the voltage so that it can reduce the resistance. If the resistance reduces, the loss also reduces. We can also increase the thickness of the cables which will reduce the resistance and then the loss of energy.
Furthermore, we can also reduce loss by raising the voltage during the energy production at the power station.
Compared with other energy sources, how much is the cost-effectiveness of hydroelectric power?
The investment cost-effectiveness is not comparable. It is highly cost-effective. The amount of investment per megawatt of electricity with solar power and wind power is very expensive as compared with the same megawatt of electric power generated by hydroelectric power.
In addition, one can also compare the relative advantage of hydroelectric power over solar and wind power is the capacity to carry a load. If there are a large number of users like people, businesses and other consumers in big cities, the effectiveness of electric power supply is measured by how fast can it reach the end users and satisfy their needs. Hydroelectric power can carry a large amount of load at a time. Since there is a large population in need of electric power supply hydroelectric power is preferable to serve the demand properly.
In terms of the economic benefit, does hydroelectric power still have an upper hand over solar and wind?
In terms of economic benefit, hydroelectric power is a blessing for Ethiopia. Other countries can build solar or wind farms if they want to. But they cannot build a hydroelectric power plant unless they have a river with the necessary level of discharge.
But if a country has a hydroelectric power plant it can also export it to the neighboring countries as it can travel long distances and carry big loads.
If wind and solar energy have less efficiency, why do some countries rush to build wind farms and solar energy plants?
As long as a country can access hydroelectric power directly or indirectly, it does not choose to build wind and solar energy plants. It is much easier if they import hydroelectric power from a neighboring country. But if you see some countries building solar and wind power plants it is only because the finance sources want to sell the equipment or technologies of solar and wind farms which are manufactured in their own countries.
What about using solar and wind energy in remote areas where it is difficult to reach through transporting hydroelectric power?
If there is no possibility of transporting hydroelectric power to a certain remote area, solar and wind energy can be sought as alternatives, but still, they have to carry the drawbacks mentioned like efficiency, running cost and maintenance cost, among others. In remote areas, the most probable users of off-grid solar and wind energy could be farmers or other individual households. So it is easy to imagine how these people can afford the investment as well as running costs, and maintenance cost and knows how to utilize them. Therefore, hydroelectric power transported from a distance still is the best option, while wind and solar can be considered as a last and most desperate options.
What do you recommend for the development of an off-grid energy supply?
To expand the effective off-grid energy supply in Ethiopia, the government has to amend the country’s energy retail policy. The policy allows the private sector to engage in the generation of energy but does not allow them to retail it themselves. It allows the retail of energy only in areas that it specified. This prohibits the private sector from innovating off-grid power generating solutions and investing in them. Otherwise, if the policy allows the private sector to retail power in any place of their interest it will create jobs for many people and speed up the electrification process in the country.
Thank you for your time
You are most welcome
The Ethiopian Herald August 13/2022
