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Saturday,October 24,2020 12:58 PM

Geothermal power a cheaper option

By Vision Reporter

Added 25th June 2006 03:00 AM

In the face of Uganda’s energy crisis, alternatives that increase the diversity of energy supply sources and capitalise on resources in different regions must be developed. Jennifer Austin explores one option.

In the face of Uganda’s energy crisis, alternatives that increase the diversity of energy supply sources and capitalise on resources in different regions must be developed. Jennifer Austin explores one option.

THE effect of the energy crisis on individuals and businesses is evidence of the importance of electricity in the productivity of the economy and everyday life.
Lack of electrification has also long been recognised as a major obstacle to development in rural areas. Todate, hydropower has been the main source of energy for electricity production in Uganda. However, it is clear that this reliance on a single power source is undesirable, especially when that source is dependent on climatic fluctuations.
The current short-term ‘solution’ to load shedding, which is to import large diesel generators, is both expensive and harmful to the environment. These generators burn diesel fuel which, like the burning of all fossil fuels, releases harmful gases that contribute to acid rain and smog and irritate the human immune system.
As the world population grows and countries develop, the demand for fossil fuels will continue to grow, pushing the price higher. At the same time, advances in alternate energy technologies are likely to make them more efficient and more affordable in the future.
Geothermal, literally meaning heat of the earth, refers to the huge amount of energy contained in the earth’s hot core, where temperatures range between 4,000 and 7,000 degrees Celsius. Scientists and engineers are constantly improving our ability to use that tremendous heat source in productive ways. Geothermal water can be used directly for heating and the hottest springs can be tapped to produce electricity in an efficient and environmentally friendly way.
Thermal energy is usually obtained through the burning of fuel sources. This heat is then used to create high-pressure steam, which turns generator turbines to make electricity. By tapping directly into a geothermal heat source, we can eliminate the need to burn fossil fuels to produce the heat and steam needed to make electricity.
Water deep beneath the earth’s surface is already hot enough that it ‘flashes’ to steam when brought to the surface, where the pressure is lower. This steam can be used directly to turn generator turbines to make electricity. In areas where the water is not as hot, it can be used to heat a liquid that boils to a gas at a lower temperature than water, and this gas is then used to turn the turbine to produce electricity. In both cases, the need to burn fossil fuels to produce the heat is eliminated.
A geothermal power plant sits right above its power source, ensuring a constant uninterrupted power supply, regardless of climate fluctuations or political unrest that can disrupt the supply of other power sources. Costs are saved since there is no need to buy fuel or transport it to the power station, and the harmful emissions and greenhouse gases produced by fossil fuels are eliminated. Geothermal energy can be used 24 hours a day throughout the year and as long as the deep underground reservoirs are managed properly, the energy supply is virtually inexhaustible.

Geothermal in East Africa
Estimates place the geothermal electricity generation capacity of East Africa as high as 2,500 MW. In Western Uganda, the hot springs around Lake Albert could produce as much as 450MW of electricity, which is more than the current power demand of the entire country.
Kenya has had geothermal electricity plants since 1981 and now has 129 MW installed, accounting for 10% of its power production. Kenya’s Ministry of Energy says it plans to increase geothermal capacity to 576 MW in the next 20 years.

In conjunction with donors, the Government of Uganda is carrying out technical assessments of the geothermal potential in three main sites in western Uganda, including Kibiro, Katwe and Buranga. Preliminary drilling and testing is nearly complete in Kibiro and in the early stages in Katwe. Development efforts in Buranga are still in the very early stages.
The results of these pre-feasibility studies will be compared to identify which of the three major geothermal areas is most promising for development. The next step in the process is to drill deep exploration wells, which are 2-2.5 km deep. If tests on these wells are positive, they can then be used for electricity generation. Three deep exploration wells will be drilled at the identified site for testing. This step will cost an estimated $15m. Funding for the next stage of development has not yet been identified. However, the World Bank has supported the early exploration and Government is applying for continued funding.
While most of the hydropower sources are in eastern Uganda, the geothermal hot spots are in the west, which makes them even more valuable for increasing the coverage of the electric grid across the country. Ministry of Energy officials estimate that a power plant could be up and running within 10 years. The initial plant would be about 40 MW and could be expanded from there to meet demand. Geothermal power plants have higher upfront building costs than traditional power plants, but are cheaper than hydropower plants.
They have reasonable maintenance and operation costs relative to other power stations and zero fuel costs. Per kilowatt-hour production costs are equivalent to hydropower production costs, with projections from the world energy assessment estimating that improved technology will reduce the generation cost to 1-8 cents per kWh in future, making it even cheaper than projected hydropower sources.

Environmental friendliness
The earth’s core is constantly radiating heat outward, so this energy is completely renewable. Unlike other renewables like solar and wind power, the energy source for geothermal electricity is constant and independent of weather or other climatic fluctuations, thus more reliable. Geothermal power plants do not emit any greenhouse gases or other harmful fumes.
The primary environmental concern would be groundwater contamination if the water pumped up from the geothermal reservoirs was released.
However, systems can be built to collect the used geothermal water and re-inject it into the reservoir. This keeps the water from escaping into the surface environment, helps maintain the water pressure in the well and allows the water to be reheated and re-used.
In the US and other places, geothermal plants have even been built within protected national parks. Kenya’s power stations, called Olkaria I, II and III, are located in Hell’s Gate National Park near Nairobi and cause little disruption to the land and animals.
Putting a geothermal plant in a wilderness could have secondary effects as a result of power lines and roads to the plant, although the plant itself does not take up very much space, and regular land use practices can take place directly around it.
Though much of the attention for large energy development is focused on building more hydropower dams near Jinja, preliminary studies suggest that geothermal energy resources in western Uganda could be another viable option for large-scale electricity production. Their location in western Uganda means they are well positioned to compliment hydropower production in the east to help supply the national grid and reduce Uganda’s dependence on hydropower.
Ends

Geothermal power a cheaper option

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