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The power of the unknown:Geothermal energy in Zimbabwe

Global efforts to eradicate dependency on finite fossil fuels have ushered renewable sources of energy to into the spotlight. Renewable energy is a clean, non-depletable source of energy, which has a much lower environmental impact than conventional energy sources. Renewable energy guarantees sustainable future energy supplies without jeopardising the environment and the future of generations to come.

The Zimbabwean economy has for several years, been faced with power challenges and shortfalls. The power production capacity of the nation has failed to meet the current level of consumption and demand. This shortfall has led to the unreliability or non-existence of supplied electricity. Recent pronouncements by the Government of Zimbabwe of its target to achieve upper middle-income economy status by 2030, have enhanced the demand for energy. Most of Zimbabwe’s electricity is generated by five power producing plants that are situated across the country. The following information in this regard has been provided by the Zimbabwean Power Company:

Power Plant Energy Source Installed Generating Capacity Generation Statistics as at 27 March 2019
Kariba South Power Station

 

Hydropower 1050MW 927MW
Hwange Thermal Power Station

 

Coal 920MW (current expansion project will increase generation capacity to 1520MW) 232MW
Bulawayo Power Station

 

Coal 30MW 0MW
Munyati Power Station

 

Coal 100MW 0MW
Harare Power Station Coal 50MW 15MW

As demonstrated above, Zimbabwe’s power plants are not generating at their capacity. The power stations have passed their lifetime of 25 years and poor maintenance has left them derelict. In order to cater for the national deficit, the country relies on imported power from South Africa and the Hydro Cahora-Bassa of Mozambique.

There is a need for Zimbabwe to accelerate the development of its renewable energy options. An alternative and reliable form of energy which we recommend for consideration is geothermal generated power. Geothermal energy is a form of renewable energy which can produce sustainable electricity using the Earth’s own resources. It is generated and stored in the Earth and can be captured from hot water springs or reservoirs located near the surface of the Earth. These hot springs are found where water percolates into areas of volcanic activity in the Earth’s crust and becomes superheated before forcing its way back to the surface. Heat derived from the hot water can be converted into electricity through electromagnetic induction. Geothermal heat can provide electrical power that is not dependent on weather conditions, making it a reliable renewable source of energy. Given climate change, hydropower has become very unpredictable as droughts continue to sweep across the nation. Wind and solar energy are also extremely dependent on weather conditions, whereas geothermal power can be accessed through hot springs and is readily available 365 days a year.

Little to no exploration studies regarding this renewable form of power have been conducted in Zimbabwe. Although estimates have been made as to its generating capacity, not much is known about its true potential. The nation has several thermal hot springs situated in Binga and Manicaland. There are over thirty known sites in Zimbabwe where hot water issues from the ground. The heat generated from the hot springs can be used to generate electricity through geothermal power plants.

The three known types of geothermal power plants which convert thermal energy to mechanical energy and finally to electrical energy are as follows:

1. Binary plants

Binary plants pass geothermal fluid, that has a much lower boiling point than water, through a heat exchanger, causing the fluid to turn into vapor and drive a turbine.

2. Dry steam plants

Dry steam plants take steam out of fractures in the ground and divert it directly to a turbine these are the oldest type of geothermal power generation plants.

3.Flash plants

Flash plants are the most common and pull high-pressure hot water into a cooler, causing the fluid to rapidly vaporize or “flash” resulting into an emission of steam which is then used to drive a turbine.

Binary plants can exploit low temperatures and do not release geothermal fluids, or environmental hazards into the environment – making them the most preferable mechanism for geothermal power generation in Zimbabwe. Other innovative ways in which geothermal power can be generated are through the conversion of waste heat from industrial processes, power stations and transportation, into electricity through engineering that will permit the thermal (heat) energy produced from the waste to drive a turbine.

According to the Independent UK, Kenya is currently the largest geothermal energy producer in Africa. Kenya’s geothermal power contributes over 40% of the country’s electricity generation. The East African nation has successfully harnessed its geothermal capabilities – generating 45 MW in 1985 and now generating an estimate of 630 MW with nearly 400 MW of that production coming online since 2014. Kenya began exploring geothermal power in the late 1970s and according to the Geothermal Council Resource (a United States industry association), the rise of Kenya’s geothermal industry ranks ninth in the world. The Infrastructure Consortium for Africa and the United Nations Environment Programme has estimated a potential of 20 000 MW of geothermal energy across Eastern Africa and nations such as Tanzania, Uganda, Rwanda, Djibouti, Eritrea and Comoros have done preliminary exploration for geothermal potential. The challenges faced by many African countries in the harnessing of their full geothermal potential are lack of technical expertise, poor governance and corruption – factors which all tend to hinder big infrastructure projects in developing countries. A further impediment is funding for project costs. Tapping into geothermal potential will be a long and expensive process that will involve very special expertise, requiring scientists to do geological, geochemical and geophysical surveillance. Notwithstanding, Zimbabwe’s positioning on the Great Rift Valley of Africa is ideal for geothermal exploration as most geothermal developments occur in tectonically active areas. The valley is also known to hold over thirty active volcanoes and countless hot springs.

The key to our economic revival is inextricably tied to increased dependable, affordable and widely distributed power. The potential of energy available pulled against the populations dire need, demonstrates the importance of considering other forms of power generation in Zimbabwe. It is time to consider advanced research and data acquisition of geothermal power and development, so that we may decipher its capabilities and possible negative impacts. Zimbabwe is well endowed with power generation possibilities. If the nation continues to be mired in dependency and debt due to power importation, it is unlikely that the economy will achieve upper middle-income status by 2030.

Author: Lisa Dutiro