“Geothermal energy is potentially the largest – and presently most misunderstood – source of energy in the world today.” Former U.S. Vice President Al Gore, Our Choice
Geothermal energy has been improving human lives throughout recorded history. The ancient Romans used it for heating their chambers and public baths. Native Americans used hot mineral springs for bathing, cooking, and washing clothes. Most people in Iceland use it to heat water and buildings. And now the Zambian company Kalahari GeoEnergy is looking to exploit geothermal energy as a dependable and renewable source of electricity.
Regions around the Pacific Ring of Fire have already added geothermal energy to their power resources. The heat source is near-surface magma associated with active volcanism, of which the surface manifestation includes fumadors and geysers. In Africa geothermal power production is also a reality, with current production in Kenya at approximately 600 megawatts with a projection of 2,000 megawatts by 2020. Other than volcanic areas, geothermal energy can also be found in sedimentary basins associated with significant faulting; this is what has been found in Zambia.
Energy Production in Zambia
Ninety six percent of power produced in Zambia is currently hydroelectric. But the industry has been affected by climate change during the last several years, both in reduced rainfall and increased evaporation. With a rapidly growing economy, requiring a greater supply of electricity, the country needed to diversify its power generation from such high reliance on hydroelectric production.
Sixty percent of Zambia’s energy goes to mining (largely copper). Mines cannot operate at full capacity with reduced or erratic supply, without the risk that they will close or go into a ‘care and maintenance’ stage, pending resumption of stable power supply. Many mine operators start looking elsewhere for extraction projects. Thus unpredictable energy production has the effect of destabilizing the economy.
Although geothermal energy will not be sufficient to supplement hydropower alone, it can become a fundamental component of Zambia’s energy equation. Compared to other sources of energy, geothermal is sustainable, renewable, and predictable – the earth’s core will not cool during human time. It is also dispatchable, in that it can be exploited at any time or all the time, which is not the case for other renewables such as solar and wind.
Exploration & Timing
Due to regional geography and hydrochemistry identified in the initial phases of the project, Kalahari GeoEnergy has focused exploration efforts on the Kafue Trough in southern Zambia. Following detailed geophysics, the company drilled five wells totaling 1,980 metres. The results indicate that the target can support a power generation project of at least 10 MW, and potentially greater. The key criteria required for a geothermal system are present: temperature, permeability, and fluid.
The company is planning to develop a 20 MW power project in two 10 MW sequential phases – a manageable size considering the experience of contractors, available finance, and the need to develop a comprehensive regulatory framework. Furthermore, this size of project may also be eligible for standardized renewable energy feed-in tariffs and power purchase agreements.
Power would be generated using the Organic Rankin Cycle binary process, whereby hot geothermal fluids are pumped from the reservoir through a heat exchanger and the cooled fluids are pumped back into the reservoir, thereby creating a sustainable operation. The heat exchanger contains a working fluid (normally a refrigerant) that has a low boiling point that flashes into steam. This is used to make mechanical energy that drives the turbine. The entire process is completely enclosed, so there are no emissions. The water temperature required for this kind of process was once 150ºC, but new efficiencies have reduced that necessity to 130ºC, as well as lowering production costs.
Kalahari GeoEnergy will drill three further test wells this year. If successful, the company will commence a feasibility study that could be completed by July 2017. If all continues to go well, they could have power production by mid-2019. The company has so far used their own funds and has been able to keep costs low.
After this target is developed Kalahari GeoEnergy has another target site about 150 km (100 miles) away. Success at one site could be replicated at this and other similar sites. Hypothetically, their thermal system model and application of binary power technology could be extended to other Karoo basins found throughout Southern Africa – which is the long-term goal of the company.
Meanwhile, the timing fits well with Zambia’s (and Southern Africa’s) power crisis. Although there are much bigger planned projects in the works, they are not likely to be operative until the mid-2020’s, which means that Kalahari GeoEnergy is well placed for its own success. They are the only geothermal company in the region and the only one on the continent, outside of East Africa.
Energy in Africa is a fundamental necessity for development, education, and health. In Zambia only 5% of the rural population has access to electricity and one third of the people have access to fresh, clean water. So an important initiative for Kalahari GeoEnergy is to improve the health conditions and consequent quality of life in target area communities.
Traditional community water sources are either seeping geothermal fluids or contaminated wells. The geothermal fluids seep out of the earth in a series of hot springs with high mineral content (including those detrimental to health, such as fluorine). The wells are commonly contaminated with pathogens and residues from the activities of the local population. Cholera is prevalent. Kalahari GeoEnergy is testing a locally produced slow bed filtration unit to improve the quality of well water.
The company’s power plant will reject thermal energy lower than 90ºC. So the company is looking for potential secondary applications, including using the rejected thermal energy to pasteurize cow’s milk (70-80ºC) produced by herds in the vicinity of the plant. This could help strengthen the local community’s economy and prevent the drain of people to the cities.
In order to protect the environment, itself, and at the same time increase rural access to modern power, Kalahari GeoEnergy is also working on concepts for off-grid distribution, including fuel cells that would do away with the need for fixed power line infrastructure. The company believes that, like the step from land line telephones to smart phones, there will be cost effective ways of creating off-grid distribution.
The company’s project is sustainable in more ways than those above. Using a binary production system creates geothermal energy with zero emissions and a small visual footprint – a 10 MW geothermal power plant is about the size of two tennis courts. And geothermal energy never runs out. With hot water pumped out, stripped of its heat, then pumped back into the reservoir to reheat, the cycle can repeat forever. The biggest visual impact would be the transmission poles to connect the plant to the grid.
As the company’s CEO, Mr. Peter Vivian-Neal, observed in a recent interview, “We’re not depleting the planet. Our grandchildren will still have this resource.”
Written by Susette Horspool
Visit For More www.kalaharigeoenergy.com
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04 December 2014