precipitation and hydroelectric power

Gibe III; from peak water.

Construction on the Gibe III Dam in Ethiopia, the fourth largest dam in the world, began in 2006 and is a highly controversial hydroelectric project. Ethiopia should earn over $400 million annually from power exports, much of which will be exported to Kenya. Environmentalists claim that construction of the dam will further reduce human-available water supply in the already drought-stricken Gibe III region, which spans Ethiopia and parts of Kenya, as well as drastically reduce water levels in Lake Turkana in Northern Kenya. Dam-induced water shortages will be exacerbated by the erratic rainfall patterns predicted by climate change. Widespread protests over dam construction reflect disenchantment with both dams and hydroelectric power generation across Kenya, in part due to increasingly variable rainfall under climate change.

A child fishing on Lake Turkana, in Northern Kenya. Fishing
is an important source of income in this region and will likely
be hurt by the construction of Gibe III. 

Movement away from hydroelectric power coincides with increased power needs in Kenya due to  booming populations and higher per capita demand for electricity. Currently, less than 20% of Kenyans (and only 5% of rural Kenyans) have access to electricity, and frequent rolling blackouts due to electricity shortages are common throughout the country. Many businesspeople say that blackouts are one of the key barriers to economic growth.

In the face of the country's desperate need for energy, however, the source of this energy is in flux. Historically, most power production in Kenya has been hydroelectric, with dam-generated power supplying over 80% of the country's electricity at its peak. The largest power producer in Kenya, Kenya Electricity Generating Company, is curtailing its output from hydropower, choosing instead to rely more on other sources of renewable energy such as solar and geothermal. The company indicated that this shift will reduce their dependency on often erratic weather for power generation. With precipitation slated to become even more erratic, it is essential to diversify modes of power generation in Kenya in order to keep up with rising demand.

Climate change projections for the region suggest increased mean rainfall and increased variability in rainfall. While increased rainfall in the region could lead to increased capacity for hydroelectric power, due to the increasingly erratic rainfall patterns, higher electricity generation is likely unfeasible for most large dams. One approach to generate hydroelectric power from increased rainfall would be to increase storage capacity in existing dams, but this is an expensive endeavor. Some dams have successfully modified timing of discharge to accommodate increased variability in rainfall, but these approaches require substantial data on in-stream flow rates. Coupled with uncertainty in the predictions of rainfall amounts and variability, this approach seems too data-intensive for the majority of dams in Kenya.

A small hydroelectric dam in Kenya, from treehugger.com

While large-scale power generation on the Gibe III scale may be a thing of the past in Kenya, small power generation (~500 KW generation) can be used to help the government's efforts to increase rural access to electricity, and excess energy can often be given back to the National Grid. While these projects have a high installation cost, and often suffer from inadequate data on water flow in rivers, they can help increase electricity generation in rural areas that have not historically had energy. In addition, these efforts can help provide a source of water during dry seasons, mitigating the agricultural effects of increased variability in precipitation.

As Kenya moves away from large-scale power generation via hydroelectric power, toward energy production that is less dependent on erratic rainfall patterns, large dams may become less and less common. Given high variability in rainfall that has led to closing of hydroelectric dams due to low water availability, these changes will likely lead to a more consistent electricity supply, increasing Kenya's economic prosperity. In my next post, I will discuss how Kenyans are coping with changes in precipitation patterns in the context of another important component of Kenya's economic prosperity, rainfed agriculture.