The Kenya Electricity Generating company has started the second phase of drilling steam wells at Olkaria that will propel geothermal energy as the main source of power as erratic weather makes hydro-generation increasingly unreliable.
KenGen is aiming to raise geothermal production from 150 megawatts or 14.2 per cent of total supply to 430 megawatts by 2014, with another 540 megawatts being added four years later. That would reduce dependence on hydro -power which currently feeds 72 per cent of energy to the national grid.
The 50 steam wells that have been confirmed to have a capacity of 280 megawatts will see the construction of four new plants, two each at the Olkaria I and Olkaria IV fields, that will be driven by the steam.
“Geothermal is a stable, environmental-friendly and relatively cheaper form of generation,” said Geoffrey Muchemi, the Geothermal Development manager at KenGen during the rigging of steam wells at the Olkaria fields, Naivasha, last week.
The current expansion of steam power is informed by a study by KenGen and energy consulting firm McKinsey & Company that shows geothermal, despite being capital intensive, is the cheapest and most sustainable energy option for Kenya.
“Projections show that hydro- power costs 12.5 US cents per kilowatt hour compared to 6.4 US cents for geothermal electricity,” the report says. The study ranks natural gas second at an average cost of 8.4 US cents followed by nuclear (8.6 US cents), coal (9.3 US cents) and medium speed diesel (10.2 US cents) .Solar was found to be the most expensive option, at 30-50 US$c/kwh.
When the second phase of the project is completed by 2018, geothermal power will be 970 megawatts, accounting for about 30 per cent of electricity produced. The ultimate goal is to make geothermal the base load – making up to 49 per cent of the total power supply.
The electricity producer has acquired two new electric rigs—the equipment that is used for drilling steam wells —at a cost of $24 million each. This is in addition to an old rig the firm had and three other contracted rigs.
The new diesel electric rigs consume 5,000 litres of diesel per day; cutting fuel charges by up to 75 per cent compared to the old diesel powered drilling shafts that require 20,000 litres per day.
The purchase of the rigs from Chinese based Dong Ying Haixin Petroleum equipment that have a drilling capacity of up to seven kilometres beneath the earth’s crust was informed by studies that show the deeper the steam well, the cheaper the cost of sinking it.
For example, the oldest steam well at Olkaria I with a depth of 1 kilometre produces an average of 2.5MW each; Olkaria II wells, 2.2 kilometres deep yield 3.5MW each; yet wells at Olkaria III with an increased depth of three kilometres generate an average of 7MW each. With an 800 metre increase in depth, the output at each of Olkaria III wells is double the capacity of Olkaria II wells. Some of the large and deep steam wells at Olkaria IV generate between 10-18MW of power each.
The current batch of wells will be drilled to a depth of 3 kilometes with vertical dimensions of 800 to 1,000 metres; each well taking about 50-55 days to complete. The phase two drilling will see KenGen sink 164 wells at a cost of $1.2 billion, financed by the ministry of energy. But a study is ongoing to establish the cost of setting up the power plants that will be fed by the wells.
When this geothermal dilation comes to fruition, the cost of electricity in the country may come down by about 50 per cent, owing to its affordability and tenacity in the face of current erratic weather patterns.
The country’s only independent power producer (IPP) in geothermal generation is OrPower4, which produces a total of 48MW from the Olkaria III reservoir.
In the Eastern Africa region, Ethiopia is the only other country to venture into geo-generation producing a total output of 8MW.