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November 19, 2018

Raw geothermal steam can power plants at cheaper cost

Steam from a geothermal well at the Menengai Geothermal station in Nakuru seen during a visit by Tanzania officials .
Steam from a geothermal well at the Menengai Geothermal station in Nakuru seen during a visit by Tanzania officials .

The government’s plan to create a special economic zone in Nakuru’s Menengai area is slowly taking shape with the launch of a project that uses direct heat from a steam well to power its operations.

The project includes a milk processing plant, a laundry, horticultural greenhouse and an aquatic fish pond which will be powered by heat tapped and channeled through pipes from the 30MW steam well.

Energy Principal Secretary Joseph Njoroge says the government is betting on the lower operational costs and the expected industrial accumulation to attract investments in the greenfield energy — the use of natural gas to run operations.

The increase in the steam technology is set to place Kenya in the same league as USA, New Zealand and Iceland countries that have diversified the use of geothermal energy away from traditional electricity generation for industrial growth.

“As an emerging middle-income industrial society, direct use of geothermal energy is the remaining big thing for our country. It is the game changer in which our wealth as a country will be generated,” said Njoroge.

He says the Menengai basin will be the country’s second geothermal energy-fed special economic zone after Olkaria in Naivasha from where about 280MW of steam has already been injected to the national grid.

Geothermal Development Company managing director Godwin Mwawongo says it is anticipated to be a critical job creation opportunity which will boost the country’s economy.

Kenya is endowed with massive geothermal deposits estimated at over 10,000MW, spread across the Rift Valley, parts of Homa Bay and Kwale at the coast.

The completion of the 30MW single largest geothermal well at Menengai is approximated to save the government billions of shillings.

As the project is now 80 per cent to completion, the government is now calling on investors and interested parties to put in more efforts for the uptake of the multi-billion project.

Experts say once the plant starts streaming to the national grid, many power bills especially in industrial parks will be reduced by more than 30 per cent.

The design concept for the plant unit is that the low pressure geothermal well will be used to provide the heating fluid.

The well then discharges at a wellhead pressure of 1.6 bar and 95°C. About 10 tons of brine (usually a solution of salt in water) at 95°C flows into a water bath where a stainless steel heat exchanger coil is used to heat cold water from 25°Celsius to around 85°Celsius per hour.

The heated clean water will then be used as a source of heat to the four applications.

The powered dairy unit is a milk processing unit that will use the heat from geothermal water to pasteurised milk.

The geothermal heated water at 80°Celsius is delivered to a 150 litres batch pasteuriser which uses electricity as a source of energy.

GDC business development general manager Paul Ngugi says the hot water is able to run a milk processing plant with a capacity of between 250,000 to 500,000 litres of milk in a day.

Ngugi, with over 17 years of geothermal expertise, says geothermal energy for milk processing would result in an energy cost reduction of up to 60 per cent.

Energy advisor at Usaid Africa bureau John Garrison says as more investors will be looking for an opportunity to grab the benefits of the direct use of geothermal, most products will be competitive in the markets thus lowering the price.

“The direct energy can be used to dry crops like maize and beans in big cereal farms and can run a full capacity abattoir processing plant,” said Garrison.

Garrison said so far if all the applications are well harnessed, it will be the first time for such direct geothermally powered applications to be used not only in Kenya but the whole of Africa.

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