Mega energy project in Nakuru to help farmers cut on production costs

A steam well at Menegai crater geothermal energy plant in Nakuru. The well is the main source of geothermal energy, which will be used for farm operations.

NAIVASHA: Farmers in South Rift have a reason to toss some mursik (sour milk) following some exciting energy development.

A State agency that deals in clean energy has come up with a source of energy that will help power their milk processors, greenhouses and fish ponds.

For the last two years, the Geothermal Development Company (GDC) and the US Agency for International Development (USAid) have been working tirelessly to establish how to utilise massive natural heat stored within the earth’s crust. And the big breakthrough has been attained.

Last week, senior State officials, top GDC managers and geothermal experts witnessed the first launch of geothermal heat expected to be rolled out in a massive scale for the benefit of farmers.

The Sh400 million project has conducted pre-feasibility studies that analyse cost-effective means of extracting geothermal energy for agriculture-related process, including drying tea, cereals, powering dairy pasteurisation, heating greenhouses and fish farms.

A key figure in the ambitious project, Brian Dugdill, a geothermal expert tells Smart Harvest that the use of geothermal heat to deliver energy will enable farmers and food processors increase production and improve food security.

“Energy is a big factor for farmers. So with this, they will undertake various processes at a cheaper cost. To realise this goal, we are seeking to leverage private and public sector partnerships to improve farming and agro-processing,” he explains.

The project hosted at Menengai crater geothermal field in Nakuru County, with an aim of demonstrating direct application of heat, will benefit potential investors and local communities.

Mr Dugdill says heat from the crater can be transported for about 10km from the source through pipes and interested farmers farming within that radius can negotiate with GDC for facilitation.

He says harvested steam can be piped to farmers’ doorsteps. Four of the lined up projects launched were geothermal heated greenhouse, geothermal heated aquaculture ponds, geothermal powered dairy and geothermal powered laundry.

“The milk in the morning finds its way either through the informal or the formal markets. In the day, it’s easy to transport. But the evening milk doesn’t get to the markets because it can’t be cooled to enable it to be transported overnight to ready markets that are further away. That’s where this project comes in,” he explains.

COOLING PROCESSES

Dugdill says dairy homeowners who use electric powered systems will save up to 50 per cent by switching to a geothermal system.

“Nakuru town is one of the fastest growing towns in Kenya, where several industries are starting their operations. This provides vast opportunities for utilising the geothermal energy directly,” he elaborates.

The heating and cooling processes of dairy processing can benefit from direct utilisation of the geothermal energy in Menengai.

Better still, most dairy processing plants in Nakuru are situated close to the geothermal plants; thus, transporting the geothermal fluid from the source to the target location will be relatively easy.

“Geothermal wells have already been drilled close to some of these locations, and the use of geothermal fluid in the dairy industry can be considered a by-product while electricity production is the primary product,” he says.

He says the smallest single unit of geothermal powered milk plant can process between 250,000 to 500,000 litres of milk every day.

In far areas but rich in geothermal heat energy along Rift valley, coast region and parts of Nyanza, the expert says it is possible to drill shallow wells purposely for heat production and not electricity.

Bahati constituency which hosts Menengai crater, is one of Nakuru’s best tomato producers and with the introduction of this new system of farming, farmers will improve yield by more than 30 per cent, reveals the expert.

FORGET DIESEL BOILERS

According to GDC project manager, Martha Mburu, for the geo-mega dairy processing facility, geothermal energy can provide both thermal energy and even electrical power given the excellent geothermal resources found at the Menengai caldera.

This energy, she says, will displace diesel boilers normally used in Kenyan dairy processing plants.

“In the meantime, milk would be procured from Nakuru milk sheds using collection systems in concert with a producer milk grading and incentive payment scheme based on quality. Farmer-owned milk bulking companies would deliver raw chilled milk in insulated milk tankers to the plant within two-three hours of milking,” she explains.

The concept here is that a low pressure geothermal well is used to provide the heating water.

The well discharges at a wellhead pressure of 95 degrees centigrade that flows into a water bath where a stainless steel heat exchange coil is used to heat cold water from 25 degrees centigrade to 85 degrees centigrade.

At the dairy unit, the geothermal heated water at 80 degrees centigrade is delivered to a 150 litres batch pasteuriser away from the electricity pasteurisation as source of energy.

A feasibility study for a medium sized milk processing plant undertaken in 2014 showed that using geothermal energy for milk processing demonstrates that it will result in energy cost reduction of up to 60 per cent.

At the dairy unit, heated water from a nearby water bath is circulated around water tanks whereby raw milk is heat to high temperatures until all bacteria is killed. By-product is warm water, which may be returned to the well or used to clean milking equipment after being heated further.

INTRICATE PROCESS

“Remember that energy alone accounts for seven percent of the operation cost of a milk processing plant,” Dugdill says.

For decades, dairy farmers especially in the rural and undeveloped rural areas have witnessed millions of litres of milk go into waste due to lack of proper cooling storage system.

The geothermal energy will also come in handy in laundry systems. Heated water in the laundry will be used in the washers and dryers. This is how it will work. The hot water to the washer is mixed with cold one to the required temperature of the clothes to be washed.

“The electrical heating element in the dryer is replaced with a specially designed fan coil unit which uses geothermal heated water at about 80 degrees centigrade to ensure the clothes are dry,” explains Dugdill.

The aquatic ponds are heated to and maintained at 29 degrees centigrade for optimal fish metabolism hence enhanced faster growth. Here, the geothermal heated water is mixed with cold water to attain the required temperature.

Of interest, is how overflow water from the fish ponds, which contains fish waste is used for irrigation in the green house. According to Dugdill, the fish waste has useful nutrients for tomatoes hence reduces commercial fertiliser requirements.

Maintaining aquatic ponds at a constant temperature of 29 degrees centigrade decreases maturity period of fish from six to four months for Tilapia hence profitability is increased by more than 40 per cent. A single fish pond of five metres square carries approximately 1,000 fish at a time.

At 50 degrees centigrade, the heated water is circulated around the greenhouse to control the humidity at night, early morning and during wet seasons of the year where humidity inside greenhouses rises above 85 per cent.

The fertilised water is fed to the plants at controlled intervals throughout the day. The expert says greenhouse heating reduces use of fungicides by the reduction of humidity.

A constant optimum temperature inside the greenhouse results in the enhanced growth rate of plants as well as quality.

He reveals that greenhouses increases profitability by more than 30 per cent as well as increasing market share of the tomatoes due to the use of green energy.