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Aah! GDC pasteurizes milk using geothermal heat

The Geothermal Development Company (GDC) has embarked on the use of geothermal steam to pasteurize
milk at its Menengai base in Nakuru County. This makes GDC the first such entity in Africa to deploy this technology.

Currently, the company is pasteurizing 1,200 litres per month exclusively for in-house use. This is a breakthrough with a high potential for scaling for commercial use. It heralds a new age of industrial processing using geothermal heat. In the current geothermal past model, GDC has registered a cost saving of 40 per cent.

“It’s a success. Geothermal heat is cost-effective and environmentally friendly,” says Eng Martha Mburu, GDC’s manager in charge of the Direct Use Department.

In geothermal parlance, “direct use” refers to other applications of geothermal energy apart from electricity. The industrial principle behind direct use is heat. Milk pasteurization is just one of the many industrial processes that can benefit from geothermal heat.

“Our pasteurizer was meant for research and marketing,” Eng. Mburu explains. “For the past six years, we have gathered interesting data and lessons. Now we’re confident that the future of milk pasteurization is through geothermal energy.”

Indeed. With this technology, Kenya is on the cusp of a paradigm shift in manufacturing. The success of a geothermal pasteurizer will translate to major savings in energy costs. Processors will no longer need to cut down trees for wood fuel or import heavy oil to heat boilers for pasteurization. From a carbon credit point of view, this shift will also be a big win for the environment.

If this technology is scaled, the future of energy and the economy is the Age of Geothermal. This projection is informed by various factors, including climate science and the attendant global movement towards a green economy. Geography too has handed geothermal a lead role to power the country’s future. Kenya has a geothermal largesse of about 10,000 MW. Fundamentally, geothermal’s availability factor of 95 per cent cements its space as Kenya’s anchor

For pasteurisation, Menengai is strategic. Nakuru is an agricultural hub with large-scale production of milk. The dairy
sector is worth Ksh. 10 billion. A value-addition facility, especially for stallholders, has the potential to revolutionize the milk supply business.

In fact, GDC is also seeing an opportunity to empower the milk value chain in the region. First, local cooperatives are
encouraged to start their own small and mid-sized pasteurization processors. This will curb milk losses especially in times of gluts. Unpasteurized milk has a shelf-life of three days.

“We will establish a bigger facility where local dairies can lease for a few hours to pasteurize their milk. That way, they don’t need the heavy initial capital,” Eng. Mburu says.

Direct Use Engineer Japhet Towett quenches his thirst with a cup of the freshly pasteurized milk at the Menengai Direct Use Pilot Project

Time is of the essence if this value is to be unlocked for commercial purposes. “We have to start early,” says Mr Japheth Towett, the GDC officer coordinating the pasteurization project.

In the morning, he leads GDC’s communication team to Rongai Dairy Co-operative Society to collect milk. Here, Mr Dennis Sang, the supervisor, is upbeat. He sees a future of guaranteed business.

“Any outlet for our milk is welcome. GDC pays cash for the milk. That’s good for the farmers because they don’t have to wait too long for payments,” Mr Sang says. “However, we would also want to diversify and start pasteurization of our own. We hope GDC can assist us.”

The milk is tested for integrity at the dairy and again at the pasteurizing unit.

“Quality is critical,” Mr Towett says.

His team then pours can after can into the pasteurizer. He then checks all the knobs and gauges. Satisfied, he switches on the pump to supply hot water to the pasteurizer. Soon, the machine starts humming as the agitator rotates calmly as it mixes the milk to ensure homogeneity.

“See?” Mr. Towett announces. “The inlet temperature is 70 degrees. That’s the hot water from the geothermal heat
exchanger. Then, the outlet is 63 degrees.” This shows that the milk is extracting heat from the hot water – an indication of pasteurization.

After two minutes, the temperature gauge starts to rise.

“We check the gauge every 15 minutes until it reaches the target of 67 degrees,” Mr Towett says.

After that, the hot water supply and the one exiting the pasteurizer are both stopped. This retains some hot water in the jackets of the pasteurized for 30 minutes to ensure maximum pasteurization. This water is then drained, and another inlet of cold water is allowed to circulate in the system to cool down the milk from 67 degrees to 40 degrees. After that, colder water from an ice bank is circulated again to cool the milk to four degrees. At that point, the milk is ready for storage – or drinking.

That was the point at which this writer could not resist the urge for a glass. Cold. Smooth. On a hot day, the glass is like balm to the body.

Milk pasteurization is a key plank in food security and responds well to the manufacturing pillar in the Big Four presidential agenda.

“This is just a start,” says Eng. Mburu. “There’s an abundance of heat here. It’ll change this country.”

Steam Edition 15 Digital Copy

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