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MTN unveils giant cooling solar plant

By Lwavela Jongilanga, Portals journalist
Johannesburg, 10 Jul 2014
The 484m^2 plant will reduce MTN's carbon footprint and substantially reduce its electricity consumption.
The 484m^2 plant will reduce MTN's carbon footprint and substantially reduce its electricity consumption.

MTN yesterday unveiled what it calls the first cooling plant in Africa, housed at its Roodepoort head office in Gauteng.

According to the telecoms operator, the cooling plant will power its data centres in continuation, with its aim to reduce its carbon footprint.

The system is driven by a technology called linear Fresnel concentrating solar power that uses heat generated from the sun and has a peak cooling capacity of 330kW.

It consists of 242 solar mirrors covering a total area of 484m^2, which track the sun to generate pressurised hot water at 180^0C. The hot water in turn powers an absorption chiller that produces chilled water circulated into the data centre for cooling of IT equipment.

The mirrors follow the movement of the sun, based on the GPS location, orientation and the date and time. This information guides the system to track the sun to concentrate on the central absorber tube where heat is generated.

The absorption chillers use a lithium bromide water solution which uses water as the refrigerant.

When it rains, the mirrors move into a self-cleaning position, and on cloudy days, the mirrors turn down into a protective stow position.

Speaking at the unveiling, Andreas Kuenne, minister of economic and global issues at the German Embassy, said this is an important milestone for Sub-Saharan Africa. "Renewable energy is top of the mind not only in SA, but around the world. President Jacob Zuma emphasised in his recent state of the nation address the importance of renewable energy and energy security for SA."

Cooling circuit

Chiller cooling capacity: 330kW
Type of chiller: double-effect hot water
Hot water temperature: 180^0C->160^0C
Hot water flow rate: 10m3/h
Condensing water temperature: 32^0C->25^0C
Condensing water flow rate: 69m3/h
Chilled water temperature: 11^0C->6^0C
Chilled water flow rate: 56m3/h
Chiller operational weight: 6.9tons
Chiller thermal efficiency: 1.4 (at nominal condition)
Chiller electrical consumption: 3.2kW
Chiller electrical COP: >100

Olu Soluade, MD of AOS Consulting Engineers, said the development of sustainable solutions and the implementation of technologies for the benefit of mankind is the prerogative of all.

"The continuous commitment to the reduction of our carbon footprint is the hallmark of sustainable development administered by professionals," he said.

Gabriele Eichne, project manager for renewable energies at German-based Dena, revealed this project is part of the worldwide 'Dena Solar Roofs Programme' coordinated by the German Energy Agency and supported by the German Federal Ministry for Economic Affairs and Energy.

The system was designed by REACH Renewable and AOS Consulting Engineers.

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