Renewable energy, and in particular solar energy, has been getting a bit more attention over the last couple of year. Not only because it lowers the carbon footprint of whoever is using it, but it is also cheaper.
Mobile operator MTN has taken that to heart, and installed Africas first concentrated solar cooling plant at their 14th Avenue Data Centre in Johannesburg. The plant will be used to power the air conditioning system for the entire building, saving it money and lowering their dependence on the local electricity grid.
You wouldnt normally associate a telecommunications company with energy efficiency, but this isnt our first renewable energy project. Our tri-generation plant installed a couple of years ago powers the very building we are in. We have a number of renewable energy projects, and have been recognised in the space, MTN said during a press conference.
The system consists of 242 solar mirrors covering a total area of 484 square metres, which track the sun to generate pressurised hot water at 180 degrees Celsius. The hot water in turn powers an absorption chiller that produces chilled water circulated into the data centre for cooling of IT equipment.
It is driven by technology called Linear Fresnel Concentrating Solar Power (CSP) and has a peak cooling capacity of 330 kW.
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, MTN explained.
The Solar Cooling Plant is a collaboration between MTN, Industrial Solar, Voltas Technologies and Luft Technik, and supported by the German Energy Agency (DENA)
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 (BMWi). We are happy that this innovative system generating green energy is now a part of the MTN strategy to reduce its carbon footprint. So this lighthouse project is a win-win-situation for all, said Gabriele Eichner from DENA.
An aerial view of the Concentrated Solar Panel system
For those that want a little bit more technical detail, the solar field consists of:
Number of Modules: 22
Module Dimensions (h,w,l): 4.5m, 7.5m, 4.06m
Primary Mirrors: Glass with metal support structure Number of Mirrors: 242
Mirror Arrangement: 2*11 Rows Mirror Area: 484m2
Control: Closed-loop Mirror Tracking: Uniaxial
Primary Motor Drives: 24V, 15W
Number of Motors: 22
Secondary Reflector: Highly Reflective Aluminium
Absorber Tube: Schott PTR 70 (vacuum)
Solar Loop Fluid: Superheated Water
Operating Temperature: 180°C Operating Pressure: 16bar
Specific Weight: ~28kg/m2
Specific Thermal Peak Power: 562W/m2 (at reference conditions)
Peak Thermal System Capacity: 242kW
Annual Gross Heat Production: 391MWh
Source
Examples of a concentrating solar power technology
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