Cellular major MTN South Africa has approved two gas-powered generation developments for its Doornfontein (1 MW) and Newlands (6 MW) sites, in Gauteng, based on the success of its 2 MW trigeneration plant at its Roodepoort headquarters.

MTN will expand this methane-powered plant by another 5 MW within the next two years, which will meet all its baseload heating, cooling and electricity requirements of its head offices.




The main drivers for the company’s expanding its alternative energy projects, including the recent launch of the linear Fresnel concentrated solar power plant at the Roodepoort main campus, are to reduce exposure to high electricity price increases and mitigate a potential future carbon tax.

“Our trigeneration plant is quadgeneration-ready, which means that we can install systems to capture carbon dioxide (CO 2 ) when a tax is announced. We aim to capture food-grade CO 2 , which is high quality and will reduce our return on investment period for the system to two years, or, failing that, industrial-grade CO 2 , in which case our return on investment will be about four years,” says MTN South Africa technical infrastructure head Willem Weber.




The triple requirements of reli- ability, availability and cost transparency are crucial for MTN, which has reported steady and strong growth in its data services, which leads to an increase in power consumption. The threat of high electricity costs limiting MTN’s potential to increase data services has led to its board investing significant time and capital to reduce its power consumption and secure cost-effective electricity supply over the long term.

Weber says MTN’s technology group, comprising technical teams throughout the world, facilitates the sharing of the teams’ experiences among one another, which helps to roll out effective technologies across the group’s footprint.

However, technologies and applications must each be individually validated for the specific operating environment in which they might be applied, as the different operating conditions and financial returns will impact on the applicability and viability of any technology, he emphasises.

Weber states that, under the King Commission rules, MTN South Africa has to provide financial and sustainability reports, which make the commercial viability and sustainability of any project crucial. He adds that all the projects are also audited against their initial design capacity, making proper design, cost effectiveness and operating performance crucial.

“Further, MTN’s shareholders are also putting pressure on the group to improve the environment friendliness of its operations and to decouple, where viable, the group’s growth from infrastructure constraints in the territories where we operate,” says Weber.

The gas-fired generation plant powers MTN’s mission-critical data centres on the campus, including those running its billing systems, indicating the importance of the plant and MTN’s potential use of alternative energy sources in future.

MTN is also investigating biomass gasification and coal-bed methane developments as alternative sources of feedstock gases, but Weber notes that prospects for security of gas supply are good and price-increase modelling done by the group indicates a materially lower price per kilowatt hour for gas than predicted electricity prices.

Two 1 MW General Electric Jenbacher internal spark ignition methane-gas generators produce electricity and heat at the main campus. The heat is then extracted from the machines’ oil, manifolds and exhaust systems to heat water. The heated water is also used in closed-circuit absorption chillers to provide cold water. The vacuum and chemical absorption chillers use hydrophilic lithium bromide (LiBr) to accelerate the phase change inside the chillers, which drives the cooling process, while the water and LiBr are reused in a closed loop.

Further, the water used by the plant’s six cooling towers is used as grey water to flush the toilets on the main campus. The trigeneration plant provides hot and cold water for the entire campus.

Base Station Power

MTN has more than 8 000 base stations in South Africa’s urban areas that have been hard-hit by electricity price increases and, therefore, it is developing plans to introduce more alternative- energy sources for these stations.

“We have completed several alternative-energy projects for our base stations, with a few of our base stations in the Kalahari, in the North West, powered by lead-acid batteries, wind and solar photovoltaic sources,” says Weber.

He adds that the technology team has noticed that wind tends to pick up in the evenings, offsetting the decrease in photovoltaic power to an extent, enabling the stations to run longer on renewable energy.

Weber says that MTN’s first few designs were overengineered, but this learning curve has enabled the company to roll out new alter- native-energy systems for the base stations quicker and more efficiently.

“We have detailed knowledge of environmental effects, such as changes to seasonal renew- able-energy generation patterns and how much power we can draw from the batteries during low-generation periods, enabling us to size the systems correctly for each base station.”

The 2 MW methane-fired plant took two years, between 2008 and 2010, to complete, but Weber says the 5 MW expansion will be completed in less than a year, owing to the knowledge and experience that have been acquired since then.

“We are a telecommunications company, not an infrastructure or engineering company. However, we were [going through] a learning curve and the implementations helped us to understand all the fine details of implementation, design capacity, generation, costs, operational variances and tax instruments that can be used to facilitate our moving off-grid. We believe we have sufficient knowledge in-house to ensure that our alternative-energy projects are efficient, cost effective, correctly sized and durable over the long term.”

MTN has also been testing the use of high- temperature salt batteries, specifically vanadium red oxide batteries, at its base stations to reduce electricity demand, as the cooling required to maintain lead-acid batteries uses up to 40% of a base station’s power.

Electricity-Supply Displacement

MTN’s going off-grid immediately enables another company to use the surplus power available from the grid, without any new infrastructure or increased power generation required, says Weber.

“Our main focus is business continuity and sustainability, but any new energy projects will help our country, which is struggling under the effects of a significant electricity crunch, subsequently limiting productivity and the easy growth of existing industries.”

Weber adds that energy will become more important throughout Africa as development and commerce increase, with MTN also participating in the fuel cell initiative by government agency US Agency for International Development, which promotes the use of hydrogen fuel cells in Africa.

However, while security of supply is important, the key criteria for successful alternative- energy projects, regardless of the location, remain the financial viability, reduced complexity and cost transparency of the projects across the supply chain.

“Reducing complexity helps us to maintain low mean times to repair, while maintaining high performance and utilisation of the technologies during operation is key to meeting return on investment targets.”

Over the long term, MTN aims to be energy independent, but Weber emphasises that each alternative- and renewable-energy application will be used only when they make economic sense and that MTN South Africa will continue using electricity provided by Eskom.

“Our goal is sustainability of our operations, from an environmental, commercial and energy point of view,” concludes Weber.