The buzz in energy efficiency these days is trigeneration: waste heat is not wasted but used for heating or cooling. To see such a facility on the continent, you have to visit MTN’s headquarters in Johannesburg’s northwestern suburb of Fairland
Trigeneration is the concurrent production of electricity, heating and cooling. The technology can provide power, hot water, space heating and air conditioning from a single system. It is efficient because it avoids the losses associated with the transporting of electricity. It also captures waste heat that would normally escape.
“MTN’s trigeneration facility is the first of its kind in Africa and possibly the world,” said MTN’s core implementation manager Willem Weber.
Bright-red piping carries natural gas through the MTN facility and leads to an engine room where monstrous green generators roar away, turning the gas into electricity. The excess heat, at some 400°C, is captured and used to operate an absorption chiller, which, like a fridge, creates cool water that is used to power an extensive air-conditioning system.
Furthermore, water from six cooling towers is used to cool down heat from the engines. Not to be wasted, this water is later used to flush toilets on the campus.
Weber said MTN was forced to think out of the box when it came to finding a viable power source for the campus, which requires the power of 400 households. “We discovered a substation for an FNB building in the area was being built and we asked to join on to that supply,” he said. But when they learned the power would only come online in 2011 another plan was needed.
Subsequently, MTN’s innovative trigeneration technology was the first of its kind to register with the United Nations Framework Convention on Climate Change for carbon credits. It is unique because it uses heat to generate cold water without using electrical energy in the process. Other trigeneration systems simply use the waste heat to heat another system.
Going green may be a good idea in itself but, in a competitive industry such as telecommunications, it has to make business sense. MTN’s headquarters uses two gigajoules of methane — equivalent to two megawatts (MW) of electricity — to produce 3MW of power. Some 1.6MW of this energy is needed for the air conditioning alone. The entire campus requires 7MW — the remainder of which is sourced from the grid.
The generators at the trigeneration facility give off 40% of the carbon that normal grid power does and it costs about 65 cents per kilowatt hour — more than 30 cents cheaper than units of conventional electricity — and will be even more cost-effective when another 25% annual tariff increase comes into effect this year.
It is certainly not just about the corporate image, Weber said. “We had to prove why it was financially viable.”
Natural gas is clean-burning and offers a consistent supply, but simply using this to generate electricity, Weber said, would have been too expensive.
“We had to find a way to make it a workable business plan.”
Launched in October 2010, the model’s return on investment, of R22-million, is two and a half years. The contract arranged with Egoli Gas, which buys Sasol’s natural gas piped from Mozambique, was also fortuitous and a 10-year supply was secured at an excellent price.
“The telecoms industry is very competitive and we need to focus on where our costs [such as power] affect the consumer. One cent difference on the cost of a megabyte makes you obsolete,” said Weber.
MTN’s competitor, Vodacom, will also launch an energy-saving structure, which is being dubbed “the greenest building in Africa”, based in Midrand. It will reportedly be carbon neutral and experiment with renewable technologies.
MTN said its project was a learning curve. A new facility, which will be launched in Centurion in two months, will use a new and improved trigeneration model Weber believes is far more efficient.
Weber said MTN was also looking into a business model around generating electricity from discarded macadamia nut shells in Nelspruit, a major producing area, where there are tonnes of discarded nut shells.