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There is no doubt that gas, alongside renewables, has an important role to play in meeting Africa’s future electricity demand
An increasing number of countries across the continent are planning to take advantage of low-cost renewables to build significant new electricity capacity. But to do that a lot of flexibility needs to be built into the power system so it can operate efficiently with high levels of intermittent renewables.
Wärtsilä Energy understood very early that increased flexibility was going to be the key enabler of the transition towards a renewable energy future. They developed market-leading flexibility technologies covering future-fuel enabled balancing power plants, hybrid solutions, energy storage and optimisation technology, including the GEMS energy management platform.
Fabien Cadaut, senior marketing manager for Wärtsilä Energy Business in Africa, explains, “Unlike unflexible gas turbines, gas engines have the flexibility needed to help integrate the massive projected expansion of renewables in Africa, because they are capable of responding to daily variations in demand and withstand the intermittent nature of renewables. To maintain a balanced system, flexible forms of electricity must be available to ramp up output at the same rate that wind or solar output fluctuates.”
Engine-based technologies provide the best response times to effectively adapt to sudden excess or shortfall in electricity production. Their modular format also means that they can be sized to meet specific requirements. This makes them easier and faster to install than larger gas turbine plants and facilitates expansion as energy requirements increase.
Gas turbine power plants on the other hand involve a continuous combustion process. They require a constant energy supply to generate consistent output. They are not adapted to operate on a stop-start basis, nor are they designed to cope with the intermittent nature of renewables.
Even if from a pure cost perspective, reciprocating gas engine and combined cycle gas turbine technologies offer comparable results, gas engine technology adapts faster to balance the intermittency and unpredictability that characterise addition of renewables into the power generation mix and thus facilitate their growth and integration into the system.
Systems need to respond across different time frames, from seconds to minutes. This is something that combined cycle gas turbine technology is not designed to do. Even if gas turbines can in theory provide some level of flexibility by being run at partial load, this mode of operation is very inefficient, driving up costs and carbon emissions.
On the other hand, flexible gas engine power plants are made up of multiple engines which can be fired-up instantaneously, these plants offer a large range in power supply availability which complements renewable energy without sacrificing efficiency. If a sudden rainstorm, for example, cuts the supply of solar energy and drives up electricity demand as lights are switched on, a number of internal combustion engines can be turned on within minutes to supply the required electric demand. They can be turned off just as quickly when the storm passes.
Finally, flexible power plants consume nearly 50% less water than similarly sized combined cycle gas turbine plants and 75% to 85% less water than a coal or nuclear plant with cooling towers. In a context of global warming and hydric stress, water consumption is a parameter that cannot be ignored.
Given its numerous advantages, it comes as no surprise that Wärtsilä’s engine gas technology is becoming the gas-to-power technology of choice in an increasing number of African countries. To learn more about the company's offerings, click here.