Cogeneration and Distributed Power in Africa
By: Alexander Marshall
With the focus on ensuring stable supplies of power in many African countries, the benefits maximising fuel efficiency are often overlooked. Fuel costs have increased over recent decades, and the need to maximise scare resources means cogeneration or combined heat and power (CHP) technology is now getting the recognition it deserves.
Cogeneration maximises the energy in a fuel by utilising not only the electricity that is produced by the generator but also the surplus heat for localised use. About 45% of the energy in the fuel is converted to electricity, with 45% being converted to heat – either in the form of hot water, steam, or hot air for drying. If both heat and electricity are fully recovered the total fuel efficiency is about 90% meaning fuel, cost and carbon savings for the end user. This technology can be developed further, if some of the heat is used to create cooling water, through absorption chiller technology, then a trigeneration system is created – also called combined cooling and power. This cooling can be deployed in refrigeration and air conditioning systems.
CHP is also a form of distributed power generation. Many developed countries outside the African continent have historically relied on large centralised power plants that rely on significant investment in transmission and distribution infrastructure. The inability to use all of the energy in the fuel at source, along with transmission losses means that many countries are moving towards distributed power generation. The African continent has the opportunity to develop its power generation network in different manner with a more distributed power generation system in order to give more efficient, reliable electricity supplies.
Cogeneration technology is now being deployed across the African continent. As a company Clarke Energy has supplied GE’s Jenbacher gas engine cogeneration systems into Tunisia, Nigeria, Tanzania and South Africa. Applications have included power plants for leading drinks brands, pharmaceutical, telecommunications and food companies. Businesses that have access to supplies of gas or have a current long-term allocation, can use their energy source more efficiently if it is used in a cogeneration unit rather than a boiler. A gas supply of 80,000GJ per annum could provide 1MW of electricity and 1MW of heat for onsite use.
With growing availability of gas on the continent, coupled with unstable domestic power supplies, the market for cogeneration technology is on the up in Africa.
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