Developing decentralised, distributed generation
Many countries in developing nations created power generation networks based upon large centralised power generation stations with significant investment in power transmission and distribution networks. From the African context this has not happened yet there is a huge need to increase power generation capacity. The thought of addressing this through a small number of large gas, pharm hydro, coal or nuclear-fuelled power stations seems attractive at first, however the goals of supplying power for all in Africa, could be better addressed with de-centralised distributed generation, lots of smaller localised power stations, addressing electrification needs quickly.
A challenge with large centralised power stations is how to maximise the energy content of the valuable fuels. Coal power stations may convert energy in the fuel to only 40% electricity. With the most modern efficiency gas-turbine power plants this may be increased to 60%. All of the remaining energy is lost through heat. In addition, further power losses occur through transmission lines, where moving electricity from point of generation to user, can be as much as 2%. The investment in this transmission infrastructure is also significant as well as time consuming and poses its own challenges.
Developing countries are now moving towards more decentralised power systems, producing power close to the site of use, reducing losses and improving energy efficiency. If it incorporates a combined heat and power plant total fuel efficiency may be as high as 90-95% by using both the electricity and waste heat created during the production of power and utilisation of the original fuel. The heat can be used to generate steam, hot water or can be used directly in a drier or industrial facility. It can also be converted to cooling, though an absorption chiller. Industrial plants in Nigeria are moving towards CHP and trigeneration technology. Diageo’s Guinness Ogba brewery was one of the African pioneers.
If there is no opportunity for the deployment of biogas in a given area, an alternative would be to use natural gas or diesel. Both of these are costly fuels and are not renewable sources of energy. Therefore if these are used, then a key requirement for the asset is the maximisation of fuel efficiency. GE’s new ‘616’ diesel generator is a 2.5MW engine, that requires only 184g/kWh of fuel, meaning significant fuel savings and reduced carbon emissions versus established technology. This is currently being deployed for the first time globally at a major flour mill in Nigeria.