Decentralization gets straight to the point
Electricity in most countries is produced by large centralized power stations, which is then delivered to the point of consumption via a national power grid. But imagine a scenario where the end consumer is in a remote location and unable to access power from the grid. Or perhaps the consumer is an industrial user that has a need for heat and also wants to benefit from the security of producing its own power. Certainly there is the growing problem of grids becoming increasingly overloaded and unable to transmit any additional power that may be needed. In these situations, generation at the point of consumption is the perfect solution and is, in fact, sometimes the only option. This generation of power – sometimes combined with heat – at the point of consumption is the basic concept of decentralized energy.
Decentralized energy – lower transmission losses
Decentralized energy goes by many names. It is also sometimes known as distributed generation, on-site generation, self- or captive generation or embedded generation. Decentralized energy has some key benefits over large centralized generating facilities. Where there is a requirement for electricity only, large centralized plants often produce cheaper electricity than typical sources of decentralized generating sources such as wind, mini hydro, fuel cells, solar, small gas- or micro-turbines or reciprocating engines. Yet overall, there can be cost benefits. Transmitting electricity over long distances results in large transmission losses and high capital costs for the grid. Transmission costs can sometimes account for as much as 20 to 50 % of the costs of electricity.
Large plants also need spinning reserves to cover potential power plant trips. The reserve needs are typically 10 - 20 % above the peak consumption. Further, there is the issue of pollution from large power plants located close to cities. Decentralized power plants are small and can thus to be located at the point of consumption with limited environmental impact. Their size also means that often they are the only option where power is needed in a remote location that does not have access to a national grid.
Efficiency
Decentralized energy sources, combined with the large centralized power plants, can substantially improve the overall efficiency of a power grid. In such a scenario, the centralized power plants and the grid system can be sized for the baseload of the system, whilst the decentralized energy sources provides the seasonal and daily intermediate and peak load of the system.
But where decentralized energy really comes into its own, is for industrial and commercial applications or district heating i.e. where there is a primary requirement for heat. In this application, the use of reciprocating engines fuelled by gas or oil is the most efficient and proven solution. Decentralized power generation based on reciprocating engines offers electrical efficiencies of around 45% compared to about 30% (after transmission losses) of centralized power stations. When the heat from the fuel conversion is also utilised, the overall fuel conversion efficiency increases to more than 85%, thus reducing CO2 emissions and costs.
