One application of distributed energy (DE) is minigrids, a set of generators and load-reduction technologies that supply the entire electricity demand of a localized group of customers. By avoiding the cost of transmitting electricity from a distant central-station power plant or transporting fuel from a distant supply source, a minigrid (sometimes called a "microgrid") can significantly improve the economics of meeting energy needs using DE.
Distributed generation involves adding modular electricity generators close to the point of consumption on a power grid. Minigrids typically use the same technologies employed by electric utilities in distributed power applications, but they are not always connected to the central grid. In some cases, the generators and other distributed resources are installed to relieve utility constraints on the existing grid, with the intent to possibly disconnect these generators and their load from the grid at a later date. In other cases, an electrically isolated minigrid is created; this minigrid may then be integrated with the central grid if that option becomes attractive. The point is that the generators in a minigrid are capable of serving their load independently.
Using a mix of generating and demand-side management technologies gives the power supplier the flexibility to meet a wider range of loads.
For an example of a cost-effective application of DE using a combination of energy efficiency measures, cogeneration of electricity and hot water using fuels cells, and power generation using wind, PV, and backup diesel generators for emergencies, see the Block Island case study (PDF 210 KB). Download Acrobat Reader.
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