Back to the Future
In 1882, Thomas Edison opened the Pearl Street Station in Manhattan. As well as the first central power plant in the US, with local generation serving just 82 customers, it was effectively the first of many local microgrids. Over the next century these early microgrids expanded and grew into regional and national grids, becoming in the words of the US National Academy of Engineering,
“the greatest engineering achievement of the 20th century.”
storage such as Saft’s intensium ® Yet, while our current electrical gridscontinuetobringmajorbenefits Max containerized systems provide tobillionsofpeopleacrosstheglobe, a number of functions including thedemandformorepowerispushing maintaining grid stability as well as themtotheirlimitsinbothsizeand smoothing the output of renewable complexity.AsPhillipF.Schewesays energyresources. inhisbook‘Thegrid’:“Constructed of The main difference between intricately interdependent components, microgrids and traditional grids is the grid operates on a rapidly shrinking thattheymaintainacloserproximity margin for error. Things can, and do, go betweenthepointsatwhichelectricity wrong in this system, no matter how isgeneratedandwhereitisconsumed, many preventive steps we take. Just look eliminating the need for it to be at the colossal 2003 blackout, transmitted over long when 50 million Americans lost Electrical grids: distances. Microgrids power due to a simple error at a also provide effective “the greatest power plant in Ohio; or the one integrationwithabroad a month later, which blacked engineering range of renewable out 57 million Italians. And energy sources such achievement of assolar,windturbines, these two combined don’t even compare to the 2001 outage the 20th century” smallhydro,geothermal in India, which affected 226 and waste-to-energy million people.” plantaswellaswithcombinedheat Today, the desire for resilience andpower(CHP)systems. andautonomyofsupply,alliedtothe The main way of characterizing increasing need to deliver reliable microgrids is not so much by their and cost-efficient power to remote size as by their functionality. They off-grid communities, is driving a arebecomingincreasinglyimportant reassessment of the way that grids fordeliveringelectricitytoremoteor are configured. The result is that inaccessibleareasthataretoocostly, microgridsarefirmlybackinfavor. time-consumingordifficulttoconnect Modernmicrogridsbringtogether tothegrid.Typicalapplicationsinclude a variety of distributed energy islands,villageelectrificationprojects sources (including generation, orremoteminingcommunities. demand management and energy There is also growinginterestin storage) and loads, operating them using grid-connected microgrids, inacontrolled andcoordinated way comprising a mix of conventional either independently or as part of a generationandrenewablegeneration largergrid.Withinmicrogrids,energy sources,toensurecontinuityofsupply
andtoprotectagainstpotentialgrid faults and emergency situations. Here,thecapabilityofamicrogridto separate and isolate itself from the maingridisattractiveintheeventof natural disaster or cyber disruption formission-criticalapplicationssuch as hospitals, university campuses, industrialfacilitiesandmilitarybases. D i e s e l g e n e r a t o r s a r e t h e traditional mainstay of microgrids. However,withthecostofrenewable plantscontinuingtofall,microgrids a r e n o w e m b r a c i n g m u l t i p l e generationsources.Creatingschemes in which diesel generation and renewablescomplementeachoffers considerablesavingsintermsofthe costsoffuelpurchase,transportand handling as well as maintenance, sincethedieselgensetsarerequired to operate for fewer hours. There arealsoenvironmentalbenefitsfrom reducedgreenhousegasemissions.