IEEE Power & Energy Magazine - May/June 2014 - 75

Typically, in earthquake-prone areas,
the most suitable option to power microgrids is to rely on
diesel-fueled engine generators.

resulted in the loss of 51% of the actual generation capacity of
the country and inflated the costs of electricity to the end user
by almost 100% in march 2012.
Cyprus, being an island, has no electrical interconnections with other countries. therefore, the sudden loss of such
a significant amount of power forced the local electric utility to resort to sequential load shedding for over one month,
until backup generation units were leased and shipped to
Cyprus. residential consumers experienced two-hour power
interruptions, typically twice a day, whereas commercial
and industrial consumers were forced to shut down their air
conditioning and turn on their reserve units to aid the grid.
it is apparent that if the electricity supply in Cyprus had not
been so dependent on a highly centralized power station like the
Vasilikos power station, but instead if a number of geographically disperse microgrids were in operation, the system would
have been able to respond with higher levels of reliability.

Challenges
the use of microgrids during disasters still faces some challenges. arguably, the most important of those challenges
is that many microgrids would rely on lifelines-essential
infrastructures to operate a system, e.g., a natural gas distribution network is a lifeline for a microgrid with natural gasfueled microturbines-to keep their nonrenewable energy
sources operating. there are several approaches to address
dependency on lifelines. Perhaps the preferred approach is
to design the microgrid so it is powered with diverse power
sources. as the successful experience with the microgrid in
sendai, Japan, demonstrates, improving the design of the
lifelines so they can perform well during expected disasters
could enhance this approach.
the effect of earthquakes on buried infrastructures has
important consequences when planning microgrids in earthquake-prone areas. since renewable energy sources typically provide a limited solution for continuously powering
microgrids because of their intermittent output and potentially larger footprint, and natural gas service may be interrupted during earthquakes, options for powering microgrids
in such situations are limited. typically, in earthquake-prone
areas, the most suitable option to power microgrids is to rely
on diesel-fueled engine generators. using diesel generators was a common choice to power critical loads after the
earthquakes and forest fires mentioned above. these ad-hoc
distributed generation systems were even implemented by
electric utilities through the use of mobile diesel generators.
may/june 2014

still, these systems may not be termed as microgrids because
they do not operate in coordination or in parallel with the
main grid. ironically, such a solution takes a closer form
to what is defined as a microgrid in haiti, where the power
grid had a very poor reliability even before the January 2010
earthquake. in haiti, critical loads such as communications
facilities are usually equipped with permanent diesel generators that are used to power the load for most of the day
because of the poor reliability of the main power grid. hence,
when the earthquake occurred, these loads did not experience
significant outages because their infrastructure was already
prepared to power the loads for extended periods of time
when the main grid was out of service.
the addition of local energy storage contributes to decoupling dependencies on lifelines. however, total decoupling
would generally require adding a significant stored energy
asset such as large battery strings at the microgrid site,
which could increase its cost and footprint and lead to other
design issues-e.g., large battery installations pose structural design challenges in earthquake-prone areas. another
approach is to include renewable energy sources at the
microgrid site, such as PV arrays.
the importance of using renewable energy sources
to reduce the reliance of microgrids on lifelines presents

figure 15. A religious center used to provide emergency
relief services in Kamaishi, Japan, with the capacity of
being powered by a PV array and wind generators. The distribution power infrastructure was destroyed by the March
2011 earthquake and tsunami. (Source: A. Kwasinski.)
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Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - May/June 2014