Microgrids are smaller
versions of the national electricity grid running independently. Here you can
read about microgrids, why we need them, how they are cost effective, and their
constituents. Microgrids too have their own problems, but the future looks very
promising.
The conventional way one would
think of using electricity is to tap into the distribution system connected to
a regional or a national grid. The power plants or the power sources feed into
this grid at some point in the grid.
Take the example of an
automobile: it has an independent power source, the alternator and a storage
device, the battery. These two together with the controls meet all the
electrical power requirements of the car.
Apply a similar situation to a
household or community that has its own sources of electricity, a power storage
system, and a power control system that automatically cuts in or cuts off
generators to meet the power demand. This system is not dependent on the
national or regional grid.
Such a distributed energy
system running parallel or within the national grid system is called a
microgrid.
We can classify microgrids
broadly into four categories.
○ Remote grids, which are necessary due to
geographical features, such as islands. Consider a country like Indonesia that
has more than twenty-three-thousand islands. It is simply not practical to
connect all these to a single national grid. The power sources in these grids
are on the same conventional lines are using fossil fuel.
○ Military and security are grids necessary
to maintain data and security during a national catastrophe. The power sources
in these grids are also on the same conventional lines using fossil fuel.
○ Commercial or industrial grids catering
to a specific industrial community. The energy sources could be fossil fuel
based or energy recovered for the process like waste heat, bio fuels, or waste
products. These are mainly captive energy systems.
○ Community grids that optimize and utilize
the specific regional renewable resources to give cost effective power supply.
Fossil fuel usage is only used as an emergency backup. This is the really
effective microgrid.
The centralized transmission
grid system is definitely the backbone of the electricity distribution system,
but has its drawbacks.
○ The energy loss is almost 8 -10 %.
○ There are high investment costs in
transmission lines, step-up and step-down transformers, right of way and other
legal issues.
○ Grid management is a constantly juggling
act where it balances the generation and the demand over a wide geographic area.
○ The generating capacity has to match the
peak load, which means a lot of excess capacity is built into the system, which
increases the investment cost.
○ All the users feel the grid disturbances,
outages, frequency changes and voltage fluctuations, blackouts and brownouts.
This can affect the performance and life of electrical equipment.
The Microgrid, even though not
a replacement of the national grid, improves certain aspects especially for
communities and regions that have adequate renewable resources.
Microgrids
○ have much smaller financial commitments.
○ use renewable resources hence are more
environmentally friendly with lower carbon footprints.
○ require fewer technical skills to operate
and rely more on automation.
○ are isolated from any grid disturbance or
outage.
○ place the consumer out of the grip of
large corporations that run the generation networks.
Microgrids are cost effective
only if you can tap into locally available renewable energy resources. Solar
energy is available everywhere but with limitations. Wind, mini hydro, geothermal and bio mass are regionally available and can augment
Solar energy. This combined with a storage device, battery or super capacitors
and backup diesel generator makes Microgrids highly reliable and cheap.
Storage devices in large grid
systems are not economically or technical proven. The advent of latest
technologies in nano batteries and nano super capacitors makes electricity storage a reality
in the smaller capacity range. This is an advantage for Microgrids.
Advances in computerized
control technology make it possible to have simple and efficient controls with
less human interference and is the key ingredient that makes Microgrids
feasible.
Microgrids are all the more
efficient in communities and regions that requre heating or cooling apart from
electricty. Heat from large thermal power plants go to waste because it cannot
be economically transferred large distances. In Microgrid communities, because
of the limited geographical distances it is possible to use the waste heat from
the power generation sources for effective heating or cooling using chillers.
Follow this link to an article
on the Kythonos
island Micro Grid in Greece.
Microgrids have their share of
problems, too.
○ Availability of renewable energy
resources is a key requirement. Transporting fossil fuels to each Microgrid
community is not the economical way.
○ As growth takes place and demand
increases, the Microgrids capacity have to be augmented by additional resources.
○ A high and sophisticated level of
automation for monitoring and controlling the grid and to contain harmonics and other
parameter fluctuations is
a must to make the Microgrids feasible.
○ Availability and reliability of storage
devices like batteries or supercapacitors will play an important role in the
success of the Micro Grid.
High technology products like
nano solar cells, nano super capacitors, nano batteries and fuel cells will
make the microgrid with storage capacities a reality. Advances in automation,
power electronic control systems will also help in the popularity of Microgrids
. Even hybrid cars plugged into the home wiring can act as a generating sources
or a storage device. In larger communities mini nuclear plants could be the ideal source of energy
for the Microgrids.