The announcement on June 23
of a partnership among Softbank, Airtel, and Foxconn for investing $20
billion in India for solar and renewable energy projects is welcome
news. Many tens of gigawatts of solar generation will be deployed,
augmenting today's electricity supply. The investment will be used to
deploy large, grid-tied solar and wind projects, plus the manufacture of
solar panels.
As renewables percentage in the generation mix rises, thanks to
large-scale solar projects and distributed generation, the grid
experiences a sudden drop in supply as the sun sets. As a result, the
loads during evenings have to be met using quick-ramping power plants,
which is typically gas-fired. This phenomenon, called the "duck curve,"
was first noticed in California. It is so called because of the
peculiar shape of the load profile resembling the neck of a duck,
resulting from a sharp drop in supply at sunset.
While solar deployments increase the average electricity supply,
there arise periods of shortages at certain hours that have to be met by
conventional, fossil-fuel based power plants, and for which new
investments are necessary. Such generation is also typically expensive
since the generation plant is used only for a short time. Moreover, such
plants defeat the very value proposition of clean, solar projects.
One way to overcome this need to build conventional power plants is
to deploy storage in the grid, typically batteries, and occasionally
fly-wheels. Such storage systems enable quick ramp-up of supply at
sunset, but today are costly.
Yet a third way, not typically discussed, would be to deploy solar
panels as a part of microgrids. With microgrids, the resilience in
supply can be achieved through a clustering of microgrids, each with
complementary assets — some with more wind, some in proximity to rivers,
some with plenty of surface for solar panels, and some with battery
banks shared with other microgrids. Microgrids are inherently green and
clean. Complementary clusters of microgrids also bring down costs.
India's public policy relating to electricity must incorporate
microgrids and storage to offset the "duck curve" phenomenon, and
thereby avoid related fossil fuel investments. Unfortunately, no
microgrids — not to be confused with Solar Home Systems (SHS) — are
deployed in India as yet.
Microgrid technologies are maturing rapidly. IIM Kozhikode has
conducted economic analysis by modelling ~2-MW microgrids in several
scenarios — campuses, cluster of homes, and more. The costs are
surprising affordable when compared to the alternatives.
Microgrids deserve public policy support right away. A few dozen
microgrids of ~1 to 5 MW each may be deployed for testing and eventual
commercialization. They make sense to a) extend the reach of electricity
to the 300 million Indians without access to grid power, b) complement
Solar Home Systems, c) offset load in congested areas, on campuses and
hospitals, and d) help with grid stability as renewables proportion increases in the generation mix.
http://www.renewableenergyworld.com/articles/2015/07/why-microgrids-are-essential-in-india-s-electricity-generation-mix.html