IEEE Electrification - December 2021 - 80

VIEWPOINT
greater amounts of renewable energy.
Both the overall load shape and the
fastest-growing generation type-
solar photovoltaic-exhibit predominantly
diurnal patterns. Storage
technologies with the capability to
scale to 10 h or more will provide
the most direct benefit in the medium-term,
mostly decarbonized
power grid. Beyond grid decarbonization,
economywide decarbonization
may drive the adoption of
ultralong-duration storage, in the
100-1,000-h range. As seasonal loads
migrate to the electric power system,
the importance of seasonal
storage will increase.
Independent of decarbonization
trends, storage is also finding a role
in resilience applications. although
the financial viability of storage
requires substantially decreasing
cost as durations increase, the
value of a backup source of power
increases with the duration of an
outage. As documented in a survey
conducted by a Carnegie Mellon University
team, consumers would be
willing to pay a significant premium,
as high as US$1.2/kWh, to maintain
limited services during an extended,
multiday outage.
Such events appear to be increasing
in both frequency and magnitude.
For example, in 2009, an ice
storm in Missouri and Kentucky left
some customers without power for
weeks. The U.S. National Guard traveled
door to door with food and
emergency generators. During the
2021 winter event in Texas, hourly
electricity prices cleared at the market
cap of US$9,000/MWh for nearly
four days. Emergency load shed procedures
were in place for 105 h.
According to the Energy Information
Administration, outages due to major
events have constituted the majority
of customer-interruption hours (as
opposed to outages due to power
system malfunctions) in every year
since 2016.
Meeting the Candidates
Given the diversity of storage applications,
the final step is to examine
the technology candidates that have
a viable pathway to achieving the
required cost and performance targets.
Roughly speaking, the candidates
can inhabit two families.
The first family, termed high performance,
low cost, maintains existing
performance characteristics while
significantly reducing costs. This
family would likely provide the dailyto-weekly
durations required for the
first stage of grid decarbonization as
well as basic resilience needs. The
performance ranges for this family
should exceed 70% round-trip efficiency,
and upfront capital costs
HHI Calculation by Generation Type
4.5
3.5
4
2.5
3
1.5
2
0.5
1
Year
Coal
Other Gases
Conventional Hydro
Geothermal
HHI
Figure 3. Generation diversity (measured by fuel type) has increased over time, with no currently dominant technology.
80
IEEE Electrification Magazine / DECEMBER 2021
Petroleum
Nuclear
Wood
Solar
Natural Gas
Hydro-Pumped Storage
Waste
Wind
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
Million TWh Generated
1949
1951
1953
1955
1957
1959
1961
1963
1965
1967
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
HHI

IEEE Electrification - December 2021

Table of Contents for the Digital Edition of IEEE Electrification - December 2021