IEEE Power & Energy Magazine - November/December 2019 - 73

november/december 2019

SO2 and NOx Ibs/MWh

CO2 Ibs/MWh

(MW)

market decreased by nearly 40%
over the same time period. In addi90,000
tion to providing increased overall
operational flexibility, this chang70,000
Coal
ing fuel mix has steadily reduced
CO 2 , sulfur dioxide (SO 2), and
Gas
nitrogen oxide (NOX) emissions
50,000
since 2005 (Figure 6).
In 2017, PJM published "PJM's
Nuclear
Evolving Resource Mix and Sys30,000
tem Reliability," which documents how the availability of such
Renewable
generator attributes-including
10,000
Demand Response
operational flexibility, fuel assurance, frequency response, reac2009-2010
2013-2014
2017-2018
2021-2022
tive power, and ramping capaDelivery Year
bilities-changes with potential
*Includes Solar and Wind at Nameplate, Hydro, and Wood
future generation portfolios. This
study was motivated by a concern
that the system could become so figure 5. PJM installed capacity by fuel type. (Source: PJM Interconnection; used
dependent on the rapidly growing with permission.)
amount of natural gas and renewable resources that reliability would be negatively affected. Electricity and Transport
While natural gas-combustion turbines provide fast and The transport sector can also contribute toward the need for
accurate ramping control and great amounts of operational increased intraday balancing. This has been shown in an analyflexibility, they offer little in the form of fuel-assurance capa- sis evaluating interactions among the transport, electricity, and
bility, as they do not store fuel onsite and are dependent on heat sectors in hourly resolution for an entire year. Figure 7
the pipeline infrastructure. Thus, even if a plant is physically shows the simulation results of a typical February week for the
capable of following sharp changes in load or starting up on German energy system, illustrating the ability of controlled
short notice, there is no guarantee that fuel will be available charging of EVs to contribute to smoothing wind and solar
for the plant to meet the grid's essential reliability needs.
photovoltaic (PV)-based electricity production. An extreme
During the cold weather conditions of the 2014 North situation has been modeled with only wind and PVs as generaAmerican polar vortex, interruptions in service from natural tion and only EVs as an operational flexibility source.
gas pipelines caused nearly one-fourth of the total generator
The net load (black dashed curve) in Figure 7, i.e., the load
outages. Such outages occur during cold weather because (without EV) minus generation from wind and solar PVs,
natural gas delivery is prioritized based on different levels of includes neither other generation types, such as thermal or
contracts, with those for firm transportation (primarily for on- hydro, nor trading with neighboring countries. Many occasite residential heating) guaranteed delivery under all circum- sions with a surplus of power, i.e., negative net load values, can
stances except the most extreme. Approximately 16,000 MW be exploited to charge EVs by applying a controlled charging
of gas generation in PJM relies on nonfirm transportation
contracts, which may be interrupted based on demand. Fol1,300
9
lowing the polar vortex, PJM launched a cross-divisional
1,250
CO2 8
gas-electric coordination team to evaluate pipeline capacity
SO2 7
1,200
postings and critical notices as well as establish a knowledge
NOx 6
1,150
base of the pipeline industry and relationships with pipeline
1,100
5
companies that serve PJM generators.
4
1,050
To more closely examine the nuances of supply chain
1,000
3
risks such as limited gas availability during extreme con950
2
ditions, PJM initiated a study in 2018 to evaluate threats
900
1
to fuel security. While no imminent threat was identified,
850
0
PJM will continue to work with the gas pipeline industry to
2005 2007 2009 2011 2013 2015 2017
increase transparency of firm gas markets and evaluate and
Year
refine pipeline contingency impacts. These efforts will help
to ensure that fuel is available to the most flexible generators figure 6. The PJM emissions decrease. (Source: PJM Interwhen it is needed.
connection; used with permission.)
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IEEE Power & Energy Magazine - November/December 2019

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