The Capacity Capability Senior Task Force kicked off
its first meeting April 7 with educational presentations on a proposed method
of calculating how much power resources such as wind, solar and energy storage may
offer into the capacity market.
Effective Load Carrying Capability (ELCC) is an
established process of evaluating the capability of resources that cannot run
at their full output for 24 continuous hours. This includes resources whose
capacity varies based on weather conditions, like wind or solar, and limited-duration
resources, such as batteries or pumped hydro storage.
The task force was created by an issue charge
introduced and endorsed at the March 26 meeting of the Markets &
The reason for the effort is twofold:
- The Planning Committee has been discussing
switching to an ELCC method to calculate the capability of wind and solar units
in the capacity market.
- Stakeholders have proposed – and PJM
supports – switching to an ELCC method to calculate the capability of energy
storage resources. The proposal was offered in place of a paper hearing the
Federal Energy Regulatory Commission initiated regarding the capability of
energy storage resources.
The subject stems in part from FERC’s ruling last fall
largely accepting PJM’s compliance filing regarding FERC Order 841, which
required regional grid operators to remove barriers to the participation in
wholesale markets for electric storage resources, such as batteries.
PJM Requested More Time on Issue
PJM submitted a filing Feb.
27 requesting that FERC “hold in abeyance” until Jan. 29, 2021, a paper hearing
to investigate whether PJM’s provisions for establishing the capability of
energy storage resources in the capacity market are unjust and unreasonable.
Currently, PJM employs a 10-hour rule, under which a resource’s capability is rated
by the power output it can provide for 10 continuous hours.
FERC has not yet ruled on the request.
The problem statement associated with the issue charge
explains that as PJM’s resource mix continues to evolve to include more
renewables and emerging technologies including energy storage, so too must the
way PJM evaluates the contributions of these resources toward resource
Today, that capability is measured independent of
changes to the overall resource mix and therefore wouldn’t change according to
the amount of renewables and energy storage on the grid as a whole.
This is problematic, because there is reason to
believe that an increasing amount of variable and limited-duration resources
can affect the hourly “loss-of-load probability” risk profile.
Over time, PJM could be over- or under-valuing these
resources’ contribution to resource adequacy.
The ELCC Process
Patricio Rocha Garrido, Senior Engineer – Resource
Adequacy Planning, explained the ELCC process
ELCC, which dates to 1966, provides a way to assess
the capacity value of a resource that is tied to the loss-of-load probability
concept. In essence, it measures the additional load the system can supply using
a particular generator with no net change in reliability.
Levitt provided an overview
of how other regional transmission organizations employ the ELCC method. Also
discussed were the implications of installed capacity
(ICAP) and unforced capacity (UCAP) as well as capacity interconnection rights
Phase I of the task force will focus on solar, wind
and energy storage resources. Phase II will cover all other limited-duration
resources and intermittent resources.
The Phase I work is expected to last until the end of
the year. Its conclusions would inform a filing with FERC by Jan. 29, 2021.
Phase II is expected
to take about 12 months and will begin following the conclusion of the first
Original source: PJM