Storage Integration – Look Ahead SCED Issues for ETWG

CAES Perspectives

Brandon Whittlebrandon.whittle@stratusenergy.com

ETWG Storage Workshop

Basic CAES Traits

• ~2-120+ MW capacity for each resource• Significant duration at full output/input, measured in hours or days• Fast transitions, e.g. Charging to Discharging• Economics are very encouraging

Look-Ahead SCED Goals

Source: White Paper Functional Description Of Core Market Management System (MMS) Applications For "Look-Ahead SCED" Version 0.1.2

• Improve ERCOT Real-Time operations for both economic efficiency and system reliability by taking into account a look-ahead perspective of system operations and providing Market Participants and ERCOT Operators with a short-term look-ahead projection of system conditions (short-term future prices, expected congestion etc.)

• More efficient commitment and dispatch of QSGRs, Load Resources and Storage Resources with temporal constraints via intra-hour commitment having a study horizon of two hours.

• Add capability to enable participation of Load and Storage Resources in the Real-Time Market for Energy and Ancillary Services.

• Add capability of Real-Time Co-Optimization of Energy and Ancillary Services to efficiently utilize available Resource capacity.

• Add capability to consider future topology changes. e.g. Outages.

Real Time Storage Commitment• Storage Resources can submit Three-Part Offers for both charging and

discharging transitions.

• Duration Limited Storage Resources can submit Energy Offer Curves for charging and discharging operating modes.

MWMPC LPC

HSLLSL

$/MWh

Discharging Mode

ChargingMode

Charging3PO

Discharging3PO

Whitepaper Statements• All available (online) Storage Resource are required to participate in

Real-Time Market in both 15-minute and 5-minute time domains• A Storage Resource can be self-committed, DAM/RUC committed,

available for Real-Time Commitment application, or unavailable. • Available duration limited Storage Resources are always assumed

to be in online operating mode capable to perform both charging and discharging in continuous manner.

• A process for Verifiable Costs for the Three Part Offer from Storage Resources needs to be setup. LIFO/FIFO?

• The Storage Resources do not generate energy (i.e. they do not have fuel costs) and the Storage Resources do not consume energy (i.e. there is no consumption benefits). MISCONCEPTION?

Other Questions for ETWG• Make Whole payments are likely to be necessary.

Should Opportunity Cost be considered?• Does the definition of Storage Resource in this

case eliminate some of the abilities currently available on the generation or load side?

• Day – Ahead Ancillary Service Co-optimizationAs with a generator, should a controllable load be able to co-optimize its energy needs with its Ancillary Service sales? i.e. Buy at least the energy necessary to provide the Regulation & Responsive Reserve