Energy Services

Energy Services Benefit Members & Customers

Our System Operations and Energy Services divisions work with ACES, our energy management partner, to provide sophisticated transmission, scheduling and trading services to our Members and customers at competitive rates. We carefully evaluate new service proposals to ensure they are a win-win for both current and prospective Members and customers. For more information, visit Our Members & Customers.

Katie Hardman and Tara Davis standing in front of a whiteboard
Katie Hardman, power supply engineer, left, and Tara Davis, Member/customer services liaison, evaluate which energy imbalance market would best serve AzGT Members. See more about the EIM at Meeting Member Needs.

The ACES West Regional Trading Center operates out of AzGT’s Benson Campus.

We have attracted a number of new customers in recent years. Increased scale maximizes efficiencies and economies, and benefits all Members and customers. In addition, it helps us offer options and flexibility to meet individual needs.

AEPCO’s Energy Services Department (ES) is responsible for a variety of functions.

Energy Schedules

Our ES team partners with ACES to access nationwide scheduling and trading expertise. Confirming energy schedules in the day ahead (Pre-schedule) as well as After the Flow (ATF) date assures that AEPCO accounts for correct values in our AEPCO-developed Billing Unit Program (BUP). We verify energy schedules with our host Balancing Area (BA), the Western Area Power Administration (WAPA). Then we hand off verification to AEPCO’s System Operations department to continue the process in the Real Time market. At day’s end, schedules are sent back to ES for billing our Members and customers..


ES billing administrators validate transactional and operational activity in the BUP to ensure accuracy and timeliness. We use Itron’s MV90 system to call Member and customer meters daily, and then upload this interval data into the BUP. The BUP uses the energy schedule for market sale and purchase data, and MV90 meter data which includes generation load, to allocate resources to our Members and customers, and to make sure loads and resources are balanced. Billing administrators complete energy and transmission invoices and process invoices received. They enter invoices in AEPCO’S SAP accounting system; reports are provided to accounting on a monthly basis.

New HCC Billing System

Energy Services coordinated with AEPCO Class A Members to design a new energy and cost assignment program called Hourly Cost Causation (HCC). HCC aims to fairly assign each Member’s energy, fuel and associated costs in every hour of the day based on need and contractual obligations. We’re working toward a Jan. 1, 2023, implementation of HCC, which will replace BUP. HCC data inputs include Apache Station unit generation and fuel burn, energy sales and purchases, Member meter data, ancillary services, transmission costs and metered Balancing Area considerations.

Fuel Management

ES procures and manages coal supply and transportation to meet Apache Station generation needs, including the maintenance contract and any leasing of AEPCO’s unit train of coal rail cars. Our fuels staff procures environmental-compliance chemical additives and markets fly ash. We provide coal energy cost analysis to ACES to assist with energy scheduling. On the natural gas side, ES works with ACES to assure natural gas is delivered to Apache Station to meet generation needs by reviewing natural gas invoices, verifying that the natural gas data that accounting uses is accurate, and assuring transportation contracts are in place. ES approves gas invoices for payment and summarizes monthly activity for Members.

Resource and Operations Analytics

Our ES planning and analytics team researches how to effectively operate existing power supply resources, plans for future resources, and provides analytical support for ACES and our Members. ES power supply engineers work with Members to prepare AEPCO for the summer peak from pricing and risk perspectives to limit Member exposure. They study market history, forecast demand and consider market products to address short-term resource needs. We also develop long-range planning studies to assure that power supply resources are in place. Plans are continually updated to evaluate new opportunities.