GoHilliard Intelligence Brief: Data Centers, AEP Ohio Tariffs, and Ratepayers

Regulatory Forum: Public Utilities Commission of Ohio (PUCO)

Primary Docket: Case No. 24-0508-EL-ATA (AEP Ohio Data Center Tariff / Schedule DCT)

Geographic & Political Nexus: Ohio Senate District 16 (Western Franklin County: Hilliard, Dublin, Upper Arlington, Worthington)

Governing Issue: High-Voltage Transmission Substation Cost Allocation, Take-or-Pay Minimums, and Ratepayer Shielding Against Regional Hyperscale Load

Executive Summary

Across Central Ohio, the explosive concentration of hyperscale data centers—stretching from New Albany to the western boundaries of Hilliard and Dublin—has fundamentally collided with the state’s electric grid economics.

In PUCO Case No. 24-0508-EL-ATA, regulators adjudicated one of the most consequential utility cost-allocation battles in Ohio history: When multi-hundred-megawatt computing campuses require dedicated 138kV/345kV high-voltage transmission lines, multi-million-dollar step-down substations, and regional PJM grid enhancements, who pays the capital expenditure?

Under standard utility rate-base design, upfront transmission and distribution costs can be socialized across all general customer classes if large industrial customers under-consume or cancel planned facilities. In response, PUCO adopted a consumer-protective settlement that established Schedule DCT (Data Center Tariff). This framework mandates strict “take-or-pay” capacity commitments, 100% pre-energization construction cost liability, and mandatory load ramp requirements to prevent Central Ohio households and small businesses from subsidizing Big Tech’s grid expansion.

The Regulatory Core: Mechanics of PUCO Case 24-0508-EL-ATA

+-----------------------------------------------------------------------------------------+
|                              THE COST ALLOCATION BATTLEGROUND                           |
+--------------------------+--------------------------------------------------------------+
| Factor                   | Tech Giants' Initial Stance     | PUCO Approved Settlement   |
+--------------------------+--------------------------------------------------------------+
| Subscribed Capacity Pay  | Pay only for energy consumed     | 85% to 90% "Take-or-Pay"   |
| Pre-Energization Default | Utility/Ratepayers absorb sunk capex | 100% Exit Fee / LOA liability|
| Contract Duration        | Flexible / Short-term (3–5 yrs)  | 10–12 Year Firm Commitment |
| Upfront Study Fees       | Nominal / Socialized admin       | $10,000 – $100,000 cash     |
| PJM Grid Surcharge       | Socialized regional transmission | Direct customer allocation |
+--------------------------+--------------------------------------------------------------+

1. Minimum “Take-or-Pay” Billing Thresholds (85%–90%)

Before this docket, a hyperscale developer could request 100 MW of reserved capacity, prompt AEP Ohio to construct dedicated substation bays and high-voltage connections, but only pull 20 MW during its first several years of operation.

• The Adopted Rule: Under Schedule DCT, qualifying data centers ($\ge 25\text{ MW}$) must pay for at least 85% of their contracted capacity regardless of whether they consume the electricity. Over a four-year load ramp period, billing capacity escalates from 50% in Year One up to 90% in Year Four.

2. Letters of Agreement (LOA) & 100% Exit Liability

To protect ratepayers against speculative projects or cancellations:

• Customers must sign a binding Letter of Agreement (LOA) requiring them to reimburse AEP Ohio 100% of the buildout costs if the project cancels or delays service by more than 12 months prior to the target energization date.

• Contracts span 10 to 12 years (the ramp period plus eight years). Early termination requires paying the remaining unamortized capital investment directly.

3. High-Voltage Substation Interconnection Costs

For high-voltage transmission substations directly serving data campus developments:

• Dedicated Interconnection Facilities: Paid directly by the data center developer via direct contributions-in-aid-of-construction (CIAC).

• Network & PJM Upgrades: Regional transmission enhancements planned through PJM Interconnection are categorized to prevent cost shifting to residential consumers, backed by corporate credit and surety bonds.

What It Means for Ohio Senate District 16 (SD-16)

Ohio Senate District 16—encompassing western Franklin County, including Hilliard, Norwich Township, and Brown Township—sits at the physical convergence point of high-voltage transmission lines feeding the outerbelt commercial corridors and the Big Darby Accord preservation overlay.

1. Household Utility Bill Protection

Residential ratepayers in Franklin County have faced persistent inflationary pressure on energy delivery riders and generation supply auctions. Without Schedule DCT, the billions of dollars needed to upgrade AEP Ohio’s regional grid for artificial intelligence workloads would have flowed into base transmission rate riders, adding an estimated $5 to $15 per month to average household electric bills. The PUCO settlement creates a legal firewall between data center infrastructure expenditures and household tariffs.

2. Western Boundary Land-Use Friction

Along Hilliard’s western edge (Roberts Road, Alton Darby Creek Road, and Hayden Run Road), massive high-voltage transmission corridors are under intense pressure. Developers evaluating sites near the Big Darby watershed look for adjacent high-capacity lines. The stringent capital requirements of Schedule DCT discourage speculative land flipping, ensuring that only fully funded, verified tech loads can trigger high-voltage substation builds.

3. Industrial Competitiveness vs. Grid Stability

While hyperscalers argued that strict tariffs would drive technology investments to neighboring states (such as Indiana or Michigan), PUCO ruled that corporate economic development cannot come at the expense of residential energy affordability. For SD-16’s growing suburban population, the order protects electric system reliability without exposing suburban homeowners to the financial risk of grid over-expansion.

What you should be watching

1. Monitor PJM Interconnection Queue Filings: Watch for transmission submittals by AEP TransCo affecting the Roberts Road and Hayden Run 138kV/345kV corridors.

2. Track Local Substation Siting Cases: While PUCO governs rates and tariffs, physical high-voltage substations and transmission routes over 100kV fall under the jurisdiction of the Ohio Power Siting Board (OPSB). Track OPSB filings for substation applications bordering Hilliard municipal limits.

3. Appeals Watch: Several tech coalition members appealed aspects of the final tariff order to the Supreme Court of Ohio. Watch whether judicial review alters the 85% take-or-pay floor or the mandatory exit fee requirements.