Atmosphere Data Centers is committed to exploring a practical and measurable path toward cleaner energy at the Dickerson campus. This memo outlines the realities of powering a 24/7 hyperscale data center, explains the current limitations of the regional energy grid, and details the technologies and procurement strategies being evaluated to reduce emissions over time while maintaining the reliability required for critical infrastructure.

This technical annex provides the detailed data, methodology, and supporting analysis behind Atmosphere’s Clean Energy Path Memo for the Dickerson campus. It offers a deeper look at topics including PJM grid composition, renewable energy limitations, fuel cell technology, REC procurement strategies, and the challenges of achieving 24/7 carbon-free energy for hyperscale data centers — all grounded in current market conditions, regulations, and available technologies.

Power will be supplied via existing FirstEnergy transmission lines that border the site. Atmosphere will:

• Construct a new on-site substation and switchyard

• Fund the substation construction at its expense

• Connect directly to adjacent transmission infrastructure

No new off-site transmission corridors are required.

Backup Power

The campus will include diesel generators for emergency use and required periodic testing only. These generators:

• Are not used for primary operations

• Are subject to Maryland Department of the Environment air-quality permitting

• May include Selective Catalytic Reduction (SCR) and Diesel Particulate Filters (DPF) to reduce emissions

Fuel storage and handling systems must meet strict state requirements for spill prevention, containment, and monitoring.

• Storage facilities

• On-site water treatment and wastewater treatment buildings

• Surface parking areas

• 24/7 secured operations

Domestic Water

• Supplied by an existing on-site well

• Usage reallocated among existing wells

• No net increase in groundwater use

Cooling Water

• Sourced from the Potomac River

• Maximum daily withdrawal is approximately 900 times less than the former coal-fired power plant

• Reuses existing intake infrastructure to avoid riverbank disturbance

• Discharge temperatures will align with ambient air conditions

All withdrawal and discharge permits have been submitted to the Maryland Department of the Environment and are subject to state oversight.

Forest Conservation

The project complies with Montgomery County’s Forest Conservation Law. Approximately 500 acres of Terra Energy-owned agricultural land are proposed for permanent forest conservation easement.

System Design and Operation

• Water for the cooling process is reused multiple times (3–6 cycles of concentration) before discharge, reducing overall demand on the river.

• Daily withdrawal is not constant and can range from 0 to 500,000 gallons depending on weather and cooling demand.

• On average the campus withdraws 69,300 GDP from the Potomac River. About 46,200 GDP are evaporated and the remainder is returned to the River near its ambient temperature, under State permit conditions. That is far less than a 150-acre, 18-hole golf course in Maryland that uses about 107,100 GPD on average, according to the U.S. Golf Association, none of which is returned to local water resources.

• Water is only used for cooling when air temperatures exceed roughly 75°F, meaning little to no river water use during winter months.

• The system includes on-site storage capacity to manage operational needs efficiently and reduce variability in withdrawals.

Intake and Aquatic Protection

• Water intake is engineered for aquatic protection, using:

  • A 1-millimeter screen system to mitigate entrainment of small organisms

  • Ultra-low intake velocity of less than 0.02 ft/sec — well below the EPA’s recommended limit of 0.5 ft/sec, and about 45 times slower than the former power plant’s intake — allowing fish and other wildlife to easily move away from the intake.

• The project reuses the site’s existing river intake infrastructure, avoiding new disturbance to the Potomac River shoreline and limiting construction-related impacts.

Water Treatment Process

• Treatment relies primarily on physical filtration rather than chemicals, including multi-media filtration and micro sand filtration. These processes remove sediment and particles before water enters the cooling system.

• The only chemical used is a targeted oxidant (sodium hypochlorite) for biological control. It is only used when needed, typically in warmer temperatures and is generated on-site, eliminating transport and storage risks. Sodium hypochlorite is fully neutralized prior to discharge.

Waste and Byproducts Management

• The treatment process produces two managed byproducts:

  • Filtered solids are removed and transported offsite and are not discharged into the river. Water is recycled back into the system.

  • Cooling system blowdown is treated and returned to the river in compliance with permit limits.

Discharge and Environmental Safeguards

• Before discharge, water is treated to ensure no residual sodium hypochlorite remains and the temperature and water quality meet strict State permit requirements.

• The system is designed with a maximum potential discharge of approximately 480,000 gallons per day.

• Returned water will be near ambient river temperature, with discharge temperature regulated under State permit requirements.

Water Sources and System Scope

• Groundwater is only used for domestic purposes and not used in the cooling process.

• The project does not use municipal or County water for cooling, relying instead only on river water.

System Resilience

• The system includes a backup or redundant cooling approach in the event the primary water system is offline.

• The system will rely on on-site storage in event of a complete failure of the water system.

Fire Suppression Planning and Requirements

• The fire-suppression system is being finalized as part of the project’s detailed design and will be submitted for review and permitting. Consistent with the project’s commitment to avoid PFAS, the system will not use PFAS-containing suppression agents.