Announced on September 2, 2026, the Mammoth Solar project in Kanawha County, West Virginia, represents a capital investment of up to $350 million led by developer MN8 Energy, with Google purchasing the energy, capacity, and clean attributes to serve regional data centers, utilizing 86 MW of solar paired with a 280 MWh lithium-ion system and a 100 MWh zinc hybrid cathode long-duration storage system.
The energy transition is hitting heavy industry’s old footprints. Google, developer MN8 Energy, and zinc-battery manufacturer Eos Energy Enterprises have pulled the trigger on a hybrid energy deployment in Kanawha County. Instead of breaking greenfield land, the partnership is anchoring its infrastructure directly into a reclaimed West Virginia coal mine.
According to MN8, the capital investment on the Mammoth Solar project climbs up to $350 million. MN8 will own and operate the facility, while Google steps in as the primary off-taker. The tech giant isn’t just buying abstract green power attributes. It is securing a tightly shaped generation profile designed to match the constant, 24/7 baseload draw of its regional data centers, including a facility planned for West Virginia.
The Hardware Stack: Solar Paired With Dual Storage Chemistries
Utility-scale microgrids require rigorous capacity shaping. The Mammoth installation tackles this by splitting its storage architecture across two distinct electrochemical profiles. The build combines 86 megawatts of solar capacity with a pair of storage assets.
First comes a 70 megawatt, 280 megawatt-hour lithium-ion battery system, engineered for a four-hour discharge window. Second is a 10 megawatt, 100 megawatt-hour long-duration energy storage system supplied by Eos Energy Enterprises. This second asset utilizes Eos’s zinc hybrid cathode cell chemistry.
According to Eos, this zinc technology trades raw energy density for extended duration and a supply chain that bypasses lithium entirely. The Eos unit’s 10-hour discharge profile allows the plant to stretch solar generation deep into the evening peak. Running both storage systems in tandem lets a single PJM Interconnection grid hookup handle both short-term evening spikes and longer flat energy blocks.
Staggered Deployment Schedules and Grid Realities
Complex energy projects live or die by their construction sequencing. MN8 has mapped out a multi-year rollout that explicitly isolates technology risk. Solar panels land first in 2028. The lithium-ion battery array follows in 2029. The Eos zinc storage system brings up the rear in 2030.
Staggering the timeline lets developers capture early revenue from the solar arrays and the lithium-ion storage while the longer-duration zinc technology works its way through final manufacturing and deployment. However, this phasing means the fully realized, round-the-clock renewable portfolio described by the partners will not actually exist until four years after the initial announcement.
The site selection offers an immediate logistical advantage. Reclaimed coal mines typically come equipped with pre-graded land, established road access, and transmission stubs left over from previous industrial operations. These assets bypass the land assembly and interconnection queues that typically stall utility-scale renewables. West Virginia holds a deep inventory of this disturbed land, though it has historically seen very little utility-scale solar deployment.
Economic Impact and Local Integration
Beyond its technical scope, the project shifts local economic streams. Construction is projected to create about 200 jobs in Kanawha County. Additionally, the facility expects to pour roughly $4 million in property tax revenue into the local county and school systems over its first 20 years of commercial operation.
Neither Google nor MN8 published the exact contract terms, pricing models, or the precise legal vehicle of the transaction. The wording indicates that Google’s commitment stretches beyond a standard power purchase agreement, bundling energy, capacity, and clean attributes into a comprehensive offtake structure.
The immediate milestone to watch involves the PJM interconnection queue and the formal execution of the interconnection service agreement. Those documents will prove whether 2028 is a schedule or an intention. For West Virginia’s grid and Google’s data infrastructure, the ultimate test arrives when the final zinc modules roll onto the reclaimed mine floor in 2030.
