A Reclaimed Coal Mine Gets Solar, Lithium and Zinc

MN8 Energy is developing a project in Kanawha County, West Virginia on a reclaimed coal mine site, pairing 86 MW of solar with two different storage technologies: 70 MW / 280 MWh of lithium-ion and 10 MW / 100 MWh of zinc-based long-duration storage using Eos Energy Enterprises' Z3 system. Google will purchase the energy, capacity and clean energy attributes under a long-term agreement, helped shape the technology selection, and is using the project to serve regional data centre needs including a planned West Virginia facility. Estimated capital investment is $350 million, with about 200 construction jobs and a projected $4 million in property tax revenue over twenty years. Solar reaches commercial operation in 2028, lithium in 2029 and the zinc system in 2030.

Two storage technologies on one site is the detail worth examining, because it is a deliberate answer to a real limitation. The lithium system is 70 MW over four hours: high power, high round-trip efficiency, well suited to daily cycling and to the evening ramp. The zinc system is 10 MW over ten hours: much lower power, much longer duration, and a chemistry with different economics — zinc systems are typically heavier and less efficient than lithium but use abundant materials, tolerate deep cycling without the same degradation, and carry a very different fire risk profile.

Sizing them differently is the point. A four-hour lithium asset handles the routine daily shift; a ten-hour zinc asset covers the longer, rarer events where lithium would either be exhausted or would need to be several times larger. Building both at one connection point splits the duty between technologies according to what each is good at, rather than oversizing one to cover both jobs.

The siting is worth noting too. A reclaimed coal mine already has grid infrastructure, road access, cleared land and a workforce with relevant skills, which is why these sites keep attracting energy projects. It also puts the offtake, the generation and Google's planned regional load in the same state — the same co-location logic that appeared in the Fervo geothermal agreement in Utah last week, where a hyperscaler contracted firm generation before the load was built.