Stronghold Digital Mining (NASDAQ: SDIG) is a Bitcoin mining company based in Pennsylvania with a distinctive environmental remediation business model. Founded in 2021, Stronghold powers its mining operations by burning waste coal refuse (also called “culm” or “coal gob”) — legacy coal waste piles left over from Pennsylvania’s century-long coal industry. The company argues this constitutes environmental remediation, as it removes coal waste that would otherwise leach heavy metals into local watersheds.
Background
Stronghold was co-founded by Greg Beard (CEO) and Bill Spence (Executive Chairman), who previously operated power generation facilities in Pennsylvania. The company’s origin is in waste coal power generation: it acquired power plants that burn coal refuse and added Bitcoin mining as the electricity offtake for those plants, creating a vertically integrated operation where the revenue from mining funds environmental cleanup work.
Business Model
- Acquire abandoned waste coal power plant locations in Pennsylvania
- Burn waste coal refuse (which would otherwise sit in legacy piles) to generate electricity
- Use generated electricity to run Bitcoin ASIC miners on-site
- Market the operation as environmental remediation under Pennsylvania Department of Environmental Protection guidelines
Controversies
- “Clean mining” claims — environmental groups have questioned whether burning coal refuse (even waste coal) constitutes clean Bitcoin mining, given that it still produces CO₂ and particulates
- Regulatory scrutiny — EPA and state regulators have reviewed the environmental accounting of waste coal combustion
- Financial volatility — Stronghold struggled with debt and financial pressure during the 2022 bear market, restructuring obligations with equipment lenders
Related Terms
Sources
- Stronghold Digital Mining Website — official corporate site.
- SDIG on NASDAQ — financial data.
- Bloomberg — Waste Coal Mining — an explainer on the waste coal model.