There is more energy in known reserves of coal than in any other non-renewable resource. However, traditional methods of coal-energy conversion have higher associated carbon dioxide (CO₂) emissions per unit of useful energy produced than oil or gas conversion technologies. Coal also poses other environmental challenges due to trace species in the fuel.

Current fuel processing and exhaust scrubber technologies have made traditional coal combustion cleaner than ever. Integrated Gasification Combined Cycle technology for coal is being tested but is still capital intensive and does not fully address the inherent CO₂ emissions.

Technologies that use coal efficiently while avoiding or capturing CO₂ might allow use of coal in a low greenhouse gas future. CO₂ separation and storage technologies could leverage the vast amounts of energy stored in coal reserves without increasing atmospheric concentrations, while coal-based hydrogen production might allow another pathway for coal energy to be cleanly distributed to the point of use.

• Coal Energy Conversion with Aquifer-Based Carbon Sequestration
  
  

• A Collaborative Research Effort on Integration of Coal Energy Conversion with Aquifer-Based Carbon Sequestration (Stanford University)
• A Collaborative Research Effort on Integration of Coal Energy Conversion with Aquifer-Based Carbon Sequestration (Brigham Young University)