Energy reserves are quite well understood and have been recorded for many decades with varying degrees of accuracy. It appears that global reserves of coal could last in excess of 100 years, but this cannot be stated with absolute confidence. The life of coal reserves could face depletion in some parts of the world where production rates are high. Elsewhere, carbon constraining legislation could depress demand, which could greatly extend the life of world coal reserves. Either way, the concept of supply and demand peaking will impact all coal producing and using countries eventually, but timing and extent of these peaks will differ. This report revisits analyses on fossil fuel depletion, and how various approaches to peak analysis and projections can impact the understanding of coal reserves.