There is concern within some factions of the energy industry about an approaching global crisis caused by peak oil production. To shed light on the subject, this book assesses the threat that depletion poses to the availability of fossil energy resources. It does so by estimating cumulative supply curves for conventional petroleum (oil, gas, and natural gas liquids) and for three unconventional sources of liquids (heavy oil, oil sands, and oil shale). The analysis extends the important study conducted by the US Geological Survey (2000) on this topic by taking account of (1) conventional petroleum resources from provinces not assessed by the Survey or other organizations, (2) future reserve growth, (3) unconventional sources of liquids, and (4) production costs. The results indicate that large quantities of conventional and unconventional resources are available and can be produced at costs substantially below current market oil prices of around US$140 per barrel. These findings suggest that fossil energy is likely to last far longer than many are now predicting and that depletion need not drive market prices above the relatively high levels prevailing over the past several years.