In biophysical terms, such as energy return on investment (EROI), energy sources for the global economy have grown more expensive over the last few decades This trend is likely to be more pronounced in the near-term future as conventional oil and gas are depleted and difficult-to-extract unconventional oil and gas become a larger part of the fossil-fuel supply On the one hand, this will lead to ?energy sprawl??the growth of the energy sector, as this sector consumes a much larger portion of the energy it extracts?leaving less energy surplus for other sectors On the other hand, we will see an unsustainable imbalance between the fuel prices that fossil-fuel companies will need to meet their costs and the fuel prices that the larger economy can afford to pay This article reviews the historical role of inexpensive energy in economic growth, discusses the declining availability of conventional oil resources, and examines the increasing reliance on expensive, unconventional petroleum resources such as shale oil in the United States
The Rising Costs of Fossil-Fuel Extraction: An Energy Crisis That Will Not Go Away