An energy crisis or energy shortage is any significant bottleneck in the supply of energy resources to an economy. In literature, it often refers to one of the energy sources used at a certain time and place, in particular, those that supply national electricity grids or those used as fuel in industrial development. Population growth has led to a surge in the global demand for energy in recent years. In the 2000s, this new demand – together with Middle East tension, the falling value of the US dollar, dwindling oil reserves, concerns over peak oil, and oil price speculation – triggered the 2000s energy crisis, which saw the price of oil reach an all-time high of $147.30 per barrel ($926/m³) in 2008.