Energy use in fossil resource production On the impact of changing energy requirements of conventional and unconventional fossil resource production on global energy use and CO2 emissions towards 2100
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The fossil resource base is vast and can supply the world’s energy demand for quite some time in terms of potential amounts available in the subsurface. However, when regarding the increasing energy requirements for production of these resources, feasible amounts may very well be only a fraction of the total. The analyzed data by the IEA indicates that gas requirements and other inputs are increasing for the production of conventional oil and gas; energy requirements for coal production are stagnating. For processing of fossil fuels, energy inputs were decreasing over time. Case studies on unconventional oil production show that a larger amount of energy is required than for the production of conventional oil, due to the lower physical quality of the unconventional hydrocarbons. These resources can be upgraded to higher quality products that are comparable with conventional products, although at an energy cost. These upgrading and retorting processes make up the largest part of upstream energy requirement for unconventional resources, although they mainly consist of internally provided bitumen or kerogen. Case studies on unconventional gas also show an increase in energy requirements compared to conventional gas. These changes mainly occur due to the decreasing reservoir quality and the need for unconventional methods as hydraulic fracturing. The energy requirements for conventional and unconventional fossil resource production are incorporated in the TIMER model using an input output energy approach. The effects of the interdependent fossil resource production systems are analyzed by looking at the global primary energy use and CO2 emissions towards 2100. Baseline scenario results show that the changes made induce 13% higher annual primary energy use in 2100 than projected in the original model. Corresponding annual CO2 emissions are projected to be 13.5% higher in 2100. These results add more pressure on efforts to sequestrate emissions. Mitigation scenarios are simulated by imposing a carbon tax on CO2 emissions, either on direct emissions only, or on both direct and indirect emissions that result from upstream energy losses. The relative differences in energy use and emissions between the original and enhanced model are smaller than in the baseline scenario due to substitution effects, but only when the carbon tax incorporated upstream energy losses. Imposing only a direct carbon tax leaves annual CO2 emissions at a level of 15% higher towards 2100 compared to the original model. This indicates that it would be beneficial to incorporate fuel life cycle losses, when designing effective mitigation strategies.