Calculating primary energy and carbon emission factors for the United States' energy sectors

Energy consumption is the main source of most anthropogenic carbon emissions. For effectively reducing carbon emissions, a complete life cycle energy and carbon evaluation of products is important, which takes into account all primary and delivered energy used and lost in the manufacturing process. All delivered energy usage should be converted to primary energy units so that the actual total carbon emissions can be quantified. A set of constants, also known as primary energy factors (PEFs), are used to translate delivered energy into primary energy units. The PEFs can be converted into carbon emission factors (CEFs) using carbon intensities of fuels. To ensure completeness, a PEF for a delivered fuel should be calculated by including all direct and indirect energy consumed and lost in generating and supplying the delivered fuel. Literature points out the need to establish a standard and complete method to calculate PEFs and CEFs. In this paper, we investigate the current state of PEF calculation in order to establish a method to more completely calculate a PEF. We also calculated PEFs and CEFs for the United States' economy using three methods to compare results and highlight the issue of energy double counting. The results demonstrate that a process or input-output-based hybrid method can cover most direct and indirect energy inputs and provide a complete PEF calculation.