Life Cycle Analysis of Natural Gas Extraction and Power Generation 3 Upstream Data Upstream data include the supply shares of natural gas and coal, as well as the energy requirements and material flows for the key activities for extraction, processing, and transport. These data are used to model the RMA and RMT stages in NETL's natural gas and coal models. 3.1 Natural Gas The primary unit processes of this model are based on data compiled by NETL. Secondary unit processes, such as production of construction materials besides steel, are based on third party data. Appendix A includes details on how these data are assembled in a model and references the detailed documentation in NETL's unit process library. Where data for the inventory are available, high and low values are collected, along with an expected value. When results are presented, three cases are shown: an expected case, a high case, and a low case. The high and low results (error bars on the results) are a deterministic representation of the variability on the data and not indicative of an underlying distribution or likelihood. 3.1.1 Sources of Natural Gas This inventory and analysis includes results for natural gas domestically extracted from seven sources in the lower 48 states:
The National Energy Technology Laboratory produced a well-to-wheels
(WTW) life cycle greenhouse gas analysis of petroleum-based fuels
consumed in the U.S. in 2005, known as the NETL 2005 Petroleum Baseline.
This study uses a set of engineering-based, open-source models combined
with publicly available data to calculate baseline results for 2014.
An increase between the 2005 baseline and the 2014 results presented
here (e.g., 92.4 vs 96.2 g CO2e/MJ gasoline, + 4.1%) are
due to changes both in modeling platform and in the U.S. petroleum
sector. An updated result for 2005 was calculated to minimize the
effect of the change in modeling platform, and emissions for gasoline
in 2014 were about 2% lower than in 2005 (98.1 vs 96.2 g CO2e/MJ gasoline). The same methods were utilized to forecast emissions
from fuels out to 2040, indicating maximum changes from the 2014 gasoline
result between +2.1% and −1.4%. The changing baseline values
lead to potential compliance challenges with frameworks such as the
Energy Independence and Security Act (EISA) Section 526, which states
that Federal agencies should not purchase alternative fuels unless
their life cycle GHG emissions are less than those of conventionally
produced, petroleum-derived fuels.
This study updates the Petroleum Refinery Life Cycle Inventory Model (PRELIM) to provide a more complete gate-to-gate life cycle inventory and to allow for the calculation of a full suite of impact potentials commonly used in life cycle assessment (LCA) studies. Prior to this update, PRELIM provided results for energy use and greenhouse gas emissions from petroleum refineries with a level of detail suitable for most LCA studies in support of policy decisions. We updated the model to add criteria air pollutants, hazardous air pollutants, releases to water, releases to land, and managed wastes reflecting 2014 reported releases and waste management practices using data from the U.S. Environmental Protection Agency Greenhouse Gas Reporting Program, National Emissions Inventory, Discharge Monitoring Reports, and Toxic Release Inventory together with process unit capacities and fuel consumption data from the U.S. Energy Information Administration (U.S. EIA). The variability of refinery subprocess release factors is characterized using log-normal distributions with parameters set based on the distribution of release factors across facilities. The U.S. EPA Tool for the Reduction and Assessment of Chemical and Environmental Impacts life cycle impact assessment (LCIA) method is used together with the updated inventory data to provide impact potentials in the PRELIM dashboard interface. Release inventories at the subprocess level enable greater responsiveness to variable selection within PRELIM, such as refinery configuration, and allocation to specific refinery products. The updated version also provides a template to allow users to import PRELIM inventory results into the openLCA software tool as unit process data sets. Here we document and validate the model updates. Impact potentials from the national crude mix in 2014 are compared to impacts from the 2005 mix to demonstrate the impact of assay and configuration on the refining sector over time. The expanded version of PRELIM offers users a reliable, transparent, and streamlined tool for estimating the effect of changes in petroleum refineries on LCIA results in the context of policy analysis.
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