Greenhouse Gas Life Cycle Assessment Research Articles

Developing a greenhouse gas life cycle assessment framework for natural gas transmission pipelines

As demand for natural gas increases, it is important to understand its life cycle emission intensity. A framework is developed for performing bottom-up greenhouse gas (GHG) life cycle assessment of natural gas transmission pipelines to assist project environmental assessments. Three large-scale pipelines in Canada were examined: Alliance mainline (50 million m3/d, 3000 km), Prince Rupert phase 1 (PR1, 57 million m3/d, 878 km), and Prince Rupert phase 2 (PR2, 102 million m3/d, 878 km). Fundamental engineering principles are used for calculation accuracy, with a sensitivity analysis to identify key parameters. The model boundary includes pipeline construction, operation, and decommissioning. The resulting transportation GHG emission intensities are 1.49, 0.77, and 1.78 gCO2eq/GJ.km for the Alliance, PR1, and PR2 projects, respectively. The operating phase represents 78%–95% of the overall emissions. Operating at higher pressures could reduce emission intensity by up to 49% by increasing flow efficiency. The research provides a user-friendly open-source template that can be used to examine alternative scenarios.

Energy and greenhouse gas life cycle assessment and cost analysis of aerobic and anaerobic membrane bioreactor systems: Influence of scale, population density, climate, and methane recovery

This study calculated the energy and greenhouse gas life cycle and cost profiles of transitional aerobic membrane bioreactors (AeMBR) and anaerobic membrane bioreactors (AnMBR). Membrane bioreactors (MBR) represent a promising technology for decentralized wastewater treatment and can produce recycled water to displace potable water. Energy recovery is possible with methane generated from AnMBRs. Scenarios for these technologies were investigated for different scale systems serving various population densities under a number of climate conditions with multiple methane recovery options. When incorporating the displacement of drinking water, AeMBRs started to realize net energy benefits at the 1 million gallons per day (MGD) scale and mesophilic AnMBRs at the 5 MGD scale. For all scales, the psychrophilic AnMBR resulted in net energy benefits. This study provides insights into key performance characteristics needed before an informed decision can be made for a community to transition towards the adoption of MBR technologies.

Greenhouse Gas Life Cycle Assessment of Products Arising from the Rendering of Mammalian Animal Byproducts in the UK

Animal byproducts (ABP) are unavoidable byproduct of meat production that are categorized under EU legislation into category 1, 2, and 3 materials, which are normally treated by rendering. Rendering is a thermal process that produces rendered fat and protein. Heat is provided from the combustion of natural gas and self-produced rendered fat. The main objectives of the study were (i) to assess energy intensity in the UK rendering industry, and (ii) to quantify the greenhouse gas emissions associated with the production of mammalian rendered products using life cycle assessment. Thermal energy requirements were 2646 and 1357 kJ/kg, whereas electricity requirements were 260 and 375 kJ/kg for category 1 and 3 ABP respectively. Fossil CO(2) emissions were -0.77 and 0.15 kg CO(2)e/kg category 1 and 3 mammalian rendered fat respectively and 0.15 kg CO(2)e/kg processed animal protein. These were low relative to vegetable products such as palm oil and soya bean meal because (i) ABP were considered wastes that do not incur the environmental burden of their production, and (ii) the rendering process produces biofuels that can be used to generate energy that can be used to offset the use of fossil fuels in other systems.