| Description |
With numerous options for mitigating CO2 emissions, the need to address global climate change, and limited financial resources, it is essential to evaluate greenhouse gas (GHG) mitigation strategies to prioritize investments of time and capital. This research adopts a life-cycle approach toward this prioritization for three GHG mitigation strategies: (1) aqueous CO2 mineralization, (2) oxyfiring for unconventional transportation fuels, and (3) underground coal thermal treatment (UCTT). As this research moves from strategy (1) to strategy (3), it progresses from using literature data to close collaboration with other researchers to design and perform experiments and simulations needed to assess GHG impacts. The evaluation of each strategy includes quantitative consideration of all major energy and GHG flows and a qualitative consideration of other potential barriers, i.e., resource availability and hazardous byproducts. Commercial-scale, aqueous CO2 mineralization involves the reaction of CO2 with an industrial caustic or a waste containing a reactive metal oxide to form a solid mineral carbonate. The evaluation revealed that once the full-life cycle material and energy balance are considered, this technology has limited applicability at the large scale. The industrial caustic pathway has a high energy penalty (50 to > 100%) and produces toxic byproducts (chlorine gas). The reactive metal oxide/waste pathway has a lower energy penalty (10 to 20%), but its applicability is limited by the availability of wastes containing reactive metal oxides. Oxyfiring with CO2 capture is one of the most promising CO2 mitigation strategies for the fossil energy sector. Chapter 3 discusses whether oxyfiring with CO2 could help fuels derived from oil sand and shale meet a low-carbon fuel standard. The results showed that this strategy is feasible, but it will likely place these fuels at a competitive disadvantage. UCTT is a novel technology to heat coal in situ and produce a lower carbon content, higher heating value syngas or liquid fuel. Results indicate that UCTT has a limited potential for CO2 mitigation because of the large energy ""losses"" to the coal in situ caused by the large volumes of coal that are heated to low temperatures, resulting in limited product. |
