Dozens of scenarios are published each year outlining paths to a low carbon global energy system. To provide insight into the relative feasibility of these global decarbonization scenarios, we examine 17 scenarios constructed using a diverse range of techniques and introduce a set of empirical benchmarks that can be applied to compare and assess the pace of energy system transformation entailed by each scenario. In particular, we quantify the implied rate of change in energy and carbon intensity and low-carbon technology deployment rates for each scenario and benchmark each against historical experience and industry projections, where available. In addition, we examine how each study addresses the key technical, economic, and societal factors that may constrain the pace of low-carbon energy transformation. We find that all of the scenarios envision historically unprecedented improvements in energy intensity, while normalized low-carbon capacity deployment rates are broadly consistent with historical experience. Three scenarios that constrain the available portfolio of low-carbon options by excluding some technologies (nuclear and carbon capture and storage) a priori are outliers, requiring much faster low-carbon capacity deployment and energy intensity improvements. Finally, all of the studies present comparatively little detail on strategies to decarbonize the industrial and transportation sectors, and most give superficial treatment to relevant constraints on energy system transformations. To be reliable guides for policymaking, scenarios such as these need to be supplemented by more detailed analyses realistically addressing the key constraints on energy system transformation.
A low-swirl burner (LSB) developed for laboratory research has been scaled to the thermal input levels of a small industrial burner. The purpose was to demonstrate its viability for commercial and industrial furnaces and boilers. The original 5.28 cm i.d. LSB using an air-jet swirler was scaled to 10.26 cm i.d. and investigated up to a firing rate of Q ס 586 kW. The experiments were performed in water heater and furnace simulators. Subsequently, two LSBs (5.28 and 7.68 cm i.d.) configured to accept a novel vaneswirler design were evaluated up to Q ס 73 kW and 280 kW, respectively. The larger vane-LSB was studied in a boiler simulator. The results show that a constant velocity criterion is valid for scaling the burner diameter to accept higher thermal inputs. However, the swirl number needed for stable operation should be scaled independently using a constant residence time criterion. NO x emissions from all the LSBs were found to be independent of thermal input and were only a function of the equivalence ratio. However, emissions of CO and unburned hydrocarbons were strongly coupled to the combustion chamber size and can be extremely high at low thermal inputs. The emissions from a large vane-LSB were very encouraging. Between 210 and 280 kW and 0.8 Ͻ Ͻ 0.9, NO x emissions of Ͻ15 ppm and CO emissions of Ͻ10 ppm were achieved. These results indicate that the LSB is a simple, low-cost, and promising environmental energy technology that can be further developed to meet future air-quality rules.
Elemental sulfur recovery from SO2-containing gas streams is highly attractive as it produces a saleable product and no waste to dispose of. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox(reduction of SO2 with coke) and Claus plants(reaction of SO2 with H2S over catalyst). This project will investigate a cerium oxide catalyst for the single-stage selective reduction of SO2 to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified in recent work at MIT as a superior catalyst for SO2 reduction by CO to elemental sulfur because of its high activi_ and high selectivity to sulfur over COS over a wide temperature range(40{3-650 "C). The detailed kinetic and parametric studies of SO2 reduction planned in this work over various CeO2-formulations will provide the necessary basis for development of a very simplified process, namely that of a single-stage elemental sulfur recovery scheme from variable concentration ,7,"as streams. The potential cost-and energy-efficiency benefits from this approach can not be overstated. A first apparent application is treatment of regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought "Claus-alte:rnative" for coal-fired power plant applications.
The objective of this effort is to establish the technology required for private sector use of an advanced coal-fueled gas turbine power system. The system is to burn low-cost, utility-grade coal, and yet comfortably meet the EPA New Source Performance Standard (NSPS) for coal-fired steam generators. Plant thermal efficiency is to surpass competing coal-utilization cycles. Development of a successful high pressure slagging combustor is the key to meeting these objectives. As subcontractor to Westinghouse, Avco Research Laboratory/Textron (ARL) has designed and fabricated a subscale slagging combustor based on earlier MHD and boiler-type units. The new device is currently in a 12½-month developmental series of tests. Based on these series of tests, Westinghouse is to design, manufacture, and test a full-scale slagging combustor in a test cell at nominal field operating conditions. The activities described in this paper are sponsored by the Morgantown Energy Technology Center of the Department of Energy.
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