A prefilter for mitigating PH3 contamination of a Ni-YSZ anode

Ni-YSZ is used as the anode of a solid oxide fuel cell (SOFC) because it has excellent electrochemical performance for operation with coal-derived syngas. However, trace impurities, PH₃ H₂S AsH₃, and Sb in coal-syngas can cause SOFC degradation. Described here is a means of removing PH₃ impurity from syngas by using a Ni-based prefilter. In one test, a thin Ni-based filter was set upstream of a Ni-YSZ anode-supported SOFC. The SOFC was exposed to syngas with PH₃ under a constant current load at 800 °C. The filter decreased 20 ppm PH₃ in the feed to a level which did not degrade the SOFC for over 400 h until the filter became saturated. In another test, both H₂S and PH₃ were co-fed to the cell with Ni-based and Fe/Ni-based filters. The interaction between these two impurities did not significantly impact the filter performance with respect to PH₃ removal for both filter formulations. The cell performance was evaluated by current-voltage measurements and impedance spectroscopy. Post-mortem analyses of the cell and filter were performed by means of XRD, SEM/EDS and XPS. With proper filter design, the Ni-YSZ SOFC can operate on contaminated coal-syngas without degradation over a prescribed period of time.     

Formulation and characterization of ultra-thick electrodes for high energy lithium-ion batteries employing tailored metal foams

Increasing the thickness of a battery electrode without comprising cell electrochemical performance, such as power density and cycling stability, is very challenging. In this work, we demonstrate the utility of 3D (three dimensional) Cu foam framework as a current collector for building carbon negative electrodes as thick as 1.2 mm. When tested in a bipolar configuration, electrodes of 1.2 and 0.6 mm thick delivered capacities of over 350 mAh g⁻¹ (>95% of theoretical capacity) up to a C/5 rate. We have also assembled a full cell composed of a 1.2 mm thick negative electrode with Cu foam as the current collector and a 1.2 mm thick L333 (LiNi_1/3Mn_1/3Co_1/3O₂) positive electrode with Al foam as the current collector. The cell exhibited good capacity retention at low rates. These results underscore the promise of 3D foam structures in terms of enabling ultra-thick electrodes for high energy density battery applications.     

Mapping woody-biomass supply costs using forest inventory and competing industry data

The goals of energy independence and sustainability have motivated many countries to consider biomass-based energy sources. The United States has substantial and increasing forest resources that could be used to produce both electricity and liquid fuel. However, these forest resources are highly heterogeneous in terms of the wood’s properties, the logging cost, the spatial distribution, and the value to other industries. These factors make predicting costs and selecting plant locations particularly challenging. When dealing with forest biomass, feedstock cost and location have frequently been highly simplified in previous studies. This paper presents a methodology for combining highly resolved forest inventory and price data with records of competing industries to develop detailed maps of feedstock availability. The feedstock sourcing strategy of the proposed bioenergy plants is modeled by a cost-minimizing linear program, as is the feedstock selection of the competing mills. A case study is performed on the southeast United States.     

Evaluation of two round baling systems for harvesting understory biomass

The objective of this study was to evaluate the performance and to estimate costs of two round baling systems for harvesting understory biomass. One system was a cutter-shredder-baler prototype (Bio-baler). The other system required two successive operations. The first operation was cutting and shredding with a Supertrak tractor equipped with a Fecon mulcher head. The second operation was baling with a Claas baler. The machines were evaluated in three different pine stands on the Osceola National Forest in Florida, United States. Data collection included time study, fuel consumption and bale measurements. Material was collected from a sample of bales for heat and moisture content determination. On the most representative site (Site 2), the Bio-baler recovered 8.05 green t ha⁻¹ while the mulcher and the Claas baler recovered 9.75 green t ha⁻¹ (43 and 52 percent of original understory biomass, respectively). Productivity was 0.30 ha h⁻¹ for the Bio-baler and 0.51 ha h⁻¹ for the Claas baler. Density of the bales was 321 green kg m⁻³ for the Bio-baler and 373 green kg m⁻³ for the Claas baler. Average net heat content was 6263 MJ bale⁻¹ for the Bio-baler and 6695 MJ bale⁻¹ for the Claas baler with biomass containing 38 percent of moisture content on a wet basis. Cost per unit area was less with the Bio-baler (US$320.91 ha⁻¹) than with the mulcher-baler system (US$336.62-US$596.77 ha⁻¹).     

Japan's new basic energy plan

In June 2010, the Japanese cabinet adopted a new Basic Energy Plan (BEP). This was the third such plan that the government has approved since the passage of the Basic Act on Energy Policy in 2002, and it represents the most significant statement of Japanese energy policy in more than four years, since the publication of the New National Energy Strategy (NNES) in 2006. Perhaps more than its predecessors, moreover, the new plan establishes a number of ambitious targets as well as more detailed measures for achieving those targets. Among the targets are a doubling of Japan's “energy independence ratio,” a doubling of the percentage of electricity generated by renewable sources and nuclear power, and a 30 percent reduction in energy-related CO₂ emissions, all by 2030. This paper explains the origins of the 2010 BEP and why it was adopted. It then describes the content of the plan and how it differs from the NNES. A third section analyzes the appropriateness of the new goals and targets contained in the BEP and their feasibility, finding that achievement of many of the targets was likely to be quite challenging even before the March 2011 earthquake, tsunami, and nuclear crisis.     

Chemical characterisation and ruminal nutrient degradability of hulled and hull-less oats

The objectives of this study were to determine the chemical and ruminal nutrient degradability characteristics of two hulled (Calibre and AC Mustang) and one hull-less (AC Belmont) oat varieties. Ruminal nutrient degradability characteristics of the oat varieties were determined relative to barley using one ruminally fistulated cow. Neutral (NDF) and acid (ADF) detergent fibre levels were higher (P < 0·05) in hulled than hull-less oats. Hulled AC Mustang had higher (P < 0·05) NDF and ADF content than hulled Calibre. Starch content was higher (P < 0·05) in AC Belmont (590 g kg⁻¹) than Calibre (457 g kg⁻¹) and was higher in Calibre than AC Mustang (415 g kg⁻¹). Crude protein was higher (P < 0·05) in hull-less than hulled oat. Both hulled varieties had similar CP content (average 124 g kg⁻¹). Estimated digestible energy value was highest (P < 0·05) for AC Belmont (16·94 MJ kg⁻¹), intermediate for Calibre (14·18 MJ kg⁻¹) and lowest for AC Mustang (13·34 MJ kg⁻¹). Ruminal dry matter and NDF degradability were higher (P < 0·05) in hull-less than barley and was higher in barley than hulled oats. Ruminal starch degradability exceeded 900 g kg⁻¹ for all tested feeds and had the order AC Belmont = barley > Calibre = AC Mustang. It was concluded that oat varieties used in this study varied considerably in their chemical composition and ruminal degradability. When compared with barley, hulled oats had lower while hull-less oats had higher ruminal degradability. © 1998 SCI.     

A study of stabilization of P3HT/PCBM organic solar cells by photochemical active TiOx layer

We describe a study of the stabilization behavior of P3HT/PCBM organic solar cells under air and UV irradiation using a 20 nm thin TiO_x protection layer made by partial hydrolysis of a Ti-alkoxide and spin coating in air. Data on the degradation of solar cell performance under air and under UV exposure are presented indicating that significant improvements are observed with TiO_x layer protection. The protection mechanism has been investigated by transmission IR and UV spectroscopy and by ESR spectroscopy. The results of this study suggest how sol-gel derived TiO_x films containing organic functionalities serve as effective passivation films for protection from oxygen when excited by photons, where the photooxidation of the bound organic moieties causes oxygen gas scavenging.     

A numerical study of vortex interactions with flames developing from ignition kernels in lean methane/air mixtures

In this work, the outcomes of interactions of counter-rotating vortex pairs with developing ignition kernels are studied. The conditions are selected to represent those in a lean-burn natural-gas engine with hot-jet ignition. The evolution of flame surface area during kernel–vortex interaction is quantitatively and qualitatively examined. It is observed that flame development is accelerated and the net flame surface area growth rate, i.e. heat release rate, increased with increasing vortex velocity. In general, increasing the vortex length scale increases the surface growth rate, i.e. increases heat release rates, but for small length scales, i.e. when the ratio of vortex length scale to kernel diameter is small, high flame curvature induced during the interaction leads to flame weakening and slower growth rates. When the vortex velocity is high relative to the flame speed and the length scale is comparable to the kernel diameter, the vortex breaks through the ignition kernel carrying with it hot products of combustion. This accelerates growth of the flame surface area and heat release rates compared to a kernel with no vortex interaction. On decreasing the vortex velocity and increasing the length scale, the wrinkling of the kernel becomes important. This also results in increased surface growth rates and higher heat release rates.     

AN EXPERIMENTAL STUDY OF THE EFFECT OF PARAFFINIC SOLVENTS ON THE ONSET AND BULK PRECIPITATION OF ASPHALTENES

ABSTRACT

Asphaltene onset concentration and bulk deposition were measured for a typical live reservoir oil titrated with n-C₆H₁₄, n-C₅H₁₂, n-C₄H₁₀, C₃H₈, C₂H₆, CH₄ and CO₂ at 100° C (212 ° F) and 29.9 MPa (4340 psia). The concentration of titrant at asphaltene onset was observed to decrease approximately in a linear fashion with decreasing molecular weight of the paraffinic solvent; CH₄ did not induce any asphaltene precipitation. Bulk deposition experiments were performed using a solvent: oil volume ratio of 10:1; the results indicated that the weight percent of asphaltenes precipitated increased exponentially with decreasing molecular weight of the paraffinic solvents. More importantly, the asphaltene molecular weight showed a maximum for n-C₄H₁₀ precipitated asphaltenes. Possible explanations for this unusual result are presented.     

A PROCEDURE FOR THE PRODUCTION OF ULTRA-PURE PRECURSORS FROM COAL FOR THE MANUFACTURE OF VALUE-ADDED CARBON PRODUCTS - TREATMENT OF THE RESIDUE

ABSTRACT

Solvent extraction of coal results in a coal-derived extract containing the solvent-soluble organic portion of coal free of almost all mineral matter. A residue is also produced and consists of most of the mineral matter. Although a procedure has been developed to manufacture ultra-pure coke precursors for value-added carbon products from coal-derived extracts, treatment/rc-usc of the residue is necessary to make the process economically attractive and environmentally friendly. In this study, a technique has been developed to beneficiate the residue by specific gravity fractionation. It is found that nearly 70 % of the residue can be separated into a fraction containing less than 3.5% ash for a typical WV bituminous coal using an organic liquid having a specific gravity of 1.5. This treatment enables the residue to serve as a low-ash boiler fuel or a suitable precursor for the manufacture of materials such as activated carbons. Consequently, the potential for coal-derived precursors leading to new and non-conventionai marketable carbon products can be realized easily.