Study of the differences in collection scope of raw materials of biomass CHP plants caused by regional factors.

Combined heat and power (CHP) plants fueled by biomass can collect and utilize waste straw resources in a productive way. This paper considers the impact of regional factors on biomass energy potential and the energy needs of the population, so as to study the differences in construction of biomass CHP plants and the collection scope of raw materials, and proposes evaluating suitability for biomass energy development based on scope of resource collection. Taking five counties in China as its study areas, this paper assesses biomass energy potential. A topology system of biomass CHP plants has been reasonably established in different counties through ArcGIS, the required installed capacity has been calculated according to the number of persons served by such plants. Finally, the collection length and corresponding value range of raw materials of CHP plants along roads has been obtained based on biomass energy potential and energy demand. The result shows that the differences in area, straw yield and biomass fuelization rate depending on regions have a great impact on biomass energy potential, while the residue-to-product ratio of straw and biomass calorific value have less of an impact. When the biomass energy per capita of a region reaches 9.75GJ/person, it is suitable for biomass energy development. The installed capacity in the biomass CHP plant system of each study area is mostly within the scope of 3-59 MW, and the collection length of corresponding biomass resources of such plants along roads is mostly within the scope of 5.09-25.23 km.

A method for determining the optimal number and location of biomass energy facilities.

The site selection of biomass energy facilities has always been a key part of energy spatial planning. The site suitability evaluation criteria of the existing studies are not comprehensive. On the other hand, most of the existing studies are to determine the only site, while less research on the multiple-facility planning. The aim of this paper is to identify the most effective number and location for biomass energy facilities. To achieve this objective, the Geographic Information System (GIS) is utilized to perform the following tasks: Generate a site suitability map for potential biomass energy facilities and identify suitable site candidates. The standardization of site suitability evaluation indicators is based on fuzzy logic, and indicator weights are determined based on the Analytic Hierarchy Process (AHP) evaluation of experts' opinions. 2. Develop planning schemes for biomass energy facilities for various number of proposed facilities, and subsequently determine the optimal scheme using multi-objective fuzzy comprehensive evaluation. The weight of each indicator is again determined using the AHP method. Following the analysis, it was found that in the case study of Fuxin City, the plans of 1 and 40 biomass energy facilities can achieve the lowest cost and the highest energy self-sufficiency level. However, both options have potential drawbacks that must be considered. The plan of 30 energy facilities has the highest comprehensive benefits, corresponding to the 30,919.75 yuan of transport cost (3748 yuan lower than the average transport cost) and 75.49% of energy self-sufficiency (67.21% of the average value). This work maximizes the comprehensive positive impacts in economic, environmental and social aspects.

The effect of biomass raw material collection distance on energy surplus factor.

The collection radius of biomass raw materials is an important factor affecting the volume of raw materials for energy utilization. At present, it is usually studied based on a single biomass combined heat and power (CHP) plant. However, as the heat transfer threshold of biomass CHP plant is limited, it is necessary to consider the optimal collection radius and biomass raw material allocation under the distribution mode of multiple power plants to improve the overall utilization rate of raw materials. Biomass raw material collection distance threshold (BCDT) refers to the maximum road length between the resource point (that allows the transportation of raw materials to the biomass CHP plant) and the biomass CHP plant. Under the mode of multi-power plant planning, the greater the BCDT is, the more destinations there will be for raw materials to be transported to from the same resource point, and the more flexible the transportation plans and allocation of transportation volumes will be. This also means more raw materials can be ultimately used for energy utilization, which leads to higher transportation cost. Therefore, determining the appropriate BCDT plays a key role in the unified planning of biomass raw materials. Based on the limitation of heat transfer threshold, this paper carries out multi-power plant planning with Fuxin City as the research object. Based on such planning, ArcGIS is used to generate biomass raw material planning schemes with different BCDTs. Then the transportation cost and energy surplus factor (ratio of renewable resource potential to energy demand) of each scheme are calculated and compared. The results show that there is a positive correlation between BCDT and the energy surplus factor. With the increase of BCDT, the growth rate of the energy surplus factor gradually becomes slower. The study also allows to set the utilization threshold of biomass energy utilization capacity and obtain the corresponding BCDT. In order to achieve a higher energy surplus factor, it is recommended that 40 km be used as the BCDT when carrying out uniform planning for biomass raw materials. At this time, the utilization of biomass energy utilization capacity is 75%, which can achieve a high degree of energy self-sufficiency and ensure its economic competitiveness.

Accelerating O-Redox Kinetics with Carbon Nanotubes for Stable Lithium-Rich Cathodes.

Lithium-rich cathodes (LRCs) show great potential to improve the energy density of commercial lithium-ion batteries owing to their cationic and anionic redox characteristics. Herein, a complete conductive network using carbon nanotubes (CNTs) additives to improve the poor kinetics of LRCs is fabricated. Ex situ X-ray photoelectron spectroscopy first demonstrates that the slope at a low potential and the following long platform can be assigned to the transition metal and oxygen redox, respectively. The combination of galvanostatic intermittent titration technique and electrochemical impedance spectroscopy further reveal that a battery with CNTs exhibited accelerated kinetics, especially for the O-redox process. Consequently, LRCs with CNTs exhibit a much better rate and cycling performance (≈89% capacity retention at 2 C for over 200 cycles) than the Super P case. Eventually, TEM results imply that the improved electrochemical performance of the CNTs case also benefits from its more stable bulk and surface structures. Such a facile conductive additive modification strategy also provides a universal approach for the enhancement of the electron diffusion properties of other electrode materials.

Eliminating Graphite Exfoliation with an Artificial Solid Electrolyte Interphase for Stable Lithium-Ion Batteries.

Although graphite materials with desirable comprehensive properties dominate the anode market of commercial lithium-ion batteries (LIBs), their low capacity during fast charging precludes further commercialization. In the present work, natural graphite (G) is reported not only to suffer from low capacity during fast charging, but also from charge failure after many charging cycles. Using different characterization techniques, severe graphite exfoliation, and continuously increasing solid electrolyte interphase (SEI) are demonstrated as reasons for the failure of G samples. An ultrathin artificial SEI is proposed, addressing these problems effectively and ensuring extremely stable operation of the graphite anode, with a capacity retention of ≈97.5% after 400 cycles at 1 C. Such an artificial SEI modification strategy provides a universal approach to tailoring and designing better anode materials for next-generation LIBs with high energy densities.