Modeling the biomass of energy crops：Descriptions, strengths and prospective

The assessment of the biomass of energy crops has garnered widespread interest since renewable bioenergy may become a substantial proportion of the future energy supply, and modeling has been widely used for the simulation of energy crops yields. A literature survey revealed that 23 models have been developed or adapted for simulating the biomass of energy crops, including Miscanthus, switchgrass, maize, poplar, willow, sugarcane, and Eucalyptus camaldulensis. Three categories（radiation model, water-controlled crop model, and integrated model with biochemical and photosynthesis and respiration approaches） were addressed for the selected models according to different principles or approaches used to simulate biomass production processes. EPIC, ALMANAC, APSIM, ISAM, MISCANMOD, MISCANFOR, SILVA, DAYCENT, APEX and SWAT are radiation models based on a radiation use efficiency approach（RUE） with few empirical and statistical parameters. The Aqua Crop model is a typical water-crop model that emphasizes crop water use, the expression of canopy cover, and the separation of evapotranspiration to soil evaporation and plant transpiration to drive crop growth. CANEGRO, 3PG, Crop Syst and DSSAT are integrated models that use photosynthesis and respiration approaches. SECRETS, LPJm L, Agro-BGC, Agro-IBIS, and WIMOVAC/Bio Cro, DNDC, DRAINMOD-GRASS, and Ag TEM are integrated models that use biochemical approaches. Integrated models are mainly mechanistic models or combined with functional models, which are dynamic with spatial and temporal patterns but with complex parameters and large amounts of input data. Energy crop models combined with process-based models, such as EPIC in SWAT and CANEGRO in DSSAT, provide good examples that consider the biophysical, socioeconomic, and environmental responses and address the sustainability and socioeconomic goals for energy crops. The use of models for energy crop productivity is increasing rapidly and encouraging; however, relevant databases, such as climate, land use/land cover, soil, topography, and management databases, arescarce. Model structure and design assumptions, as well as input parameters and observed data, remain a challenge for model development and validation. Thus, a comprehensive framework, which includes a high-quality field database and an uncertainty evaluation system, needs to be established for modeling the biomass of energy crops.

Evaluation of Potential Productivity of Woody Energy Crops on Marginal Land in China

Energy crops are a basic material in the bioenergy industry, and they can also mitigate carbon emissions and have environ- mental benefits when planted on marginal lands. The aim of this study was to evaluate the potential productivity of energy crops on marginal lands in China. A mechanistic model, combined with energy crop and land use characteristics, and meteorological and soil parameters, was used to simulate the potential productivity of energy crops. There were three main results. 1） The total marginal land in China was determined to be 104.78 × 106 ha. The 400-mm precipitation boundary line, which is the dividing line between the semi-humid and semi-arid zones in China, also divided the marginal land into shrub land and sparse forest land in the southeast and bare land, bare rock land, and saline alkali land in the northeast. 2） The total area of the marginal land suitable for planting energy crops was determined to be 55.82 × 106 ha, with Xanthoceras sorbifolia and Cerasus humilis mainly grown in the northern China, Jatropha curcas and Comus wilsoniana mainly grown in the southwest and southeast, and Pistacia chinensis mainly grown in the central area, while also having a northeast-southwest zonal distribution. 3） Taking the highest yield in overlapping areas, the potential productivity of target energy crops was determined to be 32.63 × 106 t/yr. Without considering the overlapping areas, the potential productivity was 6.81× 106 t/yr from X. sorbifolia, 8.86× 106t/yr from C. humilis, 7.18 ×106t/yr from J. curcas, 9.55 × 106t/yr from P. chinensis, and 7.78 ×106 t/yr from C. wilsoniana.

Assessing the Availability of Land and Water Resources for Production of Energy Crops in Southern Africa

Production of energy crops is perceived as a potential source of alternative energy for petroleum oil. However, it is cru-cial to ensure that there is adequate land and water available for production of energy crops before indulging into the business of producing such crops. This paper assesses the availability of land and water resources for production of energy crops in the SADC region using landuse/landcover data, hydrological and meteorological data, as well as socioeconomic data. It is found that Botswana and Mozambique have large amounts of bushland that can be used for expansion of agricultural land including production of energy crops. Zimbabwe has the highest amount of land under cultivation, which makes it difficult for the country to expand its agricultural land. However, land reform processes taking place in Zimbabwe provides a good opportunity to diversify agricultural production including reallocation of farms for production of energy crops. Mozambique has favorable rainfall for production of maize and sugarcane, whereas Zimbabwe can explore growing Jatropha on degraded land and use irrigation for cultivation of sugarcane. High frequency of crop failure in Botswana makes it difficult to grow maize or sugarcane as energy crop. The country can promote production of sweet sorghum, which is traditionally grown by small scale farmers, and explore production of Jatropha in degraded and desert land. A regional approach to address land and water requirements for production of energy crops is considered important as compared to planning for production in each country as the constraints and potential of each country can be fully recognized. More detailed country specific research is needed on the production of the specified energy crops to ensure sustainability of the production systems.

The Production of Biofuels in South Africa： Policy and Availability of Energy Crops

Biofuels could contribute, on a worldwide basis, to the attainment of international energy-policy objectives in three ways： by reducing dependence on imported oil; by increasing the availability of renewable energy sources; and by dealing with environmental issues. One such environmental issue is the unsustainable use of agricultural land. There is a need in South Africa there to convert to sustainable and renewable energy resources, such as biofuels, but the production of biofuels will ultimately place pressure on the limited and fragile agricultural resources of the country. This paper sets out firstly to investigate national agricultural policies which could impact on the production of biofuels. It points out that national agricultural policies are hampering the domestic production of biofuels in that the focus is on land reform and increasing the volume of agricultural exports, whereas the provision of food and energy to meet domestic needs features only as a secondary aim. The second objective of this paper is to investigate the possibility of utilising energy crops for biofuel production in South Africa. Annual agricultural production, surplus import and export figures, provide an indication of the capacity of South African farmers to produce crops for biofuel production.

Energy and Autohydrolysis By-Products from Industrial Crops

The world is experiencing a growing shortage of raw materials which is especially severe in the energy sector and being worsened by the unfavorable environmental impact of a consumerist cultttre revolving around the exploitation of non-renewable resources. In this work, the calorific value and chemical composition of liquors resulting from the autohydrolysis of six different lignocellulosic materials was determined （Eucalyptus globulus, Arundo donax, Leucaena diversifolia, Paulownia fortunei, Sunflower stalks and Chamaecytisus proliferus） and was assessed for the obtainment of energy, sugars and other chemical products by using of integral fractionation based on autohydrolysis. Autohydrolysis processes have been considered interesting in the case of timber species studied compared with herbaceous species with variations in the extraction of the xylan fraction at 180℃ between 19.68% for Eucalyptus globulus and 36.79% for Leucaena diversifolia and 200℃ between 57.86% for Paulawniafortunei and 79.13 % for Chamaecytisusproliferus. In general, all materials show a solid fraction ＂more energy＂ from the hydrolysis to 200℃ than 180℃ and raw materials. It is interesting as the potential economy valuation of the liquid fractions of the hydrolysis, the solid waste recovery present more energetic profitability.

Energy Balance in Crop Production

The most appropriate method of energy balancing in crop production is the process analysis where fossil energy input is considered rather than manpower or solar energy. In our approach, fossil energy input is split to direct and indirect input components. Direct energy input includes the consumption of diesel fuel required for field operations taking into account the influences of location and management conditions. Moreover, energy consumption for construction of agricultural machines is also considered as direct energy input. Indirect energy inputs include seed material, plant protection agents, fertilizers and operation of machines. Production and utilisation of nitrogen （N） fertilizer represents by 50% of energy consumption in agricultural systems. Data from a field experiment conducted during 1995-2000 on a fertile sandy loess in the Hercynian dry region of central Germany were used to determine the energy efficiency of winter oilseed rape （Brassica napus L.） as affected by nitrogen （N） fertilization. Our results show that different N management strategies affect the energy balance of the seed oil. Lowest energy input and energy output occurred in the unfertilized crop. The energy efficiency was determined using the parameters energy gain （net energy output）, energy intensity （energy input per unit grain equivalent GE; term GE is used to express the contribution that crops make to the nutrition of monogastric beings）, and output/input ratio. The most favourable N rate for minimum energy intensity was 80 kg N hal while that needed for maximum energy gain was 160 kg ha1. Output/input ratio was the highest at 80 kg N ha-l.

Roles of Bioenergy and Green Hydrogen in Large Scale Energy Storage for Carbon Neutrality

1.Roles of biomass and bioenergy in solar energy storage Biomass comprises plant-based material,for example,wood,microalgae,energy crops,and agro-forestry residues,as well as organic waste from industries,farms,and households,and plays a key role in solar energy capture and storage.

Marginal land in China suitable for bioenergy crops under diverse socioeconomic and climate scenarios from 2020 to 2100

Maximizing the development of renewable energy plays a critical role in mitigating the climate crisis.Marginal land provides space for the development of biomass energy;however,it remains unclear how the amount and spatial distribution of marginal land that is suitable for energy crop development will change in the future.Here,we project energy marginal land changes in China following the shared socioeconomic pathway(SSP)and/or repre-sentative concentration path(RCP).We provide datasets of mar-ginal land,agriculturally suitable land,and potentially suitable for energy crops under historical scenarios and six future scenarios(i.e.SSP1-1.9,SSP1-2.6,SSP4-3.4,SSP2-4.5,SSP4-6.0,and SSP3-7.0)for the period 2020-2100,with a spatial resolution of 5 km.Under the six scenarios,from 2020-2100,the area of suitable marginal land ranged from 1.90-16.28(Jatropha curcas L.)to 37.37-73.97(Panicum virgatum L.)(×10^(4)km^(2)),depending on the choice of energy crops and climate scenario.Based on the growing suitability of eight important bioenergy crops-Ricinus communis L.,Saccharum officinarum L.,Pistacia chinensis Bunge,Panicum virga-tum L.,Jatropha curcas L.,Miscanthus giganteus J.,Manihot esculenta Crantz,and Sorghum bicolor Moench-our dataset can be used to identify suitable locations for specific energy crops.This new syn-thetic dataset could support the development of multiscenariobased solutions related to carbon neutrality,ecosystem services,and energy transition.

拱架送/回风方式对日光温室冬季作物冠层区热环境的影响

传统日光温室被动的热环境调控模式难以满足温室作物冠层区空气温度和速度调控需求,且能源利用效率低下。为了改进日光温室热环境精准调控方法和提高温室能源利用效率,该研究结合日光温室围护结构特点,提出了一种日光温室拱架的送/回风方法,并基于温室作物多孔介质模型,建立了拱架送/回风系统温室的数值传热模型。采用空气温度与速度不均匀系数、气流速度适宜区面积比、能量利用系数以及累计有效积温等评价参数,研究了下送上回、中间回风和上送下回等3种温室拱架送/回风方式对日光温室冬季作物冠层区热环境的影响。结果表明,与中间回风和上送下回通风方式相比,下送上回通风方式对不同作物冠层高度处的空气温度和速度调控的结果最优,且不同作物冠层高度处气流速度适宜区面积比和累计有效积温都最大。当采用下送上回通风方式时,与送风干管风速为9、11和12 m/s相比,送风干管风速为10 m/s的能量利用系数最大,在作物冠层高度0.4、0.6、0.8和1.0 m处的能量利用系数分别为0.976、0.982、0.985和0.987,并且不同作物冠层高度处的空气温度不均匀系数和速度不均匀系数也都最小。因此,下送上回通风方式的推荐送风干管风速为10 m/s。该研究可为日光温室热环境的精准调控提供参考。

农作物秸秆低碳墙体材料研究现状

综述了近年来国内外关于农作物秸秆在建筑墙体材料中的应用及研究进展,从生产技术、制备工艺、配合比设计等方面出发,重点介绍了农作物秸秆低碳墙体材料的力学性能、保温隔热性能、阻燃性能等优良特性,并对农作物秸秆低碳墙体材料现阶段所存在的缺陷和不足给出了合理建议,对其未来发展方向及应用前景做出了展望。

垃圾秸秆焚烧炉应用现状及发展建议

随着城市化进程的加快和人们生产生活水平的提高,垃圾秸秆的处理与利用问题日益突出。垃圾秸秆焚烧炉具有可回收能源、环境友好等优点,开发和应用垃圾秸秆焚烧炉是解决垃圾秸秆问题的重要途径。基于此,本文介绍了垃圾秸秆焚烧炉的基本原理与分类,深入分析了垃圾秸秆焚烧炉的应用现状,并针对目前存在的技术滞后、废气处理难度大、投资周期长、国际合作欠缺等问题,提出了促进技术研发与创新、强化环境管理和减排、加强政府支持与政策引导、加强跨国合作与学习交流等发展建议,以期为促进垃圾秸秆资源化利用,降低生态环境污染,助力乡村振兴提供参考。

Harvesting Technologies and Costs for Switchgrass Production

As today’s society searches for renewable energy sources that could be an alternative to fossil fuels, biomass and biofuels provide a promising solution. Switchgrass is one of feedstocks that can be utilized as a renewable energy source. When farming, one of the most important considerations is efficiency. This consists of several factors, including time, fuel use, economic and power efficiencies of equipment. Inefficient field operations could increase harvesting costs and in turn could cause hesitation when a farmer decides to participate in biomass production. This literature review will cover the main elements of biomass and biomass handling relating to determining harvesting efficiency and biomass quality for switchgrass round bales. Specifically, the following sections include past research activities relating to biomass harvesting, biomass bale quality during outdoor storage, logistics models, and data collection methods during biomass harvesting. The objective of this review is to examine status and needs for switchgrass round bale harvesting operations and the expenses that come with it.

Camalote Grass (Paspalum fasciculatum Willd) as a Sustainable Raw Material for the Production of Lignocellulosic Ethanol

The current trend of replacing a percentage of gasoline with ethanol has promoted the development of new processes for its production from lignocellulosic biomass. This work reports the production of ethanol from the Camalote grass (Paspalum fasciculatum Willd). The lignocellulosic biomass was subjected to acid hydrolysis at 125C and 15 psi with H2SO4 concentrations at 5%, 10%, and 20%, obtaining an average of reducing sugars (pentoses and hexoses) from the hydrolyzed juice with 12.3%, 10%, and 17% Brix, respectively. The sugars were fermented using yeast of the Saccharomyces cerevisiae at 30C for 48 hours. Finally, the ethanol was distilled at 78C, and the average yields were obtained through analysis of variance with a 95% confidence level. The values indicate that there is a significant difference (p > 0.05), the Tukey study shows that all the % v/v averages are different from each other. For H2SO4 concentration at 5% (10.33 ± 2), H2SO4 at 10% (9.33 ± 1.8), and H2SO4 at 20% (6.33 ± 2). The acidity analysis for the ethanol obtained from each treatment gave a value of 1.8 mg/L of acetic acid in all cases.

河南省主要农作物秸秆资源分布及资源化利用需求分析

河南省是农业大省,农作物秸秆资源丰富,为提高区域秸秆资源化综合利用率,促进秸秆资源化利用产业化发展,文章对河南省主要农作物秸秆资源量、秸秆养分蕴含量等进行了估算,明确了河南省秸秆资源分布特征,同时结合河南省秸秆资源化利用需求量,计算分析了全省秸秆资源化利用潜力。结果表明:2022年河南省主要农作物秸秆理论资源量和可收集资源量分别为10386.88万t和8108.91万t,主要分布在驻马店、南阳、周口和商丘,区域秸秆资源量差异较大;2022年河南省可收集秸秆中氮、磷、钾蕴含量分别为66.64万t、19.66万t和105.94万t,可收集秸秆量理论上可以代替当年全省氮肥需求量的42.28%、磷肥需求量的27.38%,可全量代替当年的钾肥需求量;牲畜饲料化秸秆需求量为1375.48万t,占全省可收集秸秆资源总量的16.96%;基料化秸秆资源需求量为184.95万t,占全省秸秆资源总量的2.28%;可收集秸秆全部能源化利用可替代4086.25万t标准煤。

基于作物安全性的农业温室综合能源系统低碳控制方法

农业温室综合能源系统(agricultural greenhouse integrated energy system,AGIES)需深入考虑作物安全生长环境条件,优化调控多源设备功率,实现系统经济、低碳运行。提出了一种基于作物安全性的AGIES低碳控制方法,构建含电、气、热AGIES供能架构,建立各农业设备功率模型,阐明能量流和功率耦合设备的能量转换机制。研究农作物生长的光照、温度、供水安全边界条件,提出作物的日光照量与小时光照量合理范围、室内恒温供热功率范围、科学供水用电功率范围与用电时间范围,并采用数学模型详细描述。提出了电、气、热碳排放核算指标,建立综合运行成本和碳排放成本最低的功率优化控制模型,采用粒子群算法求解,得到优化用能方案。通过算例仿真验证了所提方法的可行性和有效性。

基于涡动相关的农田蒸散量及作物系数研究

为研究作物蒸散发和作物系数对作物水资源利用效率及产量的影响,本研究利用EC3000涡动协方差系统对农田蒸散量(ET)、作物系数(Kc)、净辐射(R_(n))、土壤热通量(G)、感热通量(H)和潜热通量(LE)进行分析,并对农田作物的蒸散发及其对作物系数的影响进行了研究。结果表明:(1)2021—2022年作物生长期间作物蒸散量(ETc)分别为582.95、609.63 mm,不同生长阶段作物系数(Kc)在0.39~1.43范围内呈现波动变化。(2)净辐射(R_(n))、土壤热通量(G)、感热通量(H)和潜热通量(LE)的日均值分别为135.92、5.81、15.27和81.89 W/m^(2),LE/R_(n)为64%,能量闭合率(EBR)为0.78。本研究结果为柴达木地区作物生产提供了理论依据。

California Simulation of Evapotranspiration of Applied Water and Agricultural Energy Use in California

The California Simulation of Evapotranspiration of Applied Water （CaI-SIMETAW） model is a new tool developed by the California Department of Water Resources and the University of California, Davis to perform daily soil water balance and determine crop evapotranspiration （ETo）, evapotranspiration of applied water （ETaw）, and applied water （AW） for use in California water resources planning. ETaw is a seasonal estimate of the water needed to irrigate a crop assuming 100% irrigation efficiency. The model accounts for soils, crop coefficients, rooting depths, seepage, etc. that influence crop water balance. It provides spatial soil and climate information and it uses historical crop and land-use category information to provide seasonal water balance estimates by combinations of detailed analysis unit and county （DAU/County） over Califomia. The result is a large data base of ETc and ETaw that will be used to update information in the new California Water Plan （CWP）. The application uses the daily climate data, i.e., maximum （Tx） and minimum （Tn） temperature and precipitation （Pcp）, which were derived from monthly USDA-NRCS PRISM data （PRISM Group 2011） and daily US National Climate Data Center （NCDC） climate station data to cover California on a 4 kmx4 km change grid spacing. The application uses daily weather data to determine reference evapotranspiration （ETo）, using the Hargreaves-Samani （HS） equation （Hargreaves and Samani 1982, 1985）. Because the HS equation is based on temperature only, ETo from the HS equation were compared with CIMIS ETo at the same locations using available CIMIS data to determine correction factors to estimate CIMIS ETo from the HS ETo to account for spatial climate differences. CaI-SIMETAW also employs near real-time reference evapotranspiration （ETo） information from Spatial CIMIS, which is a model that combines weather station data and remote sensing to provide a grid of ETo information. A second database containing the available soil water holding capacity and soil depth information for all of California was also developed from the USDA-NRCS SSURGO database. The Cal-SIMETAW program also has the ability to generate daily weather data from monthly mean values for use in studying climate change scenarios and their possible impacts on water demand in the state. The key objective of this project is to improve the accuracy of water use estimates for the California Water Plan （CWP）, which provides a comprehensive report on water supply, demand, and management in California. In this paper, we will discuss the model and how it determines ETaw for use in water resources planning.

Estimation on the Total Quantity of Biomass Energy and Its Environmental Benefit Analysis in Shandong Province

[Objective] The aim was to estimate the total quantity of biomass energy and analyze its environmental benefit in Shandong Province.[Method] Based on the data from the statistics yearbook of Shandong Province in 2010,the total quantity of biomass resources and biomass energy in Shandong Province in 2009 was estimated,and its environmental benefit was analyzed.[Result] Biomass resources in Shandong Province mainly refer to crop residues,forest residues,grassland changed from degraded land.If degraded land became grassland,the total quantity of biomass resources and biomass energy in Shandong Province in 2009 was 182.808 8 million tons and 2.68×1015 kJ respectively.Meanwhile,the reduction of total emission of CO2,SO2 and nitrogen oxides was up to 241.265 million tons,and the reduced emission of SO2 accounted for 48.9% of annual SO2 emission in Shandong in 2009.Planting energy crops plays important roles in the development of new energy sources,reduction of greenhouse gas emission and environmental protection.[Conclusion] The study could provide theoretical foundations for the establishment of energy policy and study on development strategy of biomass energy in Shandong Province.

Cotton Production Systems for Soil and Energy Conservation in Coastal Plain Soils

Cotton growers in the southern USA are facing new production problems that are reducing farm profits and sustainability: 1) herbicide-resistant weeds are spreading throughout the Southeast, 2) thrips are consistently ranked as an important insect pest group Beltwide, 3) the most effective tool for managing nematodes and thrips (aldicarb) currently is only available in the southeastern USA in limited amounts, and 4) fuel costs have increased significantly over the last ten years. An interseeding system was developed at Clemson University that allows planting of cotton into standing wheat, about 2 - 3 weeks before wheat harvest. This system, which combines benefits of crop residue and minimum tillage operations, has the potential to alleviate many of the production problems cited above, while enhancing farm profits and soil properties. Crop residue associated with the interseeding production system reduced weed populations and required significantly less herbicide inputs compared with the conventional system. Columbia lance nematodes populations were reduced in the interseeding system by 83% without an application of nematicide. Populations of thrips were reduced by 74% in the interseeding production system. No differences were observed between the yields from interseeded and the conventional full-season cotton. However, revenues from the interseeding system were higher due to harvest of the wheat crop. In addition, the interseeding system consumed 35% less fuel than the conventional production systems.

Evaluation of the Effect of Agricultural Management on Energy Yield and Greenhouse Gas Emission Reduction of Bioenergy Production Chains

The role of energy crops in reducing fossil energy use and greenhouse gas emission is much debated. To improve decision making on the use of crops for producing bioenergy, a tool (Energy Crop Simulation Model or E-CROP) has been developed to calculate 1) sustainable crop dry matter yield levels as function of agricultural inputs, and 2) gross and net energy yield and greenhouse gas emission reduction, covering the entire bioenergy production chain from sowing to distribution of bioenergy. E-CROP can be applied to a wide range of crops, soils, climatic conditions, management choices, and conversion technologies. This paper describes E-CROP and focuses on its application on four arable crops, as cultivated on two contrasting sites in the Netherlands (potato and sugar beet for bioethanol, winter oilseed rape for biodiesel and silage maize for bioelectricity) and on the effect of crop management (viz. irrigation and nitrogen fertilisation). In all situations, gross energy output exceeded total energy input. Calculated for an average situation, net energy yield ranged from 45 to 140 GJ.ha-1. Lowering irrigation and/or fertilisation input levels generally resulted in a reduction of net energy yields. The net reduction of greenhouse gas emissions in the average situation ranged from 0.60 to 6.5 t CO2-eq.ha-1. In general, N2O emission from nitrogen fertiliser caused large variations in the net reduction of greenhouse gas emission, which even became negative in some situations. Lowering nitrogen fertilisation to levels that are suboptimal for net energy yields enhanced the net reduction in greenhouse gas emission, implicating that both goals cannot be optimised simultaneously. Agricultural knowledge is important for optimising the outputs of bioenergy production chains.