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.

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.

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.

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.

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.

The Suitability of Maize as a Bio-ethanol Crop in South Africa

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 addressing environmental issues. It is an absolute necessity in South Africa to utilise sustainable and renewable energy sources, such as biofuels, but the production of bio-ethanol will ultimately place pressure on the limited and fragile agricultural resources of the country. Because of the proposed bio-ethanol plant at Bothaville this paper will firstly develop a methodology suitable for South African conditions in order to establish whether agricultural crops could be used for the production of biofuels. Secondly, it probes the suitability of maize as a biofuel crop in this country by investigating four possible bio-ethanol potential scenarios which are qualitatively formulated to provide a comprehensive overview of this study. Only in the best-case scenario could maize produce the required volumes as set out by the South African government for 2013.

The Effect of Mechanical Conditioning on Physical Conditions of Miscanthus Plants

Miscanthus is an emerging dedicated energy crop, which can provide excellent yield on marginal lands. However, this crop is more difficult to harvest than many conventional energy crops such as corn stover and switchgrass due to its tall and rigid stalks. Crop samples for laboratory studies were collected from the field and the effects of roll spacing, roll speed, and crop input of a mechanical conditioning device on the physical conditions of miscanthus were studied in a lab setting. Test results showed that mechanical conditioning is effective to change the physical conditions of miscanthus to make baling possible or easier. Results also showed that the roll spacing had the most significant impact on the physical conditions of miscanthus, shown by a 115% increase in conditioning over a 0.95 cm (75%) reduction in roll spacing. Increased roll spacing and speed were shown to decrease the amount of torque required to condition the miscanthus.

Genetic Variation and Yield Performance of Jerusalem Artichoke Germplasm Collected in China

Jerusalem artichoke （Helianthus tuberosus L.） is a perennial tuberous plant rich in inulin and is a potential energy crop.This study was conducted in a semiarid region of the Loess Plateau to investigate variations in morphological and agronomic characteristics and yield performance of 59 Jerusalem artichoke clones collected from 24 provinces in China.The germplasm we collected exhibited variations either in qualitative or in quantitative traits.Substantial genetic variations （genotype coefficient of variation 〉20%） in the main stem diameter,main stem number per plant,branch number per main stem,tuber number per plant,tuber size,tuber yield,and top yield （i.e.,aboveground biomass） were found as well.Seven clones had a tuber yield ranging between 9.1-10.6 t ha-1,7 clones had a top yield ranging between 18.1-31.3 t ha-1,and 15 clones had a total biomass yield （i.e.,tuber and top weight） between 25.0-35.0 t ha-1 on an oven-dried weight basis under the drought soil and climatic condition in the semiarid region.The 59 Jerusalem artichoke clones were clustered into 8 groups based on 17 quantitative traits,and indicated that the most prevalent clones planted by farmers exhibited relatively low variation.Correlation analysis was conducted on the morphology and agronomy of the clones.This investigation suggests possible genetic improvement of Jerusalem artichoke for a higher tuber yield or a top biomass yield,and as a promising application for inulin or bioenergy in semiarid regions.

Preliminary evaluation of five elephant grass cultivars harvested at different time for sugar production

Five elephant grass cultivars, Pennisetum purpureum, cv. Huanan （Huanan）, P. purpureum, cv. N51 （N51）, P. purpureum, cv. Sumu No. 2 （Sumu-2）, （ Penniseturn americanum x P. purpureum ） x P. purpureum cv. Guimu No. 1 （Guimu-1） and P. americanum cv. Tift23A x P. purpureum cv. Tilt NS1 （Hybrid Pennisetum）, at three harvest stages were studied. With dilute sulfuric acid pretreatment followed by enzymatic hydrolysis, it is found that cel- lulose conversion of the five elephant grass cultivars harvested in August and September is higher than that har- vested in October. The cellulose conversion for elephant grass cultivars harvested in August and September follows an order of Hybrid Pennisetum 〉 Sumu-2 〉 Huanan 〉 Guimu-1 〉 N51. This may be explained by the fact that lignification is gradually strengthened with time, inhibiting degradation of cellulose and hemicellulose. Moreover, cellulose conversions of Hybrid Pennisetum, Sumu-2 and Huanan harvested in August and September are higher based on hierarchical clustering results.

Phytoremediation Potential of Selected Energetic Plants （Miscanthus giganteus L. and Phalaris arundinacea L.） in Dependence on Fertilization

This paper present the influence of fertilization in cultivation Miscanthus giganteus L. and Phalaris arundinacea L. in the process of phytoremediation of Cd, Ni and Zn. Research show that after first year of vegetation, Cd （0.344 mg·kg^-1 dry mass （d.m.）） and Zn （29.47 mg·kg^-1 d.m.） were the most absorbed metals by the biomass ofMiscanthus giganteus L. grown on soil fertilized with municipalsludge （OW）. However, in the case of the reed canary grass, the correlation can be attributed to the Ni （3.76 mg·kg^-1 d.m.） and Zn （122.6 mg·kg^-1 d.m.）. In turn, after the second year of vegetation, all of the tested metals are characterized by a lower absorption as compared to the first year. In the case of reed canary grass, Cd and Zn content in the biomass after the second year of vegetation was similar to the control, while the Ni concentration was lower in relation to the control. In the case of Miscanthus giganteus L., it was observed that the concentration of Ni and Zn in the biomass after the second year of vegetation was similar to the control, while the Cd content varied in dependence on the applied fertilizer.

The Effect of Willow Short Rotation Coppice Cultivation on the Biodiversity Quality of Ground-Layer Invertebrates

The biodiversity quality of ground-layer invertebrates within the cropped area of a plantation of the biomass crop willow short-rotation coppice (SRC) grown within a floodplain was compared to the biodiversity quality of the neighbouring plots of floodplain grassland and a mixed deciduous woodland plantation. Pitfall traps were used to collect ground beetles (Carabidae) and arachnids (Araneae and Opiliones) in the plots over a period of two years. A range of biodiversity indices was used to assess the biodiversity quality of each of the three plots, and the willow SRC was compared to each of the controls using Mann-Whitney tests. The willow SRC transitioned from almost bare ground to young woodland during the two years of the study, which affected comparisons with alternative land uses as the habitat during the second year was very different from the habitat at the start of the study. Compared to plantation woodland, in the first year, the effect was mostly positive, but this declined in the second year. Compared to grassland there was a largely negative effect in both years. However, when in combination with other habitats, willow SRC cultivation on floodplain land may have an overall positive effect on invertebrate biodiversity quality.

ORGANIC CARBON STOCKS IN A SILTY TEXTURED SOIL FOLLOWING REINTEGRATION OF A 20 YEARS OLD MISCANTHUS×GIGANTEUS SITE INTO A CROP ROTATION

Miscanthus×giganteus may play an important role in replacing fossil energy resources by bio-based alternatives.One further advantage of miscanthus production is the generally high soil organic carbon(C_(org))enrichment in soils.Due to declining yields,miscanthus stocks are commonly reintegrated into crop rotation after approximately 20 years.Currently there is only few information,whether these high amounts of(C_(org))can be conserved while intensifying soil tillage and crop management after reintegration.Therefore,we monitored(C_(org))stocks in a control with more than 20 years of continuous miscanthus and in a treatment with reintegration of a 20-years old miscanthus stock into an organic crop rotation.Based onδ^(13)C soil values,we calculated an annual(C_(org))enrichment of 0.98 Mg·ha^(-1)·yr^(-1)C under miscanthus.More than 95%of the miscanthus-C was determined in the upper 0.25 m of soil.Continuing miscanthus cultivation did not affect yields during the first five extension years and(C_(org))stocks increased further.Following reintegration,(C_(org))stocks remained constant during five years,which was mainly attributed to the humification and/or stabilization of high amounts of destroyed roots and rhizomes.A significant decrease in(C_(org))(-5.7 Mg·ha^(-1)C)compared to the continuing miscanthus cultivation was at first measured six years after reintegration into crop rotation,underlining the need of long-term investigations.Our data also show,that miscanthus production cycles can be extended in our region,and that sowing of the alfalfa grass mixture after rhizome/root destruction was efficient in preserving(C_(org))stocks for at least first five years after reintegration.

Advancement in biogas production from the solid waste by optimizing the anaerobic digestion

The crisis of fossil fuel and their negative impact on the environment has caused concern among the scientific communities leading them to look around for renewable sources of energy.This review has emphasized the efficient utilization of organic municipal solid waste as well as agriculture waste in an anaerobic digester for the production of biogas as a sustainable renewable energy.Recent advances in biogas production along with previous research work have been discussed to offer a comprehensive synopsis of the accumulated knowledge.This review also elucidates about the design of an anaerobic digester,the prospect of anaerobic digestion and opportunity in new advances in technology.Biogas is one of the most accepted sustainable renewable energy.The characterization,elimination of contaminants,pretreatment,anaerobic diges-tion in optimum condition and utilization of energy crops enhanced the efficiency of an anaerobic digester.Pretreatment of segregated organic solid waste increased its putrescibility and further biogas production.The optimized parameters in this review were pH,temperature,loading rate,C/N ratio and solid/liquid ratio of the feedstock.The flow rate of the feedstock was optimized according to the available volume of the digester,residence time and the characteristics of the feedstock.The design of an anaerobic digester should be preferably cylindrical in shape,with a diameter ranging from 6 to 40 m,the depth ranging from 7.5 to 15 m and the conical floor having a slope around 15%.A comprehensive reform in technical,economic,and social policies is essential to accomplish a sustainable energy system considering biogas as a future renewable energy.The flowsheet of the biogas and methanol production has been given in Fig.1.

Use of oleaginous plants in phytotreatment of grey water and yellow water from source separation of sewage

Efficient and economic reuse of waste is one of the pillars of modern environmental engineering. In the field of domestic sewage management,source separation of yellow（urine）,brown（faecal matter）and grey waters aims to recover the organic substances concentrated in brown water,the nutrients（nitrogen and phosphorous）in the urine and to ensure an easier treatment and recycling of grey waters. With the objective of emphasizing the potential of recovery of resources from sewage management,a lab-scale research study was carried out at the University of Padova in order to evaluate the performances of oleaginous plants（suitable for biodiesel production）in the phytotreatment of source separated yellow and grey waters. The plant species used were Brassica napus（rapeseed）,Glycine max（soybean）and Helianthus annuus（sunflower）. Phytotreatment tests were carried out using 20 L pots. Different testing runs were performed at an increasing nitrogen concentration in the feedstock. The results proved that oleaginous species can conveniently be used for the phytotreatment of grey and yellow waters from source separation of domestic sewage,displaying high removal efficiencies of nutrients and organic substances（nitrogen 〉 80%; phosphorous 〉 90%; COD nearly 90%）. No inhibition was registered in the growth of plants irrigated with different mixtures of yellow and grey waters,where the characteristics of the two streams were reciprocally and beneficially integrated.