Total Energy Output Research Articles

3D lithium ion battery fabrication via scalable stacked multilayer electrodeposition

This study focuses on the creation of 3D full cell lithium ion batteries via a multilayer stacked electrode approach. The electrodepositon based processes enable individual, deterministic control of all cell dimensions, and thus allow for tunable total energy outputs while maintaining excellent intrinsic performance. Incorporation of electrodeposited nanoporous lithium manganese oxide cathodes and thin film nickel–tin anodes into a vertically interdigitated multilayer cell enables energy densities of up to 193 Wh l−1 and power densities of up to 1233 W l−1. Additionally, the multilayer fabrication increases device areal and volume scalability over multiple orders of magnitude, resulting in total energy outputs of up to 20 mWh and power outputs of 178 mW.

A sustainable biorefinery approach for efficient conversion of aquatic weeds into bioethanol and biomethane

The study outlines an economical biorefinery concept to evaluate the potential of three aquatic weeds Eichhornia crassipes, Lemna minor and Azolla microphylla for co-production of ethanol and methane. Four different scenarios were investigated viz., scenario A-hydrothermal treatment followed by anaerobic digestion and ethanol fermentation respectively (HT → AD → EF), scenario B- thermochemical treatment followed by anaerobic digestion and ethanol fermentation respectively (TC → AD → EF), scenario C- hydrothermal treatment followed by ethanol fermentation and anaerobic digestion respectively (HT → EF → AD) and scenario D- thermochemical treatment followed by ethanol fermentation and anaerobic digestion respectively (TC → EF → AD). Sequential hydrothermal treatment and anaerobic digestion (HT → AD) in scenario A enhanced the hemicellulose removal by 68.5–73.5% and simultaneously enriched the cellulose content by 41.2–54.5%. This contributed to highest ethanol yield (0.167–0.231 g/g biomass) in scenario A, which was found comparable to that obtained in scenario D, wherein harsh and expensive thermochemical pretreatment was employed. Besides that, relatively higher methane yield of 209–257 dm3/kg TOCR (Total organic carbon removal) obtained in scenario A as compared to other scenarios (67.5–238 dm3/kg TOCR) improved the overall energy efficiency of the studied concept. The energetic assessment showed lowest total energy output (859.6–1322.7 kwh) in scenario B and C as compared to other scenarios (1041.8–1583.9 kwh), thereby confirming their incompetence in coupled bioenergy production. This study, therefore presents an economically and energetically sustainable approach for pretreatment and bioenergy production that could help in overcoming the constraints hindering the commercialization of cellulosic ethanol. The study also opens up possibility for development of coupled aquatic weeds-based wastewater treatment and bioenergy production system for an efficient exploitation of the phytoremediation property of aquatic weeds.

Energy analysis and economic assessment of a rice-turtle-fish co-culture system

ABSTRACTRice-fish system is the first globally important agricultural heritage system (GIAHS) and could be a potential option to improve modern rice production. This paper investigates energy flows and economic profits of two rice production agroecosystems in China. Results suggest that total energy input in rice-turtle-fish co-culture (RTF) was 18,889.63 MJ ha−1, less than that of rice monoculture (RM) (20,289.44 MJ ha−1). Total energy output in RTF was 82,836.57 MJ ha−1, higher than that of RM (77,221.21 MJ ha−1). The product safety index (PSI) in RTF and RM were −0.23 and −0.77, respectively, which indicated the products safety potential in RTF was higher than that of RM. The energy sustainable development index (ESI) in RTF and RM were 9.03 and 0.66, respectively, which illustrated RTF has abundant developmental potential, while RM is more of a consuming-type ecosystem. The output/input, gross profits, and net profits in RTF were 5.17, 99,531.30 CNY, and 98,729.96 CNY, respectively, all higher than that of RM (4.58, 11,335.67 CNY and 11,034.33 CNY, respectively). Consequently, RTF has greater potential to reduce agro-chemicals, improve energy use efficiency, and increase economic profits compared to RM.

Energy auditing and optimization approach for improving energy efficiency of rice cultivation in south-western Punjab, India

Abstract Rice (Oryza sativa L.) is an important energy intensive cereal crop in India. In the present study, energy input and output were audited to optimize energy use in rice cultivation using data collected from 40 farmers during face-to-face interview. Average total energy input (EI) of 52.4 ± 1.3 GJ ha−1 produced total energy output (EO) of 259 ± 4.7 GJ ha−1, with energy productivity (EP) of 0.16 kg MJ−1. Results revealed that rice cultivation was energy efficient with energy ratio (ER) of 5.0 ± 0.12 and net energy gain (NEG) of 206 ± 4.5 GJ ha−1. In rice, irrigation water (∼40%) and chemical fertilizers (24.7%) had highest contribution towards EI. A non-parametric production function of DEA (Data Envelopment Analysis) applied to optimize energy use in rice, elucidated 20 decision making units (DMUs) as efficient, whilst 50% as inefficient. The average technical efficiency (TE), pure technical efficiency (PTE) and scale efficiency (SE) of rice farms were 0.94, 0.97 and 0.97, respectively. Our results revealed that between 9.4 and 2170 MJ ha−1 energy (0.2 and 46.9% of total saving) could be saved, if inefficient DMUs adopt the management practices of efficient DMUs. An average energy saving of 579 ± 166 MJ ha−1 by efficient DMUs accounts for ∼8.8% of the EI.

Evaluation of Energy and Economic Analysis of Chestnut (Castanea Sativa Mill.) Fruit Production in Turkey

The purpose of this study is to determine and evaluate the energy use efficiency analysis of chestnut fruit production. The evaluation of situation was done for 2016 production season in Aydin province of Turkey. The agricultural input energies and output energies used in chestnut production were calculated to determine the energy use efficiency analysis. According to the study findings, the energy inputs in chestnut production were calculated respectively as 3175.20 MJ ha−1 (51.53%) chemical fertilizers energy, 1621.51 MJ ha−1 (26.32%) human labour energy, 675 MJ ha−1 (10.95%) petrol/gasoline energy, 450 MJ ha−1 (7.30%) farmyard manure energy, 213.11 MJ ha−1 (3.46%) animal labour energy and 27 MJ ha−1 (0.44%) transportation energy. Total input energy and output energy were calculated as 6161.82 MJ ha−1 and 70,800 MJ ha−1. The energy output/input ratio, chestnut fruit (yield), specific energy, energy productivity and net energy were calculated respectively as 11.49, 6000 kg ha−1, 1.02 MJ kg−1, 0.97 kg MJ−1 and 64,638.18 MJ ha−1. The performed total energy input in chestnut production could be classified as 40.73% direct, 59.27% indirect, 37.08% renewable and 62.92% non-renewable. Benefit-cost ratio was calculated as 3.29 for chestnut fruit.

Optimizing operation of a large-scale pumped storage hydropower system coordinated with wind farm by means of genetic algorithms

<p>Due to the intermittent and fluctuating nature of wind and other renewable energy sources, their integration into electricity systems requires large-scale and flexible storage systems to ensure uninterrupted power supply and to reduce the percentage of produced energy that is discarded or curtailed. Storage of large quantities of electricity in the form of dynamic energy of water masses by means of coupled reservoirs has been globally recognized as a mature, competitive and reliable technology; it is particularly useful in countries with mountainous terrain, such as Greece. Its application may increase the total energy output (and profit) of coupled wind-hydroelectric systems, without affecting the availability of water resources. Optimization of such renewable energy systems is a very complex, multi-dimensional, non-linear, multi modal, nonconvex and dynamic problem, as the reservoirs, besides hydroelectric power generation, serve many other objectives such as water supply, irrigation and flood mitigation. Moreover, their function should observe constraints such as environmental flow. In this paper we developed a combined simulation and optimization model to maximize the total benefits by integrating wind energy production into a pumped-storage multi-reservoir system, operating either in closed-loop or in open-loop mode. In this process, we have used genetic algorithms as the optimization tool. Our results show that when the operation of the reservoir system is coordinated with the wind farm, the hydroelectricity generation decreases drastically, but the total economical revenue of the system increases by 7.02% when operating in closed-loop and by 7.16% when operating in open-loop mode. We conclude that the hydro-wind coordination can achieve high wind energy penetration to the electricity grid, resulting in increase of the total benefits of the system. Moreover, the open-loop pumped-storage multi-reservoir system seems to have better performance, ability and flexibility to absorb the wind energy decreasing to a lesser extent the hydroelectricity generation, than the closed-loop.</p>

Parametric Studies on LaNi4.7Al0.3 based Hydrogen Storage Reactor with Embedded Cooling Tubes

Abstract This study reports the investigative conclusions of parametric studies conducted to understand the effect of operating parameters on absorption and desorption characteristics of LaNi4.7Al0.3 metal hydride system for thermal management applications. Reactor with improved design containing 55 embedded cooling tubes is fabricated and filled with 4 kg of metal hydride alloy. Using water as heat transfer fluid (HTF), effects of supply pressure, HTF temperature and HTF flow rate on absorption and desorption characteristics of the reactor are analyzed. Increasing supply pressure leads to prominent improvement in absorption capacity while the increase in HTF temperature enhanced desorption performance. At 20 bar and 20 °C, 46.2877 g of hydrogen (1.16 wt%) was absorbed resulting in total energy output of 707.3 kJ for 300 s. During desorption at 80 °C with water flow rate of 8 lpm, heat input of 608.1 kJ for 300 s resulted in 28.5259 g of hydrogen desorption.

Thermo-kinetics and gaseous product analysis of banana peel pyrolysis for its bioenergy potential

This study illustrated the pyrolysis of banana peel (BP) as a potential waste management solution. Samples were characterized through Fourier transform infrared spectrometry (FTIR), elemental analysis, and high heating value (HHV) calculation. After pyrolysis experiments were performed at different heating rates (10, 20, 30, and 40 °C min−1) by using a thermogravimetric analyzer coupled with FTIR (TG-FTIR), the apparent activation energies were computed with Friedman, Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO) methods, and the evolved gaseous products were analyzed simultaneously. During pyrolysis, BP underwent three devolatilization steps accompanied by the evolution of some major gaseous products, including CO2, CH4, H2O, CH3COOH, CC, C6H5OH, HCOOH, and CH3CH2OH. Among them, CC, CH3COOH, and CO2 accounted for approximately 71.56% of the total gaseous products. Gas evolution was more significantly influenced by the pyrolysis temperature than by the heating rate. Pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) analysis confirmed the presence of some high-energy compounds and valuable chemicals containing aromatic, aldehyde, ketone, and other functional groups. In terms of preliminary energy balance, more than 70% of the total energy output was attributed to the liquid pyrolytic products followed by the solid and gaseous products. The energy recovery ratio of BP pyrolysis was superior to that of other fuel feedstocks. This work provided insights into resolving environmental problems associated with BP management by pyrolyzing BP as a potential source of renewable bioenergy.

Effects of supplementing with an 18% carbohydrate-hydrogel drink versus a placebo during whole-body exercise in \u22125\u2009\xb0C with elite cross-country ski athletes: a crossover study

BackgroundWhilst the ergogenic effects of carbohydrate intake during prolonged exercise are well-documented, few investigations have studied the effects of carbohydrate ingestion during cross-country skiing, a mode of exercise that presents unique metabolic demands on athletes due to the combined use of large upper- and lower-body muscle masses. Moreover, no previous studies have investigated exogenous carbohydrate oxidation rates during cross-country skiing. The current study investigated the effects of a 13C-enriched 18% multiple-transportable carbohydrate solution (1:0.8 maltodextrin:fructose) with additional gelling polysaccharides (CHO-HG) on substrate utilization and gastrointestinal symptoms during prolonged cross-country skiing exercise in the cold, and subsequent double-poling time-trial performance in ~ 20 °C.MethodsTwelve elite cross-country ski athletes (6 females, 6 males) performed 120-min of submaximal roller-skiing (69.3 ± 2.9% of dot{mathrm{V}} O2peak) in −5 °C while receiving either 2.2 g CHO-HG·min− 1 or a non-caloric placebo administered in a double-blind, randomized manner. Whole-body substrate utilization and exogenous carbohydrate oxidation was calculated for the last 60 min of the submaximal exercise. The maximal time-trial (2000 m for females, 2400 m for males) immediately followed the 120-min submaximal bout. Repeated-measures ANOVAs with univariate follow-ups were conducted, as well as independent and paired t-tests, and significance was set at P < 0.05. Data are presented as mean ± SD.ResultsExogenous carbohydrate oxidation contributed 27.6 ± 6.6% to the total energy yield with CHO-HG and the peak exogenous carbohydrate oxidation rate reached 1.33 ± 0.27 g·min− 1. Compared to placebo, fat oxidation decreased by 9.5 ± 4.8% with CHO-HG, total carbohydrate oxidation increased by 9.5 ± 4.8% and endogenous carbohydrate utilization decreased by 18.1 ± 6.4% (all P < 0.05). No severe gastrointestinal symptoms were reported in either trial and euhydration was maintained in both trials. Time-trial performance (8.4 ± 0.4 min) was not improved following CHO-HG compared to placebo (− 0.8 ± 3.5 s; 95% confidence interval − 3.0 to 1.5 s; P = 0.46). No sex differences were identified in substrate utilization or relative performance.ConclusionsIngestion of an 18% multiple-transportable carbohydrate solution with gelling polysaccharides was found to be well-tolerated during 120 min of submaximal whole-body exercise, but did not improve subsequent maximal double-poling performance.

Decoupling of heat generated from ejected and non-ejected contents of 18650-format lithium-ion cells using statistical methods

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing versus through the ejecta material. A unique fractional thermal runaway calorimeter (FTRC), designed to characterize said critical factors, was utilized to examine the TR behavior of 18650-format Li-ion cells representing a variety of manufacturers, chemistries, capacities, and safety features. Primarily, the impacts of bottom vent (BV) safety features, varied cell casing thickness, and Dreamweaver cellulose based separators were assessed for select cell types. A subset of cells also had an imbedded internal short circuiting (ISC) device to allow examination of TR behavior initiated at lower temperatures (i.e. closer to field failure conditions). The impact of bottom rupture on TR behavior was also examined for experiments that resulted in this non-standard failure mechanism. Statistical analysis of the results for each cell configuration reveals that a lognormal distribution effectively characterizes the variation of total TR energy release. Typically 20%–30% of the total energy yield is released through the cell casing with the remainder through the ejecta material. Higher energy cells tend to exhibit more violent ejections and less predictable TR events. Inclusion of a BV feature reduces the overall severity of the TR event and can increase the predictability. Results also suggest that the magnitude of the TR event may not be directly proportional to the stored electrical energy, but rather has additional dependence on other design and failure mode factors.

Performance Analysis of Installed Solar PV System Using Homer in Tanzania: A Case Study of Zanzibar and Arusha

This study reflects two photovoltaic (PV) power generations, at Karume Institute of Science and Technology (KIST) - Zanzibar and The Nelson Mandela African Institution of Science and Technology (NM-AIST) - Arusha in Tanzania. The output data sets from each site were verified for possible PV simulation of different operational scenarios to obtain the optimum design configuration. The HOMER software was used to analyze the entire operation of the system. The effect of the accuracy of the photovoltaic integration was determined by analysis of different operational behaviors of the simulated PV levels. Furthermore, the overall performance of the station per site was analyzed for technical, economic and environmental constraints as well as their comparative cost-benefit analysis. The study finds that there is a high sensitivity in the demand for the load (i.e. load growth) whose system performance is characterized with minimum: total net present cost (NPC) of $474,745 and $29,169, feed in tariffs, levelized cost of energy (LCOE) of $1.06/kWh and $0.0118/kWh, total energy output and renewable fraction of 15% and 22% for KIST and NM-AIST respectively, thus support the use of photovoltaic power sources in the generation of energy than their counterpart alternatives because of the best technical performance and is less dependent on other external sources of energy, and simultaneously has good economic and environmental performance

Design and Operations of On-Site Combined Heat and Power Generators Under Fuel Price Uncertainty

The combined heat and power (CHP) technology produces both heat and electricity from a single fuel input, achieving an efficiency (total useful energy output divided by fuel input) as high as 90%. Because the high energy efficiency is achieved by utilizing exhaust heat, it is a common practice to design a CHP system to match the thermal demand it serves. Energy efficiency, however, does not necessarily imply cost efficiency when fuel price is variable. In this paper, we study the problem of optimizing the design (including capacity and power-to-heat ratio) and operations of a CHP system for an industrial firm facing variable fuel price. We identify two drivers for improving the overall cost efficiency of CHP: 1) the flexibility of operating the CHP system at various output levels in response to the fuel price, enabled by properly over-sizing the CHP system relative to the heat demand, and 2) the flexibility of co-operating the CHP system and the legacy boiler. Numerical examples with realistic settings demonstrate that our recommended CHP system design and operations can yield substantial long-run cost savings for the firm. The results of this paper call for revisiting the current practice of designing CHP systems, as recommended by the government and industry associations.

Energy budgeting andeconomics of weed management in dry direct-seededrice

A field experiment was conducted at Main Research Station, Hebbal, Bengaluru during Kharif 2016 and Kharif 2017 to study the effect of different herbicide combinations and weed management methods on yield, energetics and economics of dry direct-seeded rice. The experiment consisted of 12 treatments and replicated thrice in RCBD design. Among various weed management treatments hand weeding at 20, 40 and 60 DAS recorded significantly highest paddy grain and straw yield in hand weeding at 20, 40 and 60 DAS (5.50 and 7.22 t/ha, respectively) and found at par with application of bensulfuron-methyl + pretilachlor as pre-emergence fb bispyribac-sodium (5.39 and 7.16 t/ha, respectively). Weedy check recorded significantly lowest yield (1.40 and 2.32 t/ha, respectively). Among the various herbicide combinations, sequential application of bensulfuron-methyl + pretilachlor as pre-emergence fb bispyribac-sodium was found to be the most energy and economically efficient weed management strategy in dry direct-seeded rice and had maximum value of total output energy (169090 MJ/ha), net energy returns (157444 MJ/ha), energy use efficiency (14.52), net returns (’ 59,276/ha) and benefit cost ratio (2.93).

Modelling of Biofuel Potential as a Tool for Public Managers

Developing the efforts to implement sustainability policies in the energy field requires the most accurate information on the potential of available resources to properly implement concrete policies. Total net energy yields are interpreted in isolation, and studies providing information on yields of specific energy crops in net values are relatively rare. This article, therefore, provides a tool based on methodology combining Lifecycle Assessment (LCA) approaches and a model implemented in a stochastic Petri net environment to support managerial decision-making at a national and regional level. This tool allows for the comparison of net yields of more energy crops used in Central Europe. Additional crops can be added to the model. For the purpose of comparison, it is also possible to customize the model parameters for particular crops and the way they are cultivated. In comparison with oilseed rape, sugar beet, and wheat, the model shows best results in terms of net energy yields for sugar beet.

Energy efficiency of winter wheat in a long-term tillage experiment under Pannonian climate conditions

Abstract One goal in sustainable agriculture is to use fossil energy more efficiently in crop production. Information on energy consumption and efficiency of different soil tillage systems for developing energy-efficient farming systems with reduced impact on climate change is missing for the Pannonian Basin. This 12-year study on a silt loam chernozem investigated the energy efficiency of four tillage systems (mouldboard plough (MP), deep conservation tillage (CTd), shallow conservation tillage (CTs), no-tillage (NT)) in rotations taking thereby into account diesel fuel consumption, total energy input (made up of both direct and indirect inputs), grain yield, energy output, net-energy output, energy intensity and energy output/input-ratio. Input rates of fertilizer, herbicides and seeds remained constant, while values of diesel fuel consumption were measured for all tillage operations. Total diesel fuel consumption for winter wheat (Triticum aestivum L.) production was 59.8 L ha−1, 60.6 L ha−1, 48.5 ha−1 and 36.0 L ha−1 for MP, CTd, CTs and NT, respectively. Between 73% and 83% of total energy input was required by indirect energy (seeds, fertilizer, herbicides, machinery). MP and CTd each required a total energy input of about 9.3 GJ ha−1; the total energy input for CTs and NT was lower by 4.8% for both. Direct energy input (diesel and lubricant oil) was much lower with no-tillage (with 1.5 GJ ha−1) than with mouldboard plough (with 2.4 GJ ha−1), deep conservation tillage (with 2.5 GJ ha−1) and shallow conservation tillage (with 2.0 GJ ha−1). Grain yield and thus energy output were mainly influenced by year. The year effect on yield and energy efficiency parameters was larger than the tillage effect. Especially in dry years, ploughless tillage systems tended to respond with competitive yields. This resulted in an increase of energy efficiency parameters. Over all twelve years, winter wheat produced in the CTs tillage system reached the highest net-energy and output/input-ratio with the lowest energy intensity.

Bio-hythane production from residual biomass of Chlorella sp. biomass through a two-stage anaerobic digestion

Residual Chlorella sp. biomass obtained after anaerobic solid-state fermentation was used to produce bio-hythane. The residual biomass was pretreated using acid, thermal, and acid-thermal methods before their respective hydrolysates were used in dark fermentation followed by the methanogenesis of anaerobic digestion to produce hydrogen and methane, respectively. Pretreatment of the residual biomass using acid and thermal methods did not significantly increase reducing sugar production. However, a maximum reducing sugar content of 28.9 mg-reducing-sugar·g-biomass−1 was attained using an acid-thermal method, resulting in the highest hydrogen and methane yields of 12.5 and 81 mL·g-volatile-solid−1, respectively. This was equivalent to the total energy yield of 3.03 kJ·g-VS−1 or 4.6% energy recovery, based on the heating value of the residual biomass.

Energy Analysis and Greenhouse Gas Emission from Strawberry Production under Two Irrigation Systems

The aims of this study were to estimate the energy indices, greenhouse gas (GHG) emission and compare the energy balance of open field strawberry production under furrow and drip irrigation systems in Kurdistan province, west of Iran. Data used in this study were obtained from 24 strawberry growers using a face to face questionnaire method in 2014. In order to convert inputs and output into energy equivalents, energy equivalent coefficients were applied. The results indicate that total energy consumption in strawberry production was 16,206.83 and 16,525.69 MJ.ha-1, whereas the total energy output was 38,950.00 and 52,385.70 MJ.ha-1 in furrow and drip irrigation systems, respectively. Energy use efficiency and net energy in the drip irrigation system were higher than the furrow irrigation system. Nitrogen fertilizer was the major energy consumer in both of the irrigation systems. From an environmental viewpoint, the total GHG emissions were 764.28 and 1,284.19 kg CO2 equivalent ha-1 in the furrow and drip systems, respectively. In the furrow system, the nitrogen fertilizer and diesel fuel had the highest share in GHG emissions, with 51.76 and 20.72 percent of the total, respectively, but in the drip system, machinery had the highest share in GHG emissions, with 53.11 percent of the total.

Hydrogen production from pine-derived catalytic pyrolysis aqueous phase via microbial electrolysis

Microbial electrolysis of an aqueous phase generated from catalytic pyrolysis of pine sawdust was investigated for renewable hydrogen production. The microbial electrolysis cell (MEC) performance was investigated at an organic loading rate ranging from 2 to 50 g/L-day. A maximum hydrogen productivity of 5.8 ± 0.18 L/L-day was obtained, however, the productivity increased linearly only up to a loading rate of 10 g/L-day. The highest current density achieved was 6.8 ± 0.1 A/m2. The efficiency of conversion of the substrate to current in the anode decreased with increasing loading, but the initial maximum Coulombic efficiency was 98 ± 0.04%. The cathode efficiency, on the other hand, increased with loading up to a maximum of 89 ± 1.4%. Total hydrogen recovery was relatively constant for most runs at 30%, which is equivalent to an yield of 0.6 moL H2/mole COD, except at the highest loading rate. The operation of the MEC under batch mode, however, resulted in a higher hydrogen recovery of 63 ± 4%. The conversion of a wide range of compounds, including carboxylic acids, anhydrosugars, furanic and phenolic compounds present in the aqueous phase is reported. The results demonstrate potential for hydrogen production from a waste stream which can improve the total biofuel or energy yield of the biorefinery.

Establishing sustainable sweet sorghum-based cropping systems for forage and bioenergy feedstock in North China Plain

Sweet sorghum [Sorghum bicolor (L.) Moench] offers a sustainable and renewable bioenergy resource for feed and biomass production. Two separate field experiments were conducted on arable land at Shangzhuang Station and on saline-alkali land at Quzhou Station in the North China Plain. Three cultivars of sweet sorghum including early- (ZS1) (114 days), medium- (CT2) (138 days), and late-maturity (LN3) (160 days), were sole cropped on arable land in 2006–2007. Using the same cultivars, sweet sorghum based - double cropping systems with winter wheat rotation were analyzed on saline-alkali land in 2009–2011. This study aims to determine the planting potential of three sweet sorghum cultivars and develop an optimized sweet sorghum - based double cropping system on saline-alkali land to maximize the production outputs. The aboveground biomass yield, energy output, theoretical ethanol yield (TEY), and chemical composition of three sweet sorghum cultivars - based cropping systems were assessed. Results indicate that: (1) the annual average dry biomass yield and dry matter content of the three sweet sorghum cultivars showed an overall uptrend with the increasing crop growth length. The average dry biomass yield of three sorghum maturity groups on arable land were 48.9% higher than that on saline-alkali land. (2) Sweet sorghum cultivars of late- (LN3) and medium- maturity (CT2) displayed better chemical composition for both bioenergy utilization (higher starch, soluble sugar, cellulose and hemicellulose and lower ash) and forage quality (better relative feed value (RFV) and lower acid detergent fiber (ADF) and neutral detergent fiber (NDF)). (3) The double cropping system of medium-maturity sweet sorghum (CT2) and winter wheat presented the best total dry biomass yield (24.9 t ha−1), energy output (394.6 GJ ha−1), and theoretical ethanol yield (6857 L ha−1). Therefore, this double cropping system can be recommended for extensive planting in the North China Plain for bioenergy or forage production.

Synergistic co-digestion of wastewater grown algae-bacteria polyculture biomass and cellulose to optimize carbon-to-nitrogen ratio and application of kinetic models to predict anaerobic digestion energy balance

This study investigated enhancing methane production from algal-bacteria biomass by adjusting the C/N ratio through co-digestion with a nitrogen-poor co-substrate – cellulose. A biomethane potential test was used to determine cumulative biogas and methane production for pure and co-digested substrates. Four kinetic models were evaluated for their accuracy describing experimental data. These models were used to estimate the total energy output and net energy ratio (NER) for a scaled AD system. Increasing the algal C/N ratio from 5.7 to 20–30 (optimal algae:cellulose feedstock ratios of 35%:65% and 20%:80%) improved the ultimate methane yield by >10% and the first ten days production by >100%. The modified Gompertz kinetic model demonstrated highest accuracy, predicting that co-digestion improved methane production by reducing the time-lag by ∼50% and increasing rate by ∼35%. The synergistic effects increase the AD system energy efficiency and NER by 30–45%, suggesting potential for substantial enhancements from co-digestion at scale.