Maize Straw as a Valuable Energetic Material for Biogas Plant Feeding

Towards sustainability: An integrated life cycle environmental-economic insight into cow manure management

Waste management signifies an equilibrium between environmental and economic factors. However, a comprehensive understanding of the integrated life cycle environmental-economic performance of waste management activities remains unclear. To facilitate a systematic linkage between the economic and environmental sectors, a regionalized life cycle assessment-based life cycle costing method was developed based on China's actual status quo. The cow manure utilization was set as an entry point to explored long-term environmental-economic performance of milk production under various manure utilization pathways. The results show that trade-offs were observed between internal and external costs as well as various environmental indicators. The choice of waste utilization is the focal point of environmental-economic trade-offs in the cow raising system. The optimal environmental-economic performance was achieved through the manure fertilizer utilization pathway, yielding a remarkable three-fold increase in marginal environmental benefits. Compared with fertilizer utilization, the manure direct returning to field reduced the carbon footprint by 12% while induced an external cost of $14.3. The wastewater treatment pathway is $ 5.5 lower in internal costs but $ 11.7 higher in external costs than those of fertilizer utilization. Overall, utilizing manure has potential to mitigate the upward trend of carbon footprint and external costs. However, achieving the carbon peak remains a significant challenge. A promising solution is the recycling of straw resources within cropping systems, particularly in hotspot regions (e.g., Inner Mongolia, Heilongjiang, Hebei, and Shandong). A comprehensive analysis of the dynamic interplay between cropping systems and cow raising systems is critical steps towards realizing a carbon-neutral future within the dairy production.

Methane Production Potential from Apple Pomace, Cabbage Leaves, Pumpkin Residue and Walnut Husks

Circular economy aims to eliminate organic waste through its transformation, composting and processing into other products or energy. The main aim of the study was to determine the specific methane yield (SMY) of anaerobic digestion (AD) of four different fruit and vegetable residues (FVR). In addition, the reduction in greenhouse gas (GHG) emissions was calculated based on the assumption that maize will be replaced by the FVR as a feedstock for biogas production. The SMY of four residues (apple pomace, cabbage leaves, pumpkin peels and fibrous strands and walnut husks) was measured in the biomethane potential test (BMP) in wet anaerobic digestion technology. The highest SMY (297.81 ± 0.65 NL kgVS−1) was observed for cabbage leaves while the lowest SMY (131.07 ± 1.30 kgVS−1) was found for walnut husks. The concentrations of two inhibitory gasses (NH3 and H2S) in biogas were low and did not affect the AD process. Only biogas produced from cabbage leaves was characterised by higher NH3 and H2S concentrations resulting from the highest protein concentration in this waste. FVR used as feedstock in biogas production may decrease the area of maize cultivation. Therefore, the GHG emissions from maize cultivation will be reduced. In Poland only, the use of four studied FVR as feedstock for biogas production would contribute to the reduction of GHG emissions by 43,682 t CO2 eq.

Evaluation of the Effects of Using the Giant Miscanthus (Miscanthus × Giganteus) Biomass in Various Energy Conversion Processes

The giant miscanthus (Miscanthus × giganteus) is one of the most essential energy plants. It also finds various alternative uses, including installing belts to prevent soil erosion. Biomass from such belts should be removed and rationally managed every year. The parameters of miscanthus biomass were investigated in terms of its suitability for combustion and anaerobic fermentation. Under the conditions of the experiment, miscanthus achieved a stable yield already in the second year of vegetation, mainly due to the high planting density. Energy parameters turned out to be typical for straw biomass (calorific value 18.06 MJ/kg). Relatively low ash melting temperatures (<1400 °C) and their chemical composition meant a high risk of contamination depositing on heating devices, which is often indicated as a shortcoming of biomass compared to hard coal. Miscanthus silage can be a valuable substrate for anaerobic digestion, but it requires a sufficiently early harvest, which affects the yield of biomass. The yield of energy in biomass obtained after drying plants was 163,623.6 MJ/ha. In contrast, the yield of energy from biomass collected in summer and processed into biomethane was much lower and amounted to 72,978.2 MJ/ha.

Effects of Harvest Maturity on the Chemical and Energetic Properties of Corn Stover Biomass Combustion

Over the last decade, there has been increased interest in applying biomass as a raw material for producing biofuels used for thermochemical conversions. Extensive use of biomass could lead to controversial competition for arable land, water, and food; therefore, only waste materials and agricultural by-products and residues should be used to produce biofuels. One suitable by-product of agricultural production is crop residue from the harvest of maize for grain (corn stover). The harvest residues of corn stover consist of four fractions, i.e., husks, leaves, cobs, and stalks, which are structurally and morphologically distinct. The aim of the study was to determine the effect of selected maize cultivars with distinct FAO (Food and Agriculture Organization of the United Nations) earliness classifications on the chemical and energetic properties of their corn cob cores. We determined the chemical properties based on elemental analysis, and the energy properties based on the heat of combustion and calorific values. The content of ash and volatile compounds in the corn cobs were also determined. The results indicated that the heat of combustion of fresh and seasoned corn cob cores ranged from 7.62–10.79 MJ/kg and 16.19–16.53 MJ/kg, respectively. The heat of combustion and calorific value of corn cob cores in the fresh state differed significantly and were strongly correlated with maize cultivars with distinct FAO earliness.

Influence of the Fertilization Method on the Silphium perfoliatum Biomass Composition and Methane Fermentation Efficiency

Biogas production is one of the solutions for replacing fossil fuels, which promotes the widespread use of green energy. The aim of this study was to determine the potential of Silphium perfoliatum as an energy crop for biogas production, as well as the effect of different fertilization doses (0, 85 and 170 kg N ha−1) on the production potential (NL CH4 kg−1 VS) of Silphium perfoliatum. The study investigated the use of different feedstocks, such as raw and ensiled Silphium perfoliatum biomass. The methane production ranged between 193.59 and 243.61 NL CH4 kg−1 VS. The highest biogas production potential was achieved with the biomasses which were cultivated with the highest fertilization dose (170 kg N ha−1), both for raw and ensiled crop biomasses, although the difference from the other fertilization doses was not significant. The feedstock (biomass and silage) and digestate parameters were investigated as well. The use of Silphium perfoliatum for biogas production seems very promising since its methane production potential was found to be similar to that of the most common energy crop, such as maize, indicating that Silphium perfoliatum can compete in the future with maize.

Effects of Coal and Sewage Sludge Ashes on Macronutrient Content in Maize (Zea mays L.) Grown on Soil Contaminated with Eco-Diesel Oil

Petroleum hydrocarbons, as aggressive components of diesel oils, after migration to the land environment can alter the activity and efficiency of ecosystems. They can also be dangerous to animal and human health. Eco-friendly methods for the reclamation of affected soils is necessary to manage degraded lands. One such method is the use of ashes. The aim of this research was to determine how soil pollution with diesel oil (brand name, Eco-Diesel) affects the chemical composition of maize (Zea mays L.) and whether the application of ash from a combined heat and power plant, as well as from sewage sludge incineration, could reduce the potentially adverse impact of diesel oil on plants. The research results demonstrated that soil contamination with Eco-Diesel oil modified the content of selected macronutrients in the analyzed crop plant. Eco-Diesel oil had a negative effect on maize yield. The highest diesel oil dose in a series without neutralizing substances had a positive effect on the accumulation of most elements, except nitrogen and sodium. Soil enrichment with ash differentiated the content of macronutrients, mainly nitrogen and phosphorus, in the aerial biomass of maize. The ashes increased the yield of maize and content of some macronutrients, mainly nitrogen but also calcium, the latter in a series where soil was treated with ash from sewage sludge thermal recycling. Both types of ash also resulted in a decrease in the plant content of phosphorus, while ash from hard coal caused a slight reduction in the content of potassium in maize. Ash of different origins can be an effective solution in the reclamation of degraded soils, which may then be used for growing energy crops.

Energy and Economic Balance between Manure Stored and Used as a Substrate for Biogas Production

The aim of the study is to draw attention to the fact that reducing methane and nitrous oxide emissions as a result of traditional manure storage for several months in a pile is not only a non-ecological solution, but also unprofitable. A solution that combines both aspects—environmental and financial—is the use of manure as a substrate for a biogas plant, but immediately—directly after its removal from the dairy barn. As part of the case study, the energy and economic balance of a model farm with dairy farming for the scenario without biogas plant and with a biogas plant using manure as the main substrate in methane fermentation processes was also performed. Research data on the average emission of ammonia and nitrous oxide from 1 Mg of stored manure as well as the results of laboratory tests on the yield of biogas from dairy cows manure were obtained on the basis of samples taken from the farm being a case study. The use of a biogas installation would allow the emission of carbon dioxide equivalent to be reduced by up to 100 Mg per year. In addition, it has been shown that the estimated payback period for biogas installations is less than 5 years, and with the current trend of increasing energy prices, it may be even shorter—up to 4 years.

Biogas Generation from Maize and Cocksfoot Growing in Degraded Soil Enriched with New Zeolite Substrate

Degraded lands are potential areas for obtaining biomass which can serve as an energy source after its conversion into biogas. Thus, the studies on biogas production from maize and cocksfoot biomasses obtained from degraded soil supplemented with additions of new zeolite substrate (Z-ion as the nutrient carrier) and on arable soil (reference soil) were carried out during batch digestion tests. It was found that the biogas and biomethane potentials and specific energy of the test species growing in degraded soil enriched with Z-ion additions (1% and 5% v/v in the cases of cocksfoot and maize, respectively) did not differ significantly from the values of these parameters that were found for the plants growing in arable soil. The application of Z-ion to the degraded soil (especially in a dose of 5% v/v) resulted in an increase in the nitrogen content and decrease (below the lower optimum value) in the C/N ratio in the plant biomass. However, these changes did not negatively influence the final values of the biogas or methane potentials or the specific energy found for the maize biomass. Therefore, the study results indicated the usefulness of Z-ion substrate for improving the growth conditions for energy crops in degraded soils and, as a consequence, obtaining a plant feedstock suitable for the digestion process.

Biodiversity and Community Analysis of Plant-Parasitic and Free-Living Nematodes Associated with Maize and Other Rotational Crops from Punjab, Pakistan

Maize (Zea mays L.) is one of Pakistan’s essential staple food crops. Plant-parasitic nematodes (PPNs) are a significant restraint in maize production. However, free-living nematodes (FLNs) provide crucial ecological functions such as suppressing pests and nutrient mineralization. This study aimed to assess the community analysis of plant-parasitic and free-living nematodes associated with maize and other rotational crops (those cultivated in sequence with the maize in the same field) from Punjab, Pakistan. The occurrence percentage was observed per 500 g soil for each nematode genus. The present study revealed that 24 species of plant-parasitic and free-living nematodes were identified from maize crops and other rotational crops from 16 localities through Punjab, Pakistan. Nematode communities were analyzed by absolute frequency, relative frequency, relative density, and prominence value, while cluster analysis was based on the presence or absence of nematode in different localities. The overall proportion of plant-parasitic nematodes was 35%, while free-living soil nematodes recovered 65%, out of 210 samples of maize and other rotational crops. Several major genera of plant-parasitic nematodes were reported during the present study viz., Ditylenchus, Filenchus, Helicotylenchus, Hemicriconemoides, Heterodera, Hoplolaimus, Malenchus, Pratylenchus, Psilenchus, Rotylenchulus, Seinura, Telotylenchus, Tylenchorhynchus, and Xiphinema Community relationship revealed the overall dominance of Heterodera zeae, with the highest incidence (55.71%) followed by Tylenchorhynchus elegans (33.33%) and Helicotylenchus certus (24.76%). The results provide valuable information on the community structure of nematodes in maize and other rotational crops of maize in Punjab, Pakistan. Moreover, this data can be used as a preventive measure before PPN incidence results in greater losses on maize.

The Influence of the Pressure-Thermal Agglomeration Methods of Corn Bran on Their Selected Physicochemical Properties and Biogas Efficiency

The article presents the research made on the effects of methods of pressure-thermal agglomeration of corn bran, as well as the influence of processing parameters on selected physicochemical properties and biogas efficiency. Corn bran moistened to four levels of moisture content was used for the tests: 20%, 25%, 30% and 35% of dry matter. The pressure-thermal treatment was carried out with the use of a Brikol SJ25 pellet maker and a TS-45 single-screw extruder. In the tests of the extrusion-cooking process, three rotational speeds of the extruder screw were applied: 70, 90 and 110 rpm. The following characteristics were examined: efficiency of the extrusion-cooking and pelleting process, as well as the energy consumption. The water absorption index (WAI), the water solubility index (WSI), bulk density, kinetic strength, structure analysis by the ART/FTIR method, energy potential and the efficiency of cumulated biogas and cumulated methane per dry mass, as well as fresh mass and fresh organic matter and a series of microscopic pictures were completed. The analysis of the ATR/FTIR infrared spectra of the tested pelleted and extruded samples showed clear changes at the molecular level. Biogas production of extruded corn bran increased by several percent, as compared to untreated material.

Solid Fraction of Digestate from Biogas Plant as a Material for Pellets Production

One of the anaerobic digestion process products in an agricultural biogas plant is digestate (digested pulp). Large quantities of digestate generated in the process of biogas production all over the world require proper management. Fertilization is the main management of this substrate, so it is essential to look for new alternatives. The work aims to determine and discuss the possibilities of using digestate solid fraction (DSF) for pellets as biofuel production. Pellets from DSF alone and pellets with sawdust, grain straw additives were analyzed. The lower heating value (LHV) based on the dry matter for all analyzed pellets ranged from 19,164 kJ∙kg−1 to 19,879 kJ∙kg−1. The ash content was similar for all four samples and ranged from 3.62% to 5.23%. This value is relatively high, which is related to the degree of fermentation in the anaerobic digestion process. The results showed that the DSF substrate after the anaerobic digestion process still has energy potential. Analyzing those results, it seems that DSF can be a highly valuable substrate for solid biofuels production.

Agricultural Residue Management for Sustainable Power Generation: The Poland Case Study

The European Union has set targets for renewable energy utilization. Poland is a member of the EU, and its authorities support an increase in renewable energy use. The background of this study is based on the role of renewable energy sources in improving energy security and mitigation of climate change. Agricultural waste is of a significant role in bioenergy. However, there is a lack of integrated methodology for the measurement of its potential. The possibility of developing an integrated evaluation methodology for renewable energy potential and its spatial distribution was assumed as the hypothesis. The novelty of this study is the integration of two renewable energy sources: crop residues and animal husbandry waste (for biogas). To determine agricultural waste energy potential, we took into account straw requirements for stock-raising and soil conservation. The total energy potential of agricultural waste was estimated at 279.94 PJ. It can cover up to 15% of national power generation. The spatial distribution of the agricultural residue energy potential was examined. This information can be used to predict appropriate locations for biomass-based power generation facilities. The potential reduction in carbon dioxide emissions ranges from 25.7 to 33.5 Mt per year.

A Method of Fast Segmentation for Banana Stalk Exploited Lightweight Multi-Feature Fusion Deep Neural Network

In an orchard environment with a complex background and changing light conditions, the banana stalk, fruit, branches, and leaves are very similar in color. The fast and accurate detection and segmentation of a banana stalk are crucial to realize the automatic picking using a banana picking robot. In this paper, a banana stalk segmentation method based on a lightweight multi-feature fusion deep neural network (MFN) is proposed. The proposed network is mainly composed of encoding and decoding networks, in which the sandglass bottleneck design is adopted to alleviate the information a loss in high dimension. In the decoding network, a different sized dilated convolution kernel is used for convolution operation to make the extracted banana stalk features denser. The proposed network is verified by experiments. In the experiments, the detection precision, segmentation accuracy, number of parameters, operation efficiency, and average execution time are used as evaluation metrics, and the proposed network is compared with Resnet_Segnet, Mobilenet_Segnet, and a few other networks. The experimental results show that compared to other networks, the number of network parameters of the proposed network is significantly reduced, the running frame rate is improved, and the average execution time is shortened.

Chemical Characteristics of Selected Grass Species from Polish Meadows and Their Potential Utilization for Energy Generation Purposes

Analyses were conducted on 10 grass species from permanent grasslands in the Noteć Leniwa and Noteć Bystra valley. Their chemical composition was assayed, and their heat of combustion and heating value were determined. The cellulose content ranged from 33.38% to 38.68%, while the content of lignin ranged from 15.42% to 21.99%, and that of hemicellulose from 30.27% to 34.31%. The heating value of grasses was comparable to that of wood from 2- to 3-year-old willows and other fast-growing energy crops. However, the calorific value of naturally dried grasses may be slightly lower. The quantities of minerals in these grasses, exceeding those in wood, did not result in a lowering of their heat of combustion. The analyses clearly showed that the investigated grass species may be successfully used for energy generation purposes.

Biogas Plant Exploitation in a Middle-Sized Dairy Farm in Poland: Energetic and Economic Aspects

Although cow manure is a valuable natural fertilizer, it is also a source of extreme greenhouse gas emissions, mainly methane. For this reason, this study aims to determine the impact of investments in a biogas plant on the energy and economic aspects of the operation of a dairy farm. A farm with a breeding size of 600 livestock units (LSU) was adopted for the analysis. In order to reach the paper’s aim, the analysis of two different scenarios of dairy farm functioning (conventional–only milk production, and modern–with biogas plant exploitation) was conducted. The analysis showed that the investment in biogas plant operations at a dairy farm and in using cow manure as one of the main substrates is a more profitable scenario compared to traditional dairy farming. Taking into account the actual Polish subsidies for electricity produced by small biogas plants, the scenario with a functioning biogas plant with a capacity of 500 kW brings €332,000/a more profit compared to the conventional scenario, even when taking into account additional costs, including the purchase of straw to ensure a continuous operation of the installation. Besides, in the traditional scenario, building a biogas plant allows for an almost complete reduction of greenhouse gas emissions during manure storage.

Potential of Straw for Energy Purposes in Poland—Forecasts Based on Trend and Causal Models

The mitigation of climate change poses a major challenge to the legal framework which aims to stimulate the development of renewable energy sources. The European Union’s direction for the use of renewable energy is distributed generation and an increased use of by-products and organic waste, especially in the production of next-generation biofuels. The main aim of this study is to evaluate the production potential of straw in Poland and the possibility of its use for energy purposes, including a forecast for 2030, on the assumption that the management of this resource is in accordance with the provisions of the Polish Code for Good Agriculture Practice. In Poland, in the years 1999–2018, the average annual surplus of straw harvested over agricultural consumption equalled 12.5 million tons (4.2 Mtoe). Its largest surpluses were in the Dolnośląskie, Kujawsko-Pomorskie, Lubelskie, Wielkopolskie, and Zachodniopomorskie voivodeships (NUTS2). Based on the developed panel models, forecasts for straw surpluses in Poland are presented in three perspectives: realistic, pessimistic, and optimistic. The forecasts show regional differentiation until 2030. Each of the three perspectives indicate a slow increase in these surpluses, and depending on the adopted version, it will range from 10.6% to 21.9%.

Energy Efficiency of Comminution and Extrusion of Maize Substrates Subjected to Methane Fermentation

The production of methane in the anaerobic digestion process is a proven technology, but it is characterized by low cost-effectiveness. The pretreatment of substrates seems to be a promising technology, which may increase the cost-effectiveness of biogas installations. The aim of the study was to investigate the influence of the comminution and extrusion of maize silage and maize straw silage on the course and yield of anaerobic digestion. The use of a pretreatment (comminution, extrusion) is justified when its energy balance is positive. The greatest increase in the methane yield per dry matter (12.4%) was observed after the extrusion of maize straw silage at 175 °C. The change in the methane yield resulting from the extrusion of maize silage and maize straw silage at 150 °C was small and amounted to 6.4% and 9%, respectively. The comminution caused an increase in the methane yield and accelerated the fermentation of substrates. The methane yield from maize silage was 38.4%, whereas the yield from maize straw silage was only 8.3%.

Optimization Model for Biogas Power Plant Feedstock Mixture Considering Feedstock and Transportation Costs Using a Differential Evolution Algorithm

In this paper, an optimization model for biogas power plant feedstock mixture with respect to feedstock and transportation costs using a differential evolution algorithm (DEA) is presented. A mathematical model and an optimization problem are presented. The proposed model introduces an optimal mixture of different feedstock combinations in a biogas power plant and informs about the maximal transportation distance for each feedstock before being unprofitable. In the case study, the proposed model is applied to five most commonly used feedstock in biogas power plants in Croatia and Hungary. The research is performed for a situation when the biogas power plant is not owned by the farm owner but by a third party. An optimization procedure is performed for each scenario with a cost of methane production that does not exceed 0.75 EUR/m3 in 1 MWe biogas power plant. The results show the needed yearly amounts and the maximum transportation distance of each feedstock.

Decision Support System for the Production of Miscanthus and Willow Briquettes

The biomass is regarded as a part of renewable energy sources (RES), which can satisfy energy demands. Biomass obtained from plantations is characterized by low bulk density, which increases transport and storage costs. Briquetting is a technology that relies on pressing biomass with the aim of obtaining a denser product (briquettes). In the production of solid biofuels, the technological as well as material variables significantly influence the densification process, and as a result influence the end quality of briquette. This process progresses differently for different materials. Therefore, the optimal selection of process’ parameters is very difficult. It is necessary to use a decision support tool—decision support system (DSS). The purpose of the work was to develop a decision support system that would indicate the optimal parameters for conducting the process of producing Miscanthus and willow briquettes (pre-comminution, milling and briquetting), briquette parameters (durability and specific density) and total energy consumption based on process simulation. Artificial neural networks (ANNs) were used to describe the relationship between individual parameters of the briquette production process. DSS has the form of a web application and is opened from a web browser (it is possible to open it on various types of devices). The modular design allows the modification and expansion the application in the future.

Coupling of Rural Energy Structure and Straw Utilization: Based on Cases in Hebei, China

China’s coal-based energy structure is the main reason for the current high-level air pollution and carbon emissions. Now in the North China Plain, the government is vigorously promoting “coal to gas” and “coal to electricity” in the country and the vast rural areas. The development and utilization of biomass resources in agricultural areas is also an effective means of replacing coal. We propose the idea of forming a complementary rural energy structure of “biogas, briquetting, electricity (BBE)” model based on centralized biogas production (CBP) and straw briquetting fuel (SBF) to improve the rural energy structure. This article uses emergy analysis methods to analyze actual cases. It needs to have strengths and avoid weaknesses in mode selection. The process of the analysis reveals the disadvantages and improvement measures. Under the current capacity load, the emergy input and output, eco-economic indicators, sustainable development indicators, environmental load indicators, and economic value have their own advantages and disadvantages. Assuming 100% capacity load, the indicators have great optimization space. Reducing labor input during the planting phase can effectively reduce emergy input. The government needs to provide corresponding support based on the strengths and weaknesses of the project to keep the project sustainability. The development of complementary integration based on local conditions is an important measure to optimize the energy consumption structure in rural areas and improve the ecological environment.