Incorporating agricultural waste-to-energy pathways into biomass product and process network through data-driven nonlinear adaptive robust optimization

An increasing global population, rising energy demands, and the shift toward a circular bioeconomy are driving the need for more resource-efficient waste management. The increase in the world population—now exceeding 8 billion as of 2024—results in an increased need for alternative proteins, both human and feed grade proteins, as well as for biopolymers and bioenergy. As such, agricultural, forest, and marine waste biomass represent a valuable feedstock for production of food and feed ingredients, biopolymers, and bioenergy. However, the lack of integrated and efficient valorization strategies for these diverse biomass sources remains a major challenge. This literature review aims to give a systematic approach on the recent research status of agricultural, forest, and marine waste biomass valorization, focusing on cascade processing (a sequential combination of processes such as pretreatment, extraction, and conversion methods). Potential products will be identified that create the most economic value over multiple lifetimes, to maximize resource efficiency. It highlights the challenges associated with cascade processing of waste biomass and proposes technological synergies for waste biomass valorization. Moreover, this review will provide a comprehensive understanding of the potential of waste biomass valorization in the context of sustainable and circular bioeconomy.

Biomass materials are been considered as a useful and important raw material for energy production for different countries including India. Biomass materials originated from agricultural and kitchen waste have several benefits; considering these benefits it offers different advantageous uses like the production of cooking gas, generation of power and the conversion into value-added recycled items. By efficient and effective utilization of agricultural and kitchen waste for above mentioned purposes may be a good solution for waste management. Waste biomass has the ability to generate renewable power, cooking gas, etc. and it also has the possibilities to generate services for rural youths in different countries like India, other Asian and African countries. At present, global development is an agenda but this has several disadvantages due to human and industrial activities that are directly and indirectly related to challenges of human health, the health of our planet and its ecosystems. Agricultural waste and kitchen wastes are available in plenty; therefore, the focus is to be given to the use of these wastes into alternative fuels to minimize environmental pollution. Around the world, in many countries including India, this waste biomass is maybe one of the best choices for clean energy production, especially for modern energy applications like bioenergy power plants and biomass gasifiers that produce biogas. In principle, they use a significant amount of waste biomass (food waste, agriculture residue and forestry biomass). It is expected that till 2040, biomass waste-based power generation will increase five to six times than present power generation and this will contribute to the reliable power supply in the rural areas. Therefore, to support modern biomass-based technologies, the use of agricultural and kitchen waste for bioenergy should be increased; as of now, these supplies are limited due to high costs and low finance support. This is a fully developed resource, its utilization has not only the potential to provide common benefits like electricity generation and biogas production but its use can also reduce the required dumping area. We can also diminish the chances of air, water, and soil contamination and ecological health. Subsidies and incentives schemes are promoted by India’s Ministry of Renewable Energy to use waste as a renewable energy source and to encourage technologies based on biomass waste utilization. All the aspects of clean energy production from agricultural and kitchen waste biomass are reviewed and discussed in this chapter.

Agriculture is a source of emissions of the greenhouse gas methane into the environment. These emissions can be reduced by appropriate storage of animal slurry and manure, with proper fertilization and processing of organic agricultural waste into biogas, where methane is captured and used as an energy source. Biogas is a renewable source of energy that is produced by microbial anaerobic digestion in biogas plants. As a substrate in biogas plants using different types of organic biomass such as animal manure and slurry, crop residues, spoilt silage, waste from food processing industry and biodegradable industrial and municipal waste. Biogas can be used to produce heat and electricity or purified to biomethane as a fuel for vehicles. Digestate can be used as a high-quality fertilizer. Biogas as a renewable energy source represents a replacement for fossil fuels, thus reducing greenhouse gas emissions from fossil sources. The system of financial supports for electricity produced from biogas is applied in Slovenia. There were 24 operating biogas plants in Slovenia in year 2014. Slovenian biogas plants currently produce the majority of biogas from energy crops. As only the minority of biogas is produced from animal excrements we will primarily support the development of agricultural microbiogas plants that will use animal excrements and organic waste biomass from agri-food sector as substrates.

The objective of this work was to design a heat integrated, cost-effective, and cleaner combined heat and power (CHP) generation plant from low-cost, fourth-generation biomass waste feedstocks. The novelty lies in the development of systematic sitewide heat recovery and integration strategies among biomass integrated gasification combined cycle processes so as to offset the low heating value of the biomass waste feedstocks. For the biomass waste based CHP plant technical and economic analysis, the process was based on low-cost agricultural wastes like straws as the biomass feedstock and further established for a more predominant biomass feedstock, wood. The process was modeled using the Aspen simulator. Three conceptual flowsheets were proposed, based on the integration of the flue gas from the char combustor, which was separately carried out from the steam gasification of biomass volatalized gases and tars, and carbon dioxide removal strategies. The cost of energy production included detailed levelized discounted cash flow analysis and was found to be strongly influenced by the cost of feedstock. On the basis of a combined energy generation of ∼340−370 MW using straw wastes priced at 35.3 £/t or 40 Euro/t, with 8.5% and 8.61% by mass moisture and ash contents, respectively, the cost of electricity generation was 4.59 and 5.14 p/(kW h) for the cases without and with carbon capture respectively, with a 10% internal rate of return and 25 years of plant life. On the basis of the carbon capture value assigned by the Carbon Credits Trading scheme, a much constrained viable price of 22 £/t of such agricultural waste feedstocks for CHP generation was obtained, while up to 60 £/t of waste feedstocks can be economically viable under the UK Climate Change Levy, respectively.

The resource efficiency of biofuel production via biomass pyrolysis is evaluated using exergy as an assessment metric. Three feedstocks, important to various sectors of U.S. agriculture, switchgrass, forest residue, and equine waste, are considered for conversion to bio-oil (pyrolysis oil) via fast pyrolysis, a process that has been identified as adaptable to on- or near-farm application. Biomass and biofuel production pathways are defined, material flows are determined, and exergy in- and outflows associated with biomass production and conversion are computed, including the depletion of exergy from its natural state (cumulative exergy demand, CExD). Sources of exergy depletion are quantified and categorized by energy carriers, e.g., electricity and diesel fuel, and materials, e.g., fertilizer, as well as renewable and nonrenewable resources. Yields for biomass to bio-oil conversion by fast pyrolysis are determined experimentally. Breeding factors, a measure of exergy production (the ratio of the chemical exergy of the output product to process exergy inputs), are determined for the production of biomass and bio-oil. The quantification of exergy depletion for process pathways enables the possible identification of more sustainable (resource efficient) pathways for biomass and bio-oil production. It is shown, for example, that feedstocks grown primarily for biomass such as switchgrass may be less sustainable using the exergy measure compared to use of residue (e.g., forest thinnings) or waste biomass (e.g., equine waste). With regard to the pyrolysis process, there is substantial reduction in exergy depletion when the coproducts noncondensable gases and biochar are recycled and utilized as a source of heat. The sustainability of biomass production and conversion, as measured by exergy depletion, is strongly influenced by energy carriers. The study reveals that the method of electricity production, i.e., on-site generation or grid electricity, as well as the choice of grid electricity can have a significant impact on sustainability. The exergy content of the bio-oil produced varies from 24 to 27 MJ/kg bio-oil, which is much lower than traditional fuels. However, the cumulative exergy depletion for the production and conversion to bio-oil varies from approximately 4 to 11 MJ/kg bio-oil, which is also much lower than traditional fuels. Breeding factors for biomass production and conversion to bio-oil based on cumulative exergy depletion vary from approximately 2 to 5, demonstrating the potential exergy benefit of bio-oil production using fast pyrolysis.

Chapter 1 - Introduction to waste biomass processing and valorization

The process of anaerobic digestion is well known for digestion of wastewater and sludge, but now it has been widely implemented for production of renewable energy worldwide. Biogas from anaerobic digestion process is one of the most perspective alternative energy sources. Directive EU for renewable energy targets has been determined to 25% in 2020 for Estonia. Presently (2010) in Estonia the share of renewable ener­gy rose to approximately 21%. The annual of municipal solids waste (MSW) generated in Estonia accounts for 0.5 million tons or, taking into account the urban population (1.344 million inhabitants), 372 kg per capita. Up to 56% of total municipal solids waste generated in Estonia is easily biodegradable and can be used for biogas production. The volumes and qualities of different types of biodegradable fraction of municipal waste, industrial waste and waste of landscaping, agricultural waste and sewage sludge generated in Estonia during the period from 2002 to 2011 were analysed and their energy potential was estimated. The obtained data demonstrates that the main sources for biogas production are sewage sludge and animal manure. Also wastes of food industry, biodegradable municipal waste, and herbaceous biomass and agriculture products may be used. Special attention is paid to agricultural products and waste. The minimum energy potential from waste in Estonia may be estimated as 306.69 GWh per year, but this is only 3% from total energy production in Estonia. For the achievement of the recommended level of using renewable energy in Estonia in 2020, other natural sources of energy such as solar, wind, rain, etc. will be used.

Chapter 5 - Waste Biomass Resource Abundance, Energy Potential, and Availability

Prospects for energy recovery during hydrothermal and biological processing of waste biomass

The abundant condition of organic waste in urban areas of Surabaya requires a solution not only regarding the process of compost, but also how to utilize the biomass organic waste in a framework to socialize the use of urban yard narrow land into a form of cultivation of vegetables that contribute to the nutrition for the family. This potential will be synergistic with Surabaya city government policy related to urban yard Empowerment program that inspires the idea of how to utilize organic waste biomass into something useful for plant growth and reduce the accumulation of excessive waste and odor that is not delicious for the people of Surabaya. By implementing the appropriate technology to utilize waste biomass of organic waste into a material of burial or organic fertilizer after through the process of composting or fermentation to become organic fertilizer that is beneficial for plants. The purpose of this research is to know the influence of organic waste biomass from the results of the posting of urban organic waste against the growth test and the results of mustard crops. Based on the research results, it can be concluded as follows: 1. There is a significant influence of the composition of urban garbage organic fertilizer against the growth parameters and results of the mustard crops in the variables studied, including: length of the plant, the number of leaves, the length of the roots and fresh weight per plant. 2. The value of fresh weight yield per highest crop is achieved by P3 treatment (15% from the weight of planting media) by 313.82 grams and effective and efficient treatment, it is also supported by growth variables such as plant length, number of leaves and root length; Even though statistically different P3 treatments are not significant with the P5 treatment (25%) and P7 (35%). Keywords: organic waste Biomas, mustard greens.

In this paper, thermal degradation (TGA) and pyrolysis studies of sunflower shell biomass (SSB), eucalyptus biomass (EB), wheat straw biomass (WSB), and peanut shell biomass (PSB) were carried out using the thermogravimetric analysis and stainless steel tubular reactor. Thermal degradation of all biomass wastes was examined at a heating rate of 10 °C/min in nitrogen atmosphere between 20 and 800 °C. Experiments of pyrolysis were carried out in a tubular reactor from 300 to 700 °C with a heating rate of 10 °C/min, a particle size of 0.1–0.3 mm and nitrogen flow rate of 100 mL.min−1, which the aim to study how temperature affects liquid, solid, and gas products. The results of this work showed that three stages have been identified in the thermal decomposition of SSB, EB, WSB, and PSB wastes. The first stage occurred at 120–158 °C, the second stage, which corresponds to hemicellulose and cellulose's degradation, occurred in temperatures range from 139 to 480 °C for hemicellulose, and from 233 to 412 °C for cellulose, while the third stage occurred at 534–720 °C. It was concluded that temperature has a significant effect on product yields. The maximum of bio-oil yields of 37.55, 30.5, 46.96, and 50.05 wt% for WSB, PSB, SSB, and EB, were obtained at pyrolysis temperature of 500 °C (SSB, PSB, and WSB) and 550 °C (EB). Raw biomass, solid and liquid products obtained were characterized by elemental analysis, Fourier transformed infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), and x-ray diffraction (XRD). The analysis of solid and liquid products showed that bio-oils and bio-chars from agricultural biomass wastes could be prospective sources of renewable fuels production and value added chemical products.

Organic farm waste management in degraded banana-coffee-based farming systems in NW Tanzania

Graphitic carbon is a valuable material that can be utilized in many fields, such as electronics, energy storage and wastewater filtration. Due to the high demand for commercial graphite, an alternative raw material with lower costs that is environmentally friendly has been explored. Amongst these, an agricultural bio-waste material has become an option due to its highly bioactive properties, such as bioavailability, antioxidant, antimicrobial, in vitro and anti-inflammatory properties. In addition, biomass wastes usually have high organic carbon content, which has been discovered by many researchers as an alternative carbon material to produce graphite. However, there are several challenges associated with the graphite production process from biomass waste materials, such as impurities, the processing conditions and production costs. Agricultural bio-waste materials typically contain many volatiles and impurities, which can interfere with the synthesis process and reduce the quality of the graphitic carbon produced. Moreover, the processing conditions required for the synthesis of graphitic carbon from agricultural biomass waste materials are quite challenging to optimize. The temperature, pressure, catalyst used and other parameters must be carefully controlled to ensure that the desired product is obtained. Nevertheless, the use of agricultural biomass waste materials as a raw material for graphitic carbon synthesis can reduce the production costs. Improving the overall cost-effectiveness of this approach depends on many factors, including the availability and cost of the feedstock, the processing costs and the market demand for the final product. Therefore, in this review, the importance of biomass waste utilization is discussed. Various methods of synthesizing graphitic carbon are also reviewed. The discussion ranges from the conversion of biomass waste into carbon-rich feedstocks with different recent advances to the method of synthesis of graphitic carbon. The importance of utilizing agricultural biomass waste and the types of potential biomass waste carbon precursors and their pre-treatment methods are also reviewed. Finally, the gaps found in the previous research are proposed as a future research suggestion. Overall, the synthesis of graphite from agricultural bio-waste materials is a promising area of research, but more work is needed to address the challenges associated with this process and to demonstrate its viability at scale.

Orange peel is an organic waste that contains vitamin C, essential oils and pectin. The essential oil content in orange peel and cinnamon waste can ward off ants and can be used as a versatile cleaning liquid with white vinegar as a solvent. The purpose of this study was to determine the characteristics of cleaning fluids based on orange peel waste, white vinegar, cinnamon, and rosemary leaves as cleaning liquids that can ward off ants and find out their impact on the surrounding environment. The results obtained in the organoleptic color test in the form of 7 out of 10 respondents chose a brownish-yellow color, there was an organoleptic aroma test in the form of 10 respondents judged that at a distance of 25 cm the aroma was still strongly smelled, there is a test of effectiveness as a cleaning fluid, 10 respondents rated it very clean. Also on the test of effectiveness as an ant’s repellents fluid, 10 respondents rated ants away at a range of time from 1-5 minutes. It can be concluded that VCO is a versatile cleaning fluid made from natural ingredients and can ward off ants.

Polylactic acid, a biodegradable biopolymer derived from renewable resources, is increasingly recognized as a sustainable alternative to conventional petroleum-based plastics that have contributed to toxic environmental pollution worldwide. Yet, various pathways to produce polylactic acid may differ in their environmental footprint and resource demands. In this study, we evaluate life cycle assessment data to compare polylactic acid production through six different routes: three from agricultural biomass feedstocks, and three from waste feedstocks, focusing on three sustainability parameters, including carbon intensity, energy intensity, and material intensity. The major findings show lower carbon emission intensity due to lower energy and material intensities that are required for producing polylactic acid from waste feedstocks than from agricultural biomass feedstocks. This research highlights the importance of optimizing polylactic acid production processes to minimize energy and material use for reduced carbon emissions and thereby maximize the sustainability value of this alternative polymeric material. Future research should focus on process innovations to further reduce carbon emissions.