Towards circular economy solutions for the management of rice processing residues to bioenergy via gasification

An economic assessment of two circular economy scenarios of fluidized bed gasification-based systems for combined heat and power (CHP) generation, fueled with rice processing wastes, was conducted. In the first scenario, the gasification plant with a capacity of 42,700 t/y of rice husks provides a waste management solution for 5 small rice processing companies, located at the same are, while in the second scenario the gasification unit of 18,300 t/y capacity provides a waste management solution to only one rice processing plant, being a custom-made solution. The first scenario is the most economically viable, with an annual revenue of 168 €/(t*y), very good payout time (POT=1.05) and return in investment (ROI=0.72). The economic assessment was based on experiments performed at a laboratory-scale gasification rig, while the economic analysis was based on the SMARt-CHP technology, developed at Aristotle University, Greece. The experimental proof of concept of rice husks waste gasification was studied at a temperature range 700-900oC, under an under-stoichiometric ratio of O2/N¬¬2 (10/90 v/v), as gasification agent. Producer gas’s LHV maximized at 800oC (10.9 MJ/Nm3), while the char’s BET surface reached a max of 146 m2/g at 900oC. Recommendations were also provided for a potential pretreatment of rice husks in order to minimize de-fluidization problems of the gasification system

Investigation study for technological application of alternative methods for the energy exploitation of biomass/agricultural residues in Northern Greece

Biomass energy potential is addressed to be the most promising among the renewable energy sources, due to its spread and availability worldwide. Apart form that, biomass has the unique advantage among the rest of renewable energy sources, to be able to provide solid, liquid, and gaseous fuels that can be stored, transported, and utilized, far a way from the point of origin. For the northern region of Macedonia in Greece, biomass utilization is considered to be a major issue, due to the considerably intensive regional agricultural activities. Wood by-products, fruit cores, rice husk and cotton gin waste provide a promising energy source for the region. The energy potential of the available agricultural biomass produced in the region is much enough to cover the 10% of the annual oil consumption utilized for thermal applications. However, the cost of energy utilization of biomass is considerably high due to the high cost of the logistics concerning the collection, transport, and storage of biomass. The available utilization technologies developed, to handle efficiently all different species of biomass, cover a wide technological range. One of the most promising technologies involving thermal treatment of biomass and the production of a gaseous fuel (biogas) for industrial heat applications and electricity production, is the thermochemical conversion. In the present work, an investigation concerning biomass potential for energy production in the region of central Macedonia in Greece, utilizing several locally produced biomass species, is conducted. Emphasis is put on the energy utilization of agricultural by-products and residues. Agricultural sector is of greal importance due to the considerably intensive agricultural activities in the region of Central Macedonia

Probing synergies between lignin-rich and cellulose compounds for gasification

The fixed bed gasification of lignin rich and deficient mixtures was carried out to probe the synergistic effects between two model compounds, Lignin Pink (LP) rich in Na and Cellulose Microcrystalline (CM). Reaction conditions utilized the most commonly used air ratios in current wood gasifiers at 750 °C and 850 °C. It was found that by increasing the lignin content in the mixture, there was a selectivity change from solid to gas products, contrary to a similar study previously carried out for pyrolysis. This change in product mix was promoted by the catalytic effect of Na edge recession deposits on the surface of the char. As a result, the water gas shift reaction was enhanced at 850 °C for the LP48CM52 mixture across all air ratios, this was evidenced by a strong correlation between the produced H2 and COx. Meanwhile, by lowering the lignin content in the mixtures, the reactivity of cellulose microcrystalline was found to generate more char at higher temperature, similar to lignin mixtures when undergoing pyrolysis

Targeting sustainable bioeconomy: A new development strategy for Southern European countries. The Manifesto of the European Mezzogiorno

ABSTRACT: This policy-oriented opinion paper, which has taken the form of a Manifesto, is co-authored by scientists and engineers from Southern European Union countries that are presently experiencing deep and complex systemic crises: Portugal, Spain, Italy, Greece and Cyprus. With their Manifesto, the authors advocate the adoption of a new development model, focusing on the target of sustainable bioeconomy, around which other development themes and topics will crystallize. Implementing this model will act as a locomotive to get the economies and societies of these countries efficiently out of their crises, and smoothly into greener post-crisis pastures. The proposal is articulated in ten critical steps or theses for immediate action by the policy- and decision-makers, as well as industry, markets and other key actors within this troubled area of the European Mezzogiorno. Corroborating evidence of these theses comes in the form of short reports or "letters" on the key topics of this Manifesto from the countries and regions concerned.info:eu-repo/semantics/publishedVersio

Agricultural and forest biomass for food, materials and energy: bio-economy as the cornerstone to cleaner production and more sustainable consumption patterns for accelerating the transition towards equitable, sustainable, post fossil-carbon societies

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Economic Assessment of Polypropylene Waste (PP) Pyrolysis in Circular Economy and Industrial Symbiosis

Plastic waste has a high energy content and can be utilized as an energy source. This study aims to assess the economic feasibility of polypropylene plastic waste (PP) pyrolysis. A literature review was carried out to determine the optimal pyrolysis conditions for oil production. The preferred pyrolysis temperature ranges from 450 °C to 550 °C, where the oil yields vary from 82 wt.% to 92.3 wt.%. Two scenarios were studied. In the first scenario, pyrolysis gas is used for the pyrolysis heating needs, whereas in the second scenario, natural gas is used. An overview of the economic performance of a pyrolysis plant with a capacity of 200,000 t/year is presented. Based on the results, the plant is economically viable, as it presents high profits and a short payback time for both scenarios considered. Although the annual revenues are smaller in scenario 1, the significant reduction in operating costs makes this scenario preferable. The annual profits amount to 37.3 M€, while the return on investment is 81% and the payback time is 1.16 years. In scenario 2, although the plant is still feasible and shows high profitability, the annual profits are lower by about 1.5 M€, while the payback time is 1.2 years

New Forms of Social Learning in Mediterranean Higher Engineering Education: Change Lab for Gender Equality Transformation, Methodology, Design Principles

Educating students to understand the dynamics of complex systems and acting with responsibility and equality in their professional/private life is pivotal. Implementing social changes in higher engineering education institutions is a challenge. This work is grounded empirically in the tailored practices of the gender equality Change Lab embedded in the network of Mediterranean engineering schools, which is a collective organizational integrity. We used action research and practical learning in our methodology. Design principles are provided, and methodological setup is included. We advocate that in order to mainstream gender equality, develop structures, and overcome some of the known limitations, we need to have conceptual clarity, well-targeted interventions, reflexivity, and empirical evidence. Moving from separate bureaucratic centrally-managed higher education institutions to interconnected networks that can organize self-assembling collaboration in the form of labs, with mutually beneficial partnerships contemplating social innovations, can challenge the melting of the traditional boundaries towards inclusive education. This can be done amidst university reforms conducive to such a transformation. Particular attention is paid to the role of HORIZON 2020 Taking a Reflexive Approach to Gender Equality for Institutional Transformation (TARGET) project in conceptualizing gender equality learning and system change in Mediterranean engineering schools

Economic Assessment of Polypropylene Waste (PP) Pyrolysis in Circular Economy and Industrial Symbiosis

Plastic waste has a high energy content and can be utilized as an energy source. This study aims to assess the economic feasibility of polypropylene plastic waste (PP) pyrolysis. A literature review was carried out to determine the optimal pyrolysis conditions for oil production. The preferred pyrolysis temperature ranges from 450 °C to 550 °C, where the oil yields vary from 82 wt.% to 92.3 wt.%. Two scenarios were studied. In the first scenario, pyrolysis gas is used for the pyrolysis heating needs, whereas in the second scenario, natural gas is used. An overview of the economic performance of a pyrolysis plant with a capacity of 200,000 t/year is presented. Based on the results, the plant is economically viable, as it presents high profits and a short payback time for both scenarios considered. Although the annual revenues are smaller in scenario 1, the significant reduction in operating costs makes this scenario preferable. The annual profits amount to 37.3 M€, while the return on investment is 81% and the payback time is 1.16 years. In scenario 2, although the plant is still feasible and shows high profitability, the annual profits are lower by about 1.5 M€, while the payback time is 1.2 years

Exploring Greek Citizens’ Circular Thinking on Food Waste Recycling in a Circular Economy—A Survey-Based Investigation

Food waste is one of the biggest global challenges. Thinking and acting for closed-loop cycles for energy and resources recovery is pivotal for meeting the Sustainable Development Goal 12.3 (SDG 12.3) by 2030. In this paper, the multifaceted problem of food waste and Greece’s national policy of circular economy is briefly given. Greece produces the highest annual per capita food waste output (142 kg) in Europe, indicating that the problem is rather large for the country. The solution to the problem inextricably linked to the implementation of the food waste hierarchy, was investigated through a survey integrating the possibility of energy recovery. The tailored questionnaire sent via e-mails and social media with the goal of identifying a snapshot of Greek citizens’ conceptions and practices regarding the management of their household food waste, and their familiarity with circular economy concepts. Results have shown that most respondents are aware of the problem’s existence, however, without considering it as important, according to 1565 responses gathered and analyzed using the IBM SPSS Statistics 27.0 program. Greek individuals are eager to recycle their food waste without expecting anything in return, but the majority seek recommendations on how to do it

Balancing Waste and Nutrient Flows Between Urban Agglomerations and Rural Ecosystems: Biochar for Improving Crop Growth and Urban Air Quality in The Mediterranean Region

Mediterranean ecosystems are threatened by water and nutrient scarcity and continuous loss of soil organic carbon. Urban agglomerations and rural ecosystems in the Mediterranean region and globally are interlinked through the flows of resources/nutrients and wastes. Contributing to balancing these cycles, the present study advocates standardized biochar as a soil amendment, produced from Mediterranean suitable biowaste, for closing the nutrient loop in agriculture, with parallel greenhouse gas reduction, enhancing air quality in urban agglomerations, mitigating climate change. The study’s scope is the contextualization of pyrolytic conditions and biowaste type effects on the yield and properties of biochar and to shed light on biochar’s role in soil fertility and climate change mitigation. Mediterranean-type suitable feedstocks (biowaste) to produce biochar, in accordance with biomass feedstocks approved for use in producing biochar by the European Biochar Certificate, are screened. Data form large-scale and long-period field experiments are considered. The findings advocate the following: (a) pyrolytic biochar application in soils contributes to the retention of important nutrients for agricultural production, thereby reducing the use of fertilizers; (b) pyrolysis does not release carbon dioxide to the atmosphere, contributing positively to the balance of carbon dioxide emissions to the atmosphere, with carbon uptake by plant photosynthesis; (c) biochar stores carbon in soils, counterbalancing the effect of climate change by sequestering carbon; (d) there is an imperative need to identify the suitable feedstock for the production of sustainable and safe biochar from a range of biowaste, according to the European Biochar Certificate, for safe crop production