Project Deliverables

In both China and Greece a detailed survey was conducted to identify the most promising biodegradable and non-biodegradable agricultural residues for final exploitation. The residues are selected on the basis of criteria such as abundance and environmental impact taking into account also the possibilities for alternative useful uses. Data on the available agricultural residues are selected by national literature, by on-site surveys and through cooperation with the relevant agricultural organizations and national agricultural ministries.

In both China and Greece a detailed analysis was conducted to specify the prospects for an economically viable introduction of each of the bio-products of the processing plants into the energy market.

Experiments are conducted on the anaerobic bacterial digestion of a variety of biodegradable agricultural residues aiming at the optimization of biogas production depending on their specific nature and properties. Key parameters for examination are the number of the processing steps (hydrolysis, acidogenesis, acetogenesis, mehanogenesis), the process mesophillic or thermophillic temperature, the dry matter content, pH, internal mixing and retention time, and the way in which the substrate is fed. Experiments are conducted to isolate the influence of key parameters on the quantity and quality of the final biogas product.

Anaerobic digestion is theoretically modeled and optimized on the basis of the results obtained through the experimental work of T.2.1. Quite often the experimental data cannot give a detailed insight into the biological process since the measurements lump together several components and give therefore only a global view. Theoretical modeling isolates the influence of each specific parameter, also allowing its study in wide operation ranges. Modeling also brings new insights on the interdependence of the operation parameters and dynamically provides optimal processing strategies that are invisible otherwise. A computational model is created to accurately simulate and optimize the performance of the digester depending on the feedstock used and the key operation parameters identified by T.2.1.

Experiments are conducted on the catalytic pyrolysis of various selected non-biodegradable agricultural residues aiming at the optimization of the operation conditions (temperature, pressure, residence time etc) depending on the user needs for bio-char, bio-oil or uncondensed gases. Design and development of innovative catalytic systems are performed by UOWM in order to improve the quality and the quantity of the produced bio-oil and chemicals. Efforts are concentrate on exploring the prospects of various catalysts such as zeolites (alkali ion-exchange zeolites, alkali ion-loaded zeolites) and supported alkali metals (alkaline metals on alumina or silica, alkali metals and alkaline metal hydroxides on alumina). All catalysts are tested in terms of catalytic activity, selectivity and resistance to deactivation by carbon formation and deposition on their catalytic surface (BUCT, BUPEE, BENRAN). Catalysts are characterized before and after reaction by a variety of methods such as the ICP, BET, XRD, NH₃-TPD, CO₂-TPD, TPR, XPS, TEM, TPO, Raman, SEM, etc. (UOWM, KUST).

Pyrolysis is theoretically modeled and optimized on the basis of the results obtained by the experimental work of T3.1. Pyrolysis has been widely investigated in order to understand the mechanisms and kinetics at different scales, vs. particle level, multi-phase reacting flow, product distribution and reactor performance, process integration and control. However, there are a number of uncertainties in current biomass pyrolysis models, especially in their ability to optimize process conditions to achieve desired product yields and distribution. Key parameters in all these models are the characteristics of the feedstock, the physical and chemical properties of the biomass particles and the residence times of both solid and gas phases in the pyrolysis reactors. An experimentally validated computational model is constructed to accurately simulate the observed pyrolysis phenomena together with their influence on the quantities and qualities of the desired products. The model then allows the optimization of the pyrolysis process depending on the user needs for bio-char, bio-oil or uncondensed gases.

Experiments are conducted on the catalytic reforming of the biogas and bio-oil that were produced by T2.1 and T3.1 aiming at the optimization of the operation conditions (temperature, pressure, residence time etc) for maximizing conversion, hydrogen production and catalyst’s life. Design and development of innovative catalytic systems are performed by UOWM in order to improve these features. Effort is focused in exploring the prospects of various catalysts that have active metals (transition metals like Ni or precious metals) incorporated into the lattice of perovskite type oxides. All catalysts are tested in terms of catalytic activity, selectivity and resistance to deactivation by carbon formation and deposition on their catalytic surface. The catalysts are characterized before and after reaction by a variety of methods such as the ICP, BET, XRD, NH₃-TPD, CO₂-TPD, TPR, XPS, TEM, TPO, Raman, SEM, etc.

Experiments are conducted on the catalytic reforming of the biogas and bio-oil that were produced by T2.1 and T3.1 aiming at the optimization of the operation conditions (temperature, pressure, residence time etc) for maximizing conversion, hydrogen production and catalyst’s life. Design and development of innovative catalytic systems are performed by UOWM in order to improve these features. Effort is focused in exploring the prospects of various catalysts that have active metals (transition metals like Ni or precious metals) incorporated into the lattice of perovskite type oxides. All catalysts are tested in terms of catalytic activity, selectivity and resistance to deactivation by carbon formation and deposition on their catalytic surface. The catalysts are characterized before and after reaction by a variety of methods such as the ICP, BET, XRD, NH₃-TPD, CO₂-TPD, TPR, XPS, TEM, TPO, Raman, SEM, etc.

The reforming reactions of biogas and bio-oil are theoretically modeled and optimized in comparison to the results obtained by the experimental work of T4.1. Computational models can handle complexity across multiple levels of analysis, allowing data across these levels to be integrated and related to each other. For each reforming reaction, the influence of key parameters on the reactor performance including reactor temperature, reactor pressure, steam to methane feed ratio (S/C), and carbon dioxide to methane feed ratio (CO₂/CH₄) are investigated by a specifically made multi-objective computational algorithm allowing the recognition of optimal operation conditions. Finally, the experimental and computational results commonly identify the best approaches for the design and development of specifically indented biogas and bio-oil catalytic reformers.

The overall plant performance is theoretically modeled and optimized using the experience and results obtained from the experimental work of the project (WP2, WP3, WP4). By integrating the sub-models of T2.2, T3.2 and T4.2 a new model is created to optimize the overall plant performance depending on the agricultural feedstock used and the user needs for bio-char, bio-oil, uncondensed gases, biogas, syngas, hydrogen or energy. The resulting model allows the dynamic simulation - evaluation of the time characteristics of the parameters of a plant for different load scenarios and configurations without having to interfere with the day to day operations. This saves time and money since, for example, the need for real-world test series with expensive measurement equipment is minimised. The results of the model are validated by the experimental results of the project and provide the guidelines for the optimal operation of the final processing plant by the end users.

Moreover, the overall plant performance is modeled and optimized to provide the required anode feed stream of a Solid Oxide Fuel Cell (SOFC) electricity generating stack. External or internal steam reforming of the gas feed stream may be employed and SOFC operation temperatures above 800^oC may be used. The model provides results on the efficiency, power output and thermal behavior of the SOFC stack subject to the constraints of the biogas or syngas feed stream compositions taken by the agricultural residue processing plant.

An assessment for the following is performed: origin, quantity and characterization of the raw materials, proposed treatment process to produce high marketable products, fixed cost, required personnel, operational cost, product cost, market (supply and demand, competition), sale price, profit, financing possibilities, lifetime, etc. After definition of the operational parameters, the process flowchart is constructed via a hierarchy of design decisions, namely structure of input-output, recycling, separation and thermal integration. The limitations that may arise are examined, such as the registration of these new materials according to EU and China regulations. Knowing the above components, the rate of return on investment is estimated and the first conclusions for the undertaking of this investment are drawn. Risk assessment analyses (partial and summarized) take place and the relative elasticity analysis for certain major cost-effecting parameters is carried out. At the end of the task all the preparatory measures for the exploitation of the results are taken and a new business plan is performed.

A thorough environmental assessment of the integrated unit is carried out using Life Cycle Assessment.

For each participating country, the feasibility of the integrated unit is exploited via a small scale demonstration unit that is developed and tested at an already existing anaerobic digester / biogas producing facility (in the case of Greece this project will be carried out at the anaerobic waste treatment plant constructed and operated by SIRMET for LA Farm S.A.).