Chen-Yeon Chu

Biohydrogen production by dark fermentation: scaling-up and technologies integration for a sustainable system

Currently, the use of alternative renewable energies is broadly supported in many countries, some of which are seriously evaluating the possibility of using hydrogen as an alternative fuel in their power systems. Hydrogen production by biological processes, such as dark fermentation, is a very promising alternative. However, this process has only been studied on the laboratory scale, and there is limited experience at the pilot scale. The main reasons of non-scaling hydrogen production by dark fermentation at large scale are unpurified hydrogen production, stability of the bioprocesses, as well as their low conversion yields joined at the formation of byproducts. Improvement of energetic yields of dark fermentation requires a better knowledge of the microorganisms involved in the mixed culture and their possible interactions, as well as the use of appropriate substrates and strategies, such as solid-state fermentation, the purification of hydrogen and the coupling of dark fermentation with other biological processes as anaerobic digestion. The present work offers an overview of the current knowledge dealing with H2-production by dark fermentation and its integration into a concept of an environmental biorefinery. Several key points are addressed, such as the benefits of using local waste as substrates, the new solid-state fermentation processes, the coupling of hydrogen purification with the production process, the association of the H2-producing process with other biological processes, such as anaerobic digestion towards biohythane production (H2/CH4). Information about pilot plant experiments was added to illustrate the feasibility of producing fermentative hydrogen and methane from organic waste at a pilot scale, as developed at Feng Chia University (Taiwan).

Sulfation and attrition of calcium sorbent in a bubbling fluidized bed.

A bubbling fluidized bed reactor was used as a desulfurization apparatus in this study. The height of the bed was 2.5m, and the inner diameter was 9cm. The bed materials were calcium sorbent and silica sand. The effects of the operating parameters of the flue gas desulfurization including relative humidity, temperature, superficial gas velocity, and the particle size of calcium sorbent on SO2 removal efficiency and calcium sorbent conversion and attrition rate in the fluidized bed were investigated. It was found that the temperature effect in our system was negligible from 40 to 65 degrees C. A higher relative humidity had a higher calcium conversion and a higher sulfur dioxide removal efficiency. Moreover, a smaller particle size of calcium sorbent had a lower calcium conversion in the cyclone but a higher sulfur dioxide removal efficiency. A lower superficial gas velocity resulted in a higher sulfur dioxide removal efficiency and a higher calcium conversion, thus, the total volume of the flue gas treated was maximum near the minimum fluidization velocity. Finally, an attrition rate model proposed in this study could predict the elutriation rate satisfactorily.

The Autonomous House: A Bio-Hydrogen Based Energy Self-Sufficient Approach

In the wake of the greenhouse effect and global energy crisis, finding sources of clean, alternative energy and developing everyday life applications have become urgent tasks. This study proposes the development of an “autonomous house” emphasizing the use of modern green energy technology to reduce environmental load, achieve energy autonomy and use energy intelligently in order to create a sustainable, comfortable living environment. The houses’ two attributes are: (1) a self-sufficient energy cycle and (2) autonomous energy control to maintain environmental comfort. The autonomous house thus combines energy-conserving, carbon emission-reducing passive design with active elements needed to maintain a comfortable environment.

Scale-up and Commercial Applications of Biohydrogen Production Processes

Abstract Extensive researches in the past have shown substantial improvement and development in both the yield and the volumetric production rates of biohydrogen. Yet, for commercial-scale applications that are cost-effective, biohydrogen yields and production rates must outdo significantly the existing accomplishments. Until now, there have been no reports of a commercial-scale biohydrogen production system in the world. This chapter deals with technoeconomic evaluation, fundaments of scale-up, and pilot-scale studies to help in the setup of a commercial-scale system. The scale-up process with the key component of kinetics and hydrodynamics of a fermenter is further supported by data mining of reported pilot-scale systems.

Biohydrogen Production via Lignocellulose and Organic Waste Fermentation

Hydrogen is a promising energy carrier and a replacement for fossil fuels, since it is clean and has high energy and its application does not contribute to the greenhouse effect. Renewable resources, such as lignocellulosic materials and organic wastes, in particular, dark fermentative hydrogen methods, as the feedstock for hydrogen production have great potential for supplying hydrogen.

Optimal Absorbent Evaluation for the CO2 Separating Process by Absorption Loading, Desorption Efficiency, Cost, and Environmental Tolerance

The CO2 absorption capacities of potassium glycinate, potassium sarcosinate (choline, proline), mono-ethanolamine (MEA), and tri-ethanolamine were evaluated to find the optimal absorbent for separating CO2 from gaseous products by a CO2 purification process. The absorption loading, desorption efficiency, cost, and environmental tolerance were assessed to select the optimal absorbent. MEA was found to be the optimum absorbent for separating the CO2 and H2 mixture in gaseous product. The maximum absorption loading rate was 0.77 mol CO2 per mol MEA at temperature of 20°C and absorbent concentration of 2.5 mol/L, whereas desorption efficiency was 90% by heating for 3 h at 130°C. MEA was found to be an optimal absorbent for the purification process of CO2 during gaseous production.