Renewable Energy Global Innovations features: A techno-economic comparison of Fischer–Tropsch and fast pyrolysis as ways of utilizing sugar cane bagasse in transportation fuels production

Significance Statement

In recent years, critical issues such as energy security, petrol price upsurge and increasing consciousness of global warming, have all garnered attention from all walks of life to focus on the prospects of a bioenergy sector. The concept of biorefinery has recently emerged where biomass has already been identified as the sole source of renewable energy which has properties similar to fossil fuels. Sugarcane is currently the most cost-effective feedstock for the biofuel production and could become even cheaper and more advantageous if the waste bagasse would also be converted to biofuels. From various technoeconomic analysis, two techniques: the fast pyrolysis-hydro processing route and gasification coupled with Fischer–Tropsch synthesis, have been considered to be feasible for application in the large-scale production of bio fuels from the sugarcane bagasse.

In a recent paper published in Chemical Engineering Research and Design Stavros Michailos and Colin Webb from the School of Chemical Engineering and Analytical Science at University of Manchester in collaboration with David Parker at University of Exeter compared the economic and technological feasibility of the fast pyrolysis-hydro processing route (repurposed to enhance hydrogen production) and gasification coupled with Fischer–Tropsch synthesis processes. They aimed at resolving which between the two processes would deliver final products of fuels that can be directly used within the inherent technological infrastructure cheaply.

The adaptability of gasification followed by Fischer–Tropsch synthesis and fast pyrolysis coupled with hydro processing were examined against economic and thermodynamic criteria. Sugarcane bagasse was adopted as the feedstock at a flow rate of 100 metric tonnes per hour. The research team then utilized the Aspen plus process simulation software to build robust and thermodynamically rigorous simulations of the constituent processes of these biofuel conversion options processes. Mass, energy balance of the constituent processes, the overall thermochemical energy and economic efficiencies were calculated for each option based on the quantification and assessment of the yield.

From the comparative analysis of two near term biomass-to-liquid fuels conversion options, the researchers observed that the higher fuels productivity associated with the Fischer–Tropsch process resulted in in higher thermodynamic efficiencies than fast pyrolysis process. During fast pyrolysis, lignin is exploited in a steam cycle to generate electricity while in Fischer–Tropsch process, lignin is gasified and thereby it contributes to liquid fuels production. Moreover, almost forty percent of electricity generated by fast pyrolysis CHP unit is utilized to compress hydrogen. According to economic assessment Fischer–Tropsch process outplays fast pyrolysis process achieving higher values for all economic indicators. In addition, it is more lenient to variations of the elementary financial specifications. Conversely, the fast pyrolysis process delivers higher product diversity.

In light of the aforementioned remarks and outcomes, the choice of the best alternative conversion route depends on many aspects including factors aside from those enumerated in this study, such as market demand and location of the plant. However, at the moment and solely based on thermo-economic criteria Fischer–Tropsch process is more efficient than fast pyrolysis process mainly due to higher thermodynamic performance, minimal risk and substantial economic returns.

Reference

Stavros Michailos¹, David Parker², Colin Webb¹. A techno-economic comparison of Fischer–Tropsch and fast pyrolysis as ways of utilizing sugar cane bagasse in transportation fuels production. Chemical Engineering Research and Design. Volume 118 (2017) pages 206–214.

Show Affiliations

1. School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
2. School of Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK

 

Go To Chemical Engineering Research and Design Read more research excellence studies on: Renewable Energy Global Innovations (http://ift.tt/21cCPA4)

Renewable Energy Global Innovations features: Novel plant development for a high performance 3 kW integrated wind and solar system

Significance Statement

Professor Hsing-Sheng Chai and colleagues in Taiwan proposed to investigate the performance of a parallel system of four Savonius wind rotors with a solar panel deflector. The work is published in peer-reviewed Journal of Renewable and Sustainable Energy.

Since emphasis has been placed on renewable energies to protect the world from unwanted pollution, Chai and colleagues also join other research groups in improving savonius wind turbine which was used to generate energy. The savonius is a drag-type wind turbine, where the blades are the only driving force which the wind drag act. The rotational speed of the rotors and the relationship between the tip-speed ratio TSR and power coefficient Cp are to be considered.

According to the research team, to improve the performance of savonius wind rotors, they placed a series of rotors in a line, with a fixed distance between them, with each one rotating at a specific phase angle. The team in their view to improve the performance of 3 Kw integrated wind and solar system, they considered the number of blades, the wind velocity, the height of the rotor, and the blade overlap ratio. A system of four two-bladed savonius wind rotors in parallel matrix was constructed. The team employed a computational fluid dynamics software, Fluent, to analyze the flow fields then compared the simulations to their own experimental data.

They experienced magnus effect as each rotor absorbed momentum from other rotors during rotation, and is responsible for the additional rotation of the downstream rotor and the periodic coupling of local flow between the two rotors, enhancing the performance of the overall system. They found that the higher the wind velocity the better the performance of the system. The TSR values at the slopes of the simulation and experimental curves differ, this is because in simulations, the rotational speed of the wind rotors and inlet wind velocity are fixed values. A fast rotating wind that wind will easily passes through wind rotors, thereby causing Cp to decrease as a result of the wind not doing significant work on the rotors, said the research team.

This study experimentally tested novel four Savonius rotor system with a solar panel so as to improve the system performance and they were able to generate 14.55kWh of power per day at an efficiency of 21.7%. The results of this study show that the two-bladed configurations have better performance than the three-bladed ones, except with respect to the starting torque.

About The Author

Dr. Hsing-Sheng Chai is an assistant professor of Aletheia University in Taiwan. He obtained his PhD degree from National Chiao Tung University. His PhD major is mechanical engineering, while Bachelor and Master major is aerospace engineering. Renewable energy, thermal engineering, combustion science, fire safety, and computational fluid dynamics are the research topics appealing to him.  

Journal Reference

Hsing-Sheng Chai¹, Chang-An Chen², Chiun-Hsun Chen², Novel Plant Development for a High Performance 3 Kw Integrated Wind and Solar System, Journal of Renewable and Sustainable Energy 8, 045302 (2016).

Show Affiliations

1. General Education Center, Aletheia University, 32 Zhenli St., Danshui Dist., New Taipei City 251, Taiwan, R.O.C.
2. Department of Mechanical Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan, R.O.C

 

Go To Journal of Renewable and Sustainable Energy Read more research excellence studies on: Renewable Energy Global Innovations (http://ift.tt/21cCPA4)