For more than half a century, Fischer-Tropsch synthesis (FTS) of liquid hydrocarbons was a technology of great potential for the indirect liquefaction of solid or gaseous carbon-based energy sources (Coal-To-Liquid (CTL) and Gas-To-Liquid (GTL)) into liquid transportable fuels. In contrast with the past, nowadays transport fuels are mainly produced from crude oil and there is not considerable diversity in their variety. Due to some limitations in the first generation bio-fuels, the Second-Generation Biofuels (SGB)' technology was developed to perform the Biomass-To-Liquid (BTL) process. The BTL is a well-known multi-step process to convert the carbonaceous feedstock (biomass) into liquid fuels via FTS technology. This paper presents a brief history of FTS technology used to convert coal into liquid hydrocarbons; the significance of bioenergy and SGB are discussed as well. The paper covers the characteristics of biomass, which is used as feedstock in the BTL process. Different mechanisms in the FTS process to describe carbon monoxide hydrogenation as well as surface polymerization reaction are discussed widely in this paper. The discussed mechanisms consist of carbide, COinsertion and the hydroxycarbene mechanism. The surface chemistry of silica support is discussed. Silanol functional groups in silicon chemistry are explained extensively. The catalyst formulation in the Fischer Tropsch (F-T) process as well as F-T reaction engineering is discussed. In addition, the most common catalysts are introduced and the current reactor technologies in the F-T indirect liquefaction process are considered. process overview IntroductionThe over-reliance of the world's nations on conventional fossil fuels puts our planet in peril. The continuity of the current situation will result in the rise of a combined average temperature over global land and ocean surfaces by 5 ∘ C in 2100, bringing a rise in sea levels, food and water shortages and an increase in extreme weather events. The global warming, caused by humans, is one of the biggest threats to our future well-being [1]. In addition, oil reserves are limited and these reserves are decreasing dramatically. This reduction alongside the other relevant economic factors affects the world's oil prices. The need to run engines with the new generation of liquid fuels is inevitable. The investigations by the US Energy Information Administration (EIA) published in 2013 expressed a 56 percent increase in the world's energy consumption by the year 2040. Total world energy demand will have risen to 865 EJ (exajoule) by this year. The total world energy consumption was reported as 553 EJ in 2010. The outlook indicates that renewable energy is one of the fastest-growing energy sources in the world; where its usage increases 2.5 percent per year. Despite increasing success in the renewable energies, it is predicted that the fossil fuels will supply al-

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This paper proposes a new fault-tolerant strategy to revamp performance of three phase multilevel converters with a single faulty switch. The proposed faulttolerant strategy is based on application of a modified Selective Harmonic Elimination (SHE) technique in conjunction with the Fundamental Phase-Shift Compensation (FPSC) method. The proposed faulttolerant strategy makes the most use of converter capacity in the faulty condition, generates balanced line voltages, and eliminates a wide range of lower order harmonics to limit the Total Harmonic Distribution (THD) of the converter voltages in the faulty condition. In this paper, first a brief background about Cascaded H-bridge (CHB) multilevel converters and SHE technique is provided. Then the proposed fault-tolerant strategy and the modified SHE technique are presented. Finally, several experimental results are provided to validate the operation of the proposed strategy. . His research interests include modeling, design and control of power electronic converters, electricdrive vehicles and solar energy systems.

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