Liquid and gaseous fuels from biotechnology: challenge and opportunities

Abstract

This paper presents challenging opportunities for production of liquid and gaseous fuels by biotechnology. From the liquid fuels, ethyl alcohol production has been widely researched and implemented. The major obstacle for large scale production of ethanol for fuel is the cost, whereby the substrate represents one of the major cost components. Various scenarios will be presented for a critical assessment of cost distribution for production of ethanol from various substrates by conventional and high rate processes. The paper also focuses on recent advances in the research and application of biotechnological processes and methods for the production of liquid transportation fuels other than ethanol (other oxygenates; diesel fuel extenders and substitutes), as well as gaseous fuels (biogas, methane, reformed syngas). Potential uses of these biofuels are described, along with environmental concerns which accompany them. Emphasis is also put on microalgal lipids as diesel substitute and biogas/methane as a renewable alternative to natural gas. The capturing and use of landfill gases is also mentioned, as well as microbial coal liquefaction. Described is also the construction and performance of microbial fuel cells for the direct high‐efficiency conversion of chemical fuel energy to electricity. Bacterial carbon dioxide recovery is briefly dealt with as an environmental issue associated with the use of fossil energy.

Hemicellulose bioconversion

“…Bacillus polymyxa produces D-(-)2,3-BD whereas Klebsiella pneumoniae (Aerobacter aerogenes) produce meso-form and also some of the L-(+) form. Bacillus subtilis, Seratia marcescens and Aerobacter hydrophia produce mixtures of different forms [69]. Saha and Bothast [119] isolated Enterobacter cloacae NRRL B-23289 from local decaying wood/corn soil samples while screening for microorganisms for conversion of arabinose to fuel ethanol.…”

Bioethanol Production from Fermentable Sugar Juice

“…This property makes them potential bioagents in fermentation technology from the beginning of its history. Sugar fermentation using single cell microorganism, that is, yeast, is one of the oldest practices in biotechnology, widely used for the production of drinking alcohol, namely, beer and wine, in the past time, while, nowadays, this practice is industrially used to produce fuel ethanol from renewable energy sources [ 52 ]. Major characteristics of ethanologenic microorganisms to be employed in industrial plants are higher ethanol yield (>90.0% theoretical yield), tolerance to ethanol (>40.0 g/L), good ethanol productivity (>1.0 g/L/h), good growth in simple and inexpensive media, capability of growth in undiluted fermentation broth with resistance to inhibitors, and ability to retard contaminants from growth condition, for example, acidic pH or higher temperature [ 53 ].…”

“…Some microorganisms such as dried yeast or Saccharomyces cerevisiae [ 54 – 57 ], S. diastaticus [ 58 ], Kluyveromyces marxianus [ 59 , 60 ] , Pichia kudriavzevii [ 26 ], Escherichia coli strain KO11 and Klebsiella oxytoca strain P2 [ 61 ], and Zymomonas mobilis [ 62 – 65 ] have been studied for ethanol production from sugar juices. Among these ethanol producing microorganisms, S. cerevisiae is the most attractive choice in fermentation due to its greater efficiency in sugar conversion to alcohol and capability of producing flocs during growth, making it easier to settle or suspend on need [ 52 ], and high tolerance to ethanol [ 66 ]. Moreover, fermentation of some crop juices containing sucrose employs this yeast for its ability to hydrolyze sucrose into glucose and fructose with invertase enzyme.…”

Lipid accumulation and biosynthesis genes response of the oleaginous Chlorella pyrenoidosaunder three nutrition stressors

“…Rapid exploitation of fossil fuels in modern society has been widely recognized as highly unsustainable. The limited storage and the contribution of fossil fuels combustion to air pollution are two main concerns that current energy consumption status bring about [ 1 ]. Biofuel from photosynthetic microorganisms was regarded as an ideal strategy to produce renewable energy.…”