Hydrogen production by biological processes: a survey of literature

doi:10.1016/S0360-3199(00)00058-6

International Journal of Hydrogen Energy

Volume 26, Issue 1, January 2001, Pages 13-28

https://doi.org/10.1016/S0360-3199(00)00058-6 Get rights and content

Abstract

Hydrogen is the fuel of the future mainly due to its high conversion efficiency, recyclability and nonpolluting nature. Biological hydrogen production processes are found to be more environment friendly and less energy intensive as compared to thermochemical and electrochemical processes. They are mostly controlled by either photosynthetic or fermentative organisms. Till today, more emphasis has been given on the former processes. Nitrogenase and hydrogenase play very important role. Genetic manipulation of cyanobacteria (hydrogenase negative gene) improves the hydrogen generation. The paper presents a survey of biological hydrogen production processes. The microorganisms and biochemical pathways involved in hydrogen generation processes are presented in some detail. Several developmental works are discussed. Immobilized system is found suitable for the continuous hydrogen production. About 28% of energy can be recovered in the form of hydrogen using sucrose as substrate. Fermentative hydrogen production processes have some edge over the other biological processes.

Introduction

Today global energy requirements are mostly dependent on fossil fuels (about 80% of the present world energy demand). This will eventually lead to the foreseeable depletion of limited fossil energy resources. Presently, the utilization of fossil fuels are causing global climate change mainly due to the emission of pollutants like $CO_{x}, NO_{x}, SO_{x}, C_{x} H_{x}$ , soot, ash, droplets of tars and other organic compounds, which are released into the atmosphere as a result of their combustion. In order to remedy the depletion of fossil fuels and their environmental misdeeds hydrogen has been suggested as the energy carrier of the future. It is not a primary energy source, but rather serves as a medium through which primary energy sources (such as nuclear and/or solar energy) can be stored, transmitted and utilized to fulfil our energy needs.

Hydrogen is the most plentiful element in the universe, making up about three-quarters of all the matter. The atmosphere contains about 0.07% hydrogen, while the earth's surface contains about 0.14% hydrogen. Hydrogen is the lightest element. The mass of 1 l of hydrogen is $0.09 g$ , while the mass of 1 l of air is about 1.2 g. The higher heating value of hydrogen is 3042 cals/m³ (considering water as a product). In combustion, water is the main product, thus, hydrogen is regarded as a clean non-polluting fuel. As compared to other gaseous fuels like water gas, hydrogen is harmless to humans and the environment [1], [2].

Today environmental pollution is a great concern to the world, mainly due to rapid industrialization and urbanization. So, increasing focus is being placed on clean energy alternatives for satisfying growing energy demand. Hydrogen has various other uses [3], [4], [5], which can be broadly divided into the following categories:The above stated areas of hydrogen utilization is equivalent to 3% of the energy consumption today, and is expected to grow significantly in the years to come.

At present hydrogen is produced mainly from fossil fuels, biomass and water. The methods of hydrogen production from fossil fuels areMethods of hydrogen production from biomass areMethods of hydrogen production from water areOut of the above listed processes, nearly 90% of hydrogen is produced by the reactions of natural gas or light oil fractions with steam at high temperatures (steam reforming). Coal gassification and electrolysis of water are other industrial methods for hydrogen production. These industrial methods mainly consume fossil fuel as energy source, and sometimes hydroelectricity [6], [7], [8], [9], [10]. However, both thermochemical and electrochemical hydrogen generation processes are energy intensive and not always environment friendly. On the other hand, biological hydrogen production processes are mostly operated at ambient temperatures and pressures, thus less energy intensive. These processes are not only environment friendly, but also they lead to open a new avenue for the utilization of renewable energy resources which are inexhaustible [11], [12], [13], [14], [15]. In addition, they can also use various waste materials, which facilitates waste recycling. The objective of this paper is to review literature on different biological hydrogenation processes and make a comparative analysis.

Section snippets

Biological hydrogen production processes

Biological hydrogen production processes can be classified as follows:

2.1	Biophotolysis of water using algae and cyanobacteria.
2.2	Photodecomposition of organic compounds by photosynthetic bacteria.
2.3	Fermentative hydrogen production from organic compounds, and
2.4	Hybrid systems using photosynthetic and fermentative bacteria.

Microbiology

Different microorganisms participate in the biological hydrogen generation system such as green algae, cyanobacteria (or blue–green algae), photosynthetic bacteria and fermentative bacteria, which are tabulated in Table 1. About 50 years ago Gaffron et al. discovered that the eucaryotic unicellular green algae, Scenedesmus obliquus, is able to evolve molecular hydrogen by means of a hydrogenase in the light under anaerobic conditions [16]. This is called direct biophotolysis. It is possible to

Major enzymes

There are three fundamentally different hydrogen producing and metabolizing enzymes found in algae and cyanobacteria:

(1)	the reversible or classical hydrogenases,
(2)	the membrane-bound uptake hydrogenases, and
(3)	the nitrogenase enzymes.

Genetic manipulation of microorganisms

Cyanobacteria in general, possess three hydrogen metabolizing enzymes: nitrogenase, membrane-bound hydrogenase, and soluble hydrogenase. Hydrogenases are mostly involved to utilize hydrogen. So, attempts have been made to maximize the amount of hydrogen production by manipulation of metabolic scheme, namely by maximizing the hydrogen-producing nitrogenase and minimizing that consumed by the so called hydrogenase. So, hydrogenase negative gene has been found to be useful for the hydrogen

Theoretical considerations

Little information is available on the kinetics of biological hydrogen production processes. However, Kumar et al. studied the cell growth and substrate degradation kinetics of Enterobacter cloacae IIT-BT 08 with the help of Monod model [76]. Substrate and biomass concentration profiles of the experimental and simulated data are significantly different from each other. This might be due to substrate and/or product inhibition. Since in the hydrogen generating system the product is gaseous

Typical results obtained from the biological hydrogenation processes

The purpose of biological hydrogen studies is to develop commercially practical hydrogen production processes by exploiting hydrogen producing ability of microorganisms through modern biotechnology. Attempts have already been made by several researchers to find out the suitability of different biological processes. Some important research works are discussed herebelow in order to understand present-state-of-art.

Energy analysis

The yield of hydrogen from sucrose is $6.0 mol / mol$ sucrose. Assuming overall fuel cell efficiency as 80% [85], Gibb's free energy of hydrogen as $56.7 kcal / mol$ , the lower heating values of hydrogen and sucrose as 58.3 and $1234 kcal / mol$ , respectively, the following energy analysis was done: $energy recovery from substrate = lower heating value of hydrogen × H_{2} yield / lower heating value of sucrose =58.3×6.0/1234=28.34%,$ $final conversion efficiency = Gibb's free energy for H_{2} × H_{2} yield × overall efficiency of fuel cell / lowerheating value of$

Comparative studies

So far, as microbial hydrogen production is concerned, Table 3 has been prepared to give the comparative studies on the different microbial hydrogen-producing systems. It is clear that the rate of fermentative hydrogen production is always faster than that of the photosynthetic hydrogen production. The merits and demerits of the different biological processes are presented in Table 4. It has been found that most of the biological processes are operated at an ambient temperature (30–40°C) and

Purification of hydrogen

The gases produced by biological processes mostly contain hydrogen (60–90% v/v). However, different impurities like CO₂ and O₂ are present in the gas mixtures. CO₂ acts as fire extinguisher. This is sparingly soluble in water. Scrubbers can be used to separate CO₂. Fifty percent w/v KOH solution is a good CO₂ absorbent. So, it can be used for CO₂ removal. The presence of O₂ in the gas may cause a fire hazard. Water solubility of O₂ is less as compared to that of CO₂. Alkaline pyrogallol

Acknowledgements

Financial assistant received from the Department of Biotechnology, Government of India as a Biotechnology Overseas Associateship to Dr. D. Das is thankfully acknowledged.

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Hydrogen production by biological processes: a survey of literature

Abstract

Introduction

Section snippets

Biological hydrogen production processes

Microbiology

Major enzymes

Genetic manipulation of microorganisms

Theoretical considerations

Typical results obtained from the biological hydrogenation processes

Energy analysis

Comparative studies

Purification of hydrogen

Acknowledgements

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Enzyme Microbial Technol

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Biochim Biophys Acta

Biochimie

Arch Biochem Biophys

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Bioresour Technol

Biochem Biophy Res Commun

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Biomass

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Int J Hydrogen Energy

Hydrogen manufacture by electrolysis, thermal decomposition and unusual techniques.

Anoxygenic phototrophic bacteria: physiology and advances in hydrogen technology

Adv Appl Microbiol

Vertical tubular photobioreactor: design and operation

Biotechnol Lett

Biological hydrogen production by Enterobacteraerogenes

J Chem Eng Jpn

Fermentative and photochemical production of hydrogen by algae

J Gen Physiol

Hydrogen evolution by several algae

Planta

Biological hydrogen production by $Enterobacter aerogenes$