This document summarizes different methods of biological hydrogen production including dark fermentation, photo fermentation, and biophotolysis. Dark fermentation uses anaerobic bacteria like Enterobacter and Clostridium to break down organic materials into hydrogen gas. Photo fermentation uses photosynthetic bacteria to convert organic acids into hydrogen using light as an energy source. Biophotolysis uses algae or cyanobacteria to split water into hydrogen and oxygen directly or indirectly using solar energy. Integrated dark and photo fermentation can improve hydrogen yields. Ongoing research in India aims to develop these biological methods as renewable and clean alternatives to current hydrogen production methods that release greenhouse gases.

1. BIOHYDROGEN PRODUCTION
MITAL CHANDEGARA
BIOTECHNOLOGY
16

2. CONTENT
• Introduction
• Why hydrogen?
• Methods of hydrogen production
1) Physicochemical
2) Biological
• Ongoing projects in India
• Reference

3. INTRODUCTION
• Biohydrogen
• Use of fossil fuel is increase (transportation , power & heat
generation)
• Increased CO₂ level
• Global warming ( climate change )
• Alternative option (environment friendly)

5. • Most abundant element on the earth (H₂O)
• Simplest one (1e +1p)
• Highest energy content(122kJ/g , 2.75 times higher
than HCs)
• Clean fuel (no green-house gas emission)
• Combustion of H₂ produce water
• Globally accepted as environmentally safe energy
recourse

6. Hydrogen production
Physicochemical Biological
1) Steam reforming of light HCs
2) Thermal cracking of natural gas
3) Partial oxidation/gasification of
heavier HC or coal
4) Electrolysis of water
1) Dark fermentation
2) Photo fermentation
3) Bio-photolysis
4) Integration of dark + photo
fermentation

7. NEED OF BIOHYDROGEN
• Uses of hydrogen in different industries
(fertilizer = ammonia, oil refinery = hydrotreatment of crude oil for
sulphur removal)
• Global H₂ demand fulfilled by 1st 3 Pc method
(major drawback - high energy intensive & emits greenhouse gases)

8. DARK FERMENTATION
• Either obligate or facultative anaerobes are capable to utilize various
organic material as a substrates
• Occurs in ab of oxygen
• Facultative anaerobes like Enterobacter , Citrobacter
• Obligate anaerobes like clostridium

9.  In Enterobacter…..
PFL :pyruvate
formate lyase
FHL :formate
hydrogen lyase

10. In clostridia…..

11. Advantages:-
• Produce valuable metabolites as by-products
• No requirement of light & oxygen
• Variety of carbon sources can be use
Limitations:-
• Produce gas mixture hence further purification require
• Accumulation of acid leads to pH drops & inhibit H₂ synthesis
• Relatively lower energy yield

12. PHOTO FERMENTATION
• Photosynthetic bacteria (PNS bacteria such as Rhodopseudomonas &
Rhodobacter )
• Anaerobic condition
• Photosynthetic pigments
• Short chain organic acid utilization
• Light as source of energy
• Nitrogenase

14. Advantages:-
• No release of O₂ (no E inhibition)
• High H₂ yield efficiency
• Uses wide spectral of light energy (450-590-visible ,800-875nm nIR)
Limitation:-
• Limited availability of organic acid
• Practical application (SA/V)
• High construction cost

15. BIOPHOTOLYSIS
• 2 types
1) Direct biophotolysis
2) Indirect biophotolysis

16. 1) DIRECT BIOPHOTOLYSIS
• Green algae
• Hydrogenase
• PS II split water into O₂ & H+ ion
Advantage:- Substrate – water (easily available)
Limitation :- O₂ inhibit hydrogenase

18. 2) INDIRECT BIOPHOTOLYSIS
• Cyanobacteria
• Vegetative cell & heterocyst
• Nitrogenase

19. OPPP:- oxidative
pentose phosphate
pathway
(CH₂O) :- saccharide

20. INTEGRATION OF DARK & PHOTO FERMENTATION
Dark
fermentation
Photo
fermentation

26.  Introduction to biofuels by D. M. Mousdale
 Production of biological hydrogen in india by Prof. Y K Yadav, Dr sachin kumar
& Raman Rao
 Review on recent developments in biological hydrogen production processes
by Debarata Das , Namita Khanna, T. Nejat Veziroğlu
 Review on outlook of fermentative hydrogen production techniques :- An
overview of dark, photo and integrated dark-photo approach to biomass by
Puranjan Mishra, S. Krishna, S. Rana & Lakhveer singh
 Ministry of new & renewable energy