Renewable biological systems for alternative sustainable energy production. (FAO Agricultural Services Bulletin - 128) (1997): Chapter 3 - Production of fuel alcohol from cellulosic biomass: 3.1 Introduction

Renewable biological systems for alternative sustainable energy production. (FAO Agricultural Services Bulletin - 128) (1997)

(introduction...)

Acknowledgments

Contributors

Foreword

Summary

Chapter 1 - Biological energy production

1.1 Energy and environmental issues

1.2 Photosynthesis and biomass

1.2.1 Photosynthetic efficiency

1.2.2 Biomass wastes and their conversion

1.2.3 Fuel production via microalgal CO2 fixation

1.3 General problems

References

Chapter 2 - Energy conversion by photosynthetic organisms

(introduction...)

2.1 Photosynthetic capture of solar energy

2.1.1 Solar energy

2.1.2 Why is biotechnology now applied to energy technology?

2.2 Photosynthesis mechanisms

(introduction...)

2.2.1 Plant photosynthesis

2.2.2 Bacterial photosynthesis

2.3 Hydrogen production through solar energy conversions

(introduction...)

2.3.1 Cyanobacterial hydrogen production (plant-type photosynthesis)

2.3.2 Bacterial hydrogen production (bacterial-type photosynthesis)

2.3.3 Use of photosynthesized proteins in photoelectric conversion elements

References

Chapter 3 - Production of fuel alcohol from cellulosic biomass

3.1 Introduction

3.2 Cellulase production

3.2.1 Cellulase

3.2.2 Screening of cellulase-producing microorganisms

3.2.3 Strain improvement for cellulase production

(introduction...)

3.2.3.1 Development of a process for high-titer cellulase production

3.2.3.2 Cellulase production at low cost

3.2.3.3 Potential for mass production of cellulase

3.3 Saccharification of cellulosic waste materials

3.3.1 Pre-treatment of cellulosic waste

3.3.2 Saccharification of cellulosic waste

3.3.2.1 Saccharification

3.3.2.2 Recovery and re-use of cellulase

3.3.2.3 Sugar concentration using reverse osmosis

3.4 Use of immobilized yeast cells in alcohol fermentation's

(introduction...)

3.4.1 Preparation of immobilized yeast cells

3.4.2 Continuous plant operation using immobilized yeast cells

3.4.3 Fermentation processes used in ethanol production

3.4.4 Flash fermentation using immobilized yeast cells

3.5 Alcohol production using an integrated pilot plant

(introduction...)

3.5.1 Outline

3.5.2 Pre-treatment of cellulosic biomass

3.5.3 Cellulase production

3.5.4 Saccharification of biomass

3.5.5 Enzyme recovery from biomass

3.5.6 Concentration of sugar solutions

3.5.7 Alcohol fermentation

3.5.8 Alcohol recovery

3.6 Feasibility study

3.7 Conclusion

References

Chapter 4 - Methane production

(introduction...)

4.1 Microbial consortia and biological aspects of methane fermentation

(introduction...)

4.1.1 Hydrolysis and acidogenesis

4.1.2 Acetogenesis and dehydrogenation

4.1.3 Methanogenesis

4.2 Molecular biology of methanogens

(introduction...)

4.2.1 Genetic markers

4.2.2 Molecular cloning of methanogenic genes

4.2.3 Genetic transformations

4.3 Developments in bioreactor technology

(introduction...)

4.3.1 Upflow anaerobic sludge blanket (UASB)

4.3.2 Upflow anaerobic filter process (UAFP)

4.3.3 Anaerobic fluidized-bed reactor (AFBR)

4.3.4 Two-phase methane fermentation processes

References

Chapter 5 - Hydrogen production

5.1 Introduction

5.2 Biophotolysis of water by microalgae and cyanobacteria

(introduction...)

5.2.1 Hydrogenase-dependent hydrogen production

5.2.2 Nitrogenase-dependent hydrogen production

5.3 Hydrogen from organic compounds

5.3.1 Hydrogen production by photosynthetic bacteria

5.3.2 Combined photosynthetic and anaerobic and bacterial hydrogen production

5.4 Enhancement of hydrogen-producing capabilities through genetic engineering

5.5 Research and development on biological hydrogen production

5.6 Future prospects

References

Chapter 6 - Oil production

6.1 Oil substitutes from biomass

6.2 Microalgae as biological sources of lipids and hydrocarbons

6.3 Thermochemical liquefaction of microalgae

6.3.1 Liquid fuels from microalgal biomass

6.3.2 Cultivation of microalgae

6.3.3 Liquefaction of microalgae

6.4 Algal hydrogenation

6.5 Future prospects

References

Chapter 7 - The future of renewable biological energy systems

7.1 Introduction

7.2 Biomass production potential and efficiencies

7.3 Fuel alcohol production from biomass

7.4 Methane fermentations

7.5 Fuels derived from microalgae

7.6 Conclusions

References

FAO technical papers

3.1 Introduction

Following the successive oil crises of the 1970's, renewable alternatives to petroleum as an energy source, have been intensively investigated worldwide. The Research Association for Petroleum Alternatives Development (RAPAD) was established in Japan, in May 1980, by 23 private companies with the support of the Ministry of International Trade and Industry (MITI). One of RAPAD's main tasks was to investigate the development of technologies for biomass conversion and utilization, in particular, the production of ethanol from cellulosic biomass. As a part of this project, studies were conducted in our laboratory, on the production of fuel ethanol from cellulosic biomass.

Various forms of biomass resources exist (Fig. 3-1). Among these, sugar and starch crops are inappropriate for use as energy sources since they are primary food sources, and are unstable from the viewpoints of long-term supply and cost. Cellulosic resources, on the other hand, represent the most abundant global source of biomass, and have been largely unutilized. In our study on fuel ethanol production processes, our efforts were directed toward the use of agricultural waste materials such as bagasse or sugar cane molasses, rice straw, and forestry waste materials such as wood chips from thinning.

Cellulose, a main component of plant cell walls, can be solubilized by either enzymatic or acid hydrolysis. Enzymatic processes are however preferable owing to drawbacks of the acid hydrolysis process. The development of cellulose-decomposing enzymes, i.e. high-titer cellulases, is however a problem that needs to be addressed prior to implementation of the enzymatic hydrolytic process. The commercial feasibility of ethanol production from cellulosic biomass is dependent on the availability of a cheap source of cellulase. Extensive work conducted in our laboratory resulted in the development a high titer cellulase from Trichoderma reesei which can be produced at a low cost.

In order to enhance the efficiency of the use of cellulase enzymes, immobilized yeast cells were used as the enzyme source. This resulted in the development of a continuous process for the production of ethanol from cellulosic biomass (rice, straw, bagasse, and wood) and led to the construction of a pilot plant. While this plant includes unit processes which have been studied by various research organizations (1, 2, 3), it was the first such total system to be constructed worldwide.

Figure 3-1 - Biomass resources of the world