12
Water for Energy and Fuel Production
The chapter shows how different types of fuels, fuel additives, and chemicals for
various industrial applications can be made using different upgrading strategies for
the platform chemicals. The process can handle a variety of feedstock and is proven
to be economical. A small commercial plant for this process is already in operation in Italy and larger commercial plants are being pursued in Ireland, the United
Kingdom, and the United States.
1.2.7 ChAPTer 8: ProduCTion oF hydrogen And meThAne
By AnAeroBiC digeSTion oF AqueouS WASTe
Aqueous-phase conditions are well known for carrying out biological reactions. An
anaerobic digestion of aqueous agricultural and other biological waste can produce
methane and hydrogen using suitable enzymes or consortia of microorganisms.
Water can thus biochemically react with biomass to generate methane and hydrogen.
Such reactions generate “landfill gas” (which is predominantly methane [about 55%]
and carbon dioxide) from cellulosic waste. Landfill gas is an important raw material for power generation or for the production of other gaseous and liquid fuels via
reforming and Fischer–Tropsch (FT) technologies.
Chapter 8 deals with the production of methane and hydrogen by biochemical
anaerobic digestion of biomass and waste in aqueous environment. The chapter
illustrates biochemical mechanisms to convert cellulosic waste into methane and
hydrogen. Although landfill gas is a prime example of such conversion, the aqueous waste from numerous other types of waste such as animal and human manure,
agricultural waste, forestry, and plant waste can also be converted to methane and
hydrogen (commonly known as “biogas”). Anaerobic digestion of biological waste
is one of the most energy-efficient and fastest growing industries in the world. The
chapter examines various operational issues related to this industry.
1.2.8 ChAPTer 9: ProduCTion oF eThAnol By AqueouS-PhASe FermenTATion
The biochemical conversion of sugar, glucose, fructose, and so on to ethanol and
other alcohols has been a long-standing industry. Although the fermentation process
has been used for the production of beers, liquors, and so on, its application for the
transportation fuels and their additives has become more important in the recent
years because of an increased emphasis on renewable energy.
Fuel-grade ethanol can be produced from corn, starch, barley, or sugarcane by
hydrolysis and fermentation processes. This has been commercialized for a long time.
In the recent years, more emphasis has been placed on the conversion of lignocellulosic materials to ethanol by hydrolysis and fermentation processes. Recent research
on new methods of pretreatments, acid and enzyme hydrolysis, and discovery of new
microorganisms for fermentation has allowed this biological process to be applied to
a broad range of lignocellulosic materials. New developments have also led to the production of higher alcohols such as butanol, which has a higher fuel value. Chapter 9
briefly examines our current state of art for these technologies and processes.
The future development of alcohol production from lignocellulosic materials will
continue to require better methods of pretreatment, hydrolysis, and fermentation.