1. Comparison of Three Novel Energy
Conversion Technologies, Gasification, Pyrolysis,
and Hydrothermal Carbonization (HTC) - Review
Mahbod Shafiei1, Bodo Groß2, Andreas Dengel3 and Pal Szentannai1
1BME Department of Energy Engineering, Budapest, Hungary 2IZES gGmbH, Saarbrücken, Germany 3STEAG New Energies GmbH, Saarbrücken, Germany
BioenNW PartnersBioenNW Objectives
1) Create a network of Bioenergy Support Centres (BSC) to provide support to companies,
organisations and local authorities to deliver local bioenergy more efficiently and cost-
effectively by providing feedstock testing services, developing biomass energy projects,
organising workshops and seminars.
2) Build a number of knowledge based tools to aid the bioenergy development process and
assist identification of high potential bioenergy development sites
3) Demonstrate the combined operation of anaerobic digestion and intermediate pyrolysis at a
commercial scale to illustrate a broad range of biomass types as input materials
4) Explore at least twenty five new bioenergy schemes and develop five of these to the point
of built.
Building on the project objectives above, each BSC will identify five sites in their region with the
highest potential to be turned into new bioenergy schemes. This means that a total of 25 sites
will be identified through BioenNW. The five selected sites will be taken to the point of build by
the end of the project in March 2015.
Introduction
Industrialization and population growth are among factors for the rising trend in the
global energy demand. By the year 2030, the global energy demand is forecasted to increase
by 43.64% from the current total of 472 quadrillion Btu to 678 quadrillion Btu. It is also
predicted that fossil fuel will still remain dominate source of energy by the year 2030 that
contributes toward fossil fuel depletion and climate change. Hence development of
alternative energy is inevitable. Among all renewable energies, solid wastes and agricultural
residues (biomass) has became an important source of fuel since the early 1970s.[1]
Figure 1) Rice husk, wood chips, weed grass and pod corn are used as biomass.
(Reference: www.majec-biomass.com )
Thermo – Chemical processes are mainly developed by pre treatment of biomass
following by heating material (various heating temperature in technologies) by controlling
amount of oxygen, different phase of product can be gathered which by processing of
products many range of fuels will be obtained .
Gasification, Pyrolysis , and Hydrothermal Carbonization are the thermal conversion
processes available for thermal treatment of solid wastes which different products such as
combustible gas, liquid fraction ( tars and oil) and solid ( mainly char) are gained.
Gasification
Gasification is the controlled partial oxidation of a carbonaceous material, by
supplying less oxygen than the stoichiometric requirement for complete combustion (thermal
degradation in the absence of oxygen). It proceeds at temperatures ranging between 600 and
1500 C. A striking feature of the technology is its ability to produce a reliable, high-quality
syngas product that can be used for energy production [2]. Wastes such as refinery residuals,
secondary oil-bearing refinery materials, municipal sewage sludge, and Biomass and crop
residues also have been gasified successfully according to the following reaction:
Char + limited oxygen → Gas +Tar + Ashes
Figure 2) Schematic of gasification
Product gas from gasification consists of
a mixture of carbon, carbon dioxide,
methane, hydrogen, and water vapor.
The composition of final product is
dependent on equilibrium achieved by
various gas – phase reactions. Air,
oxygen, hydrogen or steam are uses as
an agent in gasification process to
convert carbonaceous material into
gaseous products .
(Reference: www.thewatt.com)
Figure 3) Schematic of fast pyrolysis
process. By upgrading pyrolysis oil,
various fuels can be separated via
standard distillation process and three
product such as jet fuel, diesel, and
naphtha can be gained.
(Reference: www.dynamotive.com)
Hydrothermal Carbonization (HTC)
In the hydrothermal process, biomass is surrounded by water during the reaction,
which is kept in a liquid state by allowing the pressure to rise with the steam pressure in
high – pressure reactors. HTC method has attracted a great deal of attention because it
uses water which is inherently present in green biomass. Typically HTC of biomass is
achieved in water at elevated temperatures (180 -250’ C) under standards pressures (2-
10 Mpa) for several hours . HTC produces higher solid yields. [3]
Pyrolysis
Pyrolysis is thermal decomposition occurring in the absence of oxygen. The main
process for char production with significant yields is the dry pyrolysis process. Temperature
range are between 287 C to 500 C with residence time 2 second to a day [4]. one of the
characteristics of this process is flexibility of feedstock where it burns part of the load for the
heat input. Pyrolysis has three different types include: Fast , intermediate , and slow pyrolysis.
Fast pyrolysis is an effort to make the liquid product (bio–oil ) Yield from solid biomass is a
potential candidate for power generation.
Figure 4) Schematic of Hydrothermal
carbonization. The composition and
structure of the solid product (hydro
char) from HTC differs substantially
from dry pyrolysis chars. hydro char
generally has higher H/C and O/C ratios
similar to natural coal, Also HTC uses as
pre treatment for gasification which is
referred to as wet Toreffaction.
(References:www.cscarbonsolutions.de)
Conclusion
Carbonization of biomass residue and waste materials has great potential to
become an environmentally sound conversion process for the production of a wide
variety of products. Many years of research have shown that conversion technologies
have a great potential in carbon sequestration to reduce the impact of greenhouse
effect.
ACKNOWLEDGEMENTS
This work has been funded by the IZES gGmbH, Germany, as part of the project
BioenNW , and done in Budapest University of Technology and Economics, Hungary.
References
[1] Jeng Shiun Lim, Zainuddin Abdul Manan, Sharifah Rafidah Wan Alwi, Haslenda Hashim, 22
March 2012, ‘’ A review on utilization of biomass from rice industry as a source of renewable
energy’’ Process Systems Engineering Centre (PROSPECT), Faculty of Chemical Engineering,
University Technology Malaysia, 81310 Johor Bahru, Johor, Malaysia
[2] Dr. Samy Sadaka, P.E., P.Eng. ’’Gasification’’ Associate Scientist, Center for Sustainable
Environmental Technologies Adjunct Assistant Professor, Department of Agricultural and
Biosystems Engineering Iowa State University 1521 West F. Ave. Nevada, IA 50201
[3] Hydrothermal carbonization of biomass residuals: a comparative review of the chemistry,
processes and applications of wet and dry pyrolysis future science group 10.4155/BFS.10.81 ©
2011 Future Science Ltd
[4] David Chiaramontia, Anja Oasmaab, Yrjo¨ Solantaustab,26 Jully 2005,’’ Power generation
using fast pyrolysis liquids from biomass’’, University of Florence, Department of Energy
Engineering ‘‘S.Stecco’’, I-50139, Florence, Italy