Production of Synthetic Fuels and Chemicals from Biomass - Biomass Gasification, Pyrolysis and Torrefaction - page 388

high-quality diesel or gasoline from syngas derived from biomass or coal
using reaction (11.7). The composition of such products is very similar to
that of crude oil. Thus, it can be blended with petrodiesel/gasoline or used
directly in an engine.
Some promising applications for the FTS process include biomass-to-
liquid (BTL), coal-to-liquid (CTL), and gas-to-liquid (GTL) technologies. The
BTL could provide a less carbon-intensive alternative fuel that could use not
only agricultural feedstock but also waste biomass materials reducing depen-
dence on carbon-rich fossil fuels. Additionally, the absence of sulfur and
nitrogen in such biomass makes it superior to those derived from crude oil. A
major commercial motivation of FTS is that it can turn natural gas into easily
transportable liquid fuel. Such a GTL fuel could be an alternative to liquefied
natural gas with an added advantage that it could transform the gas into other
value-added chemical feedstock instead of using it as a fuel alone.
BTL conversion in FTS process may have several additional advantages
because biomass's gasification product typically contains H 2 :CO ratio of
about unity, which is ideal for iron catalysts. The absence of sulfur in bio-
mass is also favorable to most catalysts.
The most successful and well-known use of FTS is the production of liq-
uid fuel from coal by SASOL in South Africa, where syngas is converted
into petroleum products. Figure 11.3 shows a photograph of a SASOL plant
in South Africa. The FTS process is also useful for conversion of biomass
into liquid fuels and chemicals, but it is yet to be commercially utilized. FTS
process requires large central facility. Collection, transportation, and prepara-
tion of such large amount of low bulk density biomass at a central gasifica-
tion plant may have logistic problem. Additionally, large-scale gasification
of biomass is still not in commercial use.
FIGURE 11.3 Photograph of the SASOL plant in South Africa that is recognized as a leading
use of FTS process ( www.southafrica.info ).