Environmental Engineering Reference
In-Depth Information
In conclusion, it can be said that the comparison of the various routes from bio-
mass to synthetic fuels is not straightforward. Many aspects play a role, and it is
important to rightly choose the boundary conditions. To determine the efficiency,
do we consider the energy content of the produced fuel as the final outcome
(well-to-tank efficiency) or the distance that a car can drive on it (well-to-wheel effi-
ciency)? In addition to these efficiencies, there are also other definitions of efficiency,
such as the atom efficiency. For example, the carbon efficiency is the amount of car-
bon atoms in the useful product as a fraction of the carbon atoms in the feedstock. An
additional question is how to account for by-products (chemicals, electricity) that are
produced. To determine investment costs, do we consider building a plant on an exist-
ing site or do we take a
approach (see Chapter 7)? Since different authors
make different decisions regarding these aspects, one should be very careful in
directly comparing publications reporting an economic analysis of the different bio-
fuel routes.
“
greenfield
”
CHAPTER SUMMARY AND STUDY GUIDE
This chapter treats the various routes to convert syngas to transportation fuels. Most
developments in this field so far are based on syngas produced from fossil fuels.
However, we can benefit from this knowledge and experience when developing
processes to produce biofuels from syngas. We pay most attention to the most suc-
cessful route from syngas to automotive fuels up to now: the FTS, which converts
syngas into a range of hydrocarbons. We discuss both the small-scale (reaction and
catalyst) and the large-scale aspects (reactor) of the process. Subsequently, we treat
the production of SNG from syngas, which has certain similarities with FTS. We
also briefly treat the production of methanol and the conversion of methanol into
DME and gasoline. Finally, we discuss some literature on comparing which of these
routes is the most efficient one. It is not obvious to choose the boundary conditions
for such a comparison. As a consequence, there is no clear agreement about the
most viable route.
KEY CONCEPTS
Fischer
Tropsch synthesis
Anderson
-
Flory distribution
Diffusion limitations
Slurry bubble column
Multitubular packed bed reactor
Synthetic natural gas (SNG) by methanation
Methanol synthesis, methanol dehydration, methanol to olefins, methanol to gasoline
Well-to-tank efficiency, well-to-wheel efficiency
-
Schulz
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