Sweet
diesel! Scientists have discovered a process to convert sugar directly
into renewable diesel that could replace fossil fuels used in vehicles.
University of California, Berkeley
scientists found that a long-abandoned fermentation process once used to
turn starch into explosives can be used to produce renewable diesel.
Researchers teamed up to produce diesel
fuel from the products of a bacterial fermentation discovered nearly 100
years ago by the first president of Israel, chemist Chaim Weizmann. The
retooled process produces a mix of products that contain more energy
per gallon than ethanol that is used today in transportation fuels and
could be commercialised within 5-10 years.
While the fuel's cost is still higher
than diesel or gasoline made from fossil fuels, scientists said the
process would drastically reduce greenhouse gas emissions from
transportation, one of the major contributors to global climate change.
What I am really excited about is that this is a fundamentally different
way of taking feed-stocks sugar or starch and making all sorts of
renewable things, from fuels to commodity chemicals like plastics, said
Dean Toste, professor of chemistry and co-author in a statement.
The late Weizmann's process employs the
bacterium Clostridium acetobutylicum to ferment sugars into acetone,
butanol and ethanol. Researchers developed a way of extracting the
acetone and butanol from the fermentation mixture while leaving most of
the ethanol behind, while developing a catalyst that converted this
ideally-proportioned brew into a mix of long-chain hydrocarbons that
resembles the combination of hydrocarbons in diesel fuel. Tests showed
that it burned about as well as normal petroleum-based diesel fuel.
It looks very compatible with diesel,
and can be blended like diesel to suit summer or winter driving
conditions in different states, said coauthor Harvey Blanch. The process
is versatile enough to use a broad range of renewable starting
materials, from corn sugar (glucose) and cane sugar (sucrose) to starch,
and would work with non-food feed-stocks such as grass, trees or field
waste in cellulosic processes.
You can tune the size of your
hydrocarbons based on the reaction conditions to produce the lighter
hydrocarbons typical of gasoline, or the longer-chain hydrocarbons in
diesel, or the branched chain hydrocarbons in jet fuel, Toste said.
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