NEWS
BREAKTHROUGH IN HYDROGEN-POWERED
CARS MAY SPELL END FOR PETROL STATIONS
Scientists have dramatically increased the efficiency of producing clean hydrogen fuel from
plant waste in a breakthrough that could one day lead to petrol stations being replaced by
a network of roadside “bioreactors” for refuelling cars.
A
study funded by Shell Oil has shown that it is possible to
convert all 100 per cent of the sugar stored in corn stover – the
stalks, cobs and husks leftover in a harvested maize field – into
hydrogen gas with no overall increase in carbon dioxide emissions to
the atmosphere.
The researchers perfected the process by mixing the raw biomass
with a watery solution containing a cocktail of ten enzymes that turned
the plant sugars xylose and glucose into hydrogen and carbon dioxide,
said Professor Percival Zhang of Virginia Tech in Blacksburg, Virginia.
Previously it has only been possible to convert between 30 per
cent and 60 per cent of the plant’s sugars into hydrogen using either
fermenting microbes or industrial catalysts. However, the latest technique
converts 100 per cent of the plant sugars into hydrogen, Professor Zhang
said.
Producing pure hydrogen gas from crop waste and biomass is seen
as one of the most important goals of the green economy because of the
need to produce clean alternatives to petrol. However, existing methods
are inefficient, costly and are dogged by the problem of how to distribute
the hydrogen once it is made.
“All the products produced by the process are gases so they can be
separated and collected easily from the biomass substrate. Over its
lifecycle, the process is carbon neutral and we have achieved a 17-fold
increase in the rate of the reaction which makes it economically viable,”
Professor Zhang said. “This means we have demonstrated the most
important step toward a hydrogen economy – producing distributed and
affordable green hydrogen from local biomass resources.”
One of the critical developments in the process is being able to
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HSE INTERNATIONAL
directly use “dirty” biomass as the fuel rather than relying on highly
processed sugars as the source of hydrogen. In addition to being more
efficient, this means it should also be possible to build large bioreactors
the size of petrol stations near to sources of biomass, so leading to a
network of green re-fuelling stations distributed around the country,
Professor Zhang explained.
“The next problem is to work on how to scale it up. But if we receive
further funding I think in three to five years we should be able to build
a bioreactor that is something like a gas station which can produce 200
kilos of hydrogen fuel a day. This would be enough to re-fuel about 40
or 50 cars.”
The key step in the study was to identify the precise combination of
enzymes that would work together on the plant waste to convert all of
its xylose and glucose – which together account for 90 per cent of the
sugars in plant waste – into hydrogen and carbon dioxide, which can be
collected separately.
These 10 enzymes were initially made in microbial fermenters using
genetically engineered bacteria. The separated enzymes were then
added to the solution of plant waste where they continued to work
for several weeks. However, the aim eventually is for these enzymes
to continue working for months or years without being replaced,
Professor Zhang said. `
Original Source: http://www.hseinternational.co.uk/
breakthrough-in-hydrogen-powered-cars-may-spell-end-forpetrol-stations/