Náttúrufræðingurinn - 2013, Blaðsíða 85

85
Tímarit Hins íslenska náttúrufræðifélags
Á þessu stigi liggur ekki fyrir
hvort raunhæft sé að nota hitakæra
stofna til að framleiða etanól úr
íslenskum lífmassa. Framleiðsla á
etanóli á stórum skala á nú undir
högg að sækja vegna kostnaðar
og samkeppni við verð á jarðefna-
eldsneyti og etanóli úr einfaldara
hráefni. Í Bandaríkjunum er t.d.
etanólframleiðsla úr mun einfaldari
lífmassa (sterkju) enn niðurgreidd
af ríkinu. Skoða þyrfti þetta í stærra
samhengi, m.a. með skuldbind-
ing um Íslands hvað varðar
framleiðslu á lífrænu elds neyti og
markmiði og reglugerðum Evrópu-
bandalagsins hvað varðar aukið
hlutfall lífeldsneytis í fram tíðinni.
Á móti kemur, að ef etanól yrði
framleitt hér á landi myndi það
leiða til minni innflutnings á jarð-
efnaeldneyti og sparnaði í gjaldeyri.
Allt þetta þyrfti að taka með í reikn-
inginn til að gera fullkomlega grein
fyrir möguleikum á slíkri fram-
leiðslu á Íslandi.
Summary
Production of ethanol from
complex biomass with thermo-
philic bacteria
This review focuses upon ethanol pro-
duction by microbial ferment at ions
with the main emphasis on thermo-
philic bacteria. Production of biofuels
in general has gained increas ed interest
in recent years, mainly due to the sub-
stantial increase in the use of fossil fuels.
This has led to elevated concentrat ion
of carbon dioxide in the atmos phere
and is considered to be the main cause
of increasing tempera tures on Earth.
Ethanol is one type of biofuel that can
be produced by fermentation and its
production has increased hugely in the
last decade. The largest part of this in-
crease derives from simple substrates
(sugar and starch based biomass)
which are in direct competition with
the food and feed industry. Therefore,
increased interest towards the utiliza-
tion of more complex biomass, lignocel-
lulose has arisen. Fermentation path-
ways used by both bacteria and yeast
will be focused upon with the main em-
phasis on thermophilic bacteria, mainly
isolated from Icelandic hot springs.
Yields of ethanol, both from simple
sugars as well as ligno cellulosic hydro-
lysates will be focus ed upon. The main
genera of thermophilic bacteria
(Clostridium, Thermoanaerobacter, Thermo-
anaero bacterium) are described and the
pros and cons of using these bacteria
for bioethanol production are dis-
cussed. Finally, the possibility of using
such microbes for bioethanol produc-
tion from Icelandic biomass will be de-
bated.
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