Environmental Engineering Reference
In-Depth Information
Iogen operates the world's first demonstration facility of second-generation
biofuels. Opened in 2004, it makes clean-burning cellulosic ethanol fuel from
agricultural residues. Wheat, oat and barley straw are used as raw materials.
can take a mix of up to fifteen percent ethanol without modification;
higher concentrations, however, require adaptation. Bio-diesel usually
uses a different set of crops, notably oil seeds such as soy and rapeseed. It
is an oxygenated fuel, meaning that it is cleaner and improves combustion,
compared to ordinary diesel. And conventional diesel engines do not need
much modification to run on even one hundred percent bio-diesel.
How green are biofuels?
Confusingly, the strongest arguments for and against biofuels are both envi-
ronmental, and are specifically related to climate change.
Biofuels still emit some CO
2
, albeit less than oil. So how do they help fight
climate change? The answer is that they are at least in theory carbon-neutral
- in the sense that when burned they merely return to the atmosphere the
carbon that they absorbed when they were growing plants.
Granted, you could say the same about oil - that oil, when burned up, just
returns to the atmosphere the carbon it absorbed from plants and algae mil-
lions of years ago. But the difference is that we can't repeat oil's absorption of
carbon, which took place under conditions of high temperature and pressure
that can't be replicated, whereas we can repeat biomass's absorption of carbon
by planting trees or energy crops - which is what make biofuels renewable.
