Biofuels
In this paper I’m going to translate roughly the paper I had to do in my first year bachelors degree in Energy management.
Biofuels,
What are biofuels?
When energy is harvested from a living organism we consider (animal, plant,…) this a biofuel
However you can’t just use a ton of grass as fuel. First you have to modify it, this can be done using biologic, physics or chemic processes
If the organism is long dead before it is used as an energy source it is not biofuel (e.g.: coal)
History
A short summary of biofuels through the ages,
A long time ago they already knew fire, the ancient humans used wood which is a biofuel. Still I wont be talking about fire.
Between the 18th -19th century they hunted whales for its oil, but excessive fishing made the population of whales shrink and demand was too high. The whale oil was to expensive so it made way for the cheaper fossil fuels.
In the 20th century the price of fossil fuels rose, because of this there were a lot of farmers who planted crops for fermentation to make bioethanol. However the prohibition in the USA reduced the technological advances on ethanol.
At last in the 20th scientist all around the globe agreed: fossil fuels are not infinite.
Processing
Physically
The easiest way to make biofuels is using physical ways, like: boiling, pressing,…
This is how they make wood chips.
This method has some boundaries, you can’t use to humid material and not everything is suitable for this processing.
Biologically
The best part about this way of processing is that everything can be used as fuel.
This is how it works;
They toss everything into a big tank
In this tank they will start a process called: Hydrolysis
Every large molecule is sliced into smaller ones by using a water molecule – Hydro (=water) & lysis (slicing). This is necessary because in the next step, the microorganisms can only process relatively small molecules.
The second step: Fermentation
In this step the stuff we made prior comes into another tank. However this one is air sealed. No air can enter or leave. In this tank are microorganisms (the same ones used for making beer & wine). These make our bio-ethanol. This doesn’t have to be the end of the road. If we want to make biogas we can take the rest of the tank and go to another step called acetogenic.
In this step we take some molecules the are left by the microorganism and transform them into acetate, hydrogen, and carbon acid.
This 3 molecules can be combined into biogas.
This is the most common way to make biofuels.
Chemically
Just burning is the easiest way to gain energy from biofuels however you can’t just burn everything!
A second way gasification is used in the chemistry world to gain valuable gasses. In order to obtain these gasses you need to heat biofuel in a special tank to 1100-1500°C (2010-2730°F). You can already see that this one is very expensive.
Biodiesel is also made chemically; you need a carbonic acid and ethanol mix them on a high temperature with some sulfuric acid and POEF biodiesel is made. No, actually it is very though to make this, because you need very pure components.
Future?
In the world there is yearly enough biomass made (growing new trees,…) so we can feed to current consumption worldwide 4 times. Needless to say is that we can harvest it but we need to improve a lot.
Ethics!
To me ethics is as important as technology, because of that vision this question rose:
How much fertile farming ground can we sacrifice to heat our houses and use as fuel in our cars as there is hunger in the world?
Bogaerts Pieter-Jan 