Biofuel: A Net-negative Pathway
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- Biofuels are way to take out CO2 from the landmass above the surface of the earth and putting it back in atmosphere.
- This is unlike fossils where you are taking carbon stock from below the surface and putting it in atmosphere increasing its concentration.
- Besides the amount of CO2 you are putting by burning 1 kg of biomass is much lesser than the amount of CO2 the plants used to make 1 kg of plant biomass. (plants convert only 0.5% of photosynthesis to biomass)
- Thus, biofuels are net-negative in terms of carbon emissions.

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As Hydrocarbon: Biofuel v/s Fossil
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- Biofuel is small ring hydrocarbons with lots of oxygen and benzene rings. (not suitable remember)
- Fossil as we have seen is just biomass buried for millions of years under low oxygen conditions.
- Besides biomass is long polymers of sugar molecules.
- So, if we somehow remove oxygen and break the polymer, we can get biofuels.
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Biomass as Energy Store
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- Further biomass is basically solar energy trapped in the form of chemicals that make up the living beings.
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Biomass Composition
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- C 50%
- O 40%
- H 5 %
- N 1%(From protein)
- P 0.5% (From protein)
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Biomass Constituents
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- Primarily made of sugar polymers with lots O2 and closed ring hydrocarbons. (half the plant biomass is fundamentally sugar)
- Plant cells are made up of cell walls that gives a protective layer to help plants stand tall.
- The cell wall is made of microfibrils of cellulose which is basically sugar polymer. (1/2 of cell wall)
- At later stages there is an additional protective layer in the form of hard cover in trees which is called lignin.
- Lignin is plastic-like. It is not degradable, has lots of aromatics.
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