Biofuels - MT2 - Part 2 Flashcards
What are 2 problems with sources of renewable energy?
- Forms of renewable energy suffer from the problem of low energy density
- energy power is very dispersed - Renewable energy can be too expensive to elicit much market interest
- depends on the price of fossil fuels (coal and oil)
Externalities
Are cost or benefits from an economic transaction that accrue to parties not involved in the transaction
What is the mother of all externalities
GHG
What does photosynthesis use as a source of electrons?
H2O
- active participant
What does photosynthesis do?
It fixes CO2 as organic carbon by incorporating it into the biosphere
Organic
Is carbon with carbon carbon and carbon hydrogen bonds
What 4 things do plants need for photosynthesis?
- Light
- sunlight or artificial
- green light gets reflected off - Water
- water splitting enzymes - CO2
- dont need vitamins - Minerals
What are 2 types of minerals needed for photosynthesis?
- Mg
- but only a little - Chlorophyll
- mainly hydrocarbon with a little O2 and a Mg atom in the centre ring
What happens in the 1st stage of photosynthesis?
Light is used to create 2 high energy but unstable molecules
- absorption of light
- the use of that energy in making storable chemical energy
What 2 high energy but unstable molecules are created in the 1st stage of photosynthesis?
- ATP
2. NADPH
What happens in the 2nd stage of photosynthesis?
ATP and NADPH are used to force H atoms onto CO2, producing a small sugar
What % is energy conservation efficiency of photosynthesis?
5%
What does respiration do?
Returns CO2 back to the atmosphere
Raw biomass
Is any material from organisms that is burned for energy without extensive processing
What are the 2 main molecule material that get burned?
- Cellulose
2. Lignin
Cellulose
An insoluble substance that is the main constituent of plant cell walls and of vegetable fibres such as cotton
- it is a polysaccharide consisting of chains of glucose monomers
Lignin
A complex organic polymer deposited in the cell walls of many plants, making them rigid and woody
Where are cellulose and lignin found?
In plant cell walls
What are 4 sources of biomass?
- Wood
- Peat bogs
- Pellet stone
- Product of pyrolysis
- the thermal decomposition if organic material in the absence of O2
What is a key ingredient for the future?
Char
- gets left behind after the burning
What happens if you put char in the soil?
It lasts a very long time
- good way of transforming C from the atmosphere to the soil
What are 5 advantages to burning raw biomass?
- Minimal process required
- Easy to do
- Lots of fuel is previous garbage (recycle)
- Fuel is essentially free
- Recycle material in the biosphere
What are 4 limitations of using raw biomass?
- Burning biomass you get CO2 but combustion us not entirely efficient
- produces other toxic effects - Polycyclic aromatic hydrocarbons are always produced when burning biomass
- Burnt material can be a carcinogen
- Growing trees just to burn them down
- questionable use in climate change
What is alcohol?
It is an organic molecule that has a hydroxyl group (OH) attached onto it
