Transport fuels

Question 1

What are some drivers for using trasnport biofuels

Answer 1

GHG, energy supply security, legislation.
Transport make up 1/5th of total GHG

Question 2

What is the RTFO

Answer 2

Renewable transport fuel obligation
required suppliers to ensure a proportion comes from renewables

Question 3

Where do GHG emisisons come from, which generation is most intensive

Answer 3

exhaust, land use change, harvesting, processing, distribution
1st

Question 4

How is biodiesel produced?
Bioethanol?

Answer 4

transesterifications
Fermentation

Question 5

What are 2nd gen biofuels

Answer 5

non edibles including waste and lignocellulosics
fermentation and syngas derived fuel

Question 6

What is 3rd generation biomass

Answer 6

harvesting and advanced processing of ultra high yield biomass (algae)

Question 7

What does biodiesel consist of

Answer 7

triglycerides
Used to store energy, foods and soaps

Question 8

What affects the quality of biodiesel

Answer 8

% saturates
Chain length of fats
Amount of free fatty acids (hygroscopic and can form soaps)

Question 9

How does saturate % affect quality

Answer 9

Increases cetane number, cloud point, and stability

Question 10

How does the transesterification process work

Answer 10

Add methanol and a catalyst at 50C to form FAME and glycerol

Question 11

What are the properties of FAME
What does bio-ethanol produce

Answer 11

Suitable viscosity, good col temp and cetane number
Ethyl esters

Question 12

Process of oil recovery

Answer 12

Crushing of seeds
Separation of oil from the meal (mechanic above 20, solvent below
De-gumming
Further purification

Question 13

What is the max Biodiesel blend
Benefits of blend above 5%

Answer 13

20%
Reduce CO, HC, small PAH and particulates
Possibly increases NO and particulates

Question 14

Disadvantages of bioethanol

Answer 14

Only glucose is readily fermented, enzymes stop operating if ethanol conc too high
Energy intensive distillation required

Question 15

Advantages of blending ethanol

Answer 15

Can be used directly with engine adaptation or up to 22% in conventional engines

Question 16

How are 1st generation crops fermented

Answer 16

sugars - disaccharides hydrolyse in water to glu/fru which ferment
Starchs are hydrolysed (using enzymes and chemicals) and then fermented.

Question 17

How is ethanol seperated

Answer 17

Distillation (main energy) 95% and dehydration (molecular sieve)

Question 18

How are 2nd generation fuels produced ethanol

Answer 18

Sugar platform: Holocellulose converted to fermentable sugars. Lignin is wasted and often used as boiler fuel.
Syngas platform: Converted to CO and H2 using gasification. Can be converted to a range of chemicals and HC fuels.

Question 19

process of sugar platform concept

Answer 19

Milling > pre-treat > hydrolysis > fermentation
Pre-treatment used to break down cell wall
Hemicellulose readily hydrolysis to 5-carbon sugars (xylose), but hard to ferment.
Cellulose harder to hydrolysed to 6 carbon sugars (glu/fru) but easier to ferment.

Question 20

What should pre-treatment do in sugar platform

Answer 20

High rate of hydrolysis
Minimal degredation
Inexpensive and mild conditions

Uses steam explosion or sulphuric acid

Question 22

Process of syngas platform

Answer 22

Milling> gasification > fermentation and catalytic conversion > ethanol and fuels/chemicals