Lecture 14: Biofuels

Question 1

What is fracking?

Answer 1

Released vast amounts of hydrocarbons for human use

Established industrial process which getting cheaper

Question 2

Who is the biggest oil producer?

Answer 2

USA

Question 3

What did brazil do after the 1976 oil crisis?

Answer 3

Brazilian government institutionalised the National Alcohol Program to institute a switch from gasoline to ethanol from sugar cane

Mandatory blending of 10-22% ethanol fuel with gasoline

Question 4

Why is the production of ethanol from sugar cane effective?

Answer 4

1) sugar is cheap (10cents per pound of refined sugar)
2) yeast naturally produces ethanol under anaerobic conditinos
3) yeast can be continually reused (reduces cost)

Question 5

What is the yields of ethanol production from sugar cane?

Answer 5

V. high yields
1. ~74 T/ha/year -> 58 T raw cane
2. 1 T raw cane -> 740kg juice (135kg sucrose, 605kg water) +
260kg bargasse
3. 135kg sucrose -> 70L ethanol (76% sugar to ethanol efficiency)
4. Thus 1 ha -> 4000L ethanol per year

Question 6

What is the environmental costs of ethanol production from sugar cane

Answer 6

1. Inputs (all req some form of energy input)
   a. land (may once have been rainforest) - tillage, planting
   b. Water
   c. Fertiliser (energy intensive to produce)
   d. Labour (planting and cutting)
   e. Transport
2. Outputs (pollution and fertiliser run off)

Question 7

What are the main feedstocks for ethanol production in differet countries?

Answer 7

US - maize
Brazil - sugar cane
EU - cereals, sugar beet
China - maize, wheat, sugar beet
India - sugar cane, cassava

Question 8

How is ethanol produced from startch?

Answer 8

Starch (corn) > enzymatic transformation to sugar > fermentation (30C, 36-48hrs) > distillation > ethanol

Question 9

How is statch turned into sugar?

Answer 9

1. pretreatment & milling
2. Liquefaction + alpha-amylase enzyme (100C, 2hrs)
3. Saccharification + glucoamylase (60C, 15-24hrs)
4. SUAGR!

Question 10

How is biodisel produced?

Answer 10

Oil bearing seeds (rape, soy, jatropha, palm) -> crushing -> (fats >) esterification -> separation -> glycerol biodiesel

Question 11

How is biodiesel synthesised?

Answer 11

Neutralization of FFAs:
the levels of FFAs are assayed and quantity of base req to neutralize the acid is determined

Transesterification:
an amount of base (usually NaOH or KOH) slightly in excess of that req for neutralization is dissolved in the alcohol (methanol or ethanol). The alcohol or base is reacted with the oil at elevated temp (typically 50C) for several hours (4 to 8 typically)

Processing:
Lower layer = glycerol and other waste products. Upper layer = biodiesel and alcohol is separated. Often several water washes to remove alcohol, hydroxide, and soap.

Question 12

What is the impact of cutting down rainforests for palm oil?

Answer 12

174 tons of carbon emissions are generated per hectare of rainforest converted to palm oil plantation

Question 13

How did the EU drive deforestation?

Answer 13

Bad policies
1. EU mandated that 10% of transport fuel in every eu contry should be biofuels

2. Biodiesel from argentinian soy beans and asian palm oil is cheaper than that from eu rape seed
3. lots of import
4. in terms of emissions, biodiesel is 80% worse than oil, palm oil is three times worse
5. Eu has stated it wil cut out palm oil in biodiesel by 2030

Question 14

what are 2nd generation bioguels?

Answer 14

Use of ‘non-food’ parts of plants

e.g., wheat straw, sugar cane bagasse, agave and other cacti, corn stover

Question 15

Why is second generation biofuels challenging?

Answer 15

lignocellulose: hemicellulose, cellulose, ether, lignin

Question 16

Enymatic action of plant destruction

Answer 16

cellulases, cellobiohydrolases and beta-gluosidase breakdown cellulose.

Cheapest mass produced enzyme

OPPORTUNITES FOR IMPROVEMENT

EVERY PLANT CELL WALL IS DIFFERNT

Question 17

What is inbicon?

Answer 17

wheat straw pilot plant in copenhagen

4 tonnes straw/hour produces 800L of ethanol
NEW PLANT = 5.4 million litres of ethanol, 8250 tonnes of biofuel, 11,100 tonnes of animal feed from 30,000 tonnes of straw

Question 18

What are other alternatives for feed stock?

Answer 18

Cacti = dont need agricultural land
Algae = dont require agricultural land or fresh water

Question 19

How are algae (3rd gen) biofuels produced?

Answer 19

1. algae strain selected
2. grow in photoreactors
3. grow in open ponds
4. harvest algae
5. process

DIFFICULTIES: hard growing large quantities, dewatering, breaking it apart, purifying oils

Question 20

what is the problem with land and biofuel production?

Answer 20

REQUIRE VAST AMOUNTS OF LAND