Lecture 18: Biofuels Flashcards
What are biofuels?
alternatives to fossil fuels
plant biomass refined to be combusted for energy
Issues with fossil fuels
global warming
climate change
pollution
political wars
running out
Bioethanol info
US, Brazil
sugars and starches (food crops used)
alcohol by fermentation
vehicle fuel in pure form
Biodiesel info
Europe
oils and fats from plants
transesterification to make diesel
vehicle fuel in pure form
What are the issues with bioethanol C costs
high due to production, transport, inefficiencies as fuel, land use change
What is fermentation
add microbes to ferment sugars
What is distillation
remove plant solids water and yeast to make 95% pure
What is dehydration
remove water to make 97%
Which land is used for biofuels
best land
causes deforestation
How can we make biofuels better
curn non-food crops for fuels
cellulosic ethanol using non-edible plant parts and fermentation
What are 1st gen biofuels
made from food crops
high C costs
competes with land for food production
economically viable
increase CO2 due to land conversion
What are 2nd gen biofuels
non-food crops
huge investment
high energy
not viable
What is 3rd gen biofuel
lipids from algae
costly
lots of energy
fertiliser
not viable
What is 4th gen biofuel
store renewable elctricity as biofuel
convert electric to chemical
not viable
What plants could be used for 2nd gen biofuel
miscanthus, switchgrass, poplar
