Biofuels Flashcards
(29 cards)
What are biofuels
Renewable liquid or gaseous fuels made by and/ or from living organisms or the waste they produce
what are 2 main types of biofuels commercially produced
- Bioethanol
- Biodiesel
How is bioethanol produced
From sugar beet, sugar cane & corn by fermentation of soluble sugars (largely sucrose & glucose derived from starch) by the yeast Saccharomyces cerevisiae
How is biodiesal produced
By extraction of oil from soybean, rapeseed and palm crops followed by chemical esterification
What does the yeast enzyme invertase do in bioethanol production
Invertase converts sucrose to glucose & fructose
Glucose & fructose can both enter glycolysis
Sucrose can be added directly to fermentation vessel
In bioethanol production what is yeast degraded by and to produce what
- Degraded by amylases
- To produce glucose and other simple sugars
- Hydrolysis products are added to the fermentation vessel
What 2 microbes are used in bioethanol production
- Zymomonas mobilis
- Saccharomyces cerevisiae
Bioethanol production in terms of Saccharomyces cerevisiae
Saccharomyces cerevisae can convert glucose to ethanol via glycolysis
In bioethanol production what does glycolysis in yeast produce and where is the waste in this
- Produces 2 ATP for each glucose molecule & an increase in biomass
- An increase in biomass is wasted Carbon & energy which could have gone into ethanol production
How is waste in bioethanol production decr
Bioengineering of yeast allowd reduction of ATP yield (ATP = wasted carbon)
What bacteria reduces ATP yield & is used in bioethanol production
Zymmomonas mobilis
Biothenol production
In what way does Zymmomonas mobilis (anaerobic gram neg) break down glucose
Breaks down glucose via Entner-Duodoroff pathway
Bioethanol prod
What does Zymmomonas mobilis produce per glucose molecule
- 2 pyruvates
- only 1 ATP - less wasted carbon & energy
Bioethanol prod
What limits Zymmomonas mobilis broader usefulness
It can only use a few simple sugars - glucose, fructose & sucrose - for ethanol production
Bioethanol prod
Advantage of Zymmomonas mobilis over Sacchromyces cerevisae
Zymmomonas mobilis can withstand higher ethanol levels
Biodiesel prod
What is biodiesel comprised of
Fatty acid methyl and ethyl esters
Biodiesel prod
Does E. coli naturally produce triglycerides
No
Biodiesel prod
What can accumulate fatty acids as triglycerides? Can these be used directly as fuels
- Yeasts such as Saccharomyces cerevisae & some algae can accumulate fatty acids as triglycerides
- But these cant be directly used as fuels
Biodiesel prod
What has e. coli been genetically engineered to produce for biodiesel production
To produce fatty acid ethyl esters
Biodiesel prod
What has saccharomyces cerevisae been engineered to produce
To divert lipid synthesis away from triglycerides & into fatty acis ethyl esters
How do algae produce biofuels
Use energy from sunlight and CO2 to produce biomass including oil which can be converted into biodiesel
What are traditional/first generation crops made from
Edible crops
What are second or third generation biofuels made of
Non food crops or plant waste
what is much of the plant biomass from second/third gen biofuels made of
Mix of cellulose, hemicellulose and lignin known as lignocellulose
