Bi7430 Molecular Biotechnology
6. Lecture – Biofuels
Biofuels
 Alternatives to fossil fuels (crude oil, coal,…)
 Plant and animal biomass
 Primary biofuels like wood or crop waste used since
ancient ages
 Most of the currently used biofuels are plant-based
 Algae and bacteria are promising sources of biofuels for
the future
Generations of biofuels
Generations of biofuels
Generations of biofuels
Biofuels in the world
 Vast majority of the biofuels production is based in the
US, Brazil and Europe
Why are biofuels important?
 Renewable sources of energy
 Lowering of carbon emissions
 Lower energy demands than ´traditional´ processes
 Biomass can be used for extraction of biologically
active compounds and as biofuel
 Waste is biodegradable or can be used further
Crude oil consumption
Algae as biofuels sources
Biodiesel
 Methylesters of unsaturated fatty acids
 Better biodegradability than fossil-based diesel
 High energy capacity
 Can corrode the engine parts
 Higher health hazard than fossil fuels
 In the EU 5 % of biodiesel has to be mixed with liquid
fossil fuels
Algae processing
 Water removal is important
 20% humidity after
dewatering
Bioethanol
 Production depends on content of fermentable
sugars
 Production higher than 4 % (40 g/L) is necessary to
make the proces economically feasible
Bioethanol production
 Cells are pretreated using acid or enzymatic hydrolysis
 Hydrothermal pretreatment may be applied
 Ethanol fermentation by bacteria or yeast
 Saccharomyces cerevisiae
 or technical cultures
 Mannitol cannot be converted by S. cerevisiae
Hydrogen production
Hydrogen production from natural gas
 CH4 + H2O ⇌ CO + 3 H2 (at 700 – 1100 °C) – steam reforming
Hydrogen from coal
Biohydrogen production
Biohydrogen production
Nitrogenase in cyanobacteria
Biogas
Current approaches in biofuels production
 Single gene targeted approaches
 Insertion of specific enzyme
 Engineering of RUBISCO and/or PS II
 Enzyme engineering
 Systemic approaches, metabolic engineering
 Multiple insertions/deletions
 Novel metabolic pathways
 Tampering the central carbon metabolism
 Single gene targeted approaches
 Systemic approaches, metabolic engineering
Current approaches in biofuels production
 Designing photosynthetic microorganisms for production
of photobiological solar fuels
 Microbial fuel cells (electrobiofuels)
 Technical cultures of engineered (and natural) strains of
microorganisms
 Systems metabolic engineering of bacteria and yeast,
creation of cell factories for high-value desired chemicals
Biofuels produced by engineered microbes
 Lipids and fatty acids
 Fatty alcohols
 Ethanol, isopropanol
 Butanol, methylbutanol
 Hexanol, octanol
 Alkanes, alkenes
 Isoprenoids
Biodiesel in engineered E. coli
Biodiesel from Y. lipolytica
Biodiesel in E. coli
Stress engineering
 Biofuels producing bacteria may suffer from presence of
the target compound
 Stress tolerance engineering is important
 Targeted metabolic engineering
 Stress-induced mutagenesis
Reading
 Read pages 465-470
Questions