Bi9540 Biotechnology and practical use
of algae and fungi
Lecture 7 – 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 are promising sources of biofuels for the future
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
Botryococcus braunii
 Green oil producing alga
 Oils are not suitable for transesterification
 Triterpenes can be used for refinement
 Octane
 Kerosene
 Diesel
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
Microalgae Cell Wall Cell Wall composition (%) References
(% w/w) Carbohydrates Protein n.d.*
Chlorella vulgaris
(F)
20.0 30.00 2.46 67.54
(Abo-Shady et al.
1993)
Chlorella vulgaris
(S)
26.0 35.00 1.73 63.27
(Abo-Shady et al.
1993)
Kirchneriella
lunaris
23.0 75.00 3.96 21.04
(Abo-Shady et al.
1993)
Klebsormidium
flaccidum
36.7 38.00 22.60 39.40
(Domozych et al.
1980)
Ulothrix belkae 25.0 39.00 24.00 37.00
(Domozych et al.
1980)
Pleurastrum
terrestre
41.0 31.50 37.30 31.20
(Domozych et al.
1980)
Pseudendoclonium
basiliense
12.8 30.00 20.00 50.00
(Domozych et al.
1980)
Chlorella
Saccharophila
- 54.00 1.70 44,30
(Blumreisinger et
al. 1983)
Chlorella fusca - 68.00 11.00 20.00
(Blumreisinger et
al. 1983)
Chlorella fusca - 80.00 7.00 13.00
(Loos & Meindl
1982)
Monoraphidium
braunii
- 47.00 16.00 37.00
(Blumreisinger et
al. 1983)
Ankistrodesmus
densus
- 32.00 14.00 54.00
(Blumreisinger et
al. 1983)
Scenedesmus
obliquos
- 39.00 15.00 46.00
(Blumreisinger et
al. 1983)