|
| Similarities |
Differences |
| Green algae | Cyanobacteria |
|
| Physical |
|
| Both are only known microorganisms, which are able to produce photosynthetic oxygen as well as hydrogen | Eukaryotes | Prokaryotes |
| Simple growth requirement that is sunlight, water and CO2 | Only green pigments | Green pigment and blue pigment (phycobilin) |
| Able to grow on non-arable land | Need an external intervene for example sulphur-deprivation to establish anaerobic condition | Able to create the highly oxygen-reduced intracellular environment by itself |
| Transformability, so possible for complex genetic engineering | Require exogenous fixed nitrogen source for example , | Able to fix atmospheric nitrogen |
| Biomass can be further processed to make biofuels and valuable co-products | | |
|
| Phothosynthesis |
|
| Upper bound on photosynthetic efficiency ~10% (same as that for plants) | Contain two forms of chlorophyll that is chlorophyll a and b | Only chlorophyll a present. |
| Having two core photosynthetic proteins that is Photosystem I and II | | |
|
| Hydrogen production |
|
| Solar to Hydrogen efficiency <0.05% | By direct recombination of protons and elections | Two hydrogen production pathways.
(i) Side reaction of nitrogen fixation.
(ii) Recombination of protons and electrons |
| Both nitrogenase and hydrogenase are very sensitive to oxygen | Only hydrogenase enzyme is involved | Nitrogenase and hydrogenase enzymes |
| | Hydrogen production is very restricted to anaerobic condition | Able to aerobically produce molecular hydrogen |
|
