Algal mat

Algal mats played an important role in the Great Oxidation Event on Earth some 2.3 billion years ago.

These heterocysts have thick walls and lack chlorophyll, both of which limits their exposure to oxygen, the presence of which inhibits nitrogen fixation.

For the same reason, fixation may also be limited to nighttime when the light-dependent reactions of photosynthesis are shut down, minimizing oxygen production.

During the Proterozoic, stromatolites' compositions were dominated by micrite and thinly laminated lime mud, with thicknesses no greater than 100 microns.

Stromatolites can be found in places with ranging temperature such as in the marine, limnic and soil [1] Algal mats consist largely of filaments made of autotrophic bacteria and fine-grained particles.

Phototrophic bacteria such as cyanobacteria are evolutionary organisms responsible for the increased oxygen levels during the Proterozoic age.

High biomass blooms can also lead to the development of “dead zones”, formed when the algae begin to die and their decomposition depletes the water of oxygen.

Dead zones are unable to support (aerobic) aquatic life, and are responsible for losses of millions of dollars’ worth of fish annually.

Marine and aquatic biomass tentatively demonstrates high yield while requiring minimal use of arable land.

Major advantages of algae are: no competition with food crops for arable land, high growth rates, and low fractions of lignin which reduces the need for energy-intensive pretreatment and compatibility with biorefinery approach implementation.

It has been proven that macroalgae can reach 2–20 times the production potential of conventional terrestrial energy crops However, some disadvantages such as the presence of high water content, seasonal chemical composition and the occurrence of inhibitory phenomena during anaerobic digestion, make algal biofuels not yet economically feasible although they are more environmental friendly than fossil fuels.