29.7 Methods for CO2 Capture

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29.7.3

Scenario 3. Biofuels

Various studies and efforts have been done to replace fossil fuel with biofuels

(ethanol and biodiesel). Although CO2 is again recovered from the carbon present

in biofuel, it directly increases the atmospheric CO2 concentration and acts as an

anthropogenic release of carbon from fossil reserves [48]. Over the past few years, it

is so evident to get substituent of fossil fuel which thus offers to redeem the negative

effect caused by the enhanced atmospheric CO2 concentration. Another method is

the valorization of food waste for the production of biodiesel, biofuel, and biogas.

It has set milestones for the eradication of fossil-based products, especially fruits,

processed refined flour-based food products, and vegetable wastes [49, 50].

29.7.4

Biological-Based Methods to Capture CO2

Biological methods solve over-dependency on energy and provide a high number of

bioproducts.

29.7.4.1

Photosynthetic Model

Photosynthesis is a primary source of C sequestration. Photosynthetic organisms can

be used as light-capturing tools and CO2 can be used for the generation of a varied

range of products like fuel, chemicals, and material.

Marine Algae for CO2 Sequestration Macroalgal primary products can be used to sink

a considerable amount of CO2 and thus end up as a key performer in C sequestration

of GHG emissions [48]. Industrial Revolution holds an account of 48% of emissions

with the sea being the potential carbon fixer for anthropogenic CO2 emissions

[48, 49].

Marine Productivity and Capacity for Carbon Reduction Ocean photosynthesis is

responsible for the generation of the planet’s 50% of the total primary productivity

of 54–59 PgC/year. Different types of marine macrophytes have a different rate

of photosynthesis and productivity in which seaweeds and seagrasses found in

the coastal regions can account for ∼1 PgC/year [51, 52]. Kelps Microcystis and

Laminaria are the potential contributors to the biological reduction of the CO2

cycle due to maximum photosynthetic activities it fixes a huge amount of carbon

produced annually worldwide.

29.7.4.2

Substrate in Biorefinery and Carbon Management

Case 1. Algal Biorefinery Today, annually from both wild and cultivated source,

around 7.5–8 million tonnes of wet weight seaweeds are harvested. Around the

world, China produces 5 million tonnes (wet weight) and becomes the largest

seaweed producer in which Laminaria japonica is the major contributor. Besides,

800 000 tonnes from Korea with a 50% contribution from Undaria pinnatifida and

600 000 tonnes from Japan with 75% cultivation from Porphyra sp. come annually

[52]. From FAO details, a wide variety of macroalgae species are cultivated, but