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IIT Guwahati has developed a two-stage microalgae cultivation process that raises carbon dioxide capture, biomass yield, self-harvesting and bioenergy output together.
The work was led by Professor Kaustubha Mohanty of the Department of Chemical Engineering with research scholar Deepesh Singh Chauhan, and published in the journal Renewable Energy.
Stage one grows the culture under 15 per cent carbon dioxide for rapid growth; stage two drops it to 5 per cent and adds calcium and phosphorus to hold pH and sustain photosynthesis.
Trials in a two-litre bubble-column photobioreactor recorded 25.7 per cent higher biomass, 35.4 per cent higher CO2 fixation, 1.86 times higher lipid productivity and a 37.65 per cent gain in intracellular bioenergy efficiency.
Calcium addition triggered self-flocculation of the cells, giving a harvesting recovery of 98.46 per cent without high energy costs.
Microalgae are photosynthetic microorganisms that convert carbon dioxide and sunlight into biomass, and their lipids can be converted into biofuel. Growing them has never been the bottleneck - separating them from water has. The cells are microscopic and stay suspended, so conventional recovery uses centrifugation or chemical flocculants, both of which consume energy or add cost, often enough to cancel out the energy contained in the biomass. This process sidesteps that: adding calcium in the second stage makes the cells clump together on their own, a behaviour called self-flocculation, so they settle and can be collected with little energy input. That is what a 98.46 per cent recovery without high energy cost signifies.
Simple Analogy: Filtering fine silt out of a bucket of water is slow and expensive. If the silt particles can be induced to stick to one another into visible clumps, they simply sink and can be scooped off - the separation problem solves itself.
Biological fixation by algae is a utilisation pathway - the carbon becomes a product rather than being pumped underground for storage.
India has committed to net zero by 2070; industrial carbon capture and low-carbon fuels are among the routes to abating emissions from sources that cannot be electrified.
India's transport-fuel decarbonisation currently runs on ethanol blending; advanced biofuels from waste and algae are the intended next stage.
Closed photobioreactors give control over light, temperature and gas at higher capital cost; open raceway ponds are cheaper but suffer contamination and evaporation.
GS Paper 3 > Science and Technology - indigenous technology; Environment - climate change mitigation and biofuels
General Awareness > Science and Technology in the News
General Awareness > General Science
With reference to Neem tree, consider the following statements: 1. Neem oil can be used as a pesticide to control the proliferation of some species of insects and mites. 2. Neem seeds are used in the manufacture of biofuels and hospital detergents. 3. Neem oil has applications in pharmaceutical industry. Which of the statements given above is/are correct?
Answer: 1, 2 and 3
Microscopic photosynthetic organisms that fix carbon dioxide using sunlight and accumulate lipids usable as biofuel feedstock.
A closed vessel for cultivating photosynthetic organisms under controlled light, temperature and gas conditions.
Spontaneous clustering of cells into larger aggregates that settle out, enabling low-energy harvesting.
Fuel derived from algal biomass, requiring neither farmland nor food crops.