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Industrial revolution in the 20th century has pumped huge volumes of CO2 into earth’s atmosphere. According to the IPCC report, global warming is because of greenhouse gas emissions from anthropogenic activities with CO2 being the main contributor. To combat the climate change, the global community has agreed to reduce the CO2 emission in a time-bound manner in the United Nations Framework Convention on Climate Change (UNFCCC), which essentially led to extensive R&D in the area of CO2 capture and storage. To meet this need, following objectives will be followed:

1) Selection of algal cultures for optimum CO2 capture from the target source.

2) Design of algal photobioreactor based on the target source and aesthetic improvement.

3) Direct air capture to reduce air pollution.

4) Large point source capture to reduce the industrial CO2 emission.

Actions are needed to mitigate the CO2 emissions from anthropogenic activities. The major physico-chemical CO2 mitigation methods including geological storage, ocean storage, mineral carbonation, and industrial consumption. However, these techniques require CO2 to be transported and/or compressed to high pressures and hence, significant energy inputs are needed. On the other hand, algae are known to capture CO2 using sunlight as the energy source, making the process technically and economically feasible. Algae are a diverse group of macroscopic and microscopic photosynthetic organisms with growth rate 10-50 fold higher than plants, but comparatively much less space requirement. Hence, they present a promising biological approach for CO2 capture. Secondly, they release the CO2 captured in the biomass relatively slowly due to the complex nature of cell wall, allowing temporary sequestration of CO2 for some time. In the proposed activity, algal CO2 capture will be implemented directly from open air or from point sources like thermal power plant, distilleries etc.

CSIR-NEERI has demonstrated algal CO2 capture at laboratory scale photobioreactor, which is evident from the publication record. Hence, we propose that the technology is currently at TRL 2

1) Algal cultures suitable for CO2 capture from the target source.

2) Algal photobioreactor design for the target environment.

3) Direct air capture to reduce local concentration of CO2, SOx and NOx.

4) Large point source capture to reduce the CO2 emission, particularly for industries.

5) Carbon credits with the Carbon Credits Trading Scheme (CCTS) to be launched in India soon.

The direct air CO2 capture at hotspots such as busy junctions, enclosed commercial places without adequate ventilation will lead to improvement in the air quality. Besides CO2, the algae can also capture and utilize oxides of sulfur and nitrogen, which are important air pollutants. The algal PBR will be designed in an attractive manner to improve the aesthetic of the place as well. The algal CO2 capture from large point sources has huge potential, as high concentration of CO2 will facilitate faster and more efficient capture. The algal biomass thus generated can be used as feedstock for downstream processes, like preparation of feed, biochar, biofertilizer, biodiesel etc, which will result in the release of the captured CO2. Otherwise, the algal cells naturally degrade very slowly due to their complex cell wall, and will allow temporary sequestration of CO2.

CSIR-NEERI has extensive expertise in the area of algal CO2 capture and value addition. The entire activity will be undertaken by the PI. However, the civil, fabrication and related work for algal photobioreactor must be outsourced.