An IIT-Madras incubated start-up calls itself X2Fuels and Energy Pvt Ltd, because it believes it can convert any waste, including wet, city wastes, into fuels that can be blended with refinery products. The heart of the technology, pioneered by Vinu Ravikrishnan, professor, Department of Chemical Engineering, and Satya Chakravarthy, professor, Department of Aerospace Engineering, is a process called ‘hydrothermal liquefaction’ — the breaking down of complex molecules in the feedstock under controlled pressure and temperature in a pressure vessel. The process mimics Mother Earth, says Ravikrishnan. A key advantage of this process is that it gains by the presence of water, as opposed to other processes where the feedstock has to be dried first. Under the temperature and pressure conditions, water, which is a polar molecule, turns similar to hydrocarbons, which are non-polar and of lower density. And, the water quality does not matter. Ravikrishnan is studying the suitability of seawater.

For wastes that are more homogeneous, such as agri-residues and industrial wastes, X2Fuels has another process — microwave-assisted pyrolysis — or microwave-based heating, which also yields a kind of oil that can be blended with refinery products.

The oils from these two processes can also be upgraded to automotive quality by yet another process called ‘catalytic hydro de-oxygenation’ — which involves removal of oxygen using catalysts. (Elemental oxygen helps burning, but in a compound the gas hampers burning.) X2Fuels names the public sector company Engineers India Ltd among its partners.

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