New biogas reactor from IIT Guwahati

A team headed by Prof Ajay Kalamdhad of the Waste Management Research Group at IIT-Guwahati has developed a new design for a reactor to produce methane from bio-wastes. This anaerobic bi-phased baffled reactor (ABBR) is better on two counts — it can digest any kind of biomass, including wet and hard-to-degrade stuff like weeds and water hyacinth; and it’s quicker — the biomass remains in the reactor for a maximum of 15 days, roughly half that in conventional reactors. Furthermore, the system produces biogas with a higher methane content, about 70 per cent. These advantages derive largely from the baffles — flow reducers.

The researchers worked with diverse animal dung (cow, goat, rhinoceros) and piggery waste as a source of microbes and concluded that cow dung was the best for anaerobic digestion. Some organic wastes are difficult to treat anaerobically and yield lower degradation and biogas due to their complex composition or lack of one or other nutrient. Such waste is pre-treated and co-digested for improved digestion. Pre-treatment such as heating, application of electrical force, and addition of certain chemicals or specific bacteria was used to substantially improve the biogas yield of difficult substrates such as rice straw, Ageratum conyzoides, Lantana camara, Parthenium hysterophorus.

Prof Kalamdhad told Quantum that two systems are up — at IIT-Guwahati and at a start-up company in Aizawl, Mizoram. The start-up will soon sign MoUs with a few large companies in India, he said.

CECRI’s supercapacitor

The Central Electrochemical Research Institute (CSIR-CECRI), Karaikudi, has developed a process for the manufacture of 2.7V, 100F cylindrical supercapacitors. The government-owned research lab has come up with a process for making supercapacitor electrode-grade carbon as a substitute to carbon import. The value-adding to cheaper commercial carbon available in India enables affordable electrode-grade carbon for supercapacitors. CECRI also developed a ‘supercapacitor cell fabrication technology’ using the indigenous carbon. It has transferred this technology to a Chennai company, Qmax Ion, which will manufacture the supercapacitors.

Supercapacitors are energy storage devices complementary to battery and used for emergency power backup, load levelling, regenerative breaking and high power requirement. Also, in hybrid with other energy storage devices such as lithium-ion or lead-acid battery it can help meet high demand for power. Currently, the country depends on import to meet its requirement of supercapacitors and indigenous fabrication is slowly gaining momentum. There is no supply chain for the required components, including activated carbon, the basic raw material.

Low-cost anti-corrosive

Scientists at the Centre for Engineered Coatings (CEC), International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), an autonomous R&D centre of the Department of Science and Technology (DST), have developed low-cost iron-based intermetallic powders for use as a corrosion-resistant coating for materials exposed to harsh environments like high temperature in thermal power plants, where oxidation, corrosion and wear-and-tear take place simultaneously. The coatings showed four times more corrosion resistance in the aqueous corrosive media than mild steel.

The coating on a turbine blade can enhance its service life and operation hours.

At present, thermally sprayed chromium carbide-nickel chromium powder and tungsten carbide-cobalt (cermet) coatings are widely used for thermal power plant turbine blades, aerospace engine blades, landing gear shafts, steel rolls in the paper industry. However, the powders are expensive due to the need for cobalt and nickel. Besides, chromium is toxic in its hexavalent state. Replacement of these coatings with simple iron-based coatings with novel microstructural constituents is very promising.

In this regard, iron-based solid phases involving two or more metallic or semi-metallic elements (intermetallics) can play a major role, owing to their hardness and corrosion resistance. However, their deployment is restricted by low ductility.

The scientists have addressed this by synthesising iron-based intermetallic powders for the coatings, using detonation spray coating (DSC) technique. The coatings show increased wear resistance by 30-40 per cent.

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