The New Indian Express infosite is reporting that if all elements go as planned, the Indian Space Research Organisation (ISRO) will flight test their semi-cryogenic engine, which uses refined kerosene as propellant, by 2021.

With the success of the Geosynchronous Satellite Launch Vehicle Mk-III (GSLV Mk-III), ISRO’s Liquid Propulsion Systems Centre (LPSC) at Valiyamala, India, is now focusing on the next level — the development of the much-delayed semi-cryogenic technology. Unlike the cryogenic engine, which uses a combination of liquid hydrogen (LH2) and liquid oxygen (LOX) as propellant, the semi-cryogenic engine replaces liquid hydrogen with refined kerosene (Isrosene, as ISRO calls it). LOX will be retained as oxidizer.

LPSC had developed the cryogenic engine for the GSLV Mk-II and the much powerful one for the GSLV Mk-III. The idea is to replace the second stage of the GSLV Mk-III, which now uses a liquid stage, with the semi-cryo. The rocket will retain the cryogenic upper, third stage. The advantage of inducting the semi-cryogenic stage is the payload capacity of the GSLV Mk-III will increase from four to six tons. Using refined kerosene as fuel has quite a few advantages, among those being a more eco-friendly and cost-effective fuel. Also, unlike liquid hydrogen, which must be stored at (-)253 degree Celsius, it is stable at normal temperatures. The Union Cabinet had cleared the semi-cryogenic engine project in 2008 at an estimated cost of Rs 1798 crore. Although the idea was to develop the technology 2014, the project was delayed.