Indian Space Research Organisation (Isro) is developing a semi-cryogenic engine that will use eco-friendly kerosene as propellant. The advantage of using this semi-cryogenic engine in the launch vehicle is that it uses refined kerosene which is lighter than liquid fuel and can be stored at a normal temperature.
Presently, the fuel being used, which is a combination of liquid hydrogen and liquid oxygen, is heavier and needs to be stored at -253 degree Celsius. ISRO will reportedly flight-test the semi-cryogenic engine by 2021 if everything goes as planned.
Kerosene is a fuel lighter than the conventional combination of liquid hydrogen and liquid oxygen but it gives higher thrust. Therefore kerosene occupies less space and more propellant can be packed in the semi-cryogenic engine's fuel compartment.