Japanese company Interstellar Technologies (IST) has completed static fire tests of its ZERO jet engine powered by liquid biomethane. Tests have revealed the potential of biomethane derived from cow manure as an environmentally friendly rocket fuel.

To achieve excellent performance, the ZERO combustion chamber has undergone extensive research and development in collaboration with the University of Tokyo and JAXA. This led to design improvements that reduced the cost of manufacturing a rocket engine, estimated at half the total cost.

The tests will help IST advance the development and production of the 130 kN class operational model, building on information gained from the design, production and testing of the 60 kN class model.

ZERO is a satellite launch vehicle designed to meet the demand for small satellites. In response to global demand, ZERO is expanding its capabilities to launch satellites weighing up to 800 kilograms into low Earth orbit. ZERO has a length of 32 meters, a diameter of 2.3 meters and a total weight of 71 tonnes.

The rocket engine is liquid propellant, using LBM as fuel and liquid oxygen as oxidizer. IST introduced for the first time the gas generator cycle, which involves burning part of the fuel in the gas generator to drive the turbo pump at a speed of tens of thousands of revolutions per minute and feed the fuel under high pressure into the combustion chamber. .

The rocket has a two-stage design and has a needle injector, which reduces the number of components and increases combustion efficiency. The needle nozzle delivers the fuel (liquid fuel and oxidizer) to the combustion chamber of the rocket engine in a controlled manner.

The regenerative cooling system also uses fuel efficiently to cool the walls of the combustion chamber. The combustion chamber, turbo pump and gas generator have been tested and their integration is planned in the future.

Liquid methane has become the preferred fuel option for rocket launches due to its advantages such as fuel performance, price, availability, ease of circulation and environmental impact. Air Water Group is working on a closed-loop supply chain for liquid biogas-methane (LBM), produced by processing methane from biogas derived from animal manure in Hokkaido’s Tokachi prefecture.

The LBM used in the tests is made by separating and purifying methane, the main component of biogas, and then liquefying it at approximately -160°C. It is impressive that it achieved such a high purity level that it is comparable to the purity level of ordinary rocket fuel. Source