Hydrogen Steam and Inter-Cooled Turbine Engine (HySITE)

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OPEN 2021
East Hartford, Connecticut
Project Term:
06/03/2022 - 06/02/2024

Critical Need:

Emitted greenhouse gases from global air travel contribute to unacceptable global climate change. Hydrogen is a promising alternative fuel that would enable zero-carbon emissions and other emissions reductions with the appropriate novel gas turbine technologies, including novel architecture, combustor and others. While much attention has been given to make, transport, and store liquid hydrogen (LH2), little effort has been made to assess the opportunities and challenges of LH2 propulsion. There is a need to evaluate novel LH2 propulsion research and innovation that could dramatically increase fuel efficiency and therefore radically reduce specific fuel consumption.

Project Innovation + Advantages:

Pratt & Whitney will design a novel, high-efficiency hydrogen-power turbomachine for commercial aviation. The Hydrogen Steam Injected Intercooled Turbine Engine (HySIITE) concept is intended to eliminate carbon emissions and significantly reduce nitrous oxide (NOx) inflight emissions for commercial single-aisle aircraft. The HySIITE engine will burn hydrogen in a Brayton (thermodynamic) cycle engine and use steam injection to dramatically reduce NOx. Via an innovative semi-closed system architecture, HySIITE aims to achieve thermal efficiency greater than fuel cells and reduce total operating cost compared with “drop in” sustainable aviation fuels.

Potential Impact:

This technology has the potential to achieve economical zero in-flight CO2 emissions and up to an 80% reduction in nitrogen oxides (NOx).


HySIITE innovation would disrupt the aviation industry and represents an opportunity to preserve U.S. primacy in commercial aviation with novel fuels.


The HySIITE concept aims to eliminate carbon emissions associated with aviation, make flying more efficient and significantly reduce NOx inflight emissions for commercial single-aisle aircraft.


HySIITE aims to save the U.S. single aisle fleet an estimated $90B annually relative to SAF.


ARPA-E Program Director:
Dr. Peter de Bock
Project Contact:
Brent Staubach
Press and General Inquiries Email:
Project Contact Email:


Raytheon Technologies Research Center

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