Electrical Power from Thermal Energy Scavenging in High Temperature Environments

Physical Sciences Inc. and Purdue University propose to develop a novel approach to scavenging heat from high intensity thermal environments encountered during space missions and converting this thermal power to electrical power at high efficiency. Examples include extremely hot heat shields during vehicle entry into planetary atmospheres (Mars/Venus probes) and during high speed ascent through planetary atmospheres (Sample return from Mars/Venus), hot claddings of radioisotope thermoelectric generators used for powering outer planetary spacecraft and multi-decade planetary bases (Mars/Venus/Lunar), as well as combustors and nozzles of space and launch propulsion systems. In this STTR we will develop an integrated metal hydride system and spectrally-tuned thermophotovoltaic power converter system that can extract heat during periods of high thermal intensity (tens of seconds), and convert it to electricity at greater than 25 percent efficiency. Following the end of this period, the system can continue to generate useful power for additional tens of minutes. In Phase I, for the power converter system, we will demonstrate feasibility of fabricating a critical component in larger areas (5 cm x 5 cm), and for the metal hydride (MH) system, we will experimentally characterize the MH decomposition/recombination reactions that enable continual electrical power generation for a useful duration after the period of high thermal intensity has ended. In Phase II, we will produce an engineering prototype of the integrated heat scavenging electrical power generator system, fully tested in laboratory environment and in simulated operational thermal environment, together with an analytical model of a functional system.

The proposed heat scavenging electrical power converter will find applications in NASA exploration missions to planets with atmospheres, such as Venus, Mars, and likely others. Example missions include small, power-limited probes released from an orbiter to enter the atmosphere, gather data during descent, land on the surface, and continue data gathering operations for some time. The proposed technology would generate electrical power during the hot atmospheric descent as well as surface operations. Another example would be a planetary sample return mission, where a small probe ascends a high speed through the atmosphere, with the converter providing power generated from scavenging heat from the vehicle's heat shield. Planetary missions to Venus and Mars are presently a part of the NASA roadmaps. Other applications of the proposed heat scavenging power converter include generation of electricity from hot cladding of radioisotopes used in radioisotope thermoelectric generators on years-long planetary missions and proposed to be used on decades-long planetary bases.

The proposed compact power generator devices have several aerospace and commercial applications. For example, power generator can be adapted for long range hypersonic vehicles reentering the earth's atmosphere. The customers for this application are the U.S. Air Force and the Navy. Compact, portable power generators are particularly suited for power generation on a small scale, such as for individual soldiers and campers/backpackers. In these applications, the hot source would be a burner consuming hydrocarbon fuel such as a portable propane cylinder, camping stove, etc. The government customers for this application include the U.S. Army, the U.S. Special Operations Command, and the Marines. Manufacturers of camping equipment would form a very large commercial customer base for this technology. The regenerative hydrides capability of our technology will have wide commercial applications in hydrogen storage systems for a variety of uses in the future hydrogen economy, including automobiles. Customers include various DoD agencies as well as a range of commercial manufacturers.

This is early/mid-stage (TRL 3) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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