Eric Darcy is NASA’s go-to guy for battery safety. He is Battery Group Lead for Projects & Integration at NASA-Johnson Space Center in Houston, Texas, and consults frequently with the National Renewable Energy Laboratory in Colorado. His talk at the First Sustainable Aviation Symposium was titled, “Passively Thermal Runaway Propagation Resistant Battery Module That Achieves > 190 WH/KG.” The output may not sound like much, being at the middle-to-high end of lithium battery performance: but the promise of passive thermal runaway resistance is all-important. Remember, too, that larger output numbers are usually for individual cells. Putting cells into a battery pack with battery management system (BMS) components, wiring, etc. usually reduces overall performance per weight. A few years ago, Dr. Darcy told his table at lunch during a symposium, that by matching batteries closely (to a fanatical degree, it seemed), overseeing their production under conditions exceeding six sigma quality control levels, and testing them intensely, he had built battery packs for space …