Over 60% of energy that is generated is lost a s w ste heat with close to 90% of this waste heat being classified as low grade being at temperatures less than 200oC. Many technologies such as thermoelectrics have been proposed as means for har vesting this lost thermal energy. Among them, that of SMA heat engines appears to be a stro ng candidate for converting this low grade thermal output to useful mechanical work. Unfortun ately, though proposed initially in the late 60’s and the subject of significant development wor k in the 70’s, significant technical roadblocks have existed preventing this technology from moving from a scientific curiosity to a practical reality. This paper/presentation provides an overv iew of ongoing work being performed on SMA heat engines under the US DOE ARPA-E initiative. I t begins with a review of the previous art, covers the identified technical roadblocks to past advancement, presents the solution path being taken to remove these roadblocks, and describes sig nificant breakthroughs to date. The presentation concludes with details of the current fu ctioning prototype, which, being able to operate in air as well as fluids, dramatically expa nds the operational envelop and makes significant strides towards the ultimate goal of co mmercial viability.