Jack Devanney has had three mini-careers. He trained as a naval architect at MIT and spent 10 years working for the US Navy either directly or indirectly. He worked for three naval shipyards: Newport News, Electric Boat, and Litton Industries, At Litton, he was responsible for the hull form and tank testing of the Spruance Class destroyer.

From 1969 to 1978, Devanney served on the faculty of the Department of Ocean Engineering at M.I.T. where he taught courses in marine transportation and petroleum engineering. He was the youngest person ever appointed to the Panel on Naval Warfare of the President's Science Advisory Committee and the youngest fired from that position.

In 1978, Devanney left academia and embarked on a 25 year career revolving around tankers. From 1984 to 1990, Dr. Devanney was CEO of Majestic Shipping Corp, a company which he was instrumental in founding. At the time, Majestic was the largest independent American owner of very large tankers, carrying over 2% of all the oil imported into the United States in 1988 and 1989. In 1990, the Majestic fleet was sold in two transactions which valued the ships at over 315 million dollars. This fleet was purchased in the mid-80's for 42 million dollars.

Between 1990 and 2005, Devanney was a Director of Hellespont Shipping Corp, owner of as many as 14 very large tankers. In 1999, under his direction as Program Manager, Hellespont instituted the largest large tanker newbuilding program in the world at the time, four 305,000 ton VLCC's at Samsung Heavy Industries, and four 442,000 ton ULCC's at Daewoo Shipbuilding and Marine Engineering. The latter are the largest double hull tankers ever built. These eight ships were delivered in 2001/2002. Between 2001 and 2004, the ships were sold at a substantial profit.

In 2005, Devanney retired and founded the Center for Tankship eXcellence. The CTX is a non-profit devoted to improving tanker safety. The CTX published a book called The Tankship Tromedy, and some 20 papers on various aspects of tanker operation and regulation. Many of these papers focused on efficiently reducing CO2 emissions from ocean transportation.

But it was obvious that ships were a tiny part of the CO2 problem. It was also obvious that solving global warming meant providing carbon-free power in a cheap and rapidly scalable form to the billions of humans who suffered from electricity poverty. In 2011, Devanney shifted his attention to nuclear power. He formed a small team to develop a design that combined a high temperature, low pressure, liquid fuel reactor with his background in ship production. This became known as the ThorCon project. Devanney continues to serve as ThorCon's Chairman although the day to day operations of ThorCon have been turned over to younger, more capable hands.