There is a geography to every revolution. A map drawn not merely by blueprints and patents, but by climates, latitudes, and the stubborn will of men. 

The rediscovery of carbon dioxide (CO2) as a refrigerant did not start in a sterile corporate boardroom. It began in the late ‘80s, carried by the icy winds of the Norwegian fjords. At the University of Trondheim, a visionary named Professor Gustav Lorentzen (1915–1995) was chasing a ghost: the idea that nature, not chemistry, held the answers we had forgotten. Initially, his research was a whisper, small domestic heat pumps that crossed the oceans to inspire the Japanese “Ecocute”, then the research concerned mobile air conditioning systems (MAC), which, however, did not lead to immediate industrialization.  But the true, monumental odyssey, taming CO2 for commercial refrigeration, seemed like a thermodynamic chimera. It was deemed too feral, too complex, commercially barren. 

In 1996, however, the frontier moved south to the industrious plains of Italy. This application was not initially considered, as it was deemed complex and commercially uninteresting.  

Today, this invisible gas breathes life into the steel hearts of over 100,000 systems across all continents, driving high-capacity heat pumps, district heating and colossal industrial plants up to 2 megawatts. I have decided to chronicle this story, summarizing a thirty-year voyage into seven chapters. 

I am Sergio Girotto Enex founder and Honorary president of Enex Technologies. I plunged my hands into the iron and the frost as one of the key figures of CO2 evolution and have summarized the entire story into seven chapters. 

This is my journey. 

Before we depart, a good wanderer must honor his companions. 

A deep, heartfelt “thank you” goes to the pioneers who shared the dust and the pressure: Silvia Minetto – ITC-CNR (I), Gerald Heinzmann and Kurt Goetz – Kaeltering (CH), Raphael Gerber and Jonas Schoenenberger – Frigoconsulting (CH), Massimo Lorenzi – Realtime srl (I), Armin Hafner, and Petter Neksa – Sintef (N). Finally a special, enduring gratitude to Engineer Mario Dorin, atrue, relentless craftsman of the impossible.