Simple payback was 4.6 years. More sophisticated financial tools showed a return on investment of 19.2 percent, well above the average rate of return for the health care industry. One sign of that change is the increasing interest in hybrid chiller plants, which can be switched from electricity to natural gas. An owner with the ability to choose between gas or electric cooling on a daily basis will have negotiating power in a deregulated environment. Gas cooling owners are attractive to gas companies because they use gas in the summer.
Gas cooling customers are also attractive to electric companies because their load profile is flat.
In addition to hybrid plants, there are hybrid chillers that integrate a gas engine and an electric motor with a single compressor. At any time, either the engine or the motor drives the compressor. Gas cooling provides a wide range of choices for improving building performance. And in a growing number of cases, electric rates make gas cooling an economically attractive option. E-mail comments and questions.