Enel has been working on a hydrogen programme dealing with both hydrogen production and uses. The first phase deals with a hydrogen-fed, gas turbine-based co-generative cycle, in which steam injection in the gas turbine itself is adopted in order to couple high process efficiencies with very low nitrous oxide emissions. This paper presents the main results of the co-generative cycle thermodynamic analysis and focuses on the plant economic evaluations under different economic and regulatory scenarios. Results show that hydrogen can be used very effectively in this kind of plant, where electricity efficiency can reach 40% and global co-generation efficiencies can also exceed 90% in relatively small-scale power plants. However, the very high specific investment costs associated with small plants require promotion policies to be applied in order to allow profitable investments. In the future, this kind of plant could provide densely populated areas with electricity and heat with no additional side-effects on the environment.
Keywords: hydrogen production, hydrogen applications, combined cycles, steam injection, cogeneration cycle, economics, gas turbines, nitrous oxide emissions, thermodynamic analysis, investment costs, small scale power plants, electricity, heat