Hydrogen fuel use in Combined Cycle Power Plants (CCPP) is commonly thought of as using a hydrogen/natural gas fuel blend in the Gas Turbine Combustors. Current generation combustors can typically use up to 30% by volume Hydrogen with additional tuning but this provides only 8–10% of the heating value of natural gas displaced. Currently when hydrogen fuel supplies are limited continuous cofiring may result in even lower H2 fractions. For plants with duct burners in their HRSGs an opportunity to burn Hydrogen more efficiently and at lower cost exists. The technology for burning hydrogen in duct burners is well developed for use in chemical and petroleum processing plants. Hydrogen can be used as a blend with Natural gas or by a mix of 100% hydrogen burners and natural gas burners to give true dual fuel capability. This paper examines the use of Hydrogen in a modern CCPP plant duct burners with regard to heat transfer, NOX production, ammonia salt deposition changes due to increased water content in exhaust, temperature impact on HRSG components and flexibility issues.
Application to using Hydrogen with a co-located electrolysis facility and local short-term storage as a means of dealing with daily variation in renewables generation known as the duck curve are analyzed with dynamic simulation of CCPP operation. Implications for storage and Hydrogen supply capacity are addressed.
The study conclusions are that the typical CCPP duct burners in North America can be converted to Hydrogen operation equivalent to a 30% hydrogen blend for the gas turbine on an energy basis with lower cost and technical risk.