Design issues hybrid systems

The cell and stacks that compose the power section have been discussed extensively in the previous sections of this handbook. Section 9.1 addresses system processes such as fuel processors, rejected heat utilization, the power conditioner, and equipment performance guidelines. System optimization issues are addressed in Section 9.2. System design examples for present day and future applications are presented in Sections 9.3 and 9.4 respectively. Section 9.5 discusses research and development areas that are required for the future system designs to be developed. Section 9.5 presents some advanced fuel cell network designs, and Section 9.6 introduces hybrid systems that combine fuel cells with other generating technologies in integrated systems. 

As discussed previously a principal design issue in hybrid modelling is that it should allow to incorporate several different sources of knowledge. The first step in the present study is to define a flexible system structure that allows to incorporate different forms of knowledge, but also simple in the sense that one must be able to characterise it in terms of identifiability and stability or other important properties. With this main concern the following system structure is proposed ... 

The Hybrid Sulfur (HyS) thermochemical cycle task addresses the key technology issues involved in the development of a hybrid sulfur hydrogen production system - including the SO2 - H2O electrolyzer design, SO2/O2 separation, and the unique materials and process issues associated with the acid decomposition section. An electrolyser is being developed that can be used in conjunction with the sulfuric acid decomposition section being developed for the S-I cycle in a Hybrid Sulfur Integrated Laboratory-Scale Experiment. 

Continued, and progressively more detailed, investigation of the Hybrid TurboScroll CEM concept indicates no issues that seem to threaten the viability of the selected system architecture. A substantial degree of additional detailed system and component design work is required to fully explore the issues of practicality and performance, but the design team still believes that the promise of thermodynamic performance substantially equal to that of the Second Generation Scroll CEM, at a substantially reduced weight and volume, is not only achievable, but within reach. 

US NRC (2000) also raised several human performance issues associated with CBPs. The issues are as follows methodological and criterion requirements for evaluating CBP effects, role of plant personnel in procedure management, team performance, situation awareness, response planning, and operator error level of automation of procedure functions keyhole effects and use of multiple CBP procedures CBP failure in complex situations hybrid procedure systems and specific CBP design features. 

Power systems that are reliant on hybrid HESSs are inherently dependent on a good dynamic response to maintain operational stability. Functions implemented to minimize energy losses include intermittent shutdown when not in use, and this is where stability becomes critical for the rapid dynamics involved in these changes. Transient stability issues that arise from unexpected operating failures during start-up or at steady state can be predicted to an extent, and are important to consider during design. 

---