Fuel Cell/Gas Turbine Hybrid potx

Fuel Cell/Gas Turbine Hybrid S Samuelsen and J Brouwer, University of California, Irvine, CA, USA & 2009 Elsevier B.V. All rights reserved. Introduction With increasing energy demands, dwindling fossil energy resources, and environmental concerns associated with criteria pollutants and greenhouse gases, significant at- tention in the power generation community has been focused on increasing efficiency and reducing emissions. A highly efficient and low-emission concept is the fuel cell gas turbine (GT) hybrid. Hybrid systems are comprised of fuel cells integrated with a GT engine. A v ariety of potential configurations have been proposed and a number of cycles hav e been investi- gated. The adv antag e sought is a s ynergism that yields a performance that exceeds the simple sum of the tw o sys- tems. Both experimental and theoretical analyses of hybrid systems hav e demonstrated that, w hen appropriately com- bined, remarkable performance attributes can result. In particular, hybrid systems are capable of (1) unusually high fuel-to-end-use efficiency and (2) virtually zero emission of criteria pollutants. The environmental and energy-efficient performance suggests that h ybrid systems can contribute to (1) new and secure fossil-fueled energy infrastructure, (2) sustainable po wer generation w hen operated with re- newable fuels, and (3) the provision of transportation fuels including the introduction of the h ydrogen econom y. Theoretical analyses and early experimental results show that no fossil fuel-based technology can compete with the high efficiency and environmental performance of hybrid systems. In addition, the market applications for hybrid technologies range from stationary to mobile, in size from kilowatts to megawatts, and operate on fuels from coal and biomass syngas fuels to natural gas and hydrogen. For stationary applications, prototypes have been tested and the first commercial unit has been deployed in a distributed generation installation. In addi- tion, concepts are being actively developed for hybrid central plant installations. For mobile applications, hybrid technologies are projected to meet the power and pro- pulsive requirements of locomotives, ships, and aircraft and thereby meet the expanding demands for high fuel- to-electricity efficiency and reduced environmental sig- nature for such systems. Although the potential for hybrid systems is signifi- cant, the front-end risk associated with developing the technology is considerable. Broad investment in research by industry, national laboratories, and universities is re- quired to meet the market penetration that is anticipated for hybrid technology. The Concept Hybrid fuel cell GT systems are comprised of two major components: a high-temperature fuel cell (HTFC) and a GT engine. The concept was first conceived in the mid- 1970s. By 1998, more than 10 hybrid concepts had been patented, offering variations in fuel cell type, the position of key components in the integrated system, and system operating pressure. The basic concept is illustrated in Figure 1, where a fuel cell replaces the combustor of a typical Brayton (GT) cycle. This leads to direct fuel-to- electricity production from the fuel cell (in the place of chemical-to-thermal energy conversion of a combustor), with the waste heat of the fuel cell being used to provide all the compression power and the generation of add- itional electricity through a turbogenerator. Note that electrochemical production of electricity lowers emis- sions and increases efficiency. As a result, around 80% of C Air CTTC Fuel ~80% ~20% CTT Generator Cathode Electrode Anode Figure 1 Basic design concept of a hybrid gas turbine (GT) fuel cell system. 124 . reducing emissions. A highly efficient and low-emission concept is the fuel cell gas turbine (GT) hybrid. Hybrid systems are comprised of fuel cells integrated with a GT engine. A v ariety of potential. Fuel Cell/Gas Turbine Hybrid S Samuelsen and J Brouwer, University of California, Irvine, CA, USA & 2009. market penetration that is anticipated for hybrid technology. The Concept Hybrid fuel cell GT systems are comprised of two major components: a high-temperature fuel cell (HTFC) and a GT engine. The