Fuel Cells
Johannes Lindorfer, Daniel C. Rosenfeld, Hans Böhm
Abstract
A fuel cell is a galvanic cell that converts the chemical reaction energy of a continuously supplied fuel (usually hydrogen) and an oxidizing agent (usually oxygen, air) into electrical energy. Compared to more widespread thermal engines, fuel cells have the advantage of a direct conversion of chemical energy into electrical energy with higher efficiency (approx. 40%–60%). In this chapter, the main innovative fuel cell technologies (e.g., proton exchange membrane fuel cell, phosphoric acid, and solid oxide fuel cell) are explained based on their characteristics with respect to potential advantages and disadvantages for specific applications. The current major challenges due to the partly low technological readiness level of some fuel cell types are the relatively high costs, as well as durability and reliability. These three factors must be overcome in order to realize a high market penetration in the power and mobility sector. However, fuel cells are getting closer to cost-competitiveness in a growing variety of applications, ranging from vehicles to stationary and portable applications. Today's most important applications for fuel cells, measured in terms of the number of devices installed, are building and off-grid power supply but also power generation and storage applications. Another growing market is the field of vehicle powertrains in versatile applications especially where required ranges and operating times are high and hardly satisfiable by renewable alternatives like, e.g., battery powered systems. Today most of the hydrogen is derived from fossil natural gas. Hydrogen produced via renewable powered water electrolysis can provide significant environmental benefits for the fuel production. However, the environmental impact associated with the manufacture of fuel cells still represent challenges to be addressed in future years. Given a sustained policy support, together with the intense research and resulting technological progress in hydrogen and fuel cell development in the recent years, fuel cells are potentially supposed to experience a cost and performance trajectory similar to those of photovoltaics and batteries.