Fuel cell
Introduction
A fuel cell is an electrochemical cell that converts the chemical energy from a fuel into electricity through an electrochemical reaction of hydrogen fuel with oxygen or another oxidizing agent. Fuel cells are different from batteries in that they require a continuous source of fuel and oxygen (usually from air) to sustain the chemical reaction, whereas in a battery the chemical energy comes from chemicals already present in the battery.
History
The first references to fuel cells can be traced back to the early 19th century. In 1838, German scientist Christian Schönbein first described the principle of the fuel cell. He used a hydrogen and oxygen mixed gas to generate electricity. The first working fuel cell system was developed by Welsh scientist William Grove in 1842. He called his invention a "gas voltaic battery". After experimenting with a Grove cell, which used zinc and sulfuric acid to produce electricity, Grove realized that by reversing the reaction, he could also produce electricity.
Types of Fuel Cells
Fuel cells come in many varieties; however, they all work in the same general manner. They are made up of three adjacent segments: the anode, the electrolyte, and the cathode. Two chemical reactions occur at the interfaces of the three different segments. The net result of the two reactions is that fuel is consumed, water or carbon dioxide is created, and an electric current is created, which can be used to power electrical devices, typically referred to as the load.
Proton Exchange Membrane Fuel Cells
Proton exchange membrane fuel cells (PEMFCs), also known as polymer electrolyte membrane (PEM) fuel cells, are a type of fuel cell being developed for transport applications as well as for stationary fuel cell applications and portable fuel cell applications. Their distinguishing features include lower temperature/pressure ranges (50 to 100 °C) and a special proton-conducting polymer electrolyte membrane.
Solid Oxide Fuel Cells
Solid oxide fuel cells (SOFCs) are a class of fuel cells characterized by the use of a solid oxide material as the electrolyte. SOFCs operate at very high temperatures—typically between 500 and 1,000 °C. At these temperatures, SOFCs can convert more than 60% of the fuel energy into electricity, and if the waste heat is captured and used, total energy efficiencies can be as high as 80% to 85%.
Molten Carbonate Fuel Cells
Molten carbonate fuel cells (MCFCs) operate at 600 to 700 °C, a temperature that allows for the internal reforming of natural gas. These fuel cells are primarily being developed for natural gas and coal-based power plants.
Phosphoric Acid Fuel Cells
Phosphoric acid fuel cells (PAFCs) were the first fuel cells to be commercialized. Developed in the mid-1960s and field-tested since the 1970s, they have improved significantly in stability, performance, and cost.
Applications of Fuel Cells
Fuel cells can be used in a wide range of applications, including transportation, building heat and power, and portable uses.
Transportation
In the field of transportation, fuel cells are being explored for use in propulsion of passenger cars, commercial vehicles, boats and even aircraft. Notably, fuel cell vehicles (FCVs) like the Toyota Mirai and the Hyundai Nexo are already available in select markets.
Building Heat and Power
Fuel cells can be used to generate heat and electricity for buildings in a process called combined heat and power (CHP). CHP systems are highly efficient, making use of the heat that is a by-product of the electricity generation process.
Portable Uses
Fuel cells can also be used in portable power applications. These systems can be used in remote locations, for emergency power systems, and in the military.
Advantages and Disadvantages
Fuel cells have various advantages over conventional power sources, such as internal combustion engines or batteries. However, they also have some disadvantages that are currently being addressed in research and development.
Advantages
Fuel cells have a higher efficiency than traditional combustion engines, and are generally quieter and less polluting. Fuel cells do not need conventional fuels such as oil or gas and can therefore reduce economic dependence on oil producing countries, creating greater energy security for the user country.
Disadvantages
The main disadvantage of fuel cells is the cost. The catalysts that fuel cells require, particularly those that use platinum, are expensive. Furthermore, durability and reliability issues are also of concern.
Future of Fuel Cells
The future of fuel cells looks promising, with ongoing research and development aimed at reducing costs and improving performance. The potential applications of fuel cells are vast, and with continued advancement, they could significantly alter the energy landscape in the coming decades.