Photo Source: Ballard Power Systems
About Fuel Cells
A battery is an energy storage device and will stop producing electrical energy when the chemical reactants are consumed or it needs to be recharged. The fuel cell is an energy conversion device and will produce electrical energy as long as the fuel and the oxidant are fed to the electrodes. There are many types of fuel cells used in various end-use applications including transportation, industrial equipment, stationary power generation, back-up power, aerospace and defense. Various fuel cell technologies have been developed to convert many different fuels to electricity at high efficiencies.
While fuel cells were first developed in 1960’s for niche applications such as generation of power for space vehicles, a large amount of R&D has been conducted over the last fifty years and resulted in much wider use of this technology. It is now considered a “green technology” for use in many applications. Since the fuel cells can be designed to use different forms of fuel, this is one of the leading technologies for sustainable generation of power in small to medium sized industrial applications.
The Fuel Cell market and Hydrogen Fuel Cells market is relatively large and shows high growth potential. Proton Exchange Membrane or Polymer Electrolyte Membrane (PEM) fuel cells convert hydrogen and oxygen to electricity and water command a near majority market share in the Fuel Cell market. Since hydrogen can be produced from various sources, and the hydrogen fuel cells only produce water and electricity, this technology has the best potential for finding wide-spread usage in many sectors, including transportation. Honda and Toyota are already making Fuel cell powered test vehicles available in limited markets. Fuel cell companies are continuously improving technologies to provide a more cost effective catalyst, which in turn helps them to commercialize and launch products in the market. Significant efforts are also being made to develop hydrogen storage & distribution infrastructure. Due to all these efforts, the fuel cell market is likely to experience a tremendous increase in demand in the years to come.
High efficiency conversion: Fuel cells convert chemical energy directly into electricity without the combustion process. Fuel cells can achieve high efficiencies in energy conversion terms, especially where the waste heat from the cell is utilised for cogeneration.
High power density: A high power density allows fuel cells to be relatively compact sources of electric power, which is beneficial in applications with space constraints. In a fuel cell system, the fuel cell itself is nearly dwarfed by other components of the system such as the fuel reformer and power inverter.
Quiet operation: Fuel cells, due to their nature of operation, are extremely quiet in operation. This allows fuel cells to be used in residential or built-up areas where the noise pollution is undesirable.
Graphite’s Role in Fuel Cells
Graphite for this market has to meet many challenging performance characteristics before it can be used in a Fuel Cell. The traditional graphite material used in bipolar plates is usually purified using expensive hydrofluoric (‘HF’) chemical or thermal processes. Zenyatta continues to develop an innovative purification system on its unique graphite material that does not require use of these traditional and environmentally damaging processes.
Graphite is used in the bipolar plate as an electrically and thermally conductive additive. Bipolar plates, which are a major component of fuel cells, are made from high purity graphite. These plates need to be impermeable to gases, have good electrical conductivity, high strength, low weight, good resistance to corrosion and should be easy to manufacture in large quantities. Graphite must be high-grade (> 99.9% C) with low impurities with a viable, low cost purification process. Smaller amounts of graphite or carbon materials can be used in the gas diffusion layers and the membrane electrode assembly of fuel cells, as a catalyst support, as coatings for the bi-polar plates, and in solid oxide fuel cell (SOFC) components. Gas diffusion layers use high purity, fine graphite powders for controlled porosity and low electrical resistance.