Fuel cells and their ability to cleanly produce electricity from hydrogen and oxygen are what make hydrogen attractive as a "fuel" for transportation use particularly, but also as a general energy carrier for homes and other uses, and for storing and transporting otherwise intermittent renewable energy. Fuel cells function somewhat like a battery – with external fuel being supplied rather than stored electricity – to generate power by chemical reaction rather than combustion. They typically consist of numerous small cells in layers though, rather than a single large one.

Fuel Cell Components

There are several different types of fuel cells using different catalysts (chemicals, in this case probably metals, that trigger a chemical reaction without themselves being used up by it) and electrolytes (non-metallic conductors of electrical ions, classically in a solution, but for fuel cells more likely in a solid membrane). In one type, for example, however, hydrogen fed to one catalyst-containing electrode splits to a positively charge hydrogen ion (proton) and a negatively charged electron. The positive ions travel through the electrolyte to the other catalyst electrode where they combine with oxygen fed to that electrode – and electrons – to produce water and heat. The necessary electrons are drawn through an electric circuit external to the cell, creating the electrical generation. 

Fuel Cell Component Materials

The potential benefits of fuel cells are significant; however, many challenges must be overcome before fuel cell systems will be a competitive alternative for consumers. Cost, performance, and durability of fuel cell components are key areas that need to be addressed. Vehicle systems operate more efficiently at higher temperature, however, the membrane materials used in current PEM fuel cells cannot withstand these higher temperatures. The National Renewable Energy Laboratory (NREL) is developing new specialized materials that can resist high temperatures and novel methods that can reduce catalyst poisoning.

One area of research is the evaluation of inorganic solid state proton conducting systems for high temperature fuel cell membranes. The goal of this research is to acquire an improved fundamental understanding of a class of inorganic proton conductors (heteropoly acids [HPA] and their salts) that exhibit high proton conductivity at elevated temperatures (well above 100°C) and to apply that understanding to fuel cell membrane technology. The HPA exhibit proton conductivity among the highest measured in the solid state, more than an order of magnitude higher than Nafion. The ultimate goal is to develop HPA-based composite materials that can be combined with polymers and other potential supports to manufacture thin films as membrane materials for use in fuel cells.

The second area of research is the evaluation of corrosion protection of metallic bipolar plates for fuel cells. The goal of this research is to investigate and develop metal bipolar plate materials and coatings that are low-cost, lightweight, corrosion-resistant, gas impermeable, and amenable to mass manufacturing. NREL’s experience in conducting oxides, which have been used in various types of solar cells, and expertise in corrosion testing are the foundation of this effort. Based on this experience, possible suitable materials (i.e., offer appropriate corrosion protection and give high conductivity) for this application include tin oxide, indium tin oxide, and zinc oxide.

List of Hydrogen Fuel Cell Cars:

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