A fuel cell uses the chemical energy of hydrogen or other fuels to cleanly and efficiently produce electricity. If hydrogen is the fuel, the only products are electricity, water, and heat. Fuel cells are unique in terms of the variety of their potential applications; they can use a wide range of fuels and feedstocks and can provide power for systems as large as a utility power station and as small as a laptop computer.

 

Fuel cells work like batteries, but they do not run down or need recharging. They produce electricity and heat as long as fuel is supplied. A fuel cell consists of two electrodes—a negative electrode (or anode) and a positive electrode (or cathode)—sandwiched around an electrolyte. A fuel, such as hydrogen, is fed to the anode, and air is fed to the cathode. In a hydrogen fuel cell, a catalyst at the anode separates hydrogen molecules into protons and electrons, which take different paths to the cathode. The electrons go through an external circuit, creating a flow of electricity. The protons migrate through the electrolyte to the cathode, where they unite with oxygen and the electrons to produce water and heat.

 

Hydrogen Fuel Cells

Hydrogen fuel cells use hydrogen as an input fuel.  Hydrogen fuel cells emit only water, addressing critical climate challenges as there are no carbon dioxide emissions. There also are no air pollutants that create smog and cause health problems at the point of operation. Fuel cells are quiet during operation as they have few moving parts.

 

However, hydrogen is currently very expensive, and difficult to transport and store.  As hydrogen is a very small molecule and is very corrosive, it can easily leak in pipelines.  Currently a hydrogen distribution system does not exist. As such, the economics for hydrogen fuel cells is challenging.

 

Solid Oxide Fuel Cells

There are many types of fuel cells, but they all share a single common design and process: a negative electrode (an anode) and a positive electrode (a cathode) sandwiched around an electrolyte undergo an electrochemical reaction to produce an electric current. The electrolyte is an ion conductor that moves ions either from the fuel to the air or the air to the fuel to create electron flow. Electrolytes vary among fuel cell types, and depending on the electrolyte deployed, the fuel cells undergo slightly different electrochemical reactions, use different catalysts, run on different fuels, and achieve varying efficiencies.

 

For decades, experts have considered solid oxide fuel cells (SOFCs) to hold the greatest potential of any fuel cell technology due to their extremely high electrical efficiencies and low operating costs. In fact, SOFCs are likely to emerge as the fastest growing fuel cell segment over the next six years.

 

Unlike a hydrogen fuel cell, a solid oxide fuel cell does not require hydrogen storage.  Rather, a SOFC can utilize a methane stream such as natural gas or propane. The hydrogen is separated under high thermal conditions and fed into the fuel cell.  

 

As a result, SOFC’s can generate heat and power so long as the methane input stream is available.  Fortunately, the natural gas distribution system is well established.