Fuel cells, which in practical applications are actually a stack of fuel cells working in parallel, use chemical energy to produce power, rather than combustion. When stacked, hundreds of fuel cells can be used as one to power devices and operations large and small.
Fuel cell technology delivers power with approximately 60% efficiency. That is about two to three times more efficient than combustion engines and about twice the efficiency of the country’s electrical grid.
One of the benefits of fuel cells is the limited number of outputs: electricity, water and heat. When fuels other than pure hydrogen are used, there may be other outputs, as the hydrogen is separated from other fuel components. Even when this is the case, outputs like CO2 and air pollutants are less than combustion engines. The heat produced by fuel cells can be captured and used to heat buildings, further increasing the efficiency of fuel cells as a power source.
Fuel cells can be used in tandem with other sources of energy, including batteries and renewable power from wind turbines and solar panels.
Unlike batteries, the chemical reaction within a fuel cell does not have a finite lifespan. As long as the cell has fuel, it can operate efficiently. Over time, efficiency will decrease due to suboptimal operating conditions. Sensitivity to fuel impurities affects fuel cell performance as well. Current research focusing on durability and affordability will reduce these concerns and make fuel cell use more widely available and practical.
Today, fuel cell technology is used for both backup and primary commercial power, transportation and smaller applications, such as portable electronic chargers.
Hydrogen is the most common element on Earth, but pure hydrogen is not widely available. Most of the Earth’s hydrogen is stored in water, which must be broken apart so the fuel cells can use the hydrogen. The same is true of other hydrogen-rich fuel options, including methanol, gasoline, diesel, natural gas, ethanol and biogas.
The conversion of conventional fuels into a usable hydrogen fuel takes place in a reformer, either before the fuel enters the cell or within the cell itself. This process releases CO2, but less than combustion engines.
How Does a Fuel Cell Work?
Inside each fuel cell, there is a negative electrode (or anode) and a positive electrode (or cathode). Between the two is an electrolyte barrier. Hydrogen is fed into the anode and oxygen or air is allowed into the cathode side of the barrier.
The hydrogen is split into electrons and protons via a catalyst. Only the protons can squeeze through the electrolyte barrier, forcing the electrons to go around the barrier, creating an electric current. On the opposite side of the electrolyte, the hydrogen’s electrons and protons combine spontaneously with the oxygen, producing water and heat.
Generally, fuel cells produce DC current, which needs to be converted to AC current before powering a home or business. This energy also needs to be conditioned before use.
With no moving parts, fuel cells operate silently. They also take up much smaller amounts of room than other clean energy generators. This makes them a competitive option for businesses without large amounts of space.
Types of Fuel Cells
Fuel cell technology includes a handful of different types of fuel cells, which vary in their materials, operating temperature, output, application, advantages and disadvantages. The amount of power generated by a specific fuel cell is dependent on their type, as well as the cell size, temperature, humidity and atmospheric pressure.