The durability of a fuel cell is largely connected to how often it's powered on and off. The constant cycle of heating and cooling can take its toll on the parts of a fuel cell. The solid oxide fuel cell (SOFC) runs at extremely high temperatures, but improves its durability by not powering off. As long as an SOFC maintains its high temperature, there is less mechanical wear on the parts than if they constantly heated up and cooled down.
One of the most exciting and promising types of fuel cell is the polymer exchange membrane fuel cell, or PEMFC. Some predict that it will be the PEMFC that will ultimately be the type of fuel cell used to power vehicles. However, in order to be a viable alternative to a gasoline-powered engine, the PEMFC has to be able to weather the difficult conditions of the car itself and the weather outside.
A PEMFC works by forcing atoms of different charges through a membrane layer. So these membranes must be able to operate at 212 degrees Fahrenheit (100 degrees Celsius), as that is the target temperature at which a fuel cell can best handle impurities in the fuel. However, since cars are turned on and off so frequently, researchers must find a way to keep the membranes at a relatively stable temperature to improve durability.
Their durability is also challenged in low, particularly sub-freezing, temperatures. The membranes need to stay hydrated in order for the flow of hydrogen protons to continue. Once temperatures get below even 176 degrees Fahrenheit (80 degrees Celsius), the membranes start to lose some hydration. As fuel cell membranes lose hydration, they begin to lose energy efficiency. So the fuel cell requires a high-pressure hydration system in order to stay properly hydrated.