Portable Fuel Cells

Portable fuel cells are generally used to provide power where no electric grid is available. This includes such applications as camping, military, and exploration. Fuel cells have tremendous advantages over traditional generators including their quiet operation, high reliability due to fewer moving parts, and extended runtimes on small amounts of fuel.

There are several portable fuel cells on the market at this time. Some of them run on methanol while others run on a dehydrated aluminum compound that produces hydrogen when mixed with water. They come in several different sizes and are produced by several different companies.

Aluminum and Water

Most portable fuel cells produce hydrogen through a reaction between aluminum and water, though some run on methanol. Usually, aluminum develops a thin layer of aluminum oxide that prevents the metal from reacting with water. However, if the reaction is carried out in the presence of a base such as sodium hydroxide, the aluminum oxide layer will not be produced. Rather, the reaction will proceed in two steps. In the first step, aluminum, water and sodium hydroxide will react to form hydrogen gas as well as aluminate (sodium, aluminum, and hydroxide in a single, unstable compound). Aluminate will then breakdown in sodium hydroxide and aluminum hydroxide. The result is that no aluminum oxide is formed and thus the reaction can proceed until all of the aluminum is consumed.

1 kg of aluminum can produce up to 0.111 kg of hydrogen from water. The hydrogen is then used to produce electricity in a proton exchange membrane fuels cell. PEMFC’s can startup at room temperature and operate at relatively low temperatures, making them ideal for portable use. They have run times of up to 10 h using .3 kg of aluminum if power consumption is in the order of 10 W. At 50 W of consumption, the same cell will run for 2 hours.

Benefits of Portable Fuel Cells

At total weights of less than 1 kilogram, these fuel cells are substantially smaller than standard generators of the same production capacity. Additionally, the fuel only weighs one-third of a kilogram and is a solid powder, making it substantially easier to transport than liquid fuel.

Drawbacks of Portable Fuel Cells

The major drawback to these systems is cost. A small portable system like that discussed above costs around $400, roughly 4 times what a standard generator of that size would cost. Additionally, the aluminum fuel catalyst is relatively expensive when compared to standard fuels.