They come in all sizes, and will be used for everything from micro-appliances to tools and appliances, to home power units, to car power units, to building power units, to utility power plants. Fuel cells will power ships at sea and colonies in space. Fuel cells today are expensive to manufacture and depend on ongoing technological innovations to ensure their eventual economic viability. This device reformulates non-hydrogen fuels such as gasoline, methane, etc., to turn them into hydrogen. This problem is being overcome but progress is slow.
Reformers are still very expensive.
Some of the higher temperature fuel cells can actually directly process non-hydrogen fuels, methane, gasoline and ethanol, without using the reformer. This can degrade and destroy lower temperature fuel cells, as well as high-temperature fuel cells using earlier technologies. And high temperature fuel cells that can directly process non-hydrogen fuels are still expensive, too. Nothing simple here. Imagine when the next wave of consumer electronics hits.