Fuel cells represent the future of portable power sources, since they are able to generate the same amount of energy as normal batteries. The latest models are small enough to be installed in quite a wide range of portable devices and that issue alone is enough to give them a head start.
A very good example of such a complete fuel-cell based energy system is the H-300 from Horizon, which is capable of supplying up to 300W of power and doesn't require extremely advanced technical knowledge for the setup process. That being said, a fuel-cell still remains a fuel-cell and while you don't have to carry it around with the same caution as you're transporting an atomic bomb, it still requires some attention.
As mentioned before, the H-300 is a completely functional system which includes 60 energy cells (employing air and hydrogen as reactants), as well as a very efficient air-cooling system that maintains the device's overall temperature at around 65 Celsius degrees. And just as other PEMs, this one too is using self-humidified cells in order to keep a steady temperature.
The power module is very easy to install, since it is delivered with all the necessary electronics and control systems and all that you have to do in order to turn it on is to connect the fuel cell to the system/device in need of power, exactly like in the case of an external battery/power source. However just as any other PEM-based fuel cell, this one has specific volume which has been tuned in order to offer the best power/space ratio so if you want one, you'd better think of an adequate storage space first.
Using a PEM (Polymer Electrolyte Membrane) module, Horizon's H-300 is indeed a futuristic power supply especially if you think that unlike more conventional power sources, it doesn't cause any problems in the near by eco-system. And it doesn't kill the environment either. Unfortunately if you choose to buy it, it will leave you with an empty pocket since fuel cells have in general a very low performance/price ratio.