All about Fuel Cells

It all sounds too good to be true, and so it’s not surprising there are some caveats.

Firstly, fuel cells have an optimum operating temperature range, where efficiency or even damage can occur outside of these ranges. For example, PEMFC fuel cells operate between 70°C to 120°C.

Additionally, the electrolyte membrane needs to be kept moist with a flow of water that allows re-hydration of the membrane at the same rate that evaporation is occurring due to the heat by-product of the process. This is particularly important with the PEMFC design. Too little or too much and the reaction can break down as the membrane fails. For this reason temperature also needs to be managed within the cells.

Large fuel cells are being used mostly in heavy industry at the moment.

Then there’s always the issue of durability. If a cell is to be cycled frequently – as it might in a car – it needs to handle operating outside its ideal temperate range with minimal or no deterioration, otherwise it might have a very short life expectancy.

And of course, there’s the cost, also currently the single biggest hurdle in fuel cell development. Ideally, fuel cells would find their way into everything from your car to your laptop, and indeed there are already prototype fuel cell hybrid cars available, but the technology is cost-prohibitive. In PEMFCs for example, the metal plates used as electrodes and for the fuel and oxidant to flow through; the precious metal catalysts; and the proton exchange membranes are expensive to produce.

There are also some smaller concerns – for example, while hydrogen is the most abundant element in the universe, it’s not necessarily readily available on Earth. It can be produced by separating it from hydrogen-bearing compounds, like water, but this takes energy and this cost must be factored into the overall efficiency of the cell. On that note storage and safety are also issues that are still being worked on – you wouldn’t your hydrogen laptop, or worse still your hydrogen vehicle, to explode in the event of fuel cell failure.



Then, of course, there’s one final but rather important issue – an infrastructure to produce and supply hydrogen for PEMFCs. It’s chicken and egg here – people won’t buy fuel cell cars if they can’t refuel them of course, and no company will sell hydrogen fuel if no-one is buying fuel cell cars.

Fuel cells today
Large fuel cells have seen some use mostly in industry, especially with power plants, as well some institutions like hospitals, usually as a backup or supplemental power source.

CHP (combined heat and power) fuel cells, usually powered by natural gas, have been produced targeting the home market where, although the efficiency is low, the excess heat produced is used to heat the home and generate hot water. Any power generated and not used by the home can be put back into the grid and sold back to the power company.

Then of course there are hybrid cars, for which quite a few prototypes have been developed by companies like Honda, Ford, General Motors, Toyota and Mercedes. Naturally other forms of transport are viable opportunities too, everything from planes to scooters, though we haven’t seen these yet.

And, ultimately, there’s technology – mobile phones, PDAs, cameras and laptops can all be powered by micro fuel cells. There are already a number of prototype products available, such as Samsung and Casio’s laptop fuel cells and Docomo’s mobile phone fuel cell jack in Japan – which actually splits hydrogen out of water as well! Fuel cells can be extremely small – small enough in fact to fit on a silicon die.

Again, it all comes down to cost, efficiency, infrastructure and demand. In a world looking to lessen its dependency on crude oil, investment in alternative energy sources like fuel cells is a given, and considering fuel cells are generally very green pollution-wise and can – depending on the cell – be powered by cheap sources of fuel, it’s just a matter of time before they’ll be in everything we use.