Fuel cells differ from all previous generating devices. They do not burn fuel as such, but consume it via a chemical process (a bit like our digestive system). There are still heat losses, but none through combustion. Because of this, fuel cells are theoretically very efficient. They are almost silent and non-polluting. The only by-product is a tiny amount of pure water.
Fuel cell from Gemini space craft. Pic: UTC Power.
Originally conceived in the 1830s, their first practical use was in early spacecraft, military and big industrial applications. Fuel cells for camper trailers etc. have been touted since 2000, but claims that they would be on sale by 2006 proved to be largely marketing attempts to attract start-up capital. Few eventuated.
The first series production units arrived around 2009 – when the EFOY unit started to be used. Kimberley Kamper began offering it as an option around 2010.
Sizes are currently: 40 watts, 72 watts and 210 watts.All can charge 12 volt batteries (including LiFePO4).
The EFOY unit is claimed to need ultra-clean methanol obtainable in sealed canisters. It is sold by the fuel cell vendors. This may or may not be required, but using commercial grade fuel invalidates warranty.
Unlike generators, that use a lot of fuel even if running totally off-load, a fuel cell’s usage is more or less proportional to the energy drawn. Whilst not obvious, this is a major plus if you need it mostly for LED lighting and/or a small TV. A number of camper trailer users (who run EFOY fuel cells as a back up for solar) say that a 10 litre cartridge lasts several months.
A battery is still needed, but only to supply high current peak loads, e.g. microwaves etc. A 50 Ah equivalent starter battery, or even an 18 amp hour LiFePO4 is often adequate.
The units are now available from a number of dealers; prices have fallen but they still cost $4500 upward. They weigh 7 kg to 9 kg, are compact and produce power constantly if needed.
Fuel cell future
The short/medium term future for RV fuel cells is with LP gas and/or diesel-fuelled units. Several (from Nordic countries) are currently under development.
Hydrogen refuelling station in California (USA).
It is also possible that hydrogen may be used directly. That requires a virtual move to a world hydrogen economy and distribution network, but could well happen as oil production falls.
Honda’s Clarity FC and Toyota’s Mirai are 100% hydrogen powered. They sell in California, that now has over 40 hydrogen fuel stations across it to support them. Plans are well in hand to extend this to New York and Boston.
How fuel cells work
Fuel cells run directly from hydrogen, or indirectly from LPG, petrol, diesel or methanol that is processed within the unit to produce hydrogen.
A fuel cell’s construction is not unlike a chargeable battery. Each cell has a negative electrode (in this case the anode) and a positive electrode (cathode). It is filled with electrolyte. Hydrogen is fed to the anode and oxygen (or plain air) is fed to the cathode.
Each hydrogen atom forms a proton and an electron. Protons travel across the electrolyte to the cathode. Vast numbers of electrons (electricity) flow around the external circuit and provide power for whatever the unit is capable of driving.
EFOY 210 produces 210 amp hours a day. Pic: EFOY.
The electrons then arrive back at the cathode – where the protons, electrons and oxygen recombine and form the fuel cell’s only waste product – of pure water.
Each individual fuel cell produces around two volts. Those for RVs thus have six cells to produce the required 12 volts.
As with batteries, individual cells can be connected end-to-end (i.e. in series) for higher voltages, or in parallel to increase current, or in combinations thereof.
As with LEDs and lithium batteries, small scale fuel cells will eventuate. When they do, and at affordable cost, they are likely to drive small petrol-driven generators off the face of this planet.