The practical fuel cell

A revolution in on board charging is on its way

Thursday February 1st 2007, Author: James Boyd, Location: United Kingdom
Rarely is there wholescale revolution in our sport, but one admittedly fairly niche area where there is set to be considerable change is in the electrics systems on offshore race boats. Firstly there has been the advent of high efficency lithium-ion batteries as the modern day hi-tech replacement for conventional lead-acid ones. A substantial bank of these for example is being fitted to the new 182ft Eco-superyacht Ethereal, Ron Holland has designed for owner and co-founder of Sun Microsystems, Bill Joy. These will power not only the electrics but also the engine of this giant yacht. On race boats Li-Ion batteries are compact and lightweight and more robust than conventional batteries and retain no charging 'memory'.

A more recent development is on the charging side, with the advent of fuel cells. These come with significant benefits over conventional diesel generators. For readers not up to speed with this Star Trek-sounding technology, a fuel is similar to a battery, except that where batteries are for the most part 'closed cell' (ie what's in there doesn't change until the cell runs 'out of juice'), a fuel cell requires a regular supply of fuel for its anode and 'oxidant' for its cathode - imagine a replenishing battery. While anode and cathode are constantly refuelled, a fuel cell also contains a fixed electrolyte just as a conventional battery has.

We'll spare you the explanation of how fuel cells work at an electron level, except to say that they do work but in a slightly different way - they are more efficient the less current is applied to them. While typical lead-acid battery cells produce 1.5v, an individual fuel cell will produce 0.86v, and so like conventional batteries they tend to be clustered to output in the region of 30-50v.

There are significant benefits of charging batteries from a fuel cell over a conventional diesel generator on a race boat. Firstly there is weight. A typical 5KVA diesel generator weighs around 170-180kg and it is recommended that this is fitted with an anti-vibration base place weighing another 100kg. In comparison an equivalent fuel cell weighs just 50kg and no antivibration plate or dampening is needed because the fuel cell, like a battery, has no moving parts. No moving parts should also allow the fuel cell greater reliability compared to its mechanical competition.

Fuel cells have been around for some years - the principle was conceived in 1839 but working units of any usable size only came into existence in the 1950s and were subsequently used in the US Space program - but it is only in the last few years that they have become in any way of practical for the average user, due to the inconvenient products required as 'fuel' and 'oxidant'. Typically off the shelf, commercially available fuel cells today run on mentanol, but although this has a high 'energy content' it tends to produce a dirty and fairly toxic exhaust emissions.

Fortunately this is soon to change thanks to the efforts in developing new fuel cells made by Voller Energy Group plc. This Basingstoke-based company have been in the fuel cell business since 2002, and at present sell a neat portable 100w generator that runs on hydrogen. However, as Mark Tilley, from Voller acknowledges, this is not a fuel that readily available in the marine world.

A development coming on line this year from Voller is a 1KW generator capable of running on the more available Calor Gas, propane or LPG. And in 2008 they will be launching a new fuel cell that uses diesel making it ideal as a retrofit for yachts, already fitted with diesel tanks.

A significant benefit of fuel cells over mechanical generators is just how efficent and eco-friendly they are. "If you ran a typical 5KVA diesel generator for 4.8 hours, you could run the fuel cell for 200 years and get the same emissions," states Mark Tilley. Fuel consumption is equally impressive - this size of diesel generator will run £1.30 per hour of red diesel, compared to £0.30 per hour for the fuel cell.

The cleanest examples are the hydrogen fuelled ones where the exhaust is quite literally H2O, water. Gases such as LPG are relatively dirty in comparison, but still a whole lot better than a converational diesel generator, says Tilley. "LPG is a hydrocarbon so you have got lots of horrible things left over and that is where Voller are reasonably clever in that with all those carbons and hydrocarbons and sulphurs, we combine them through a number of stages with oxygen and eventually we emit just CO2, the same as a person breathes out. So it is as clean as clean can be."

For the cruising market fuel cells come with the added advantage that they also inherently emit heat and this can be harnessed up to a yacht's heating system or for making hot water. The Voller LPG fuel cell generator, using cells bought in from a manufacturer in Canada, naturally produces DC of between 32 and 52v, however it comes with an integral inverter turning the output to AC.

One can imagine the relative joy of using a fuel cell compared to a traditional generator on a round the world race boat. Typically generators are run for 1.5 to as much as four hours a day and and in the confines of an Open 60 saloon they are noisy, vibrate considerably and are generally smelly. In comparison a fuel cell is silent, has no vibration and only emits CO2. For sail boats the fuel cell requires no water inlet so installation is easier and is speced to operate at up to 35degrees of heel compared to 25degrees for a conventional generator.

Initially Voller's 5.5KVA fuel cell generator, when it comes available will cost around £12,000, a third more than an equivalent diesel generator. However Mark Tilley points out that this comes with a modest heater and water heating capability a traditional generator will not have. Two years down the line, once fuel cell prices have dropped some more, Tilley reckons the price of their kit will be down to a comparible level with that of diesel generators.

At present prototypes of the LPG fuel cells are already being trialled by the miltiary and in construction industry. However these versions are bulky - around 1m high. Tilley says that once into production they will be around half the sizes. Prototypes are also being fitted to a couple of yachts that will be used as trial horses over the course of this season, priority to the commercial launch of the product in November.

While a fuel cell sounds like a sophistic technology one wonders how robust it will be and how it would stand up to being crashed about on a round the world race. "I don’t think it will be fragile," says Tilley. There are no moving parts which must be a benefit, also: "The cell itself is just a bunch of membrane, like a bunch of filter papers in really simple terms."

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