Tech Talk...
Are fuel cells the future?
On the face of it, they tick all the boxes. Efficient, environmentally friendly, and compact,
fuel cells look like the right technology at the right time. So why have they yet to
establish themselves as propulsion units on boats? Duncan Kent traces their history
and development, explains how they work – and weighs up the pros and cons.
E
very now and then we hear HOW THEY WORK expensive.
rumblings about how some PEMs were used
super ‘Fuel Cell’ is about to PEM fuel cells work with a by NASA in the
revolutionise our lives, completely polymer electrolyte in the early days of the US
eliminating vehicle pollution and form of a thin, permeable space program and
allowing them to do 1,000mpg or sheet, which is small and are currently being
more. Well, despite loud noises light, and works at low applied to satellite
from the research departments temperatures (around and submarine
of the larger car manufacturers, 80ºC). Models using other technology. But prices
are Fuel Cells a practical reality electrolytes can reach are falling every week
and could the technology be temperatures as high as and new, more efficient
transposed into the marine 1,000ºC. models are being
environment, both for energy To speed the reaction, developed for terrestrial
generation and propulsion? platinum is employed as a catalyst and marine vehicles.
The simple answer is – yes, on both sides of the membrane. For the fuel cell Each year the giant
they most definitely could – but at Hydrogen atoms are stripped of to work, the proton exchange oil company, Shell, holds
a cost. Currently there are several their electrons at the anode and membrane electrolyte must an ‘Eco-marathon’ in which land
different types of fuel cell being the positively charged protons allow hydrogen protons to pass vehicles strive to achieve the
tested in labs all over the world, diffuse through one side of the through, but prohibit the passage most astounding fuel economies.
the most developed of which is porous membrane and migrate of electrons and heavier gases. Last year’s competition had
probably the Proton Exchange toward the cathode. The electrons The efficiency for a PEM cell the winning vehicle (albeit a
Membrane (PEM) system, which is pass from the anode to the reaches about 40 to 50 per 25kg tricycle) travelling a quite
already available to buy in ‘stacks’ cathode through an exterior cent and an external reformer is astonishing 3,198km/ltr of ethanol
that can provide up to 1.2kW of circuit, providing electrical power required to convert fuels such as – (yes, that’s 9,033mpg) – using
electrical energy using methanol along the way. At the cathode the methanol or gasoline to hydrogen. a Heliocentris 1.2kW Nexa fuel
or petrol as a fuel. Units producing electrons, hydrogen protons and stack. Boy do I want one of those!
up to 250kW are currently under oxygen from the air combine to WHERE IT ALL STARTED This technology, combined with
development. form water. modern solid-state ring-motor
Surprisingly, PEM technology was developments, means it is now
first invented at General Electric in quite possible to produce a drive
the early 1960s, through the work system capable of propelling a
of Thomas Grubb and Leonard small to medium sized sailing boat
Niedrach. GE announced an initial at hull speed, silently and using
success in mid-1960 when the a fraction of the fuel that would
company developed a small fuel be required to run a diesel engine
cell for a program with the US – even one that is part of an
forces. The unit was fuelled by efficient hybrid diesel-electric drive
hydrogen, generated by mixing system. The drawback, however,
water and lithium hydride, and is the initial cost which means
was contained in disposable that, at the moment, they come
canisters that could be easily out two or three times the price of
supplied to personnel in the a conventional power plant but if
Fuel cells have already been used on small boats, some running on hydrogen, some
field. The cell was compact and their popularity increases, naturally,
on methanol but more sophisticated power plants are planned – like this one.
portable, but its platinum catalysts that could change significantly.
58 Sailing Today July 09
ST147
TechTalk_HybridrRTG.indd 54 15/5/09 12:26:49
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