fuel cells and
|Fuel cells and battery-powered vehicles is the seventh of a series of briefing
documents on the problems of power consumption, posed by
the steady depletion of fossil fuels and most particularly
of pumpable oil.
One of a grouping of documents on global concerns at abelard.org.
|on energy||on global warming|
|sustainable futures briefing documents|
I am no vehicle mechanic, car buff or physicist. My interest is confined to the fossil fuel problems.
This subsidiary briefing document gives information on an example of a potentially non-fossil transportable fuel use. Fuel cell technology is also being increasingly used to provide small power plants for hospitals, hotels, precincts etc. This technology is scaleable.
“The automobile industry of the late twentieth century is arguably
the highest expression of the Iron Age. Complicated assemblages of some
fifteen thousand parts, reliable across a vast range of conditions, and
greatly improved in safety and cleanliness, cars now cost less per pound
than a McDonald's Quarter Pounder. Yet the industry that makes them is
overmature, and its central design concept is about to be overtaken.”
“In a hybrid-electric drive, the wheels are turned largely or wholly
by one or more electric motors; but the electricity, rather than being
stored in heavy batteries recharged by plugging into the utility grid
when parked (as is true of battery-electric vehicles), is produced onboard
from fuel as needed. This could be achieved in any of a wide range of
ways: An electric generator could be driven by an efficient gasoline,
diesel, Stirling (external-combustion) engine, or by a gas turbine. Alternatively
the electricity could be made by a stack of fuel cells—solid-state,
no-moving parts, no-combustion devices that silently, efficiently, and
reliably turn hydrogen and air into electricity, hot [warm] water, and
“[...] the trend in energy use over the last one and a half centuries
has been toward reduced carbon consumption and increased use of hydrogen.
Each predominant feedstock - from wood, through coal, then oil, natural
gas, and, ultimately perhaps, renewables - has contained more hydrogen
and less carbon than its predecessor, and each successive fuel has been
cleaner and more powerful.”
Almost all hydrogen produced industrially at the moment is obtained by reforming fossil fuel - coal, oil and particularly gas. A considerable part of the optimism for fuel cell production is to reduce pollution, as a fuel cell combines hydrogen and oxygen to form water. The water is the exhaust, just as the vast variety of filth is the exhaust from the fossil fuel industry. As present routes to obtaining hydrogen involve fossil fuels, obviously much of the filth is still generated, although it does have the advantage of being more separated from people in large conurbations. Of course, cleaning and controlling pollution in one place is more efficient, as is processing materials on a large scale rather than in many small units. In this case, forming clean fuels from fossil fuels. That is, breaking down coal, oil or gas for hydrogen at a large industrial site is more efficient than breaking petrol or diesel down in car engines.
For the future, hope lies in the more direct route of producing hydrogen from water, either by electrolysis or by high-temperature disassociation. Thus, much cleaner technologies may be used, such as windmills and nuclear power. In a nuclear power station, only about 30% of the energy is used to produce electricity. Running a nuclear power plant at higher temperatures, more of the energy otherwise wasted can be utilised to produce hydrogen through heat disassociation of water.
Thus, a recent widely used cliché: The Stone Age did not end because we ran out of stones, nor will the Fossil Fuel Age end because we have run out of oil and coal.
There many variations and hybrid versions of this type of technology, steadily moving from development towards production. The photographs and data above are from the prototype ‘F-Cell’ built on an A-class Mercedes frame. This prototype has advanced to the stage where at least seventy vehicles are on the road being beta-tested by selected drivers in everyday conditions. One of the test drivers is quoted as saying that the car reacts so quickly, that when getting away from traffic lights, he is ahead of sports cars for the first forty metres or so. He has to watch himself to avoid picking up traffic tickets.
pbk : $11.67 [via amazon.com]
Fuel cells are scalable and have a considerable range of potential applications - portable energy for electronic items such as lap tops, driving vehicles and local power plants.
The more efficient ones run on hydrogen, but transporting hydrogen has a variety of difficulties:
Therefore, reformers of various types are being developed (reformer: a device that strips out the hydrogen from the feed stock and supplies the hydrogen to the fuel cell).
For static power stations, the usual energy supply is in the form of ‘natural’ gas which can be piped, whereas for mobile units methanol is preferred.
Reformers often require expensive catalysts such as platinum.
There are problems with the life of both reformers and fuel cells [see also batteries]. Unsurprisingly, this is an area of intensive research.
Electric cars are about four times as efficient as liquid fuel-driven cars, because liquid fuel converts most of the energy into heat. This disadvantage is offset by the greater energy density available in liquid fuels relative to battery technology.
The fuel cell technology discussed above is used to generate electricity onboard. Now we come to drives using rechargeable batteries. Such batteries can be used as buffers charged as above by fuel cells, or by small liquid fuel-driven motors. Or they can be used as assist and subsidary power to a liquid fuel engine.
As you will see, a large variety of drive systems are under competitive development. These batteries can also be topped up while off-road, from the electricity mains.
As you may know from experience of car, laptop and other rechargeable
batteries, the life expectancy of these devices is not wonderful. The
large batteries (battery packs) used in electric cars can run to several
thousand dollars. For example, this
UK link quotes lightweight battery cars as running the equivalent
of 600 miles on the price of a gallon of petrol. (Remember, petrol is
more expensive in Europe - about twice the price in the USA.)
If this lives up to expectations/claims this is considerable step forward to future transport - plug-in electric charging, 250 miles range and about 0-60mph in 4 seconds!
of US oil use is for transport
Driving will be much simpler with advanced braking and transmission.systems.
Estimated battery life - 500 complete discharge cycles.
Charging is done either by using a professionally installed home charging unit, or by a portable unit, which is multi-voltage. The home charger runs at 70 amps/110 volts - this is a heavy current load, more than is required for an electric cooker, so users must ensure that their household electricity supply is not overloaded. Note that at lower amperages, for instance when using the portable charger, recharge times can be considerably longer.
The batteries will be seriously expensive to replace, so this price is difficult to come by, but see above for other battery prices.
100,000 miles of go juice in Europe will cost very roughly 10,000 euros or pounds, which is probably much more than a battery replacement cost; but more than the 1000 euros or pounds claimed for off-peak charging for the same distance. Guesses at a price for the new vehicle are currently around $100,000/£52,000, so buyers at this level are unlikely to jib at the low £1000s for battery replacement charges.
Doubtless, prices will steadily shrink as such vehicles and improved versions go into mass production. at some point this should lead to a paradigm shift. However, such expansion would result in massively expanded electricity generating requirements.
Batteries are steadily becoming lighter: lead >
nickel > lithium.
phev : plug-in hybrid electric vehicle.
The manufacturers claim these batteries require much less oversizing by virtue of their reliability and power qualities.
Several such vehicles are now claiming into the 100mpg range equivalent, togrether with high acceleration and substantial ranges.
Plug-in electricity is far cheaper than highly taxed oil prices. 70% of USA drivers travel less than 40 miles per day. Battery prices are expected to fall considerably under mass production.
Then, it will become possible to charge batteries from photovoltaic arrays on your own property, thus privatising your fuel production.
Naturally, government will be displeased to see the vast taxes from oil and their centralised systems under threat.
This proposed British car will also run on nanotechnology lithium-ion batteries. However, in this case, the technology is based on nano-titanate materials from Altairnano [4-page .pdf], where as A123Systems uses nanophosphates.
The Altairnano .pdf is an excellent introduction to problems with standard lithium-ion batteries, and the much improved performance using a nano-titanate negative electrode, in place of the more common graphite cathode. For example:
Meanwhile, a study suggesting coal to liquids is far less efficient and clean than coal to electricity, with or without sequestration, and thence plug-ins - that is, by replacing electric vehicles for ICEs (internal combustion engines).
ultracapacitors - xavier
This article, published in November 2007, is written by a team member at MIT’s Laboratory for Electromagnetic and Electronic Systems, who describes on-going improvements to ultracapacitors using nanotechnology.
One of the goals is to be able to replace car batteries with ultracapacitor power.
Other projected uses for ultracapacitors:
Similar claims from this group have been around for more than 2 years, and should be treated with caution.
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© abelard, 2006, 22 may
the address for this document is https://www.abelard.org/briefings/fuel_cells_hydrogen.php