SINCE GOTTLIEB DAIMLER FIRST ROLLED OFF IN A MOTORIZED CARRIAGE IN 1886, the mainstream automobile has always been powered by hydrocarbons (petrol, methanol). Refinements of the internal-combustion engine (ICE) have improved efficiency and lessened emissions to a level only a few percent of those early engines. Now, more than a hundred years later, the company he co-founded, Mercedes-Benz, has just started operations of the first global fleet of fuel cell cars: sixty A-Class cars in five cities. The payoff, in the form of commercial availability of zero-emissions cars and trucks, is expected in 15 years.
For some companies, the interim is hybrid powerplants, with an electric motor doing most of the stop-and-go duty in cities, with an ICE kicking in at higher speeds and to recharge the batteries powering the motor.
Fuel cell vehicles are a different matter altogether. For one, they don’t burn hydrocarbons, or even hydrogen. There have been experimental internal-combustion cars that use hydrogen as their fuel, but they still emit potentially poisonous gases and their efficiency is only half that of the fuel cell.
A fuel cell works by combining stored hydrogen with oxygen in the air, generating an electric current and, as a by-product, pure water. The most commonly-used fuel cell in cars is the Proton-Exchange Membrane. Think of it as a sandwich, with the thin plastic-film PEM as the ham and a catalyst coating as the mayonnaise. The bread slices are positively and negative charged plates into which gas ducts have been milled. Through these ducts, hydrogen flows on one side and air containing oxygen on the other. The catalyst breaks down the hydrogen atoms into protons and electrons. The protons can penetrate the membrane but the electrons cannot. As a result, a voltage builds up between the two electrodes. Join the two electrodes and you generate a direct current. Each fuel cell generates only a small amount of current, around 0.15 kW, so a stack of these cells are put together to generate enough power to drive a vehicle.
What about the source of the hydrogen, then? It’s extracted from water, using hydrolysis, and that takes energy. Positive and negative plates are dipped into water, and a current is passed through them. This splits the water into hydrogen and oxygen. Essentially, it’s the reverse of the fuel cell process.
Pollution-wise, there’s a right way and a wrong way to extract hydrogen. The wrong way is to use electricity generated from gas and coal. Unfortunately, most of today’s hydrogen is produced this way. The right way to do is to use renewable energy sources: solar, wind, and geothermal. Iceland, one of the first countries to commit to a hydrogen economy, uses its considerable geothermal resources to extract the element. Compare that to hydrocarbons, where, no two ways about it, storage and use in a vehicle will inevitably result in some sort of pollution.
Despite the imagery of the Hindenburg catching fire (actually due to the fabric of the airship’s outer skin and a new protective coating, not the hydrogen), the element, properly handled, is as safe as petrol or propane. The hydrogen is stored in high-pressure tanks beneath the floor, but multiple crash tests have proved them safe.
Right now, hydrogen gas is comparable in production cost to petrol. Water is the most abundant compound on our planet, so there’s plenty to go around. Transport costs, however, are ten times as much. The fuel cells themselves are not cheap, partly because they contain platinum. The platinum component has to be reduced to a tenth or less to make the technology more affordable.
Performance, although acceptable, still has to be improved to convince customers to switch to a fuel cell. With no increase in bulk, Mercedes is projecting a bump in power output from 60 kW to 120 kW, and range increased to 500 km.
Other challenges involve reliability, particularly startup in freezing conditions. This is no problem in the tropics, but in colder climates, a car that has pure water in its propulsion system will be encountering some unique problems when the mercury drops below zero.
When the fuel light starts flashing, a nearby hydrogen station is a must. Right now, this is still a problem, but Mercedes estimates that building that hydrogen infrastructure will cost less per year than what is currently being spent just to maintain the current oil-based network.
All of those developments in technology and infrastructure can occur rapidly. 1994’s NECAR 1 was a large van, and the fuel cell and propulsion system weighed 800 kg and took up all of the cargo area. Barely ten years later, the system fits under the floorboard of the miniscule A-Class. The most significant feature of this launch is that the F-Cell is not a concept car. It’s ready to run from day one on Singapore’s hot and humid streets.
There are six such A-Class cars running around Singapore, one with the government environmental agency, and one each for DaimlerChrysler and partners Michelin, Lufthansa, Conrad Hotel and BP. Another 55 are testing in other cities. The purpose is to gather feedback from real world testing in all sorts of conditions. They will be pitting their usability against Detroit’s freezing weather and Tokyo’s city traffic.
Just as younger generations have never known a world without the Internet or cellphones, in the future, children will not have known cars that are pollutants. If you have a small child, there is a distinct possibility that her first car will be powered by a fuel cell.
The implications of a hydrogen-powered economy derived from renewable sources, are enormous. No engine noise, no fumes, and perhaps best of all, no oil wars. Part of it began inside the 4-meter shell of the F-Cell A-Class.
By Jason Ang | Photos By Jason Ang
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