LIM TECHNOLOGY

Fuel cell technology has emerged as a promising new means for generating power. Fuel cells produce electricity from the chemical reaction of hydrogen and oxygen. A typical fuel cell consists of a cathode (negatively charged electrode), an anode (positively charged electrode), an electrolyte and an external load. Since fuel cells are charged by gasoline, methane, methanol, or hydrogen through "reformers," they can provide constant output of electricity, given the supply of fuel. This feature distinguishes fuel cell from conventional batteries which necessitate interruption for recharge. The primary fuel source for the fuel cell is hydrogen, which can be obtained from natural gas, coal gas, methanol, and other fuels containing hydrocarbons.

The fuel cell was invented by Sir William Grove in 1842. The technology advanced slowly until 1960's, when GM produced the first applicable fuel cell providing on board electric power for Gemini and Apollo space capsules. Recent decades have seen large-scale research in fuel cells. Until very recently, it was expected that the first commercially-available fuel cell vehicle could come into the marketplace in 2005. This is no longer a credible belief.

There have been significant breakthroughs in fuel-cell technologies in the past years. These technologies hold the promise for cleaner, high fuel efficient and quieter operation of cars. Their benefits are considered to be extraordinary:

Namely, 40% fuel efficiency versus 16% of the conventional internal combustion vehicles. Unlike internal combustion, fuel cells are not limited by the Carnot cycle. Moreover, fuel cells essentially have no moving parts, and thus eliminate mechanical friction.

Fuel cells are environmentally clean. The only emission from fuel cells is warm water. They are quiet; practically all the noises of a fuel cell vehicle are only from the air compressor. Fuel cell powered vehicles may have no transmission, so may provide more interior room and design freedom. Without moving parts, fuel cells requires no oil lubrication and general maintenance is little needed.

Extensive research has been devoted to the fuel cell vehicles. One pivotal technique is to produce hydrogen gas. If the pure hydrogen gas is used, it must be compressed to liquid to ensure sufficient high energy density. However, storage of liquid hydrogen encounters severe technical difficulties as special insulated containers must be created to contain the super-cold (-423 F) and extremely higher pressure liquid hydrogen. An alternative way to obtain hydrogen gas is to use a reformer to retrieve hydrogen from hydrocarbon fuels. Research has been conducted on the conversion of methanol and gasoline to hydrogen. Both methods have striking advantages as well as considerable disadvantages. Steam reforming is the leading design for converting methanol. The simplest form of methanol reformer provides the lowest-cost and smallest engine.

Unfortunately, the methanol system is not designed to handle contaminants and additives. Another concern is methanol's corrosiveness and its affinity for water. Thus, it cannot be distributed through the established infrastructure. The major advantage of gasoline-based fuel cells is that they can utilize the present production and distribution infrastructure. This advantage yields marked benefits in fuel availability and infrastructure investment costs.

The gasoline converter is necessarily more complex and expensive, but it is more tolerant of contaminants and additives contained in the fuel. In addition, due to the high energy density, the gasoline system offers twice the vehicle range for the same volume of fuel as the methanol system, just as with conventional internal combustion.

Nonetheless, application of fuel cells to vehicles are limited by several factors, and some concerns must be removed before fuel cell powered vehicles could competitively be in dealer's showroom.

Though fuel cell companies claim 40% fuel efficiency, complete analysis must be made on the "well-to-wheel" basis. This means that the measure of vehicle efficiency must be extended backwards, taking into account all the costs of refining the source fuel to the fuel cell reformer ready product which a consumer would need.

It is known that gasoline-based fuels can retain 85% of the energy contained in the crude oil, whereas natural-gas-based methanol could only hold the manufacture and distribution efficiency of about 63%. The production of methanol from coal is even less efficient, roughly at 54%. Further, even improved reformer could still account for 15% loss of the potential energy in the gasoline. The conventional electrolysis process in the reformer could lead to many times more energy loss. Therefore, the resultant "well-to-wheel" efficiency of the methanol fuel-cell system would be only 23%.

It is noted that today's new technologies in internal combustion engines could also significantly enhance the fuel economy and provide reduced levels of emission. Lighter materials, variable valve timing, advanced control on direct injection etc. allow the "well-to-wheel" efficiency increased to more than 30%. Thus, the efficiency improvement of even the gasoline-based fuel cell over the internal combustion engine is fairly small. And even though almost everyone is concerned about the ecology, most families and businesses have to measure the benefits of vehicle use and ownership against the cost both of the capital equipment and the fuel.

Fuel cells today are expensive. The reformer turning hydrocarbon fuels into hydrogen is costly to manufacture. Some high-temperature fuel cells can directly process non-hydrogen fuels, but such devices are still expensive and can be degraded and destroyed more easily.

LIMited energy density is another problem. A moderate-size car needs 100KW per kilogram for its acceleration. However, fuel cell cars that are economical to produce can only generate half that efficiency. Thus, to date, application of fuel cells are only restricted to light duty vehicles. It would seem obvious that more expensive light duty vehicles will not satisfy the broader market.

As to emissions, the reformer or fuel processor, which furnishes hydrogen to the fuel cell, can produce a significant amount of carbon dioxide, though the fuel cell system gives off much less pollution in comparison with conventional internal combustion engines. Carbon dioxide is considered to be a major contributor to global warming. Moreover, reformers can still emit small amount of regulated pollutants, like carbon monoxide. Thus, the zero-emission standard is not met by fuel cells.

In addition, continuous efforts must be made to increase the lifetime of fuel cells in order to make them competitive with the current quality internal combustion engines.

In summary, the fuel cell powered vehicle may be a promising emerging automotive technology. It claims many valuable benefits, but still has severe technical difficulties to overcome. Comparison of fuel cells with internal combustion engines should take account of the likely future advancements in the latter. Furthermore, "well-to-wheel" analysis is necessary to evaluate the ultimate fuel efficiency. In our eyes, in reality, combustion-engine cars will continue to dominate the market for many years, while fuel cell powered cars that can tolerate various fuels will be built.

It is noteworthy that in Europe gasoline has been increasingly replaced by Diesel, which offers at least a 30% improvement in well-to-wheel energy cost. Recently, LIM Technology in Maryland, USA, invented a novel two-stroke engine that does not require major investment in infrastructure. Very good "well-to-wheel" efficiency has been demonstrated by using Diesel fuel. The obtained high efficiency is attributed to its unique simpler structure. The idling fuel consumption can be reduced by 55%-70%. Moreover, the lighter engine allows the weight cut in the other systems of the car, like engine mount, chassis, rims, and axles, such that additional fuel can be saved.