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Alternative Fuels
Demand for gasoline has been the driving force in utilization and depletion of crude petroleum, which is a non-renewable resource. In recent years, tendencies have just begun to, at times, favor alternative fuels to power autos. Many possible alternative fuels exist, certainly not without their drawbacks. These alternatives include, but are not limited to, alcohols, gasohols, and both liquefied and gaseous natural gas, as well as hydrogen. As mentioned above, drawbacks do exist; the chief drawbacks being cost of adaption implementation, engineering, and cost of the fuels themselves. As stated by many a chairman of petroleum companies, alternative fuels have limited applications and too many economic disadvantages, (Derr, 30).

"Although alternatives to gasoline may have some very limited niche applications in efforts to reduce air pollution, they have too few environmental advantages and too many economic disadvantages to justify the high expectations that some regulators have of them." Quote from a speech given by the chairman and CEO of Chevron in 1994, (Derr, 30)

It seems that some automobile manufacturers may have a similar opinion. "The automobile industry is deliberately trying to sabotage electric and natural gas vehicles," (Savage 7). However, these two industries are not in the majority as low cost alternatives are constantly being developed by engineers in the United States and Europe. These industry giants also may soon have no choice but to explore and diversify into more alternative fuel options as they have done in Brazil, (Grammer, 10). Emissions standards are growing stricter throughout the States, especially in California where a percentage of cars sold must be zero emission vehicles. Concern is also growing across the Atlantic in Europe:

"According to recent findings in the U.K., the pollutions in vehicle emissions cause a range of illnesses and are the main source of atmospheric contamination. The U.K. government has been urged to double the real price of petrol, triple the use of public transport, and halve the size of its current 19 billion roads program by 2005. The findings have raised interest in possible alternative fuels," (Cavenagh, 15).

These alternatives involve modified internal combustion engines, ICE's, modified fuel delivery systems, as well as advancements in the field of electrical storage capacities. This paper will attempt to discuss the many advancements in the field of automobile alternative fuels, reduced and zero emission vehicles, and fuel delivery and ICE modifications producing reduced emissions. Positive and negative aspects to implementation will be discussed as well as an analysis made on whether the alternative approach is feasible on a mass production scale.

There have been many advancements in reducing emissions of gasoline and diesel powered vehicles. Every month we hear of another vehicle running on petroleum fuels, reducing emissions, and increasing efficiency. "Direct diesel injection into ICE cylinders increases mileage by 20%," (DiChristina, 43), for example. Also, ozone precursor release in the 1960's was on average 324 lb/Yr., whereas now it is 21 lb/Yr. In 2001 it is expected to be 12 lb/Yr., a 96% improvement (Derr, 30). But this paper is examining non-petrol fuels. There are also many advancements in the non-petroleum field, as well as advancements in engines burning gasoline in addition to other fuels such as alcohol, and various combustible gasses such as butane, propane, methane.

"Martin-Marietta Energy Systems Inc. of Oak Ridge, Tennessee, has developed a magnetohydrodynamic engine that converts the chemical energy of liquid or gaseous fuels into variable-frequency alternating-current electrical power. Nicholaos Pahis of Vernon, Connecticut, has developed a rotary internal combustion engine with an inherently balanced 8-cylinder design that ingests a constant air/fuel mixture. SSI Corporation of Atkinson, New Hampshire, has developed a computer-controlled engine that operates intermittently, driving a fixed-volume hydraulic pump/motor," (Lynch 66).

Shown above, an ICE is no longer required to power a vehicle. In the November issue of Popular Science, a fuel delivery system was overviewed; developed by an Italian auto maker, it uses an existing gasoline ICE, but adapts the fuel tank and fueling port to accept propane, methane/natural gas, and gasoline. The tank can be running low on gasoline, and the car fueled with natural gas or vice versa! Natural gas is an alternative fuel with the added bonus of cleaner and more complete combustion and thus emissions of carbon dioxide and water as opposed to hydrocarbons. Natural gas does seem a promising alternative. Currently there are an estimated one million natural gas vehicles in service, many of them used by natural gas companies, as city busses, and 250,000 of them used in Italy alone (Birch, 26). A CNG (compressed natural gas) vehicle currently emits less toxic fumes than do gasoline powered vehicles. For comparison, a CNG vehicle emits 8 lb/Yr. "ozone precursors," (Derr, 31). CNG vehicles are one of the most viable alternative options in the U.S. due to our country's huge supply of natural gas which could power autos for decades to come (Reed, 74). Also, natural gas would be cheaper to purchase than gasoline (Moore, 92). As of 1999, there were an estimated 30,000 NG autos in use in the U.S. (Reed, 74) The natural gas option is certainly not without its drawbacks. The most significant drawback would be a retrofit of existing vehicles with high pressure tanks. Retrofit costs are estimated to be $1500 to $3000 by Gene Moore, a fleet manager in Sacramento, California (Moore, 92). New CNG vehicle cost, detailed by Kenneth Derr, CEO of Chevron, in a speech, and estimated by the the U.S. Department of Energy, is $2500 to $5000 more than a "conventional car," (Derr, 31). "Natural gas needs to be highly compressed and requires a special high-pressure fueling station," (Moore, 92). "Natural gas fuel is stored on the vehicle in either compressed or liquefied form." CNG autos store at 16 to 25 MPa, and LNG's (liquefied natural gas vehicles) use pressures of 70 to 210 kPa and -160 C (Reed, 74). However, this installation of high pressure fueling stations is not an unrealistic idea; for example, Italy's countryside is inundated with high pressure natural gas fueling stations for their 250,000 natural gas powered automobiles. Many Italian citizens with CNG vehicles purchase compressors so that they may fuel their vehicles overnight. In the U.S., "natural gas utilities are expanding the infrastructure of delivery systems to make their fuels more available," (Valenti, 42). Finally, as required by law, many company fleets are converting or have converted to CNG fleets, proving that the change is indeed possible (Kisiel, 3). This renewable energy approach is feasible.

Propane, or LPG (liquefied petroleum gas) is one other option similar to CNG but with less viability (due to vehicle manufacturers not for technical reasons). LPG has been used in vehicles since the 1920's and powers nearly 500,000 vehicles in the U.S. (Moore, 93), over 350,000 vehicles (Reed, 74). Conversions to LPG powered vehicles peaked in the early 1980's due to the gasoline price increase, (Reed, 74). Benefits include the benefit of reducing CO and hydrocarbon emissions, and the fuel is readily available in regions with natural gas or petroleum refining industries, (Reed, 74). "There is a substantial infrastructure in place and advanced technologies for storing and dispensing LPG," (Moore, 93). The cost of storage devices is also less for LPG than for CNG, or LNG, (Moore, 93).

Propane does however have its disadvantages. It does not burn as cleanly as CNG. "In addition, propane vapors are heavier than air and tend to collect in low spots in explosive concentrations. Vehicle collisions that cause leaks might create dangerous situations quickly," (Moore, 93). Finally, retrofitted propane vehicles are void of warranty by all manufacturers, (Moore, 93). Until LPG vehicles are made attractive to the consumer, they will never catch on; however, certainly a cost-effective LPG vehicle seems feasible.

The next category of proven viable alternative fuels are alcohols, specifically methanol and ethanol both obtainable from petroleum and natural (biomass) sources, many domestic resources, fossil and renewable resources, natural gas, and coal, (Reed, 74). "Replacing gasoline with pure methanol or natural gas as fuels could cut ozone levels by as much as 40%," (O&GJ, 24). Methanol has certainly proved that it is a desirable fuel whose combustion products are much less harmful to the environment than those of gasoline. Methanol also has many other positive aspects of use both for the environment and for conversion of current vehicles to run with it as fuel. There have been many arguments against methanol; however, technology has rendered many of these arguments null. Methanol first does have the best potential for widespread use of all of the other fuels. A methanol powered vehicle is "fundamentally the same as a gasoline powered car," (Moore, 93). Fuel-flexable vehicles that automatically adjust to operate on alcohol fuels, gasoline, or combinations of both are excellent choices for methanol fuel use. These type of vehicles are excellent since they allow a consumer to still use gasoline if areas of the country are lacking in methanol distribution systems. These type of vehicles have already been tested, as have many of the others mentioned, in California where 1000 are currently in use, (Reed, 74). Ford, Chevrolet, and Volkswagen have been the leaders in fuel-flexable vehicles in the U.S., and Brazil which once fueled its vehicles primarily with ethanol, (Moore, 93). Methanol also has a 100% octane rating and results in lower overall emissions and higher energy efficiency than gasoline fueled vehicles, (Reed, 74). Finally, in a bold move by General Motors, in 1992, Chevrolet began taking orders for Chevy Luminas running on 85% methanol, 15% gasoline, (Frame, 1). Methanol has had its drawbacks, which petroleum companies have fought to make known, but as before, many of these drawbacks have found simple solutions with today's technology. The main problems involve aldehyde emissions, cold starting, low energy density, and corrosiveness. Aldehyde emissions, specifically acetaldehyde, occur with the incomplete combustion of alcohol, which is inevitable in an ICE. In high concentrations, this chemical can cause skin and eye irritations along with serious lung damage, as stated again by the CEO of Chevron, Mr. Derr. The chemical also has an offensive odor and harms vegetation. In the U.S., its concentrations may not exceed 360 mg/m3. Acetaldehyde though, is dissimilar to gasoline combustion products in that it cannot remain in the atmosphere long, "it quickly combines with other substances and is rendered inert," (Grammer, 12). Also, a simple catalytic converter can be added to the tail pipe as it already is with gasoline fueled vehicles, eliminating acetaldehyde emissions altogether. This has yet to be done in Brazil. Cold starting is also a drawback to alcohol fuel as alcohol has a higher vaporization temperature than does gasoline, (Grammer, 12), and it has a lower calorific value than does gasoline, (Mazzone, 59). Two solutions have been implemented to solve this problem. Originally the idea was to heat the fuel before combustion when the temperature drops, circa 1980, (Grammer, 12). Two solutions have grown from this hypothesis. The first solution was implemented in Brazil with pure ethanol vehicles which can run on either pure ethanol or pure methanol. "The system squirts a bit of gasoline into the air/fuel mixture to get the engine started. From then on, the alcohol takes over," (Mazzone, 59). The second recent solution uses "a hydrogen and carbon monoxide gas mixture produced by decomposing liquid methanol using a submerged electric arc," (Sethuraman, 157). "The device proposed has the ability to produce up to 0.01 m3/Min. (10 l /Min.) of gas with a thermal efficiency of 18% relative to the theoretical energy requirements for cracking methanol to carbon monoxide and hydrogen," (Sethuraman, 157).

Corrosiveness has been a severe drawback to methanol use, but this too has a solution. In 1981, Volkswagen began coating the fuel tank, pump, and carburetor with a bronze, copper, or cadmium coating. Other engine parts were chromed or aluminized, (Mazzone, 59). In 1993, a parylene coating of seals and gaskets with elastomer-containing components has proven to help prevent their deterioration when exposed to alcohols in the engine, (Pyle, 78). Parylene coatings were tested with a range of aggressive alternative fuels by soaking samples in the fuels for 168 hours at 158F, (Pyle, 78). Modifications to methanol vehicles or fuel-flexable vehicles include the following, "instead of a carburetor, new engines use vaporizers which inject atomized alcohol fuel into a chamber [modern fuel injectors] mixing its water content in the alcohol [more uniformly]," (Mazzone, 59). Vehicles running on 100% alcohol and no gasoline can have water included in the alcohol. Fuel-flexible vehicles running on a alcohol and gasoline blend use use anhydrous alcohol, (Grammer, 10). GM has adopted the following modifications to all alcohol burning vehicles. A stainless steel fuel tank, flame arrestors to prevent ignition of methanol vapors in fuel tanks of their new VFV, (variable fuel vehicle). This vehicle can operate on 100% alcohol, 100% gasoline, or any combination in between. Stainless steel multipoint fuel injectors for greater flow of methanol, an oxide coated, anodized fuel injector rail conveying fuel from hose to injectors, a high output fuel pump, high fluorine fuel hoses to resist chemical activity, anodized fuel pressure regulator housings to increase alcohol flow, and a fuel sensor, again for VFV's, to determine the mix of methanol, ethanol, and or gasoline to ensure proper and optimum air to fuel ratio, (O&GJ, 24).

Finally, again a limiting factor is the distribution system in the U.S., hailed as an excellent reason not to convert to methanol. Brazil did it in just 10 years, most of that conversion taking place in one year, so this argument is not viable. Currently there is no reason to install alcohol pumps because of the lack of alcohol powered vehicles, (Mazzone, 59). Methanol certainly is a feasible alternative fuel.

Ethanol, which is very similar to methanol, can be used in all of the same ways as its close cousin, with all of the same drawbacks and advantages. The only differences to discuss are production of ethanol versus methanol, and drawbacks concerning this process. Brazil has been powering vehicles with ethanol since the seventies. The decision was made to switch from gasoline to ethanol quickly by the government due to rising cost (1973) and dependence on gasoline importation, (Grammer, 10). Any argument that a conversion to alcohol fuel would be too difficult, or too expensive need only look at Brazil who made the conversion in less than one decade. Drawbacks? Yes, the first being cost. An ethanol powered vehicle is on average 10% more expensive than a gasoline powered vehicle. This 10% difference can be offset by the government in tax incentives as it has been in Brazil. Cost of converting existing vehicles to a VFV fuel is $250 in Brazil. Ford sells kits in Brazil at this price for just such a purpose, (Grammer, 11). Pollution is another problem. Pollution not from the ethanol combustion, but from the ethanol synthesis. Sugar cane is the ethanol producer in Brazil, and it must be fermented to produce ethanol. Any sugar containing vegetable can be used, for instance, sorghum, sugar beets, cassava, corn, eucalyptus, and potatoes, (Grammer, 10). In Brazil, "one ton of sugar cane not only produces 18.5 gallons of alcohol, but also 240.5 gallons of vinasse and 594 lb of bagasse." If these byproducts are discharged into the rivers of Brazil, in less than four years, "one quarter of the world's freshwater system could be killed," (Mazzone, 60) These byproducts need not and are not discharged to water though. Vinasse is concentrated and used as animal feed and as a fertilizer. Bagasse is piped right back into boilers to fuel the ethanol distilleries; thus one byproduct is used as food and the other as fuel, leaving no byproducts, (Mazzone, 60). A Brazilian land owner with more than 60 acres can produce enough cane to produce electric for his house and fuel one vehicle, (Grammer, 12). All byproducts can be used to fertilize crops and power the home plant. Ethanol is certainly a viable and feasible alternative fuel in Brazil, but is it in the U.S.? Not as much so as methanol. The U.S. is incapable of producing crops to the needed extent to fuel all of its vehicles on ethanol alone as in Brazil. Blended fuels are a possibility, and already the fuel we buy contains 10% or less ethanol. Gasohol, as it is called, already allows the U.S. to save two gallons of petroleum for every gallon of ethanol used, due to the 100% octane rating and high efficiency, as much as 40% to even 50% compared to today's 10 to 30% efficient gasoline fueled vehicles. Ethanol and methanol can also be combined as well as derived from biomass and natural gas sources. Ethanol is therefore a feasible alternative fuel in the U.S..

Hydrogen is the last alternative fuel warranting significant attention and it will quite possibly be the fuel of the future one century from now if no new methods of propulsion and or power are discovered in the next century. Hydrogen has many advantages and disadvantages most of which seem solvable by existing technology. The most obvious advantages are that it is by far the most abundant element in the universe, it packs more energy per unit of weight than any other fuel, and it burns cleanly, (Johnstone, 90). BMW has currently been researching the hydrogen alternative for one decade, (Siuru, 65). Hydrogen fuel cells are the most popular area of research at the moment in an attempt to deal with the dangerous hydrogen storage problem. The cells convert a fuel's energy directly into electricity, without combustion and without moving parts. The main features of the fuel-cell system are a fuel supply, an oxidant (typically oxygen from the air), and two electrodes with an electrolyte sandwiched between them. A type of fuel cell that promises to be both compact and inexpensive enough for a practical automobile is the proton-exchange-membrane fuel cell. Aside from cost, the features of the fuel-cell car of greatest interest to the consumer are fuel economy, performance, refueling time, and range between refueling. Fuel-cell cars operated directly on hydrogen would be 3 times as energy-efficient as comparable gasoline cars. They would also be much quieter and require less maintenance than ICE's, (Williams, 27). Current cell weight includes 97% weight for the cell, and 3% weight for the gas. A high efficiency, light weight cell is needed that will not rupture causing explosion in an automobile accident, (Knott, 28). A hydrogen fuel cell hybrid has been suggested and estimated to be 50% efficient, (Knott, 30). Ammonia can also be used as a hydrogen carrier, spawning ammonia fueled vehicles. Ammonia also has the advantage of being carbon free and has a substantial infrastructure, (Knott, 30). The U.S. Army tested but abandoned ammonia as fuel in the 1960's. Engineers at Johns Hopkins are again researching the concept.

Automobile makers in Germany have experimented with hydrogen-burning cars for 2 decades, and it will be years before they come to market. The Persian Gulf war piqued interest in alternative fuels, and new clean-air laws make hydrogen seem more sensible than it once did. Burning it mainly creates steam, most of which condenses and trickles out the tail pipe with only a few nitrous oxides left over. Japan's Mazda Motor Corp. hopes to sell a few hydrogen cars in California within 10 years. The main problem, according to Wolfgang Reitzle of BMW, is how to produce and distribute hydrogen. So far, Mercedes-Benz, BMW, and Mazda prototypes are using gasoline engines that have been modified for hydrogen, although not yet optimized. The key question is how the fuel should be stored. Mercedes has opted for gaseous hydrogen that bonds in the fuel tank with powdered metals, a fuel cell; Mazda plans a tank that stores hydrogen in metal alloy balls; BMW uses cryogenic liquid hydrogen injected directly into the cylinders, (Hoffman, 24), as well as fuel cell technology. Used correctly, the companies insist, hydrogen is as safe as gasoline, (Templeman, 59). Hydrogen is being readily researched and certainly evidences itself as being a feasible alternative fuel.

Finally I will briefly touch on turbine cars engines. They are of course not alternative fuels, but can run on them more efficiently than any conventional ICE. Although most of the work on alternative car engine technologies has concentrated on electric vehicles, run by either fuel cells or batteries, another option deserving of a hard look is the gas turbine engine. Compared with the ICE, gas turbine engines weigh less, are longer-lasting, and break down less frequently. The gas turbine engine excels in terms of emissions; it is the only automotive engine technology to have met the most stringent limits tentatively set by the Environmental Protection Agency. The gas turbine vehicle also has some clear benefits over batteries and fuel cells. They can burn a variety of fuels and are compact sources of power, capable of producing 3-4 kilowatts per kilogram, versus less than 1.5 kilowatts per kilogram from a fuel cell and 0.5-1.0 kilowatts per kilogram from a battery system of a size sufficient to provide an acceptable range, (Wilson, 55).

As mentioned in the beginning of this paper, there are advancements in the automotive and engine field constantly. The advancements in this field coupled with the viable alternative fuel options discussed in this paper could produce a vehicle excelling monetarily, technologically, realistically, and environmentally.

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