What Will Be The Fuel of The Future?

By Les Jackson
AIADA Contributing Editor

February 27, 2007; By the middle part of the 21st Century engineers and scientists see a shift to fully electric vehicles. Internal combustion-powered vehicles will be relegated to museums, parades and shows, much like carriages and steam engines are displayed today. Reaching that point will take a number of steps that must, along the way, solve the many technical, economic and social issues facing such a dramatic change.

Today’s vehicles utilize state-of-the-art technologies to achieve the low levels of emissions demanded by government regulations and public health. Sophisticated computer software in vehicles keeps them running smoothly and reliably for tens of thousands of miles without maintenance, yet they are over 140 times cleaner than those of the pre-emissions era of the late 1960s.

How clean is that? Well, to equal the emissions accumulated in a one-way drive from Washington DC to Baltimore, MD in a typical V8-powered 1968 car, you would have to drive a modern car from DC to Los Angeles International Airport and back again, a trip of over 6,000 miles.

While the industry has every right to be proud of these impressive accomplishments in emission reduction, other pressures have conspired to make the industry seek alternative technologies to power vehicles in the future. These pressures include global warming issues, petroleum supplies and energy independence, international trade, world population and a number of others, all of which merge into a difficult-to-solve "equation."

The auto industry foresaw many of these pressures a number of years ago and most manufacturers responded by embarking on research programs to investigate alternative fuels and other technologies. The goal of these programs is to eventually remove conventional internal-combustion engines from the equation, but any alternative products that come into the marketplace must satisfy the public’s expectations in the areas of comfort, safety and economy. If not, they won’t sell.

New Directions

As far as the auto industry is concerned there are no restrictions on the range of technologies to be considered. Any and all ideas will be investigated until proven unfeasible, and it’s possible that the "magic bullet" has yet to be discovered. However, the consensus of the industry is that no one technology will prove to be the solution to alternative energy or large gains in fuel economy in existing drivetrains. The solution will almost certainly be a number of different approaches that will cumulatively effect the change.

Promising new and existing technologies are now coming into the marketplace. Each has its own advantages. Let’s take a look at some…

Diesel

By far the oldest technology – and still an internal combustion system – diesel has the potential of being one of several important "bridges" to the future. Diesel engines are at least 30% more thermally efficient than gasoline engines, which means a directly-translated mileage benefit to the user. If every passenger vehicle in the U.S. was powered by an equal-output diesel engine today we would be using roughly 30% less petroleum than we do now.

We don’t, however. Currently the diesel-powered U.S. passenger vehicle fleet is less than 1% of the total. This is a tiny fraction of comparable European and Asian fleets, where over half of all new vehicles are diesel-powered. The good news is that the major issues blocking acceptance of diesel engines here (noise, soot, odor, sluggishness) have all been solved.

Today’s diesel engines are designed for quiet operation and are equipped with turbochargers, direct injection (a high-tech fuel injection system) and various exhaust treatment systems to make them as clean-running as their gasoline-fueled counterparts. The recent phase-in of ultra low sulfur diesel fuel in the U.S. allows the use of BLUETEC technology to achieve the most stringent 50-state emissions standards.

BLUETEC is technology initiated jointly by Audi, Mercedes-Benz and Volkswagen and is a uniform label for clean and highly efficient engine/exhaust management systems. For instance, Volkswagen utilizes a nitrogen oxide storage catalyst and engine management system in the new Jetta TDI that changes operating modes periodically to treat the N0x stored in the catalytic converter, along with a particulate filter in the exhaust system. Mercedes-Benz utilizes urea injection into the exhaust, along with other particulate filtering, to achieve impressively low levels of N0x.

Biodiesel

Diesel engines can theoretically run on anything that will burn, including used cooking oils, but practical considerations (foreign substances, fluidity, temperature stability and others) dictate that standards must be met. Overall, biodiesel is a domestic, renewable fuel derived from natural oils like soybean or canola, and which meets the specifications of ASTM D 6751 (rules that cover issues pertaining to those above, along with clean air and other health effects and engine warranty concerns.) Biodiesel is generally a mixture of natural oils and petroleum-based diesel fuel, typically using 2-5% of the latter.

Benefits of biodiesel, aside from lowering dependence on foreign oil, include the reduction of carbon monoxide, hydrocarbons, particulates and sulfur dioxide. Biodiesel fuel has higher lubricity, which translates to lower maintenance costs. Above all, the fuel is renewable.

Ethanol

Another renewable fuel that can be used in place of gasoline is ethanol, which is alcohol derived from plant sources. It is commonly made from corn, saw grasses and sugar cane, but can be made from a host of other crops. It has an inherently high octane number, making it a desirable fuel for high compression engines. Existing engines can be easily and inexpensively modified to run ethanol or blends of ethanol and gasoline – the most common is E85, a blend of 85% ethanol and 15% gasoline – and there are already nearly 2 million "flex-fuel" vehicles on the road in the U.S. that can run on ethanol.

A major benefit of ethanol is its extremely low emissions output, due to its high oxygen content. It dramatically reduces hydrocarbon and nitrogen oxide and carbon dioxide emissions. Ethanol greatly reduces VOC’s (volatile organic compounds) and particulate matter. It is produced through agriculture and therefore contributes to a major reduction in dependence on foreign oil.

Others

Hydrogen, compressed natural gas, propane and methanol are also fuels that can be run in gasoline engines, although significant modifications need to be made. These fuels are particularly suited to certain applications such as fleet usage, warehouse or closed-space operation. Compressed natural gas is being used extensively in urban buses as a way to reduce emissions.

Manufacturers are also using displacement-on-demand (electronically controlling how many cylinders should fire, depending upon power requirements) to make small increases in fuel mileage. Another approach is the use of 6, 7 and even 8-speed automatic transmissions to maximize the power transfer efficiencies in existing vehicles. Constant velocity transmissions are also being utilized by some manufacturers such as Nissan, which has CVT transmissions available in most of its vehicles. This technology allows the engine to run at its most efficient level during most driving situations.

Turbocharging is another well-known technology that increases thermal efficiency, thereby allowing greater power from less displacement, as smaller displacement engines use less fuel. Volkswagen has demonstrated impressive power output from a 1.4 liter engine by using both a turbocharger and supercharger. Fuel mileage is in the low 40s per gallon.

Hybrids

Hybrids are hot items these days. Toyota and Honda dominate the market at the moment and many other manufacturers either offer their own versions or will soon be doing so. Hybrids (a combination of a small gas engine, electric motor and battery storage) offer significant benefits, including lower overall emissions, high fuel mileage, quiet operation and a feeling that the owner is contributing in some small way toward solving the problems facing us. Tax incentives are available for hybrid owners.

On the drawing boards are future hybrids that promise to be even more stingy with fuel. Plug-in hybrids will have greater battery storage and the ability to be re-charged from an available outlet (at home or at work), thus increasing the operating range and decreasing the amount of time the gas engine needs to run. Fuel economies of up to 80 mpg are foreseen. Another approach is the replacement of the gas engine to a smaller displacement diesel engine. This yields the same amount of power but with a 30% increase in fuel mileage.

Fuel Cells

Fuel cell technology, used in the space program for over 40 years, is currently being developed by most major auto manufacturers or, at the least, is heavily researched. It currently shows the greatest amount of promise toward the goal of electric-powered vehicles, wherein electricity to run the motor is produced in an electro-chemical device (called a proton exchange membrane) that strips electrons from hydrogen, hydrocarbons or alcohols to produce the amount of current necessary.

The fuel cell has tremendous appeal because it can not only be used to power a vehicle but also stationary powerplants for rural, military and countless other applications. Fuel cells are environmentally clean, producing nothing more than water vapor. The fuel consumed is widely available (hydrogen is the most abundant element in the universe) and, eventually, should be inexpensively produced.

Presently Honda, DaimlerChrysler, Toyota, Hyundai, Nissan, Audi, BMW, Daihatsu, Fiat, Kia, Mitsubishi, Peugeot, Suzuki, Volkswagen, Ford, GM and Shell Oil have active fuel cell programs and test vehicles.

Les Jackson is a syndicated automotive writer whose columns appear in a number of publications. He is co-host of "Cruise Control," a weekly radio show on the USA and Cable Radio networks and Editor-in-Chief of www.SecondChanceGarage.com. Les is past-president of the Washington Automotive Press Association and is a recognized expert on automotive engineering and safety. His educational background is in mechanical engineering and physics.