In theory and in the lab, many petroleum substitutes make sense for personal vehicles. On the road, though, things are of a different matter. With gas prices at $3 a gallon, there is broad public and bipartisan political agreement that the case exists for revisiting the viability of our investment in alternative fuels. Settle in for a long ride.

Ed. Note: In this, Part I, we focus on the cases for and against Ethanol/E85, Methanol/M85 and Compressed Natural Gas (CNG) as potential petroleum substitutes. The second part of this article — cases for Biodeisel, Hydrogen and Electricity — is continued at Alternative-Fuel Vehicles on the Road: A ‘Real-World’ Guide, Pt. II.

A survey of 1,000 registered voters was conducted by Public Opinion Strategies of Alexandria, Va., for the Energy Future Coalition. The survey found that there is nearly unanimous support for a national goal of having 25 percent of the United States’ domestic energy needs met by alternative fuels by 2025. Seventy-four percent feel this goal is “very important.” Ninety percent believe this goal is achievable.

Meanwhile, notes The Washington Post, President Bush last month said that the best way for the nation to end its addiction to foreign oil is to make a transition more quickly to vehicles that run on alternatives to gasoline. Despite this, many still see mixed signals between Bush’s proposal and the government’s funding for alternative energy research.

However, before national energy policies can be planned, we need to know how petroleum substitutes make sense for personal vehicles in the real world. The following information comes via this month’s Popular Mechanics (PM), who crunched the numbers to find out “how these things stack up in the real world.”

Ethanol/E85
Ethanol is already being blended with gasoline at pumps across the country, and production continues to grow. Ethanol is ethyl alcohol, and E85 is a blend of ethanol and gasoline (85:15 percent). Most ethanol currently is made from grain, though there is also research into making ethanol in commercial quantities from other processes (e.g., switch grass).

About 1.56 gal. of E85 takes you as far as 1 gal. of gas.

“Ethanol is an excellent, clean-burning fuel, potentially providing more horsepower than gasoline,” says Popular Mechanics. In fact, ethanol has a higher octane rating and burns cooler than gasoline. On cold days, though, pure alcohol isn’t volatile enough to get an engine started, hence E85.

“The performance of E85 vehicles is potentially higher than that of gasoline vehicles because E85′s high octane rating allows a much higher compression ratio, which translates into higher thermodynamic efficiency,” says the special report. However, flex-fuel vehicles (FFVs) — cars and trucks that can burn pure gasoline, E85 or any ratio of gas/ethanol in between — that retain the capacity to run on gasoline alone can’t really take advantage of this octane boost because they also require the ability to run on pump-grade gasoline.

According to Department of Energy (DOE) studies, using ethanol in blends lowers carbon monoxide (CO) and carbon dioxide (CO2) emissions substantially. In 2005, burning such blends had the same effect on greenhouse gas emissions as removing 1 million cars from American roads.

Yet, because alcohol is a corrosive solvent, anything exposed to ethanol must be made of corrosion-resistant (and expensive) stainless steel or plastic. And when considering the viability of ethanol, the total impact of all activity related to growing corn (e.g., pesticides, fertilizer, heavy equipment and transport) needs to be taken into account.

Overall, ethanol’s outlook is hopeful. “The burgeoning ethanol industry is changing the economic landscape of rural America, as companies pour billions of dollars into production plants in a race to meet demand and ease America’s addiction to gasoline,” a recent Reuters article said. According to the Renewable Fuels Association, 95 ethanol refineries produced more than 4.3 billion gal. of ethanol in 2005.

Methanol/M85
Methanol is methyl alcohol, aka wood alcohol, and is produced through a steam and catalyst process that reconstitutes methane gas as methanol. M85 is a blend of methanol and gasoline (85:15 percent). At this time, virtually all U.S.-produced methanol uses methane derived from natural gas. However, methane can also be obtained from coal and biogas.

Methanol is a potent fuel with an octane rating that allows for higher compression and greater efficiency than gasoline, says PM. Pure methanol isn’t volatile enough to start a cold engine easily, and when it does burn, it does so with a dangerously invisible flame. Blending gasoline with methanol to create M85 solves both problems.

However, methanol is extremely corrosive, requiring special materials for delivery and storage. Also, its fuel economy is worse than ethanol’s. As with ethanol, any potential increase in efficiency from methanol’s high octane is negated by the need for FFVs to remain drivable on gasoline only. The lower energy content and the higher cost to build methanol refineries compared with ethanol distilleries have relegated methanol and M85 to the back seat.

Producing methanol from natural gas results in a net increase of CO2, hastening global warming. Unlike ethanol, the process liberates buried carbon that otherwise wouldn’t reach the atmosphere.

Its outlook is kind of “eh.” It has essentially stepped back into ethanol’s shadow as a gasoline replacement, yet methanol may still have a future. According to PM, “nearly every major electronics manufacturer plans to release portable electronics powered by methanol fuel cells within the next two years.”

Compressed Natural Gas (CNG)
Natural gas can be used to fuel internal-combustion engines. The most practical strategy is to handle it as compressed natural gas (CNG). To use natural gas, the methane component — which makes up 50 percent to 100 percent of natural gas — must be processed to remove contaminants and other useful fuels, e.g., butane and propane.

CNG’s octane rating gives it the potential to optimize an engine’s thermodynamic efficiency through a high compression ratio. However, many CNG vehicles are able to run on either CNG or gasoline, which “obviates the octane advantage.”

According to the DOE, a CNG-fueled Honda Civic GX produces 90 percent less CO and 60 percent less nitrogen oxides (NOx) than its gas-powered counterpart. Further, CO2 is reduced by 30 percent to 40 percent.

Unfortunately, for a vehicle to carry enough CNG to travel a decent distance, the gas has to be compressed significantly, at which point CNG has only about one-third as much energy as gasoline, and the tank must be significantly bigger, heavier and more expensive than a conventional one.

Yet CNG is a bargain compared to gasoline. A gallon of gas equivalent (GGE) costs about $1.20, including the cost of compression — thanks in part to the lack of taxes added to gasoline.

All considered, compressed natural gas’ potential as a replacement to gasoline is limited, despite the fact that 85 percent of our natural gas is produced domestically, a distribution network already being in place. CNG is nonrenewable, and it requires major retooling of both cars and fuel-station infrastructure.

Please continue reading this article at:
Alternative-Fuel Vehicles on the Road: A ‘Real-World’ Guide, Pt. II.