I narrowed the fuel contenders down to 5 finalists: E85, CNG, Biodiesel, Electricity and Straight Vegetable Oil. I left out hydrogen because it's readily available in fairy tales, but not on Main Street USA. Having owned at least one vehicle running on each of the fuel contestants below - the notable exception being an E85 vehicle - I feel reasonably qualified as a graduate of the school of hard knocks (or is it NOx?) to subject you to my subjective perspective. So which fuel makes a podium finish? Read on after the jump.
- Ethanol / E85
Another E85 benefit I can give a thumbs up is its high octane rating of 100-105. Personally, I'd like to see a dedicated E85 vehicle like the Europe-only, Saab BioPower turbo sedan. It takes full advantage of E85's higher octane rating to kick up the turbo boost pressure and get you another 50 hp vs. the stock turbo engine running on gasoline (91-94 octane). Current flex-fuel vehicles can adjust timing and fuel injection according to the amount of ethanol in the fuel, but they can't kick up the compression ratio. Saab's turbocharger can, in the sense it compresses more fuel and air into the combustion chamber.
Why is this important? Ethanol has a low BTU count compared to the other contestants. It only scores 75K BTU per gallon. Since ethanol's the major ingredient in an E85 blend, the well-documented increase in fuel consumption vs. regular unleaded should come as no surprise. Consumer Reports recently determined a Chevrolet Yukon flex-fuel vehicle achieved 14 mpg on regular unleaded gasoline and only 10 mpg on E85. While this is an extreme example, an increase in fuel consumption of 5-15 percent is typical according to the National Ethanol Vehicle Coalition. E85's skeleton in the closet has been this fuel consumption penalty. As the driving public gets wind of that little wart, flex-fuel vehicles are going to need every tax incentive they can get to sit pretty in the public eye. Saab's BioPower models prove you can have you cake and eat it too - get higher performance while minimizing the fuel consumption penalty of E85 by kicking up the effective compression ration with higher turbo boost.
I have to mention the land use debate involving ethanol: can we afford to dedicate enough arable land to raising corn, switchgrass, or whatever the ethanol will be produced from? The jury is still out on that one. Oh, yeah. One more thing. Ethanol's a trifle corrosive, so transport must be by truck not traditional pipeline.
Cynics point to the paltry number of E85 fueling stations in the U.S. There are fewer than 1,000 nationwide with a heavy concentration of those in, big surprise, Midwestern corn-producing states. Minnesota, for example, has over 200 E85 stations with a quantum leap to 500 predicted by 2008.
Predictably, none of these shortcomings have prevented the ethanol-plant-building gold rush that been going on in the U.S. We're looking at a total of 130 plants operating with an annual 4.6 billion gallon capacity by recent reckoning. Quite the pile-on I'd say.
To sum up, ethanol/E85 is renewable, can be domestically produced, has higher octane than gasoline and burns cleaner plus (and this is a biggie) it can be used in existing gasoline vehicles with relatively minor alterations to the vehicle's fuel storage and delivery system.
On the downside, it's energy balance isn't great right now, although it will likely improve as time goes on, and it takes a lot of arable land to grow the plants (be they corn, switchgrass, or sources of cellulose) from which to distill the ethanol. Also in the negative column, ethanol can only be used in a limited way with diesel engines. So-called "E Diesel" is only 10 percent ethanol. Ethanol's high octane rating works against its cetane rating rendering it tricky to use in diesels. But E85's major handicap is higher fuel consumption in comparison to gasoline, diesel, and most of the other alternative fuels. Higher consumption means the price must be proportionately lower than competing fuels to make it worthwhile for the consumer opting for E85 in his or her tank. This means tax incentives must be applied to the equation. Of course, there's no such thing as a free lunch. Tax incentives granted in one area, means another area of the federal budget suffers - at least in the short run. Personally, I can't feel warm and fuzzy about E85, especially in light of the benefits of the other alternative fuels we have available.
- Compressed Natural Gas (CNG)
CNG vehicles have been around for years, but you don't find them at your local Ford dealership. Because of the special fueling requirements (i.e. a pressured filing device with fail-safe fittings rather than the ubiquitous liquid fuel pumps dotting our landscape), CNG vehicles have been solely marketed to fleet owners. It's thought that the centralized fueling of a local fleet lends itself to CNG rather than the individual private owner. I've previously reported on the equipment needed for CNG operation in "the Nuns' story". The Natural Gas Vehicle Coalition website, among other useful resources, provides a list of CNG vehicles for sale. Some of these are dedicated CNG vehicles like my Dodge (i.e. only run on CNG) others are bi-fuel and therefore capable of transporting you and your goods on gasoline or gas of the CNG variety. Dedicated CNG vehicles like the Honda Civic GX sedan can have engines that are optimized for CNG's high octane rating. A bi-fuel vehicle needs to be capable of using the inferior fuel as well as CNG. This precludes CNG-only tricks like higher compression ratios.
I had the distinct pleasure of driving a CNG powered 1994 Dodge Caravan for about two years. The pleasure was two-fold. It was squeaky clean in the exhaust emissions department (lower than an E85 vehicle even) and I got free fuel for a year (that's a story for another time). The weakness of CNG as fuel is similar to that of hydrogen: onboard storage requires bulky pressurized cylinders that take up more space than a typical gasoline or diesel tank. CNG is stored at 3,000-3,600 psi pressure. I added larger than stock aftermarket tanks to my van. Even with those under the floor, my range was only about 275 miles per fill. Better than an electric vehicle, but nothing to write home about. And, no, there's not a lot of CNG fueling stations around which compounds the problem of a CNG tank's short range. I bought my CNG Dodge Caravan with eyes wide open. I had resigned myself to the restricted range of travel. I figured on staying within a 75 mile radius of my local CNG stations. Like a felon on shock probation, I couldn't plan on leaving town for any distant cities.
In summary, CNG, although limited, is domestically available in North America, has higher octane than gasoline and burns cleaner, plus it can be used in both gasoline and diesel engines.
On the downside, it's not a renewable fuel, and it can't be used in existing gasoline vehicles without extensive alterations to the vehicle's fuel storage and delivery system. Its major drawback is lack of fuel station infrastructure. While CNG is piped to most residences in the U.S., a special, pricey home fueling compressor is required for fueling and it takes a long time to fill a vehicle's CNG tank. It's not as simple as adding an E85 liquid pump to your local gas station.
Click here for Part Two of this article where we'll dig into Biodiesel, Electricity, and Straight Vegetable Oil and crown the fairest alternative fuel of them all.