The battles continue to rage between CNG and diesel proponents, partly because the issues are extremely complicated but also because they mirror the dilemmas of our time. What should have been settled on purely scientific grounds has evolved into in war of words. So the editors of School Transportation News decided to delve into some of the key points of disagreement about this contentious issue, and talked to both proponents and opponents.

Is CNG cheaper than diesel?

That certainly was the case a decade ago, but both crude oil and natural gas prices have more than doubled since 1988.

An article in the Los Angeles Times, August 22, 2000, noted that the "already historically high prices [of natural gas] spiked upward 7 percent" in the wake of a recent, enormous natural gas pipeline explosion in New Mexico. Clearly the projected low natural gas prices of only a few years ago have missed their mark.

Even with this new data, Greg Vlasic, spokesman for the Natural Gas Vehicle Coalition (NGVC) asserted,

"Natural gas prices are still 20% lower than diesel." The NGVC is CNG's main proponent. "We have to accept that the [overall] price of energy will continue to go up," continued Vlasick. "The petroleum extraction system is capable of producing more than demand, but will change in the next ten years, resulting in permanent petroleum shortages." Vlasick said that at a 1.5- percent growth in demand "natural gas supplies would not be depleted for 35 years."

But the L.A. Times article cites a 2 percent annual demand growth rate in California, and quotes Ron Barone, an analyst for PaineWebber, as saying, "The [overall] demand for [natural] gas is growing 3.5 percent to 4 percent a year, faster than most people anticipated." When confronted with these percentages, Vlasic agreed they are probably closer to accurate. Therefore, natural gas would be faced with supply shortages in roughly the same amount of time as diesel.

What about the infrastructure costs for CNG?

CNG will require new infrastructure, a fact no one refutes. Rich Kolodziej, NGVC president stated, "Most transit agencies are 80 percent subsidized on new infrastructure costs. Also, if an agency has enough buses with enough natural gas usage, the provider (gas company) will install the fueling station themselves. This is true for school districts as well. It depends on the property's usage."

Vlasick cast his eye upon diesel infrastructure forecasts. "The inherent costs of using low-sulfur diesel will include not only retrofitting refineries to the tune of billions of dollars, but fueling stations as well. The transition to clean diesel will require parallel storage systems. My understanding is that diesel fuel tanks cannot be flushed out and refilled with low-sulfur diesel. The National Petroleum Refiners Association has said it will cost 20- to 25-cents per gallon to make clean diesel."

What about the reliability of diesel-powered vs. CNG-powered buses?

The City of Lompoc Equipment Maintenance Department, Lompoc, Calif., takes care of the city's entire transit, equipment and municipal fleets (325 vehicles). According to Steve Castor, fleet foreman, the city's use of CNG has not been cost effective. "We used to operate ten CNG buses; we're (now) down to four. In our experience, the fuel has not been blended properly. We've been battling with the refiner, Pickens Corporation, on this issue. We've had ongoing problems, giving us a 50 percent down-time rate among [CNG-powered] buses in operation." Castor doesn't necessarily attribute the down time to the fuel-Lompoc has some John Deere engines (in heavy equipment) that are less sensitive to contaminated fuel, while contamination causes Cummins CNG bus engines to backfire and run poorly. "It's cost us three times more per mile because of these problems." When factoring in the rising cost of natural gas, he said. "It's almost cheaper to run diesel."

Is CNG an unsafe vehicle fuel?

Not according to the proponents. Vlasick believes that CNG's track record of safety stacks up favorably to diesel. He pointed out, "Most incidents noted in the media involving natural gas had nothing to do with the fuel."

Another perspective on the matter comes from the Gilling Corp., a manufacturer of heavy-duty transit buses. Despite the lure of federal subsidies Gillig refuses to offer CNG-powered buses. BT asked Denny Howard, Gillig's president, why.

"We don't think (they're) safe," Howard responded. "Natural gas is a great fuel application, it's wonderful when it's in our home--under 15 lbs. of pressure. When you put natural gas in a vehicle it's under 3,600 lbs. of pressure (a necessity in order to get mileage). In your house, keeping tight connections is easy. The house doesn't bounce except in an earthquake. But in a bus, connections move up and down. We don't like the idea of trying to keep [volatile] fuel under 3,600 lbs. of pressure in a [moving vehicle] carrying a bunch of people. One of my neighbors was injured when his barbecue propane tank blew. The tank was under very few pounds of pressure. The incident made us think. There have been a number of close calls in the transit industry. But no one talks about the safety issues until someone [gets hurt or dies.] People [who promote natural gas] say the equipment is safe, but it's human error that causes accidents. When there is an accident [they] always say, 'our gas didn't fail.'"