Natural gas for transportation

It seems like we’ve been here before. Natural gas is coming back into focus as a transportation fuel in North America, despite a false start from 20 years ago. There were numerous reasons for it’s initial failure, including a lack of fueling infrastructure and less-than-durable natural gas engine technology. While natural gas vehicles (NGVs) have advantages over liquid-fueled vehicles, their disadvantages are not insignificant. So what is different now, and are we witnessing the beginning of a long-term trend?

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Worldwide, there are 14.8 million NGVs in operation, but only 112,000 of those travel on American roads. Natural gas is used extensively for heating and power generation in the U.S., but only one-tenth of 1 percent is currently used for transportation. It would seem that NGVs are almost starting from zero in the United States, but the numbers are currently increasing and are projected to continue upwards.

Probably the major driver in the NGVs’ recent growth curve is the price difference between gasoline and natural gas. According the federal Department of Energy Clean Cities Alternative Fuel Price Report (July 2012), the national average price for a gasoline gallon equivalent (GGE) of compressed natural gas (CNG) is $2.05. This is quite attractive when compared to an average price of $3.52 for a gallon of gasoline, or $3.75 for a gallon of diesel. With the potential for significant fuel cost savings, fleet managers and consumers alike are taking a closer look at natural gas as a transportation fuel.

Advantages of Natural Gas
Natural gas is a fossil fuel, often produced simultaneously with crude oil. However, it is also common for natural gas to be produced by itself as “dry gas.” Natural gas is comprised mostly of methane (CH₄), which is the simplest and lightest hydrocarbon. Natural gas has varying amounts of methane, but will also contain small amounts of ethane, propane, and butane along with numerous other gases. The rule of thumb is that there should be a minimum of 90 percent methane in the natural gas for it to be considered a high quality vehicle fuel.

Natural gas has numerous advantages when used for transportation purposes. It has an octane rating of 120, so higher compression ratios and advanced ignition timing can be used. Methane has the highest energy/carbon ratio of any fossil fuel, which results in 25 percent less carbon dioxide being produced when compared to gasoline. Natural gas is a vapor when it is injected into the engine’s intake manifold, so it combines easily with oxygen and burns very cleanly. Virtually all criteria pollutants are lower when burning natural gas, including carbon monoxide, hydrocarbons, and sulfur dioxide. Natural gas also burns at lower temperatures than either gasoline or diesel. Lower combustion temperatures produce less oxides of nitrogen (NOx), making it much easier and cheaper to meet emission control standards.

At first glance, safety would be a concern with natural gas, especially when one considers that the fuel is stored on the vehicle in pressure cylinders at 3600 psi. Wouldn’t that be the equivalent of turning your car into a rolling bomb? The reality is that certified pressure cylinders are constructed to be very durable and have compiled an impressive safety record over the years. Fire is also not likely in the event of a leak or rupture, because of the specific conditions that must be present to ignite natural gas. Natural gas has a very high ignition temperature, twice that of gasoline. Beyond that, natural gas can only be ignited if it comprises 5 to 15 percent of a mixture with air. If leaks do take place, natural gas rises and dissipates rapidly, making it less likely that a combustible mixture would be formed.

One of the more important advantages to natural gas is that it is a domestic energy source. It wasn’t that long ago that our nation was struggling to maintain its natural gas production and the price was at a premium. Things have changed mightily in that regard, now that energy companies have figured out how to produce gas from America’s immense shale deposits. Current estimates are that we have 100 to 150 years worth of natural gas within our borders. This calls into question our ongoing practice of importing crude oil from countries that we are not on the best terms with. Energy independence is a critical component of national security, and natural gas could play a big role in improving our standing in that regard.

The Downside
OK, that sounds great, but where’s the catch? Well, the consumer in all of us will see some serious problems with the idea of purchasing a natural gas vehicle. The problems start with the low energy density of natural gas; that is, you must store compressed natural gas in high pressure cylinders that can’t be formed to fit the shape of the car. The problem is bad enough with pickups and vans, but on a car you wind up losing a big chunk of your trunk space. The amount of space you lose will be in direct proportion to the range of the vehicle, which is typically much lower than a gasoline-fueled vehicle.

Another problem related to pressure cylinders is the cost of conversion. Taking a non-CNG vehicle and converting it to run on natural gas will cost anywhere from $10,000 to $15,000. The pressure cylinders by themselves represent at least half the cost of the conversion. Your return on investment with a natural gas conversion is tied to two factors: miles driven and the price gap between natural gas and liquid fuels.

It doesn’t help when we remember that as recently as 2009, gasoline prices dropped to almost the same price as CNG. Without a significant price gap, there isn’t much incentive to convert a vehicle to run on natural gas.

The final issue is fueling infrastructure. According to the Department of Energy, there are currently 527 public CNG fueling stations in the U.S. This number approximately doubles when fleet operations are included. This pales in comparison to the 159,000 gasoline stations nationwide (according to the National Petroleum News Survey). Most motorists are not good at coping with range anxiety, and will only feel comfortable with a dedicated CNG vehicle if fueling stations are within a reasonable distance from their circle of operations.

Traditionally, NGVs have made better sense for fleet operations such as transit buses and taxis. Fleets can operate their own refueling stations and their radius of operations is relatively small. Fleets can also fuel NGVs overnight, which saves valuable time during the day and also allows for a more complete fill of the pressure cylinders. Since fleet vehicles often operate many more miles in a day than privately-owned NGVs, payback on initial investment takes place much more quickly than it does for a private motorist.

Light at the End of the Tunnel
One of the primary reasons that natural gas hasn’t gained momentum as a transportation fuel in North America was because its price traditionally moved lock-in-step with that of crude oil. While there were times that a significant price gap existed between natural gas and gasoline, these were short-lived. The glut brought about by the shale gas revolution has changed this dynamic, and the price of natural gas appears to have decoupled from the price of crude. Currently, compressed natural gas prices run anywhere from $1.50 to $2 per GGE cheaper than gasoline. With a spread like that, it takes a lot less time to see your conversion money back.

Another important trend is that cheap natural gas is spurring investment in CNG fueling stations in many areas of the country. In some cases, installations that were initially built for fleet operations are being expanded to include public access. A CNG fueling station typically gets its feedstock from an underground pipeline, which can be more reliable than fueling by truck that must be done with gasoline or diesel fuel. In the recent past, Hurricane Sandy has left many wondering aloud if we need to make a national push towards CNG fueling.

Another reason for optimism: with increased volume of natural gas conversions and OE installations, there is bound to be a drop in the price of the pressure cylinders and associated hardware. Somewhere in here is a tipping point where conversion to natural gas makes so much sense that the trend is self-perpetuating. We’re not there yet, but it could happen if current conditions don’t reverse themselves.

How Clean is the Honda Civic Natural Gas?

In 2001, the EPA rated the Civic GX as having the “cleanest burning internal combustion engine in the world.” That rating still applies, and the Civic Natural Gas has achieved an AT-PZEV (Advanced Technology-Partial Zero Emissions Vehicle) rating from the California Air Resources Board. One of the reasons (amongst others) the Civic Natural Gas rates so high on the emissions scale is because its sealed high-pressure fuel system has zero evaporative emissions. If you are a California resident, a very good reason to buy a Honda Civic Natural Gas is because it currently qualifies for single-occupant HOV lane access in that state (incidentally, the Toyota Prius does not).

NGV Availability
If you are looking to buy a new automobile that runs exclusively on natural gas, you’ve got an easy decision to make. That is, what color of the Honda Civic Natural Gas would you like? Honda first released it as the Civic GX in 1998, but initially only sold it to fleet customers. As time went on, Honda expanded the market to include retail sales in California, New York, Utah, and Oklahoma since these states had better developed CNG fueling infrastructure. Built in Greensburg, Indiana, the Civic GX has been renamed the Civic Natural Gas for the 2012 model year. While it is available to fleet customers in all 50 states, the Civic Natural Gas is currently available for retail sale at 199 certified Honda CNG dealers in 36 states.

Since the Civic Natural Gas’1.8 liter engine is built to run on CNG only, it has been optimized with a 12.7:1 compression ratio for higher efficiency. This is in contrast to bi-fuel vehicles that switch back and forth between gasoline and natural gas and must use a compression ratio best suited for regular unleaded gasoline. The pressure cylinder is located in the trunk and holds 8.03 GGE at 3600 PSI, giving the Civic Natural Gas a range of around 200 miles. The pressure cylinder takes up approximately half of the space in the trunk, leaving 6.1 cubic feet for carrying groceries and the like.

Virtually all other OEM NGV offerings are heavier vehicles such as vans and pickups. Natural gas fueling is a much easier sell with heavy vehicles, because their relatively high fuel consumption translates into quicker payback on the cost of conversion. The Detroit 3 all offer bi-fuel pickups, focusing on fleets as their primary customers. A bi-fuel configuration allows for maximum flexibility and range, because the system is set up to automatically switch to gasoline if the natural gas runs out.

In the recent past, Chrysler has announced that they will expand the market for their Dodge Ram 2500 CNG pickup to include retail customers. The 2012 Ram CNG is a bi-fuel vehicle, and has two pressure cylinders in the forward section of the truck bed with a total natural gas capacity of 18.2 GGE. When the CNG tanks are emptied, the truck automatically switches to gasoline and draws from an 8-gallon tank located between the frame rails. The truck’s CNG-only range is 255 miles; total range is estimated to be 367 miles. An optional 35-gallon gasoline tank extends the range out to 850 miles. This bi-fuel approach goes a long ways towards dampening the range anxiety that is often associated with alternative fuel vehicles.

Chrysler Group’s association with Fiat gives them access to significant CNG resources. Fiat is Europe’s market leader in CNG vehicle sales, with 480,000 light-duty units sold between 1997 and 2011. Going forward, it is reasonable to expect that Chrysler would investigate the possibility of expanding their CNG vehicle offerings as well as being a vocal advocate for building of natural gas fueling infrastructure.

The Payoff
If we start seeing more NGVs on the road, what service opportunities will be available to the aftermarket? For automotive aftermarket service professionals, one area that could turn into a revenue stream is CNG fuel system inspection. By federal law, the pressure cylinders and associated fuel system hardware in a CNG vehicle must be periodically inspected by a “qualified trained person.” There are several ways that a technician can become qualified to perform detailed visual inspections of CNG pressure cylinders.

A common path, however, is to take a CNG fuel system inspector training course, and then to pass a certification exam offered by CSA America. CSA is the only nationally recognized organization that certifies CNG cylinder inspectors in the U.S. or Canada. Starting with cylinder inspection could lead to other natural gas vehicle service opportunities.

There is no telling where the current shift towards natural gas will take us. However, savvy shop owners will stay on the lookout for local trends that could also be business opportunities. Keep your eyes open and your mind ready for the possibility of more natural gas vehicles in your area.

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