Should the U. S. switch to natural gas for transportation?

Authored by:
Dick Medvick
Contributing Editor
Cleveland, Ohio
Edited by Stephen J. Mraz

Americans spend about $260 billion each year on oil from outside of NAFTA for transportation. This transfer of capital to other countries increases our national debt and interest load. Fortunately, analysis shows that we can quickly convert vehicles to domestic natural gas, which would let Americans remain mobile, keep the environment clean, and provide trillions of dollars over the next half century for developing alternative energy and transportation options for the long-term future.

What the U.S. needs
In terms of energy, the U. S. gets about 14.78 quads (10¹⁵ Btu) for its $260 billion. A trillion ft³ (Tcf) of natural gas contains approximately one quad. So 14.78 quads used for transportation per year can be replaced with 14.78 Tcf of natural gas. That might seem like a lot of natural gas, but last year the U.ŒS. Potential Gas Committee reported that the U.ŒS. has at least 2,170 Tcf.

America currently uses 23.37 quads from natural gas each year for residential, commercial, transportation, and industrial applications — either directly, or by generating electricity. Adding another 14.78 quads for transportation would push the total use to 38.15 quads per year, or 38.15 Tcf of natural gas. At this rate, 2,170 Tcf of natural gas would last a minimum of 57 years. In addition, Canada has at least another 780 Tcf of natural gas, the equivalent of another 20 years of gas use. So there’s plenty of natural gas, and converting transportation to it could save North American consumers $20 trillion ($260 billion annually for 77 years). That’s money that could fund research and development into new sources of safe and clean energy and transportation.

Current NGV
CSA America, the organization that writes standards for gas appliances and accessories and alternative-energy products, has already written standards for compressed natural-gas vehicles (NGV) and filling stations. The design work is done, and NGVs are in dealers’ showrooms. Honda, for example, sells NGVs which store natural gas at 3,600 psig. Other automobile manufacturers could quickly follow suit.

And natural gas in its liquid form (LNG) is already becoming popular for long-haul trucking. It costs about $1.50 less for the equivalent of a gallon of diesel fuel, which can lead to significant savings for truckers routinely buying 20,000 gallons of diesel fuel annually.

In fact, several truck and engine manufacturers offer LNG models, including Cummins-Westport, Kenworth, PACCAR-owned Peterbilt, Navistar, Freightliner, and Caterpillar. LNG trucks still cost more, but as more models are available, costs are coming down to the point many models pay back the price premium with the first year of savings on fuel.

But there are problems with NGVs: Customers won’t buy them because there aren’t enough natural-gas filling stations and companies won’t install filling stations because there are not enough NGVs on the road.

For truckers, this chicken-and-egg dilemma is being partly solved by an agreement between Clean Energy Fuels, a national natural gas supplier, and Pilot/Flying J truck stops. They plan to install refueling pumps at 150 locations along major interstate trucking routes by the end of next year, then add at least 100 more. The goal is to make it possible for an LNG truck to travel coast to coast and border to border — anywhere a diesel rig can go.

For consumer cars and trucks, the solution to the fillingstation problem might be in the hands of the auto companies. They could design and sell bifuel vehicles, which run on natural gas or gasoline. Drivers will then be able to use lower-cost natural gas when they find a natural-gas station, or fall back to gas or diesel when they can’t. As the number of bifuel vehicles increases, the demand for natural-gas filling stations will also build. Then, when there are enough natural-gas stations, customers will feel confident buying NGVs rather than bifuel cars and trucks.

Chrysler and General Motors are already building bifuel trucks to sell. The new Ram HD CNG, for example, will be powered by a 5.7-liter Hemi V8 engine modified to operate on both fuels and alternate between them seamlessly. A small amount of gas is used for startup and then the truck can run on CNG or gas. The truck carries a CNG tank and an 8-gallon gasoline tank. CNG range is estimated at 255 miles, with the gas extending that to 367 miles.

General Motors also offers 2012 Express/Savanna vans with 6-liter V8 engines that run on natural gas or gasoline. These vans offer either a three-tank system, which provides a range up to 315 miles and doesn’t intrude on the storage area. There’s also a four-tank option which adds a 22-gallon tank in front of the passenger side of the rear axle. It extends the range to 425 miles.

In Europe, Volkswagen has a bifuel Golf Variant with a 100-hp engine that can travel 130 miles on a tank of CNG. It also carries a 14.5-gallon gas tank. And the VW Touran EcoFuel bifuel van has a 109-hp engine, which gives it a top speed of 112 mph and a range of 192 miles on natural gas. The Touran engine starts up using CNG unless the temperature is below 59°F or the CNG tank is empty, in which case it uses gas.

Natural gas and bifuel vehicles are ready for mass production and could quickly wean America off foreign oil.

The alternatives to natural gas

Natural gas looks even better as an alternative to foreign oil when you examine the other available energy sources for cars and trucks.

Electricity: Unless electricity for cars is to come from overhead or underground wires, electric vehicles will need batteries (or fuel cells, which are discussed later) for storing electricity generated elsewhere. So the U.S. would have to generate at least another 14.78 quads of electricity annually that would then go to charging batteries. But most of these sources of electricity have flaws.

Solar power requires 3,580 sq miles of panels to generate one quad of energy per year. That means the U.S. would need 52,800 sq miles of panels (which is about the size of Alabama). And this calculation assumes 100% eŠfficiency in getting electricity from solar panels into batteries. Solar power is also intermittent and panels rarely produce their rated output.

Wind power su‹ffers from many of the same drawbacks as solar power. In fact, it uses even more land per quad than solar power. There also would be high maintenance costs, which climb even higher for o‹ shore turbines. In addition, there are environmental concerns about bats, birds, noise, and vibrations.

Nuclear power is more reliable and consistent at generating electricity than solar and wind power, and it takes a fraction of the land to generate the same amount of electricity. But there are fears of accidents (Fukushima and Three Mile Island), as well as terrorist attacks. There are also issues with obtaining fuel and disposing of nuclear waste.

Hydroelectric power is unlikely to supply much additional electricity in the future as environmentalists are dead set against dams and the changes they inflict on rivers and canyons. It is likely that more hydroelectric dams will be destroyed over the next two decades than built.

Natural-gas plants built to generate electricity for batteries for electric vehicles would be a less-eŠfficient use of natural gas than burning the gas directly in NGVs. This same argument holds true for biomass (liquid fuel from plants).

Coal is another way to generate electricity, but it greatly concerns environmentalists, especially in regards to global warming. We should know in about • ve years if man-made CO₂ emissions do, in fact, cause global warming. Then we can decide whether it is wise to generate electricity from coal.

Installing enough charging stations to recharge America’s electric cars and trucks would be another challenge. The existing grid has only a 10% margin for additional capacity so it would need to be expanded. There’s also the problem of consumers not buying EVs until there are charging stations, and companies not building charging stations until there are enough EVs on the road.

The other problem with recharging is that it takes too long, especially when compared to refueling a gas or NGV vehicle. One way around this problem is to swap out entire battery packs at “service” stations. But this approach requires a tremendous number of batteries and a new business model for handling the safe exchange of battery packs.

Considerable R&D, along with some technological breakthroughs, none of which are guaranteed, are needed to come up with environmentally friendly, mass-produced batteries that meet consumer demands for range and recharging times.

Hydrogen: Because of hydrogen‘s low energy density, burning it in an internal-combustion engine would yield fewer miles per fill-up than gas. However, using hydrogen in fuel cells o€ffers a 20% increase in e…fficiency over burning it, so automotive engineers have focused on powering fuel cells with pressurized hydrogen.

Honda, for example, leases its hydrogen-powered fuelcell FCX Clarity in California, and it is built in low volume in Japan. The vehicle has a 134-hp vertical-‘flow fuel-cell stack coupled to a 134-hp motor. This combination gives the car 189 lb-ft of torque and quiet, steady acceleration. It also carries a lithium battery to handle regenerative braking. The range on a full hydrogen tank (4.1 kg at 5,000 psi) is 240 ˜miles. The cost per mile compares favorably with natural- gas and petroleum-based fuels.

Unfortunately for this approach, there is no naturally occurring free hydrogen on Earth. Therefore, it must be extracted, and there are currently three potential methods of for doing so: nuclear-power plants, electrolysis, and chemical processing.

Hydrogen could be a by-product of nuclear power but this requires a new generation of nuclear plants. And the technology still needs development, so this source of hydrogen is a long way o€ff. Using electricity (electrolysis) to break water down into hydrogen and oxygen takes more electricity than could be generated using the hydrogen, so it would only be economical if we come up with a new, low-cost way to create electricity.

The current method used by industry to produce hydrogen is by “cracking” or refining natural gas. But when the entire supply chain is considered, it is more e…fficient to just burn the natural gas in cars as a fuel than to extract hydrogen from it, even when fuel cells’ improved e…fficiency is factored in.

Biofuels: Liquids distilled from plants such as corn and rapeseed oil can be burned in combustion engines. On the positive side, liquid biofuel can be stored and distributed with the same infrastructure used for petroleum-based gas and diesel fuel. But the energy density of biofuels is relatively low. For example, it would take roughly 90,000 sq miles of rapeseed to get fuel containing one quad of energy. There are also issues with using crops as fuel instead of food.

One interesting biomass possibility is algae. The National Renewable Energy Laboratory has identified several microalgae, which are the fastest growing photosynthesizing plants. They estimate that about 800 sq miles of algae tanks “fertilized” with CO₂ could produce one quad of energy per year.