Companies and researchers are working on infrastructure and technologies to help bring the nation’s growing stock of natural gas to fuel tanks, including those of long-haul vehicles
A different kind of truck stop is coming soon to Atlanta. Greg Roche, vice president for infrastructure at Clean Energy Fuels, is presently scouting locations to build one of the California-based company’s natural gas fueling stations for long-haul trucks by the end of this year. With fracking techniques freeing more and more natural gas in the U.S., the alternative fuel is suddenly much cheaper than those made from petroleum.
“A trucker can save one third of his energy spend by switching to natural gas,” Roche notes, thanks to the historically low prices for the gaseous fuel occasioned by the boom in U.S. shale gas development via hydraulic fracturing. “It’s also good for the environment because it’s the cleanest fuel available for big-rig trucks.”
Clean Energy Fuels already operates six fueling stations dispensing liquefied natural gas (LNG) to the big trucks that ply the nation’s highways, ranging from San Diego to Seville, Ohio. Truck stops that pump LNG can be distinguished by their tall, thin storage silos—capable of keeping up to 68,000 liters of this fuel at low temperatures and high pressures. The LNG, trucked in from big liquefying plants much like diesel fuel is trucked in from refineries, then powers the trucks over hundreds of kilometers. Such a station in the port of Portland, Ore., already can handle 1,200 trucks a day.
Hard to keep on truckin’ when the rocks above and below the road are fallin’ down.
Though natural gas is a good Diesel fuel, there are some problems. As the article admits, the energy density of LNG is less than the energy density of liquid Diesel fuel, so the miles per tankful will be less, unless the tank sizes are increased significantly.
Second, a spill of Diesel fuel in a tunnel such as might happen in a wreck) presents a limited risk of disaster; it would spill onto the ground and run into the sewers under the road bed and would not likely explode or even catch fire. LNG would evaporate nearly instantly and would overwhelm the capacity of the tunnels exhaust system. There could be asphyxiations and an explosion.
It also is possible to burn natural gas in Otto cycle engines (spark engines), so automobiles could also use natural gas.
I do not understand why Obama says the new LNG-fueled trucks will be “quieter”, unless they are to be Otto cycle engines. If so, they will be less efficient than the existing Diesel cycle engines in most trucks.
I also do not understand why he claims that they will emit less pollution, unless he is talking solely about carbon dioxide. I know of no data that show Diesel engine to emit fewer oxides of nitrogen and hydrocarbons while burning LNG than when burning liquid fuel.
Don’t worry. The man-child messiah doesn’t understand what he is saying either.
Many of the taxis at Manila International Airport are LNG. The tank in the trunk takes up so much room they can’t get a decent sized suitcase in. Stupid.
LNG is used as vehicle fuel all over the world (from Australia to Africa). Get rid of the US-centric view and it is already happening.
It isn’t great (the tanks are a bit of a pain) and energy density is poor (but then so is ethanol), but you need little or no modification to an existing gasoline engine to make it gasoline or LNG.
In India, running the moto-rickshaws on CNG rather than two-stroke motors has been one of the biggest factors in improving air quality. While I admit that a properly maintained diesel engine is not bad, the 30-year-old diesel engined buses and taxis in many cities pump out large amounts of particulates that CNG/LNG does not. This is real pollution – large particulates, not pretend pollution (CO2).
With gas (not gasoline) prices this low, the only issue is distribution and since we already ship LNG around the country in the same tankers as gasoline.
It seems unfair to compare emissions from a 30-year old municipal bus liquid fired engine to those from a brand new LNG-fired engine. I think that most of those emissions could be improved by proper repair and maintenance.
I have no doubt that a two-stroke cycle engine, which burns motor oil on purpose, has higher emissions than almost anything else. But that too, seems an unfair comparison.
I agree that existing spark engines can burn LNG with little modification. I also agree that existing natural gas prices are somewhere around half in dollars per million BTU than gasoline prices.
I agree that we should exploit this opportunity to lessen our need for imported oil and that we should immediately begin constructing the needed infrastructure. But, I also think that we need to explore some of the safety issues and be sure that the risk that we are accepting is acceptable. Gaseous fuels behave differently when spilled than liquid fuels. We have a century of experience with the latter and will need to develop familiarity with the former.
I’ll take a stab at answering some of your questions – but I am no expert.
Noise – LNG burning generates less vibrations and therefore less noise. It has to do with how the gas burns evenly.
Fuel Spill – the tanks are made of thicker steel and are supposed to survive a large impact – however if a spill does occur you are correct, its very dangerous in a closed area. Certain countries actually ban LNG from tunnels and underground areas.
There are a couple ways of using LNG:
1) Use it exclusively – It emits less CO2 (if you care) and less other pollutants, especially particulates. Because LNG requires less oxygen to burn completely, there is more oxygen available in the piston for a clean burn to take place and therefore less carbon monoxide is produced. It burns at a lower temperature and so less NOx’s are produced. I have heard that engines actually last longer burning LNG, but have no experience with this.
2) Combine it with diesel fuel – This also lowers pollutants by producing a cleaner complete burn. You save on diesel, but not completely. If you run out of LNG you can drive on 100% diesel. You save 10%-15% on fuel costs.
I found a decent reference that has more details: http://210.101.116.115/fisita/pdf/A172.pdf
Robert,
Your article, from Daewoo, does compare a Diesel cycle liquid fuel engine to an Otto cycle (spark plug ignition) LNG fuel engine. Spark ignition causes burning from the plug outward and the flame front speed determines how much of a knock the ignition generates. Higher octane fuels are necessary for high-compression engines because higher octane means slower flame front speed. Diesel cycle engines have very high compression ratios and the fuel/air charge ignites spontaneously throughout the combustion chamber as soon as the pressure and temperature reach the necessary levels. Thus Diesel engines are noisier. Manufacturers of automobile Diesel engines compensate by making the cylinder wall and head metal heavier. If you remember the Diesel Oldsmobile and Buick cars from the 80s were noisy because GM created them by increasing the compression ratio and adjusting the timing on standard Otto cycle blocks. They rattled more than you infant’s toys.
Methane has a high octane number (slow flame front) and is suitable for use in both Otto and Diesel cycle engines. The Otto cycle is inherently less efficient than the Diesel cycle, so they will always get poorer fuel mileage.