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Alternative Fuels An energy source alternative to using fossil fuels. Materials or substances that can be used as a fuel, other than conventional fuels. Waste oils, vegetable oils or animal fats, which can be used alone, or blended with fossil fuels.

Alternative Fuels

Liquified Natural Gas

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Old 02-06-2016, 12:43:47 PM
cornbinder89 cornbinder89 is offline
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Default Re: Liquified Natural Gas

Schawnn's used or use to use LP. The reasoning is they run absorbsion type refrigeration, so the trucks and coolers run on the same stuff. They could run NG but LP systems are cheaper, the ones around here are LP
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Old 02-09-2016, 12:21:54 AM
Ken Karrow Ken Karrow is offline
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Default Re: Liquified Natural Gas

I've been meaning to ask this and this looks like a good thread. I see lots of trash trucks and buses in metro areas with signs saying CNG. They don't have tanks at least on the trash trucks to run very long on the CNG they carry. Are they just injecting NG into the intake and a little diesel at the injectors till the CNG tank is empty and then straight diesel? I have a hard time believing they have spark ignition engines for complete NG operation.
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Old 02-09-2016, 12:30:51 AM
pegasuspinto pegasuspinto is offline
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Default Re: Liquified Natural Gas

The engines are likely 'converted' diesels, decompressed and a spark plug added. Very common. Many municipal trucks don't have large tanks, they stay in one city maybe 50 miles a day and can hit the fuel island at the depot.
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Old 02-09-2016, 08:10:02 AM
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oldtractors oldtractors is offline
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Default Re: Liquified Natural Gas

this report is a little old, but it has a lot of good pictures and information on the 8.1L Deere CNG development.
Jim Evans
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Old 02-09-2016, 02:11:12 PM
Andrew Mackey Andrew Mackey is offline
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Default Re: Liquified Natural Gas

In spark engines, propane gives 25% less power than gasoline. It burns a lot cleaner, and is certified for indoor use, as a propane engine gives off nearly '0' monoxides. Power loss is about 25% less than gasoline as well. Natural gas consumption is 10% more than propane. power loss is also about 10% less than propane, making total loss about 35%.

Porpane burns cleanly, leaving virtually no oil contamination. It does burn hotter than gasoline, and does cause more wear in unlubricated parts such as valve seats and stems (gasoline uses sulfur to lube these parts). Most carbon deposits are caused by burning of oil in the cylinder/combustion chamber.

Natural gas burns cooler than propane, and is harder to ignite in cold weather. main exhaust component is water vapor.

With the fallen price of gas, neither propane nor natural Gas have an advantage price wise. As far as air pollution - both are superior to gasoline as far as emissions go.
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Old 02-14-2016, 01:49:45 PM
Engine Whisperer Engine Whisperer is offline
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Default Re: Liquified Natural Gas

We have a fairly local CNG filling station, it never really took off other than the municipalities. There are an awful mess of NG 350's and 454's out here pumping irrigation water, exact same deal as LP but you use a different diaphragm and weight in the carb. Plumbed up with a gas meter just like your house.
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Old 02-16-2016, 06:52:47 PM
tdmidget tdmidget is offline
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Default Re: Liquified Natural Gas

Here's the straight of it:
Since the LNG must be kept at -260 degrees F and the cylinder head is at 180 or so plus the combustion chamber is way higher I don't see those working together very long, Maybe 5 hours like the GE test. If you vaporize the LNG then you are back to 60-70% of the power potential of the engine and there is no advantage to a fuel that MIGHT be cheaper if you have to have 25-30% more locomotives.
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Old 02-16-2016, 11:19:38 PM
dkamp dkamp is offline
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Default Re: Liquified Natural Gas

A refresher on combustion- when a liquid fuel is burned, it is not the LIQUID that burns, it is the gasified state, and that state must be mixed with oxygen in order to burn.

The difference between LGN and CNG, is PHASE CHANGE. LNG is not used in motor vehicles, because it requires insulation at cryogenic temperatures, to maintain the liquid state... and it doesn't burn in liquid state, so it HAS to be evaporated in order to fuel. CNG is, as it can be managed with high pressure containment (5000psi or so).

When it comes to the 60-70% fuel energy difference, that's resolved simply through atmospheric compensation. The economy of a system is not based soley on the fuel volume consumption or power output per volume, but corrected based on fuel energy density. Diesel fuel has a much higher fuel energy density than any gaseous fuel, even has more than gasoline, but that doesn't make the other fuels less valid.

The question of wether CNG has validity, needs to be considered from many different facets. There are several truckstop chains nationwide that have CNG fueling stations for both automobiles and commercial trucks. All it consists of, is an incoming local NG line (like what comes to your house) and a multi-stage compressor system that 'boosts' the NG pressure up from a few PSI, to a few thousand PSI. It boosts slowly, charging large tanks that feed to the dispenser. Looks complex, but in reality, it's almost as simple as a hammer.

The primary benchmark of ANY fuel's viability starts with it's availability... those that aren't available, aren't desireable, while those that are, will be used in inverse proportion to their overall cost. It just so happens that the fuels we TRADITIONALLY used, were plentiful, inexpensive to acquire, and fairly safe to use, but as time went by, the refining processes grew much more complex (partially by technology of economics, but substantially moreso by rote of regulatory authority). Now, there's a situation where a very common source of natural chemical energy exists that otherwise evaporates into the atmosphere, that we could capture and burn, as long as it can be contained, transported, stored, and utilized safely. From a chemistry standpoint, there's not much complexity at putting a suction head in a sand-point well in a gas field, sucking it out, cramming it into a tank, and piping it off for use without one iota of refinement, and that's exactly what CNG is all about... there's lots of it. Drive through select areas of our country, and you'll smell it everywhere... Kansas, Ohio, Oklahoma, Illinois, Colorado, Wyoming, North Dakota, West Virginia, Pennsylvania, Montana, Indiana... and ANY municipal landfill or sewage treatment plant?

Did I mention municipal landfill and sewage treatment? Yeah, methane... Natural Gas is primarily methane... makes fires at landfills really, really dangerous. Extracting methane from sewage is popular using what's called a 'digester'... Now why would a municipality be interested in going to a CNG fleet, and using taxpayer dollars to put in a CNG booster station? Perhaps because they're discharging METHANE into the atmosphere... when they could be capturing it and burning it in their TRASH TRUCKS.

Diesel used to be that way... basically, unrefined past what gravity does when crude is sitting in a vat. Keep in mind that GASOLINE was once considered a waste byproduct, unfit for anything other than dry-cleaning linens. What happened 'tween then and now? Technological demands, politics, and environmental concerns.

One note of character with natural gas v. propane. Propane is a byproduct of fuel distillation, and as a result of the process from which it expels, it is of substantially higher purity in it's chemistry, than natural gas. NG is variable- it has the propensity to carry a variety of other compounds, some which are combustible, and some which aren't so much, and some that are rather caustic or reactive to some metals. It can yield a bit of crud and deposits that don't normally appear in propane, so having proper piping and filters, and giving the fuel system regular assessment and maintenance, is necessary... especially if it's not coming through miles of pipeline first.

Last edited by dkamp; 02-16-2016 at 11:44:44 PM.
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Old 02-16-2016, 11:42:20 PM
tdmidget tdmidget is offline
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Default Re: Liquified Natural Gas

Did you read the link I posted? To get the same power as diesel it MUST be injected as a liquid. It just didn't work. Admitting it as a vapor reduces power by 25-30%.

---------- Post added at 08:42:20 PM ---------- Previous post was at 08:32:54 PM ----------

I might add that digester gas is quite toxic, containing hydrogen sulphide among other noxious and foul smelling gases. Somehow I imagine that after about 2 garbage pickups from a digester gas fueled truck you would be complaining. It is also obvious that you have no knowledge of the refining business or the production area of petroleum. If you have to "suck" gas from the ground then there is not enough there to pay for the "sucking".
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Old 02-23-2016, 12:09:55 PM
dkamp dkamp is offline
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Default Re: Liquified Natural Gas

I actually read that, and several others, back in January of '08, because I was teaching on several locomotives for NRE, and three of them were fitted with multi-fuel systems, one of which was an injected diesel, one was a converted spark-ignition diesel, and one was a gas turbine.

The 'same power' issue isn't about the requirement of HOW the fuel is being sent, it's the ENERGY DENSITY PER UNIT VOLUME. When you transport a gas in liquid form, the energy density is substantially higher, thus, a unit of volume will carry more energy.

The actuality, however, is that in liquid state, NONE of them will burn. It's not until they're vaporized, and mixed with oxygen, that they'll burn. Diesel fuel, liquid propane, and LNG are all adherent to this circumstance.

The differences, are flashpoint, and quantity of HC bonds available in a molecule of each. Diesel fuel has more HC bonds, so it's energy release per molecule burned is higher than propane, which in turn, is higher than natural gas, but in order to properly assess the proportion of energy, one must always compare apples to apples, hence, compare liquid diesel to liquid propane to liquid natural gas.

What you did NOT read from the study, is that which was written BETWEEN the lines:

The railroads had no interest in attempting to fit their rolling stock with alternative fuels... and it wasn't because those fuels weren't a viable energy source capable of producing power... Deere's CNG engines proved from the start, that CNG was more than capable of smooth, tractible power, they also proved that they could be done quietly, and with incredible durability...and it should have come at no surprise. Natural gas has been powering engines for as long as internal combustion has been around. The gas blowing engines at Bethlehem Steel ran on a mix of blast furnace exhaust and natural gas. The FM ZC-118 in my shop ran on well-head gas supplied from the oil well that it pumped crude out of. It burns, so it works.

The railroads weren't interested, because the infrastructure to fuel, and the alterations necessary for safe use on railroads, were incredibly large opportunity costs when compared to the benefits NG could have offered. Why?

First: CNG requires storage in pressure vessels in the 5000psi range. Bad enough that you have a mile long chain of pressure vessels charged to 90-150psi for air brakes, pulling railcars full of anything from crude oil to isocyanate esthers... tack on several cars full of fuel pressurized to 5000psi, and expect anyone to feel comfortable with a railroad track...

Second, put several insulated liquid vats behind a locomotive, and fill 'em with cryogenic liquid that's pressure relieved up top, and tell every city on the planet you're rolling through.

THAT is the reason why the study you cite, says what it says. They're not going to do it, because for rail transportation, it simply isn't a wise thing to do. It doesn't matter how you introduce it to the engine, because they'll never introduce it to the main-line railway application. They can pump 5000 gallons of heavy diesel fuel into the belly-tank of a locomotive, and if it wrecks and spills, they have to clean up a spill. That scenario does NOT happen with CNG or LNG... ever.
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