The offerings for spark-ignited (SI) engines are greater than ever when it comes to the diet of hydrocarbons needed to keep them well-fed and operating properly each day. If this statement sounds familiar, it is because people said it before regarding natural gas.

Well, when it comes to gaseous fuels in general, there is another particularly pleasant one — propane — that deserves further attention. Its discovery, distribution and desirability as an engine fuel make for a compelling story. Here, I’ll first take readers back about 100 years ago for a history lesson.

Early Production

Those individuals keen on having a closer look at that black stuff coming out of the ground — particularly if they drilled down a bit to gain access to it — occasionally found something now known as “wild gas.” Though its special high energy caught the eyes of many, it is a particularly volatile product. It is a bit tough to control, as it is very flammable. 

A good chemist chap by the name of Walter Snelling spent considerable time having a further look at this stuff and working with it, and essentially “developed” what is now known as commercial propane. It has the chemical configuration of C₃H₈. This particularly energetic product could be separated out either in petroleum refining or natural gas production, and then used on its own. Snelling developed a process to do this, and thus was born the early “propane” industry.

The purity of the commercial product is good. Around a minimum of 90% of what one buys is pure propane, the rest being miscellaneous gases along for the ride.

Early Usage and Distribution

This all happened around 1912 at a time when internal combustion engines were somewhat rare. The primary initial usage for this great product started with heat requirements. Consumers welcomed its tendency to burn quite readily. It made life easier for lots of people and was welcomed for a number of industrial processes requiring packaged heat.

As this stuff was gathered — in considerable volume, as it turned out — it was necessary to find some substantial places to keep large supplies. Underground salt caverns have proven very effective. A number of these dedicated facilities exist around the United States — and Canada, too — and continue to be in constant use year after year. People built pipelines as well. In time, the very familiar tanks were developed. They are now ubiquitous to many for some professional requirements, as well as the comfort of grilling food. Propane is a readily transportable liquid but promptly gaseous when it comes to actual consumption needs.

Favorable Characteristics

From a basic performance standpoint, propane offers the benefit of easy vaporization that makes it easy to burn. It features cleaner (more complete) burning, compared to other fuels. It does not go bad like other SI fuels — in particular gasoline.

From a distribution standpoint, propane offers the benefit of becoming liquefied at relatively low pressures — more readily than natural gas. LPG (liquefied petroleum gas) is readily supplied in those familiar tanks, which are around 85% liquid with a 15% vapor volume, allowing for some breathing room for temperature changes and such things. The good thing is that, when it is released, it vaporizes easily and sophisticated controls are not required to accomplish this reversal process.

Current Production and Distributions

Consistent production continues year after year and, in the United States, around 90% of the needs of the country are supplied from domestic sources with most of the remaining 10% coming from Canada. 

An odorant is blended in, so any that escapes confinement can be identified. It does settle to the ground, since it is heavier than air. One needs to keep this in mind at refueling and shop operations, where there might be some leakage and puddling at ground level.

A very complete network supplies propane all across the country. Beyond the familiar small tanks, there are fueling stations in place. One could actually set up their own at a relatively reasonable cost. There are mobile possibilities, as well: nice, big trucks with LPG tanks on the back driving to the point where the fuel is needed.

Current Usage and Opportunities

Scooting about these days are a wide range of on-road vehicles nicely powered by “propane.” (Actually, it’s “propane autogas,” the newly adopted and preferred terminology.) The wide distribution of this fuel benefits all of these vehicles, whether set up from the factory to burn it or with a conversion done by a qualified dealer.

A wide range of off-road engines also use this great stuff, including “big block” air-cooled engines (twin cylinder and around 1,000 cc displacement). This might also include engines derived from strong diesel block construction and converted for the less stressful SI combustion process, and a number of automotive-based engines set up for off-road usage.

These engines can all be configured for strictly dedicated propane usage or dual-fuel (gasoline or propane) operation. With less carbon production in the combustion process, these will all require less overall maintenance in operation. Since propane does not “go bad” the way current gasoline containing ethanol does, overall fuel storage issues should tend to be less.

Another interesting usage is in engines set up for a blending arrangement, whereby a percentage of propane is injected into a diesel engine as a secondary basic source for the required hydrocarbons. This strategy is somewhat new, but of particular benefit when the effective price for the propane portion is lower than diesel.

And what of a specific beneficial application for the drilling world? 

Well, one thought might be for a required generator set where the loading varies considerably. In particular, sometimes not being high enough for the full capabilities of the genset. While the diesel folks would be nervous under these conditions about potential wet-stacking and emissions components that are not getting hot enough for regeneration, these unwelcome terms don’t exist in the world of pleasing propane powered spark-ignited engines.

Now that the story of this wonderful fuel has been told, of how it’s gotten us to where we are today and of all the benefits it offers, if you’re not seeing too much of it around your worksite today there’s a good chance you will be in the future. It has a clean reputation and promising characteristics and, as we have learned, it is quite near to each of us no matter where we are doing our work these days.

Lots of future possibilities.