These days, the offerings for spark-ignited (SI) engines are greater than ever when it comes to a necessary diet of hydrocarbons to keep them well-fed and operating properly each day. Whether a liquid diet (gasoline and interesting new variations) or of a gaseous nature, there are choices these days that offer operational and service advantages — as well as regulatory relief, as some options tend to burn cleaner.
With gaseous fuels providing ever increasing opportunities, it’s time to see just what they bring to the table. We’ll start at the beginning and work our way along and see just what selections are available.
An Entrée, of Sorts
Let’s start things off with a product that has only recently become viable and appealing as a fuel source: wellhead gas. Yes, indeed. For many years, this stuff coming directly out of the ground was unappetizing and would be simply “flared-off” — ignited and allowed to burn for a period of time until a well was stabilized and collection might commence.
As one might imagine, the stuff coming out of the ground is not homogeneous by any means. In addition to the primary constituent of methane, it will contain water and other trace hydrocarbon elements. And other elements that might just happen to be in the immediate neighborhood.
Well, the Environmental Protection Agency (EPA) is not too keen these days on letting unwanted stuff into the atmosphere — whether raw gas or flared gas. So there are regulations against doing so. But the savvy generator folks (in particular) have now assembled packages that are tasked to clean this stuff up to an effective level so that it can then be directed to the intake of the adjacent and modern SI engine on the package, and do some useful work in providing onsite electricity. Good stuff.
Moving Further Along
Once this precious product is collected and some initial cleanup is done, it is then sent to a proper processing site — quite often via high pressure lines crisscrossing the country — where the final, complete cleanup can be done. A little spice is added in the way of an odorant, so that one can recognize it when it’s in actual commercial use, and the possibilities for consumption are then quite promising.
One might call this commercial product distributed locally as ambient natural gas (ANG), in that it’s introduced into the pipelines running all about and is simply transported at moderate pressures and whatever temperatures are happening at the time. Ambient conditions. It’s very suitable as a fuel for engines, particularly those in stationary locations and hungry for a steady and uninterrupted supply of hydrocarbons. Backup generators come to mind. As well as prime power if the need is there and the engine is fitted with a more robust set of emissions reductions products to ensure lowest emissions levels over the greater number of operating hours expected.
Packing a Lunch
Let’s say someone has developed a fondness for natural gas — a taste, so to speak. What, then, if they wish to take advantage of its generally favorable clean-burning characteristics and, thereby, reduced maintenance requirements? Packing up a larger supply of this stuff is pretty simple. Just take some of that ANG and compress it to the 2,900 to 3,600 psi level, thereby increasing the density at about a 100 to 1 rate.
The trick is that it needs to be in a pressure vessel that can withstand such pressure and these are cylindrical in configuration. It’s not as easy to find a home for these as it might be with a liquid fuel tank that can be formed to fit into an existing space. But it can be done.
The good news is that CNG fueling stations continue to be established, both in metropolitan regions (where there would be more potential customers) as well as along transportation corridors. So it’s easier than ever to rely on this fuel source.
For a Really Healthy Appetite
What about those who just can’t get enough of this stuff, who have a real craving? Well, it’s for them that LNG (liquid natural gas) has developed as a technology and commercial product. The trick here is to pressurize the basic natural gas to such an extent — about 600 times — that it becomes a liquid and so dense — in a good sort of way — that there’s just a lot of energy available in a given volume. Before doing so, it’s required to clean it up very (very) thoroughly and even the simple odorant of the commercial product — mercaptan — will have been stripped out or never added in.
The trick here is that this stuff must be refrigerated, essentially to keep it as a liquid, and there are extra products and costs necessary to accomplish this. When one’s lunchbox requires energy to keep its contents “fresh,” one is inherently encouraged to have a crack at opening things up in the near term and “consuming” such contents before they spoil. But, for high-volume uses, LNG can be just what one might have a taste for.
The good news these days is that, from a macro level, converting natural gas into LNG allows for efficient and economical transfer of it from areas of abundance to parts of the world where there is need but limited availability. This can include transport across oceans. And this dynamic tends to keep prices low for all that have a taste for this great stuff.
At Last — The Dessert Table!
Well. Here we are. At the end of the line when it comes to our natural gas discussion and needs. But, for those who appreciate the smell of all the various hydrocarbons that enable them to get their important work done each precious day, the selections are even greater than ever. Sweet indeed.