I somehow forgot to draw your attention to Kurt Cobb’s wonderful essay on the difference between oil and “liquids” – he does a better job than anyone I know in making clear what most Americans simply don’t know about our energy – all liquid fuels are not equivalent. We have been told by implication that they are, and most people are not technically literate enough about oil and energy issues to understand the difference, so it looks like there’s plenty of oil – but of course, this isn’t oil at all. We could just as easily call it “oil.”
But first, an important question. Why do government and industry officials, oil analysts, and energy reporters equate total liquids and total oil supply? They claim that these other liquids are essentially interchangeable with oil. (I will discuss some of the not-so-savory motives behind this claim later.) In a recent report the U.S. Energy Information Administration put it this way: “The term ‘liquid fuels’ encompasses petroleum and petroleum products and close substitutes, including crude oil, lease condensate, natural gas plant liquids, biofuels, coal-to-liquids, gas-to-liquids, and refinery processing gains.” Let’s see why the “close substitutes” assumption is demonstrably false when it comes to most natural gas plant liquids and decidedly disingenuous when it comes to biofuels.
First, crude oil is what you think it is. It’s a black, hydrocarbon-rich liquid that comes out of underground reservoirs. It can also be made synthetically from other hydrocarbons such as the bitumen found in the Canadian tar sands. Oil also includes something called lease condensate which refers to the light hydrocarbons that often occur in oil reservoirs. They are gaseous in the high-temperature environment of the reservoir, but condense to liquids when they escape the wellbore and are captured by special equipment located on the oil lease. These condensates become part of the crude oil stream. They are highly prized because of the ease in refining them, though they make only a small contribution to world oil supplies.
But what are natural gas plant liquids and are they good substitutes for oil? Unfortunately, confusion reigns because a very similar but more inclusive term, natural gas liquids or NGL, includes lease condensate, already discussed above and which we know is included in the crude oil stream. Usually, when people refer to NGL, what they really mean is natural gas plant liquids (NGPL).
NGPL are hydrocarbons other than methane that are separated from raw natural gas at a processing plant. They include ethane, propane, butane and pentane. The amounts vary. For example, raw natural gas extracted off the coast of Malaysiacontains 11 percent ethane, 5 percent propane, 2 percent butane and about 2 percent of something called natural gasoline or drip gas, a low-octane fuel that is used today primarily as a solvent. Raw natural gas from the North Slope of Alaskacontains a higher percentage of methane and correspondingly smaller percentages of ethane (7 percent), propane (4 percent), butane (1 percent) and other components including carbon dioxide and pentanes (2 percent). In these two cases you can see that ethane makes up about half of the NGPL, propane makes up about a quarter, butane makes up 10 percent of Malaysian NGPL and 7 percent of Alaskan slope NGPL.
So what is ethane used for? It’s major use is as feedstock for the production of ethylene, one of the most widely used chemicals. Polyethylene is the world’s most widely used plastic and found in such things as packaging film and trash bags. Other processes turn ethylene into automotive antifreeze. Yet others turn it into polystyrene which is used in insulation and packaging. Some ethane remains in the natural gas piped to our homes and factories, but not much. So far, it’s hard to see how ethane, the most plentiful of the NGPLs, is a good substitute for petroleum-based liquid fuel products.
We are being played, folks – our collective scientific illiteracy is being used to ensure that none of us notice our oil supply issues. Read the whole article.