In 2005 I joined a Natural Gas trading company and that was also my jump from the legal to the gassy business. The notion Natural Gas was of course no stranger to me.
As a child I learned that Natural Gas is produced often together with oil by drilling deep holes into the earths crust. My phantasy dictated that one would pierce a large hollow space (a bit like a cavern) filled with oil and gas which then is released steadily to the surface in order to – well – burn up in flames that heat my bath water or cook my meal.
Reality, as it turned out, was to be different as oil and gas fields are no hollows in the earths crust but rather accumulations of spongy (to a degree) rock capped by something that seals it off against the surface.
One of the first distinctions I learned was that if its produced like an oil well, its called Natural Gas and if its produced from the decomposition of organic material its called BioMethane.
From 2005 until now I had a lot of time to learn about the different sources of gas feedstock for pipelines and LNG liquefaction plants. But something strange occurred to me. Why the hell do we call Earth crust derived methane Natural Gas and treat everything else as some other form of the same molecular mix? If Natural Gas is natural, why don’t we call crude oil “Natural Oil”? As if it would be something that’s derived from the ether.
Whats Natural Gas to begin with? If we refer to the stuff burning up in your gas stove at home, thats a high concentration of the molecule methane (CH4) with trace amounts of heavier hydrocarbons such as Ethane (C2H6), Propane (C3H8) and Butane (C4H10) plus even smaller trace amounts of nitrogen (N2), Sulfur (S2) and Mercaptan molecules plus an odorant as you want to smell if there is a leak.
But BioMethane would fit that bill exactly. In fact, everything fit to enter the Natural Gas pipeline system as a product could go for Natural Gas. The distinction only comes from the source. How is it produced.
But does that matter? Not at all as we know all to well. We care about the methane in it. All the rest does not matter to us at best. At worst it makes the gas unfit for use.
But if it does not matter where the gas comes from, why do we continue making a distinction between so called Natural Gas (supposedly because it was produced by plucking it from nature) and other sources of methane? Whats less natural in Landfill gas for example? Or methane from waste water treatment plants? Or indeed BioMethane? Is methane produced by using chemicals for fracking still Natural Gas? And why is the liquid state of methane called LNG and not Liquefied Methane or LM. And why on earth is Natural Gas only methane? Couldn’t it be nitrogen, or oxygen, or one of the rare but still absolutely natural gases. Its all mush.
But thats a bit sterile. Why not Liquefied Methane Blend as we are dealing with a something that consists primarily of Methane ( and honestly, thats really the substance you are interested in) and there is other stuff in it as it almost never comes absolutely pure?
Why is it important to give it its proper denomination? Because Natural Gas has a very specific meaning in the energy world and calling anything else that consists primarily of Methane also Natural Gas would lead to confusion. But the other Methane resources are different in many aspects (and many times superior to the so called Natural gas) so we should define one standard that does not care where the stuff comes from.
As soon as it responds to the definition of Liquefied Methane Blend (or LMB) it does not matter anymore where it comes from. Is that true?
Not really. It matters a hell lot more if the source recently extracted Carbon from the atmosphere and made methane or not as in one case we have a CO2 neutral fuel whereas the other adds supplemental Carbon to the air we breathe. And here it gets really important. Thats why I propose an add-on to LMB which reads LMB-CN00. Take the 00 and replace with the percentage of Carbon Neutral (thats what the CN stands for) in the blend and voila, we are clear. You look at it and know what you get.
LMB-CN40 would be a blend of 40% renewable and 60% non renewable methane. But wait, one thing missing here. When you burn a fuel in an internal combustion engine, the exact methane content of the fuel itself really matters for as methane itself has a very high octane number and all other stuff will worsen quality. LMB with higher methane in it will not degrade as quick as other LMB because the lighter methane evaporates at much lower temperatures than for example propane.
This means that methane will boil off quicker, heavies less quick and hence the relative concentration of heavies in the blend increases. If one starts with a higher concentration of heavies to begin with, this weathering effect (that’s what we call it in the LMB world) can alter the calorific value of the fuel and of course the octane number.
So, in order to complete the picture we should use LMBxx-CNxx. For example LMB97-CN50 would be a 97 percent methane concentration with 50% renewable in it.
Oh, if the methane is not liquefied but compressed its CMB97-CN50. One peek, and its all clear.