Two articles crossed my desk this week in two very different publications.
The first was from Nature, arguably one of the two top journals for scientific publications in the world. (The other journal is Science.)
The other was at the back of Chemical & Engineering News in a section called Newscripts. It is a weekly column dedicated to chemistry stories of interest.
The first article is titled: The uncertain dash for gas, and has a tag line that says: The United States and other countries have made huge investments in fracking, but forecasts of production may be vastly overestimated.
It points out that in 1990s, no one was talking about the hydraulic fracturing of rocks to release additional gas deposits. Companies were routinely fracking wells but it wasn't something that had floated to the public consciousness as an issue.
That said, modern drilling techniques which allow for horizontal drilling through deposits and fracturing of the surrounding rock have resulted in a boon when it comes to tapping shale deposits for natural gas.
The United States is now producing more natural gas than at any other time in its history. Canada has untold reserves now available. Australia is moving to dominate the Asian market in natural gas. The International Energy Agency predicts that natural gas production will more than triple over the next 30 years, particularly as countries such as China begin to tap their own shale deposits.
All of this paints a rosy picture. But the question of how much gas is down there is still unsettled. No one really knows for sure.
In an accompanying article in Nature by Mason Inman entitled: The Fracking Fallacy, he argues that the United States is betting on decades of supply and that is wishful thinking. His contention is that careful consideration of the assumptions behind all of the bullish rhetoric suggests that the forecasts are overly optimistic.
He may be right as initial investigations of major shale formations have tended to be very coarse grained. Sporadic wells drilled too far apart can give rise to unrealistic projections of the reserve capacity. Researchers analyzing those formations in great detail are issuing much more conservative forecasts. Their work indicates the presence of sweet spots where natural gas is concentrated and extraction will be profitable, but the same cannot be said for the whole of the shale formation.
The resulting estimates of capacity are not going to be realized in production. Or as one industry expert put it: "we're setting ourselves up for a major fiasco."
Simply put, the science is not settled.
This is where the other article that crossed my desk comes in.
Part of the Newscript column is about natural fires that have burned for millennia. The Chimaera fires near Cirali, Turkey have been burning natural gas since the time of the ancient Greeks. This and other sites around the world have been labelled eternal flames.
It would appear that the natural gas at these sites is produced by non-biological means. No microbes, just a lot of minerals associated with chromium mines.
But how does this happen?
Research by Giuseppe Etiope and his team from the National Institute of Geophysics and Volcanology in Italy suggests a possible answer. Ruthenium-catalyzed Fischer-Tropsch chemistry could be responsible for generating natural methane seeps.
Ruthenium is a fairly rare element but it has been found associated with certain chromium minerals. The researchers noticed this occurrence of ruthenium-rich chromitites in association with natural methane seeps.
Further, some ruthenium complexes have been shown to catalyze the reaction between carbon dioxide and hydrogen to generate methane.
Putting this all together, Etiope and his colleagues loaded Ruthenium oxides onto a titanium and aluminum oxide support at concentrations similar to those found in chromitite minerals. They then added carbon dioxide and hydrogen to the mixture and detected unexpectedly high amounts of methane.
The methane normally forms in chromitite minerals at temperatures above 200 C, but with the addition of the ruthenium catalysts, they were able to form methane at room temperature over a period of a few days.
In addition, peridotite minerals found in the same deposits are known to generate hydrogen gas upon hydration. The mechanism of abiotic methane generation from carbon dioxide and water may be achievable with fairly simple minerals. Whether or not it can be sustained catalytically remains to be seen.
However, if the process can be industrialized in a significant way, it might not matter that the estimates of methane available in shale formations are too high. We might be able to generate methane directly from carbon dioxide.
It is very early in the process of developing the technology but the potential is enormous. If nothing else, it would eliminate the necessity to drill and fracturing any more shale beds.
