Sunday, November 13, 2011

Gas Fracking: Good or Bad? Depends!

Recent news reports published by the internet news services tell how the EPA is seriously investigating complaints related to natural gas fracking (hydro-fracturing) near Pavillion, Wyoming. Those complaints include contamination of water supplies by methane and by toxic fracking chemicals.

I looked up the geography and geology of Pavillion: it lies in the western half of Wyoming, a region dominated by the Rocky Mountains. There will be sediments in the basins, but the fundamental underlying geology is contorted and fractured mountain zone rock.

As a result, I am entirely unsurprised that both natural gas and fracking chemicals are finding their ways into the groundwater. I am surprised that how this can be, is a still a matter of legal debate.

I am no geologist, but even I can understand what is happening, and how, and I published it as a guest column in the Waco Tribune Herald last May. Here is the original submitted text for that column, with some emphasis added now:

Coming Even Cleaner on Fracking” (submitted 5-26-11/published 5-28-11)

The “Trib’s” editors recently ran a very nice editorial on the controversy surround the process of “fracking” (short for “hydraulic fracturing”) for natural gas in shale. This article neatly laid out the two sides of the public debate, which is centering mainly on whether or not there are undesirable side effects.

I find it very interesting that the studies are "still inconclusive", seeing as how the field data is very indicative of what actually happens. It's not a simple either-or situation, it’s geology-dependent, and this is completely left out of the current public debates.

Here in Texas and nearby states, the rock layers are old seabed sediments, more or less level, and are relatively intact. Few paths exist across these layers for oil and gas to migrate upward. That is why fracking has few side effects in this part of the country. The most notable exception has been very minor earthquake tremors induced from the disposal of used fracking fluids by deep well injection.

In Pennsylvania and the other states in the Appalachian mountain zone, there have been widespread complaints about natural gas getting into groundwater, leading to fire and explosion incidents when turning on the water tap. These are real incidents, and are easy to understand if one simply looks at the geology below the surface.

In a mountain zone, the rock layers are highly contorted, fractured, and thoroughly broken-up. There are many paths for oil, and especially the far-more-mobile gas, to migrate to the surface. It is entirely unsurprising, and in fact quite predictable, that this very mobile gas, once released from a deep shale, should migrate upward and contaminate near-surface water supplies. It does so by dissolving into the water under earth pressures, similar to a carbonated beverage.

The solution to the exploding kitchen faucet problem is simple: fracking for gas is OK in continuous-layered sea bottom sediment zones, but not OK in highly-fractured mountainous zones. So, we don't frack there, period. Those gas deposits await a still-undiscovered recovery technology with fewer side effects, more suited to that kind of geology.

This does mean that the agencies regulating gas leases actually do have to regulate, and sometimes to deny permits, unaccustomed as they apparently are to such activities.

The processes of fracking and fracking-fluid disposal were specifically exempted from EPA regulation under the Clean Water Act. This happened in that secretive energy company meeting at the White House during the last administration. It is known as the Halliburton exemption.

However, the injection of diesel fuel into the earth is actually still regulated. While fracking fluid is mostly water plus a little sand or glass beads, the most common liquid trace additive in all these "secret" recipes is diesel fuel. If those recipes were widely revealed, the use and disposal of these fluids would come under direct EPA regulation again, meaning only that they take a little better care doing what they already do.

In that event, fracking for gas would still be quite profitable, just not quite as much as it is without any regulation at all. But fewer folks suffer the side effects, and that’s a good thing.

Update 1-3-15:

The recent explosion of US “fracking” technology (hydraulic fracturing plus horizontal-turn drilling) has modified the picture of oil prices versus recessions.  Unexpectedly,  the US has become a leading producer of crude oils for the world market.  Plus,  there has been an associated massive production increase and price drop in natural gas.

OPEC has chosen to take the income “hit” and not cut back their production in response.  Their reasoning is twofold:  (1) fear of loss of market share,  and (2) hope that low oil prices will curtail US “fracking” recoveries.  We will see how that plays-out.

Oil prices are now such (at around $55/barrel) that US regular gasoline prices are nearing $2.00/gal for the first time in a very long time.  This is very close to the price one would expect for a truly competitive commodity,  based on 1958 gasoline prices in the US,  and the inflation factor since then. 

It is no coincidence that the exceedingly-weak US “Great Recession” recovery has suddenly picked up steam.  The timing of the acceleration in our economic recovery versus the precipitous drop in oil prices is quite damning.  There can be no doubt that higher-than-competitive-commodity oil prices damage economies.  Oil prices are a superposition of the competitive commodity price,  overlain by an erratic increase from speculation,  and further overlain quite often by punitive price levels when OPEC is politically unhappy with the west.  That’s been the history. 

This economic improvement we are experiencing will persist as long as oil,  gas,  and fuel prices remain low.  (Government policies have almost nothing to do with this,  from either party.)  How long that improvement continues depends in part upon US “fracking” and in part upon OPEC.  Continued US “fracking” in the short term may depend upon adequate prices.  In the long term,  we need some solutions to some rather intractable problems to continue our big-time “fracking” activities. 

The long-term problems with “fracking” have to do with (1) contamination of groundwater with combustible natural gas,  (2) induced earthquake activity,  (3) lack of suitable freshwater supply to support the demand for “fracking”,  and (4) safety problems with the transport of the volatile crude that “fracking” inherently produces. 

Groundwater Contamination

Groundwater contamination is geology-dependent.  In Texas,  the rock layers lie relatively flat,  and are relatively undistorted and unfractured.  This is because the rocks are largely old sea bottom that was never subjected to mountain-building.  We Texans haven’t seen any significant contamination of ground water by methane freed from shale.  The exceptions trace to improperly-built wells whose casings leak.

This isn’t true in the shales being tapped in the Appalachians,  or in the shales being tapped in the eastern Rockies.  There the freed gas has multiple paths to reach the surface besides the well,  no matter how well-built it might have been.  Those paths are the vast multitudes of fractures in the highly-contorted rocks that subject to mountain-building in eons past.  That mountain-building may have ceased long ago,  but those cracks last forever. 

This is why there are persistent reports of kitchen water taps bursting into flames or exploding,  from those very same regions of the country.   It’s very unwise to “frack” for gas in that kind of geology.

Induced Earthquake Activity

This does not seem to trace to the original “fracking” activity.  Instead it traces rather reliably to massive injections of “fracking” wastewater down disposal wells.  Wherever the injection quantities are large in a given well,  the frequent earthquakes cluster in that same region.  Most are pretty weak,  under Richter magnitude 3,  some have approached magnitude 4. 

There is nothing in our experience to suggest that magnitude 4 is the maximum we will see.  No one can rule out large quakes.   The risk is with us as long as there are massive amounts of “fracking” wastewater to dispose of,  in these wells.  As long as we never re-use “frack” water,  we will have this massive disposal problem,  and it will induce earthquakes. 

Lack of Freshwater Supply to Support “Fracking”

It takes immense amounts of fresh water to “frack” a single well.  None of this is ever re-used,  nor it is technologically-possible to decontaminate water used in that way.  The additives vary from company to company,  but all use either sand or glass beads,  and usually a little diesel fuel.  Used “frack” water comes back at near 10 times the salinity of sea water,  and is contaminated by heavy metals,  and by radioactive minerals,  in addition to the additives.  Only the sand or glass beads get left behind:  they hold the newly-fractured cracks in the rocks open,  so that natural gas and volatile crudes can percolate out. 

The problem is lack of enough freshwater supplies.  In most areas of interest,  there is not enough fresh water available to support both people and “fracking”,  especially with the drought in recent years.  This assessment completely excludes the demand increases due to population growth.  That’s even worse.

This problem will persist as long as fresh water is used for “fracking”,  and will be much,  much worse as long as “frack” water is not reused.  The solution is to start with sea water,  not fresh water,  and then to re-use it.  This will require some R&D to develop a new additive package that works in salty water to carry sand or glass beads,  even in brines 10 times more salty than sea water. 

Nobody wants to pay for that R&D. 

Transport Safety with Volatile “Frack” Crudes

What “fracking” frees best from shales is natural gas,  which is inherently very mobile.  Some shales (by no means all of them) contain condensed-phase hydrocarbons volatile enough to percolate out after hydraulic fracturing,  albeit more slowly than natural gas.  Typically,  these resemble a light,  runny winter diesel fuel,  or even a kerosene,  in physical properties.  More commonly,  shale contains very immobile condensed hydrocarbons resembling tar.  These cannot be recovered by “fracking” at all. 

The shales in south Texas,  and some of the shales and adjacent dolomites in the Wyoming region actually do yield light,  volatile crudes.  The problem is what to transport them in.  There are not enough pipelines to do that job.  Pipelines are safer than rail transport,  all the spills and fires notwithstanding. 

The problem is that we are transporting these relatively-volatile materials in rail tank cars intended for normal (heavy) crude oils,  specifically DOT 111 tank cars.  Normal crudes are relatively-nonvolatile and rather hard to ignite in accidents.  DOT 111 cars puncture or leak frequently in derail accidents,  but this isn’t that serious a problem as long as the contents are non-volatile.  These shale-“frack” light crude materials resemble nothing so much as No. 1 winter diesel,  which is illegal to ship in DOT 111 cars,  precisely since it is too volatile. 

The problem is that no one wants to pay for expanding the fleet of tougher-rated tank cars.  So,  many outfits routinely mis-classify “frack” light crudes as non-volatile crudes,  in order to “legally” use the abundant but inadequate DOT-111 cars.  We’ve already seen the result of this kind of bottom line-only thinking,  in a series of rather serious rail fire-and-explosion disasters,  the most deadly (so far) in Lac Megantic,  Quebec. 

Volatile shale-“fracked” crudes simply should not be shipped in vulnerable DOT 111 cars,  period.  It is demonstrably too dangerous. 

Conclusions

“Fracking” shales for natural gas and light crudes has had a very beneficial effect on the US economy and its export-import picture.  We should continue this activity as a reliable bridge to things in the near future that are even better. 


But,  we must address the four problem areas I just outlined.  And I also just told you what the solutions are.  The problem is,  as always,  who pays.   What is the value of a human life?  What is the value of a livable environment?  It’s not an either-or decision,  it’s striking the appropriate balance!

Saturday, November 12, 2011

Student Pulsejet Project

TSTC welding student Justin Friend made the Waco paper Friday 11-11-11, with a pulsejet thruster he built from plans he found on the internet. He had already tested this device himself, but brought it out to the TSTC airport apron for a demonstration test Thursday morning. Most of the attending crowd were aviation maintenance and welding program students and faculty. This was a personal project for Justin, not a class project. I called Bill Whitaker, the editor at the Waco “Trib”, and he sent a reporter.

Justin is a college algebra student this semester with my colleague Otto Wilke, who attended the demo test, as did I. (Another math department colleague, Doyle Ware, also went with me to see the test.) Justin sought sheet metal geometry help from Otto, and operating and safety advice from me, once he found out that Otto and I are engineers. His welds were obviously very good, as the pulsejet tube runs very hot in places. No cracks or flaws of any kind have turned up to date.

This pulsejet tube is valveless, so there are no moving parts at all. It is a “folded pulsejet”, so that the back-spit from the short inlet contributes to its thrust. This one is a nominal 50 pound thrust device, big enough to push a go-kart around. It runs on propane. Justin cut the parts from flat stainless steel sheet, rolled them up, and welded them together, excepting the return-bend tubing. This return bend is on the exhaust side, and is the hottest part of the structure. It glows in broad daylight when running throttled up. I got copies of photos Justin made during his first tests. Two are here.


P 1030654

This device has a spark plug on the side of its combustion chamber, and a propane injection manifold tube across the inlet right at the dump into the chamber. One starts the spark, some starting air from a leaf blower, and the propane, to light it off. Once running, starting air and spark are no longer necessary. It throttles up and down a wide range of thrust by simply raising and lowering the propane feed pressure.


P1030658

This thing is dangerously noisy: I estimate around 130-135 decibels, so ear protection is a necessity. You can feel the sound waves beating on your stomach. At the TSTC demo runs, you could feel the concrete airport apron shake beneath your feet. Unlike all other forms of jet engine, pulsejets “sing” at a definite frequency, the rate of the pulsed fuel-air explosions inside the tube. This size tube “sang” at about 80 Hertz, like an earth shakingly-loud operatic bass.

I haven’t heard noises that loud in decades. Being a part of this young man’s project was a huge amount of fun. I actually knew something about this engine and could help Justin with it, because decades ago I researched the military work done on them in the 1950’s and 1960’s. I always wanted to build one myself, but never actually did it. (That may change, this was just too much fun.)

Added 11-13-11:

Here is the first of two QuickTime Movie (.MOV) files I got from Justin. You can see the tube slowly warm up and quit spewing unburned fuel from the inlet (a thin whitish spray). You can also get a sense of the 80 Hertz "singing" tonal quality of the sound, but no real hint of how loud it was. Upon shutdown, the flames from the inlet are propane residuals from the fuel line venting into a very hot environment.

video

Here is the second movie file from Justin. In this one, the tube is quite warm and operating very well at near-full thrust. You can see him disconnect the spark while it runs, with absolutely no effect upon the operation of the tube.

video

Added 12-7-11:

Since this article originally posted, Justin has mounted his 50-pound thruster to an old golf cart, and driven it at the Hearne, TX airport (an uncontrolled field). The video is of a pass he made after the tube was fully warmed up. The speed is close to the control limit for that cart.

video

Justin has since begun procuring parts and materials for a much larger thruster.