Wood Pellets, Bane or Boon for NC?: Part I

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Readers of this column may recall that I own 16 acres of property about 2 miles west of Carrboro that I operate as a hobby farm/pollinator reserve. Approximately 14 of these acres are wooded. Prior to 1992, this land was part of a 50-acre farm. There are stands of pine trees that have grown on the level areas that had been farmed prior to 1992, and there are mixed hardwoods on the sections that were too steep to have been used for crops. For the past several years I have received a steady stream of solicitations from timber companies asking if I would like for them to come harvest the trees. I have no interest in this, but let me try to explain why they do. It has a lot to do with wood pellets.

Wood pellets are made by pressing sawdust into little cylinders that are approximately one inch long and a quarter inch in diameter. wood pellets Pressing the pellets into these cylinders creates friction that heats the wood to a high temperature. The high temperature provides two advantages; it helps to dry the pellets, which improves their quality as a fuel source, and it causes the lignin within the wood to melt into a liquid, which then glues the pellets together as they are cooled. The timber industry has been making wood pellets for decades, as a way of monetizing the sawdust produced in lumber production.   In addition to the sawdust created by cutting logs, the timber companies often grind the branches and twigs from the trees into sawdust in order to incorporate them into the wood pellets as well.

Since wood pellets are small and of uniform size, they can be fed into a burner at a controlled rate from a feed hopper.  This is far more convenient in a variety of applications than using firewood. For home heating, a wood pellet stove can operate like a furnace, with the temperature of the house being used to control the feed rate of the pellets. On a much larger scale, the ability to convey wood pellets with automated equipment allows them to be used as a fuel in electric power plants. The use of wood pellets to produce electricity, primarily in Europe and particularly in the United Kingdom, is driving a tremendous increase in the production of wood pellets in the United States. This trend has both environmental and economic implications for North Carolina. I will explore those further next week in Part II of this series.

To understand why Europe is ramping up the use of wood pellets for electricity production, we need to talk first about coal and fracking. As I explained previously in The Saudi Arabia of Denial, humanity has already burned through the coal deposits with the highest energy contents. Therefore, as time passes we need to mine more and more tons of lower and lower quality coal to deliver the same amount of energy to coal-burning electric power plants. In parallel with this trend in coal mining, the practice of hydraulic fracturing (fracking) has spread through the United States. Fracking operations have dramatically increased the supply of natural gas and, through the laws of supply-and-demand, lowered its price. The combined effects of an increase in the supply of cheap natural gas and the declining quality of coal have inspired many electric power companies in the U.S. to convert from coal to natural gas as a fuel source.

Power companies in Europe are also looking for alternatives to coal, but they can’t tap into the U.S. natural gas supply. Natural gas can only be transported in an economically efficient manner via pipeline, and there are no natural gas pipelines between the U.S. and Europe. In contrast, wood pellets produced in the U.S. are easy to send to Europe. All you need is a really big boat.

The wood pellet industry in the U.S. is growing so fast that it is difficult to keep up with the statistics. Ten years ago, wood pellet production was just niche industry. Today, production of wood pellets has grown to 10 million tons a year, and timber companies in the U.S. are in the process of building new facilities which will double that capacity in short order. Much of this activity is occurring in North Carolina. But is this a trend that we should embrace or resist? I’ll give you my thoughts on that question next week in Part II.

Jeff Danner discussed this week’s column (and the Keystone XL pipeline) with Aaron Keck on WCHL.


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Chatham Commissioners Approve Temporary Fracking Ban

Chatham County Commissioners voted unanimously on Monday to ban hydraulic fracturing, or ‘fracking,’ for two years while officials update county land use plans and ordinances.

The General Assembly voted in 2012 to limit the ability of local governments to regulate fracking, but Chatham Board Chair James Crawford wrote in a press release that law does not prevent temporary moratoriums.

The new ban puts a halt to county approvals for oil and gas extraction. Crawford says board members are concerned the process produces large volumes of potentially hazardous waste and toxins. He notes the county has no facilities for treatment of such wastewater.

Chatham is one of a handful of towns and counties throughout the state that have acted to limit fracking, but it’s not clear if these bans could withstand a legal challenge from drilling companies.

Last year state legislators authorized fracking in North Carolina, though to date, no permits have been approved.

The controversial extraction process is on hold pending a state Supreme Court ruling in a lawsuit over the process of appointing members to state commissions. That lawsuit includes the N.C. Mining and Energy Commission, which would be the agency responsible for issuing fracking permits.
Chatham commissioners say they’ll spend the next two years looking for ways to mitigate potential damages, should the fracking ban be lifted.


Judge Temporarily Halts Fracking Permits in NC

A judge has ordered North Carolina not to issue any fracking permits until the state Supreme Court rules on a legal question about how state panels are formed.

Wake County Superior Court Judge Donald W. Stephens’ decision earlier this month delays the proceedings in a case by environmental groups that argues the state’s Mining and Energy Commission was formed in violation of the state constitution.

The preliminary injunction temporarily prevents the commission from accepting or processing applications for hydraulic fracturing drilling units.

Stephens writes that the state’s high court is expected to rule later this summer on a separate case that depends on a similar legal question about how state panels are formed.

The Southern Environmental Law Center said Wednesday that the ruling will halt environmental harm from fracking.


Radon, A Fracking Risk I Previously Overlooked

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Earlier this month, researchers from Johns Hopkins University published a study in the journal Environmental Health Perspectives detailing the increase in radon concentrations in homes in the state of Pennsylvania since 2004, particularly in those near to fracking operations. This is a serious issue that deserves more attention. I will explain why after providing the nickel summary of fracking.

Many underground rock formations, shale formations in particular, contain natural gas that is trapped in small pockets. To retrieve it, gas companies drill vertically to the depth where the natural gas resides, then drill horizontally in multiple directions, and finally fracture the rock by pumping millions of gallons of a high-pressure mixture of water, sand, and toxic chemicals down into the rock formation.(1) After the rock has been fractured, approximately 60% of the water is withdrawn from the well, while the sand and some of the chemicals remain in the ground. After this water has been removed, the previously-trapped natural gas can flow horizontally to the vertical hole and then up to the surface for recovery.

The graphic below from Energy Tomorrow shows the general configuration of a fracking well. The vertical portion of the well crosses through an underground aquifer on its way downward. Underground aquifers are the water source for drinking water and agricultural irrigation wells. In order to try to prevent contamination of the aquifer with either fracking fluids or the components of natural gas, the vertical portion of the well that crosses the aquifer is encased with concentric layers of steel piping and concrete.

fracking well casing

The cracks in the rock formation made by fracking, which can be as long as 500 feet, are shown above and below the horizontal portion of the well. In order to avoid opening a pathway for toxic fracking fluids to contaminate the aquifer, fracking operations should be performed at a depth which is at least 1,000 feet below the bottom of the nearest aquifer.(2) In this particular graphic, the vertical separation is shown as 6,000 feet, which is rather far removed from the aquifer. In practice, the separation is often much less than this. It should not surprise you to learn that Energy Tomorrow is a natural gas industry lobbying group.

Public concern about the health risks of fracking have focused primarily on the possibility that the toxic chemicals used in fracking will contaminate aquifers. As I discussed in Methane in the Water Part I: Toxicity, cases of this occurring, at least thus far, seem to be rare. What is quite common, particularly near the Marcellus Shale formation in Pennsylvania, is increased concentrations of methane – the primary component of natural gas – in the aquifers. A study published by researchers from Duke University concludes that methane is entering the local aquifers not through underground cracks formed in the fracking process but rather via leaks in the steel and concrete casing of the vertical portion of the well. While methane infiltration of the aquifers does present some fire and explosion risk(3), it is not toxic to humans.

OK, that may have been a bit more than the nickel summary, but the background is necessary to explore the radon-related problems of fracking. Radon is a radioactive gas which is produced during the natural decay of uranium and other radioactive elements. Therefore, areas of the country that have underground rock formations which contain radioactive elements also have radon. Homes in these areas tend to accumulate radon gas, particularly in basements and crawlspaces. Radon enters homes by diffusing through the ground and then through cracks in a home’s foundation, as a dissolved gas in the water supply, and as a minor component in the natural gas burned by the homeowner. Since radon is an inert gas, it will not be destroyed or impacted in any way by passing through the flame zone of any natural gas burners in the home. Therefore, all radon atoms in the natural gas supply to the home will escape into the indoor air.

Even without the impact of fracking operations, radon gas has long been a problem in Pennsylvania. According to the Department of Environmental Protection, approximately 40 percent of homes in Pennsylvania have radon levels that exceed recommended limits. This is an issue with which I have personal experience. In order to sell my home in Pennsylvania in 2000 to move to Chapel Hill, I had to apply sealant to the basement floor and walls, install a vapor barrier for the sump pump, and improve ventilation for our home to meet approved radon levels.

Radon exposure is a serious matter. Since it is a gas, you can breath this highly radioactive material directly into your lungs. As a consequence, radon exposure is the second leading cause of death by lung cancer in the United States, killing 21,000 people per year. While the key safety parameter is the amount you breathe in, radon limits for drinking water have been established as well. Radon dissolved in the water you drink is not considered to be particularly harmful. However, if radon is dissolved in your water, it will slowly evaporate into the surrounding air.

When natural gas is liberated from a rock formation, any other gases trapped in the formation will come along for the ride. The Marcellus Shale formation – the primary location for fracking in Pennsylvania – contains 20 times more radioactive material than a typical shale formation. Studies have shown that natural gas produced from fracking in the Marcellus Shale formation has 40 to 70 times more radon than the U.S. average.

Since we already know from the Duke study that methane from fracking wells is infiltrating drinking water aquifers in PA, we can be nearly certain that radon is as well. Once the concentration of radon increases in the local aquifers, its concentration will increase in nearby houses as well via the pathways I outlined above. With this knowledge in hand, we should not be surprised that the Hopkins study found “statistically significant correlations” between household radon concentrations with both the 2004 onset of fracking operations in PA and the distance between the house and the nearest fracking well.

On March 18th of this year, the permitting process for fracking began here in North Carolina. Despite having written about fracking and its potential risks many times, until now I overlooked the now-obvious potential radon exposure issues. Fortunately, those of us in the Tar Heel State are at less risk than my old friends in the Keystone state. According to the map on the NC Department of Health and Human Services website, the levels of radon in the counties being targeted for fracking are rather low. Therefore, our risk of radon exposure here, at least in the aggregate, is lower than in Pennsylvania. Nevertheless, there may be localized areas in which dangerous radon levels could be reached. As the NC Oil and Gas Commission reviews its regulations for fracking, this risk should be taken into consideration.

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1. For a more detailed background on fracking, please read To Frack or Not to Frack. For information on which chemicals are used in the fracking process, please read Fracking Gag Rule Part I: Trade Secret?

2. Please note that different states have adopted different regulations on the minimum vertical distance between fracking operations and aquifers. The recommendation of 1,000 feet, twice the length of the longest expected fracture, is based on my own engineering judgment and is more conservative than some state statutes.

3. For more details, please read Methane in the Water Part II: Fires and Explosions.



No Applications Yet for Fracking Permits

Gov. Pat McCrory signed a controversial fracking bill into law in mid-March. The bill lifts the state’s moratorium on hydraulic fracturing.

A spokesperson for the NC Department of Environment and Natural Resources, Jamie Kritzer, says no one has applied for a fracking permit at this point.

Kritzer says the permit process starts with “several people saying, ‘yes we agree to have drilling take place on our land that we own mineral rights on.’ That’s the first step . . . then they would be granted a drilling unit by the Mining and Energy Commission. And then they would be able to apply for a permit. But neither one has happened.”

Some North Carolina land owners do not own their mineral rights so they would not have a say in whether gas companies drill on their land. If you are unaware, you can find out who owns the mineral rights on your property through records at the county clerk’s office.


Results of my 2014 Predictions

In January, I made predictions for what I expected would be important science stories during 2014, five positive ones and four negative. Now it is time to see how well I did. Below I review my predictions, tell you what did or didn’t happen, and give myself a score on a scale of 1 to 5 for accuracy.

Positive Predictions

  1. Kick and Kill for HIV

What makes HIV very difficult to cure is its tendency to lie dormant inside of cells for long periods of time, making it invisible to the immune system. Many researchers are looking for ways to wake the dormant virus (the “kick”) so that it can then be eliminated by existing anti-HIV drugs (the “kill”).

I predicted a breakthrough on this front during 2014. While there was no big news on “kick and kill,” something else interesting did happen. Dr. Jennifer Doudna and her team at Berkeley developed a very precise and specific technique for splicing DNA molecules, known as CRISPR. Researchers at Temple University used CRISPR to slice up DNA within dormant HIV viruses hiding inside of human cells (effectively killing them), thus opening a possible and exciting pathway to a cure of AIDS. It’s not “kick and kill,” but the effect is the same, so I am giving myself a score of 3 out of 5.

  1. NASA Space Elevator

While I was mourning the cancellation of the Space Shuttle program, I predicted that NASA would start a program to build a space elevator during 2014. The key idea of this concept is to slowly pull a space vehicle to a platform suspended above the Earth’s atmosphere. This approach would dramatically reduce the cost of space flight because most of the investment and equipment is devoted to accelerating the craft away from the earth’s gravity and through the resistance provided by the atmosphere. I hoped that a project like this would help to revive both investment and interest in space exploration.

While there has been no movement on an elevator, we are making significant progress on getting back to manned space flight. This month NASA’s Orion capsule made its first test flight. Although this flight was unmanned, in the future the Orion is scheduled to take men and women to nearby asteroids and also provide data which could help us to design a ship which could transport people to Mars. I’m giving myself 2 out 5 on this one.

  1. Solar Cheaper than Coal

Due to ongoing improvements in technology, the cost of solar power keeps dropping. So much so that I predicted that during 2014, solar power would be touted as becoming definitively and demonstrably cheaper than coal. While I have read many stories addressing this question during the year, they are often muddled by the various assumptions used to calculate costs. For me, if you include the full cost of coal, including such things the proper disposal of coal ash, solar is the clear winner. However, my prediction was that this conclusion would enter the popular consciousness during 2014. I can’t really say that it has, so I am only giving myself a 1 out 5 on this one.

  1. Biodiesel

Biodiesel, at least as commonly produced, is an environmental blight.(1) Government incentives to produce ever-increasing quantities of biodiesel are driving deforestation, particularly in Brazil, as well as crowding out food production on existing farmland. Due to these factors, I predicted a noteworthy decline in the biodiesel’s reputation during the year. I have seen several stories to this effect, but nothing dramatic has happened. I think this one is at best a 2 out of 5.

  1. Specific Chemotherapy

The biggest weakness of chemotherapy is that it is given systemically. Therefore, the concentration of toxic drugs is just as high in non-diseased areas of the body as it is in the tumor. As a result, physicians have to strike a delicate balance of providing enough drugs to destroy the tumor, while not killing the patient from its side effects.

For decades now, people have been trying to develop an effective way to deliver chemotherapeutic agents selectively to the tumor. This would spare the patient from the side effects while increasing the chances of clearing the tumor. I’ve read many stories during 2014 on miscellaneous attempts to make this work. But, alas, there have been no major breakthroughs. I’m giving myself only 1 out of 5.

Negative Predictions

  1. Two Storms Hit Pensacola

Statistics tell us that, just like the same person getting struck by lightning twice, that one of these years the same city on the Atlantic coast of the United States will be struck by a hurricane twice in the same year. I went out on a statistical limb and predicted that Pensacola, FL would suffer this fate during 2014. It turns out that due to an El Nino in the Pacific Ocean this year, the Atlantic hurricane season was quite mild and Pensacola was spared.(2)

However, over in the Pacific, the big island of Hawaii was hit by hurricanes Iselle and Julio in rapid succession. So I had the ocean wrong, but the phenomenon correct. Therefore, I am giving myself 3 out of 5 on this one.

  1. Liberian Food Riots

Liberia has leased out substantial portions of its arable land to foreign countries and corporations so that they can produce oil for biodiesel. The Liberian government then uses the cash from this practice to buy and import food stuffs such as rice. This system makes Liberia particularly vulnerable to disruptions in global food supply and prices. I predicted that this vulnerability, plus a strain on global food supply from an unknown source, would lead to unrest in Liberia during 2014.

The strain came in the form of the Ebola outbreak in West Africa. While the resulting disruption to food supply and distribution did result in some serious difficulties, Liberia was spared any noteworthy civil unrest. I am giving myself a score of 2 out 5 on this one. In addition, I need to give a shout out to both the medical staff of Liberia and Doctors Without Borders, who did a remarkable job of containing the Ebola outbreak.

  1. Chicken Sales to Drop

During 2013, there were many reports that the vast majority of chicken sold in our supermarkets is contaminated with bacteria. Furthermore, more and more of these bacteria have been found to be the scary, antibiotic-resistant kind. I predicted that all of this bad press would lead to a reduction in U.S. chicken sales in 2014. I was wrong.

Chicken sales in the U.S. in 2014 are on track to be 1.8% higher than in 2013. This is driven in part by sales of a product called Chicken Fries by Burger King. A determination from the Vatican on whether or not the existence of Chicken Fries qualifies as one of the seven signs of the apocalypse should be announced in early 2015.(3) I had to give myself a 0 out of 5 on this one.

  1. Fracking in the Ukraine

In late 2013, Russia was exerting both political and economic pressure on Ukraine by threatening to cut off supplies of natural gas. I predicted that this would inspire the Ukrainian government to reach out to oil and gas companies around the world to explore possibilities for fracking. Almost monthly throughout the year, I read a new report of a deal struck with an international drilling company for fracking with the government in Ukraine. This is the only prediction for which I am giving myself 5 out of 5.

Total Score

Overall I gave myself 19 out of a possible 45 points, for a score of 42%. On the one hand, 42% is kind of pathetic.  On the other, my predictions were rather bold, so 42% doesn’t feel too bad. Most importantly, I had fun making the predictions and monitoring their progress throughout the year, and hope you did as well.


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  1. By contrast, Piedmont Biofuels in Pittsboro uses waste grease from restaurants as an oil source for its products.  This is a very environmentally sound practice.
  2. I addressed why an El Nino in the Pacific impacts the Atlantic hurricane season in Hello Arthur.
  3. This is a joke.

Fracking: A Raleigh-Riyadh Connection

As you may have noticed at the pump recently, gasoline prices have fallen by 35% over the last few months, from just below $4.00 per gallon down to around $2.60, a five-year low. During this same time period, the price of petroleum, the raw material from which gasoline is made, has dropped from $110 to $70 per barrel. A quick calculation shows, unsurprisingly, that the percent reduction in the price of gasoline is nearly identical to the percentage drop in the price of petroleum. In order to understand why gasoline prices have dropped, we need to examine why petroleum prices have dropped.

Petroleum (or oil) is a global commodity, and its price is extremely sensitive to the balance of supply and demand. Back in 2011, global supply and demand for petroleum were roughly in balance, at approximately 91 million barrels a day (MMbbl/d) each. While these conditions existed, the price for a barrel of oil hovered in a narrow range near to $110 per barrel.

The breakdown of the approximate world oil supply from 2011 is shown below:

Production  (MMbbl/d) Percentage
United States 8 9%
Saudi Arabia 10 11%
Rest of OPEC 20 22%
All Others 53 58%
Total 91

The United States uses about 19 MMbbl/d of petroleum, so back in 2011 we were producing 8 MMbbl/d (42%) of this demand and importing the other 11 (58%).

Since 2011, petroleum production in the U.S. has increased from 8 to 11 MMbbl/d, an increase of more than 30%. Since our use remains at about 19 MMbbl/d of oil, our import and export percentages have flip-flopped, with domestic supply at 58% and imports at 42%.

The increased petroleum production in the U.S. has allowed us to supplant Saudi Arabia as the world’s largest supplier of oil, and our operations have increased the global petroleum supply by about 3%, from 91 to 94 MMbbl/d. A three percent increase may not sound like much, but as I mentioned above, commodity prices are strongly influenced by the supply and demand balance. Therefore, even this seemingly small increase in supply has driven the price of a barrel of oil down from $110 to $70 per barrel.

The reason that the U.S. has been able to dramatically increase its oil production can be summarized in one word: fracking. In case you have been living in a hole (pun intended) for the past few years, fracking is the process of shattering underground rock with a high-pressure mix of water, sand, and toxic chemicals to liberate oil and gas trapped within. Since these rock formations are usually made of shale, the resulting oil is often called “shale oil.” For the past several years, thousands and thousands of fracking wells have been drilled all over the country, particularly in North Dakota, Pennsylvania, Oklahoma, and Texas. Here in North Carolina, the General Assembly is rapidly pushing through legislation to allow fracking to begin here as well.

Financially speaking, an increase of 3 million barrels a day of oil production is a really, really big deal, in that it results in an increase in revenue to the U.S. oil industry of 100 trillion dollars a year! However, to really understand the economic and political implications of the increase in U.S. petroleum production, we need to discuss why I underlined the word revenue above.

While revenue is nice, what companies really need is profit, which is revenue minus expenses. Unfortunately for U.S. oil companies, fracking for shale oil is a very expensive enterprise. It costs about $70-75 to produce a barrel of oil from a fracking operation, compared to less than $40 for a traditional oil well. As you can imagine, when the price of oil was $110 per barrel, U.S. frackers were quite pleased to be making a profit of $40 per barrel. So pleased, it turns out, that they got overzealous, drilled too many wells, and the resulting over-supply drove the price way down.

Now that the price of oil has dropped to $70 per barrel, profits from fracking operations have dropped to zero. Given that drilling companies borrow huge sums of money to drill these wells, and that the banks who loaned the money want to be paid back, this situation is rather problematic to say the least.

To alleviate their difficulties, U.S. oil companies want Saudi Arabia and the rest of OPEC to cut back their own production to reduce supply and drive the price of oil back up. Since the Saudis have traditional rather than fracking wells, they still make a healthy profit at $70 per barrel. For the moment, they have rebuffed requests from the U.S., as have all of the world’s other noteworthy oil producing nations. I suspect that they are extracting a bit of revenge on U.S. companies as payback for their role in creating the oversupply situation in the first place.

It is unclear how long the Saudis, the big dog at OPEC, will maintain their current stance. If I were a betting man (and I most certainly am), I would bet that somewhere in a smoky room in Riyadh, negotiations are ongoing to determine what concessions the Saudis require before agreeing to cut back their production.

If you live in North Carolina and are hopeful that fracking will not commence there, I’d suggest that you root for the Saudis to remain obstinate. At $70 a barrel for oil, no one will start a new fracking operation, particularly in a zone with modest production potential like the Tar Heel State. So the next time you fill up your tank at $2.60 per gallon, consider pausing for a moment to think about what that really means.


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Methane in the Water Part II: Fires and Explosions

Author’s Note:  This is the most technically complex column I have attempted to share with you in the 3.5 years I have been publishing Common Science.  The issue of methane contamination of water wells is important and much of the reporting on it has been incorrect, so, to me, this is an important piece.   I ask that you give it a try and email me at commonscience@chapelboro.com with any questions.

This is the conclusion of a two-part series of the implications and potential hazards of methane contamination of drinking water wells due to fracking. Part I explained how we know that fracking allows methane to infiltrate drinking water aquifers, and reviewed the associated toxicity implications. For the purposes of this week’s column, the key point to know is that a recent Duke University study demonstrated that drinking water wells near to fracking operations in New York and Pennsylvania had methane concentrations of up to 70 mg/L, a level many times greater than normal. Since methane, the primary component of natural gas, is quite flammable, the question I will address this week is what level of methane contamination in drinking water wells represents a fire or explosion hazard.



The graph above from the Duke Study shows the elevated concentrations of methane in well water near to fracking operations. Please note the gray band labeled “Action Level for Hazard Mitigation (US Department of Interior)” as I will be referring to it below.(1)

In order to evaluate the potential hazards stemming from methane contamination of water wells, we need to discuss some thermodynamics.(2) Methane is a flammable gas, but like all flammable gases, it can only burn in air at certain concentrations. If the concentration is too low, there is not enough fuel to sustain a fire. If the concentration is too high, there is not enough oxygen. (Essentially, the methane crowds out the oxygen.) For methane to burn when mixed with air, its concentration must be between 5 and 15%, which are known as the lower and upper flammability limits. Therefore, in order to avoid a methane fire or explosion, we need to avoid creating a vapor mixture with 5-15% of methane in air. This is almost always accomplished by keeping the methane concentration at less than 5%.

Now that we know what concentrations of methane-air mixtures are flammable, the next question for us is, “How much methane must be dissolved in my well water such that a flammable mixture of methane and air can be created?” To answer this question we need to discuss the vapor liquid equilibrium (VLE) for methane and water shown below.


methane water VLE


The X axis on this graph shows concentrations of methane dissolved in water in milligrams per liter (mg/L).  The Y axis shows the percent methane in the air above the liquid. The diagonal line represents the conditions when the liquid and vapor are in equilibrium with one another. I will explain what that means using the example below.

Start on the X axis and find 5 mg/L of dissolved methane. If you move straight up from there, you will hit the diagonal line at 2.5% methane in the vapor. What this means is that if I make a solution of 5 mg/L of methane in water and put it in a closed container, methane will evaporate out of the liquid until the vapor concentration reaches 2.5%. The reverse is also true. If I were to start with pure water and introduce a vapor mixture of 5% methane above it, methane from the vapor will dissolve into the water until a concentration of 5 mg/L is reached. At these conditions, the vapor and the liquid are in equilibrium which means that methane evaporates from the water at the same rate that is dissolving back in from the gas. This is what equilibrium means in this context.

Now that we know how the VLE graph works, let’s consider the data for 10 mg/L of dissolved methane, a concentration just high enough that the DOI recommends mitigation. In this case we see that a vapor concentration of 5% methane would be created in a closed container. As we discussed above, 5% is the lower flammability limit for methane. Since a 10 mg/L solution of methane in water has the potential to create a flammable vapor mixture above it, the DOI uses 10 mg/L as the lower limit for its action level range.

Consider again the example of water with 10 mg/L of dissolved methane, but this time let’s put it in an open container. In this case, methane evaporating from the water into the vapor space above can waft away. In most circumstances, it will float away at a rate faster than it can evaporate from the water. Therefore, the vapor space above the water cannot build up a concentration of 5% methane – the lower flammability limit – and thus cannot burn or explode. Additionally, over time in an open system, eventually nearly all of the methane initially dissolved in the water will be gone.

The issue of closed versus open areas or containers is vital to evaluating the potential hazards of methane-contaminated water wells. The first place to look for fire and explosion risks in a home water system are closed spaces where methane vapor can accumulate. In a typical home water well and supply system there are two potential trouble spots: the well head and the pressure tank. The diagram below of a typical home water well system should help illustrate the potential problems.

Home Well Design

When installing a water well, you start by digging a 4-6” diameter hole into the ground until you find the water table, typically 100-500 feet in this neck of the woods. The top portion of the large hole is protected with a steel and/or concrete casing to prevent it from collapsing. At the top of the casing there is a cap called the well head. Then a pump is placed near to the bottom of the well which pumps water up to the surface through a thin (1-2”) pipe which runs up through the well casing to just below the ground surface and then into your house.(3) Once inside your house it feeds a pressure tank which has a flexible bladder inside. The bladder supplies pressure which allows water to flow to the faucets, showers, toilets, and appliances in the house. When the pressure in the bladder drops due to water use, a pressure switch turns on the well pump, refilling the bladder, until the pressure goes back up and then the pump is turned back off.

The most likely place for methane to accumulate in this system is at the top of the well casing below the well head. Methane in the aquifer can evaporate and rise up in the space outside of the thinner water delivery pipe. In circumstances where the aquifer contains more than 10 mg/L of methane, the presence of a flammable mixture below the well head is quite likely. On occasion, well head fires and explosions have been reported when the well head is opened in the course of maintenance activity. This potential hazard can be mitigated by installing a vent on the well head to let the methane escape and float away. Note that while this will prevent the formation of an explosive atmosphere, it creates an open pathway for the methane, a potent greenhouse gas, to enter the atmosphere.

The second potential place for methane to accumulate is in the vapor space of the bladder inside the pressure tank. As we learned in our discussion of the VLE diagram, when the concentration of methane builds in the vapor space, more and more of it will dissolve into the liquid. This dissolved methane will escape into the house when you use your faucets, showers, and toilets. This is the mechanism purported to be behind the famous scene in the movie Gasland when a man lights a fire in his kitchen sink. Because the sink is an open rather than closed environment, it is difficult (but not impossible) to create a flammable mixture of methane vapor in the sink. But having methane accumulate in your pressure tank can create a possible fire hazard, and attempting to mitigate this situation seems to be the prudent course of action.

Fortunately, it is not difficult to prevent the accumulation of methane it the bladder of the pressure tank. Unfortunately, the solution is expensive. The way to remove the methane is to have the well pump first deliver the water to an unpressurized, vented tank outside the house. The methane in the water will evaporate and exit through the vent of this tank. This process can be sped up by bubbling air through the water. Then the now methane-free water from this tank must be pumped into the bladder of the pressure tank to service the house. The extra tank, pump, and associated valving and controls for this design are not cheap!

As I have outlined, the fire and explosion risks of methane-contaminated well water can be addressed by venting the well head and adding extra tanks, pumps, and bubblers, at least in theory. But the real world often does not care too much about theory. Since the aquifers in North Carolina are not currently contaminated with methane, our wells generally don’t include these safeguards. When fracking does begin here and methane starts to infiltrate our drinking water, I believe that it is unrealistic to assume that these safeguards will be installed in all, or even a substantial portion, of the wells. Who would pay for it?

Furthermore, let’s step back for a moment and consider what is really happening here.  First, the drilling companies are creating a pathway for methane from underground natural gas deposits to reach the aquifers. Then if we make the changes to our water systems I described above in order to prevent fire and explosion hazards, we will be venting methane into the atmosphere!

This is not an acceptable situation. If you cannot demonstrate that you can extract natural gas without getting methane into our water, you should not be allowed to frack.

Have a comment or question? Use the interface below or send me an email to commonscience@chapelboro.com. Think that this column includes important points that others should consider? Send out a link on Facebook or Twitter. Want more Common Science? Follow me on Twitter on @Commonscience.

(1) I contacted the Department of the Interior while researching this column and wanted to note how very pleasant and helpful they have been. The issues of methane contamination are managed by the United States Geological Service (USGS). They were prompt and informative in answering my questions and told me that a baseline study of ground water methane in Lee and Moore counties was underway. Our tax dollars at work!

(2) Long-time readers will know that my father is an emeritus professor of chemical engineering at Penn State. Much of his work centers on thermodynamics, so I suspect that upon reading this he is smiling.

(3) It stays buried underground like this so it won’t freeze during the winter.


Third Fracking Rules Hearing Held Monday in Rockingham Co.

The third of four scheduled public hearings on proposed safety rules for fracking in North Carolina takes place 5 p.m. Monday at Rockingham County High School in Wentworth.

The previous two meetings before the Mining and Energy Commission were held at N.C. State University’s McKinnon Center last Wednesday; and two days later at Wicker Civic Center in Sanford.

Five hundred people attended the Raleigh meeting, and most of the speakers who addressed the commission were opposed to fracking.

Pittsboro resident Sarah Wood, who described herself as a mother of a 2-year-old, asked for a moratorium on fracking, and posed this question to the commission members:

“Would you feel comfortable living within a mile of a fracked well? Would you really feel comfortable living that close? And if the answer is no, that you would no feel comfortable living that close to something that’s potentially that toxic, then it’s your moral duty to protect those who are going to be living that close.”

Only around 200 people attended Friday night’s hearing in Sanford, but the emotions were just as high.

Eighty-six citizens from around the state – again, most of them opposed to fracking – spoke at that hearing. Like the first one, it was marked by occasional boos, snickering and other displays during comments by a handful of fracking supporters.

Back in June, North Carolina Gov. Pat McCrory signed a bill into law that allows permits to be issued for hydraullc fracturing, or fracking. By this method, underground rock is fractured by pressurized liquid to release natural gas.

Opponents say they’re concerned that toxic chemicals used in the process will seep into drinking water. Supporters say they envision more jobs, and increased energy independence.

The fourth and final public hearing before the Mining and Energy Commission is scheduled for Sept. 12 in Cullowhee, which is in Jackson County.


Methane in the Water Part I: Toxicity

In recent weeks, there have been many reports in both the local and national media regarding a study published by Duke University showing elevated methane levels in drinking water wells located near fracking operations in New York and Pennsylvania. In my opinion, these reports do not provide sufficient information for the reader/viewer/listener to evaluate the fundamental question, “How worried should I be?” In this two-part series, I will attempt to provide a comprehensive answer to that question. To do so, I am going to have to delve a bit deeper into technical details than normal. However, with fracking coming to the Tar Heel State, I think it is important for this issue to be addressed accurately and comprehensively. So pour yourself a fresh cup of coffee and let’s get to it.

Let me start with a one-paragraph primer on fracking. First, a drilling company locates an underground deposit of natural gas, which is a mixture composed primarily of methane along with small amounts of ethane, propane, and butane. Next, the company drills down to the depth of the gas deposit and protects the well bore with steel piping encased in a layer of concrete. From the bottom of the vertical well, horizontal holes are drilled in several directions. Then a high-pressure slurry of water, sand, and chemicals is pumped into the horizontal holes, fracturing adjacent rocks. Fracturing the rocks allows the natural gas in the deposit to migrate to the vertical well bore, and subsequently to be brought up to the surface. Many of the chemicals used in the fracking process are highly toxic. (1)

As we consider the issues discussed below, an appreciation for depth will be helpful. Water wells for drinking and agriculture are almost always less than 1,000 feet deep, because that is where the water is. Fracking wells tend to be much deeper, 2,000 to 20,000 feet, because that is where the natural gas is. The separation in depth between underground aquifers and fracking operations is a critical parameter in trying to avoid water contamination. If fracking occurs at depths which are too close to aquifers, then cracks can extend from the fracking zone into the aquifer and allow fracking chemicals to contaminate the water. I have previously written about a case of this occurring in Wyoming. The physics of fracking suggest, at least to me, that the separation in depth between an aquifer and any fracking activity should be at least 1,000 feet.


The graph above, from the Duke University study, shows methane concentrations for water wells as a function of distance from fracking operations. The data clearly show that water wells closer to fracking operations have higher concentrations of methane. This graph contains a lot of information and implications, and, thus, raises a number of questions which I will attempt to answer below.

What is the source of the methane?

The two most common sources of methane in ground water are bacteria in the soil and natural gas deposits. Drilling companies frequently raise the possibility of multiple possible sources in order to suggest that methane found in ground water may not be related to their activities. However, it is actually quite easy to determine the origin of methane found in a water well. When bacteria are going about their business, they make methane and only methane. In contrast, methane from natural gas, which is produced by the decomposition of ancient organic matter deep underground, is accompanied by other decomposition products such as ethane, propane, and butane. Since the water in the wells from the Duke study contains these other hydrocarbons along with methane, there is little doubt that the methane they found was from natural gas.

Did the methane reach the underground aquifers due to fracking?

As you look at the graph above, the answer seems to obviously be “yes.” However, drilling companies have claimed that the methane may have infiltrated local aquifers prior to the fracking operations and that since the Duke study does not have baseline data collected prior to drilling, causation has not been established.

While the assertions from the drilling companies are defensible on the surface, they don’t stand up to scrutiny. Consider that all of the water wells in the Duke study are over the same shale formation that bridges the New York/Pennsylvania border. If methane in that zone was naturally migrating into the aquifers, one would expect that nearly all of the wells would be contaminated. To accept the drilling companies’ explanation that their activities are not related to the water contamination, one would also have to accept that somehow they have only drilled near to previously contaminated aquifers and that the aquifers in areas where they have yet to drill have somehow avoided the onslaught of naturally migrating methane. The odds of the drilling companies’ theories being correct are infinitesimally small.

The explanation posited by the Duke researchers is that methane is reaching the aquifers adjacent to the fracking wells by leaking through cracks in steel piping and concrete casings around the vertical well bores. I find this explanation to be far more compelling.

Is methane toxic?

The short answer is no.  Methane is essentially inert and will not undergo chemical reactions except at very high temperatures. Therefore, any methane dissolved in water that you drink will pass through your body without causing any harm. Further, as flatulence can contain up to 10% of it, methane is not unfamiliar to your gastrointestinal system.

Is methane a harbinger of other pollutants?

The essence of this question is, “If methane can migrate from the fracking zone to the aquifer, can harmful fracking chemicals such as benzene do so as well?” To explain why the answer to this question is “not necessarily,” we need to talk a little chemistry.

Methane consists of a single carbon atom in the middle attached to four hydrogen atoms. Since the four hydrogen atoms are arranged symmetrically, methane is non-polar. What this means is that the electrons within a methane molecule are evenly distributed, which results in the characteristic that methane molecules tend not to stick to each other or to anything else. Methane is also a very small molecule. Since it is small and doesn’t stick to anything, methane can worm its way through very small cracks and fissures.

Molecules which are polar have a much more difficult time migrating from place to place underground. As an example, let’s consider water (H20), a molecule about the same size as methane. In the case of water, the two hydrogens are not symmetrically arrayed around the central oxygen atom. As a result, part of a water molecule is electron rich while the remainder is electron deficient. This has the effect of making water molecules act like little magnets such that they stick to each other and many other things, like soil and rock. So it has a much harder time migrating underground.

The chemicals used in the fracking process are both much larger than methane and tend to be polar like water, limiting their ability to migrate. Therefore, the fact that an aquifer has been infiltrated by methane is not a particularly strong indicator that fracking chemicals will soon arrive.

To sum up Part I, what we know so far is:

  • fracking operations allow methane from natural gas deposits to reach drinking water aquifers;
  • methane itself is not toxic; and
  • methane in the water does not necessarily mean that other fracking chemicals will also contaminate aquifers.

Next week in the conclusion of this series, I will discuss other potential hazards of methane contamination of water wells, particularly fires and explosions.

Have a comment or question?  Use the interface below or send me an email to commonscience@chapelboro.com.  Think that this column includes important points that others should consider? Send out a link on Facebook or Twitter. Want more Common Science? Follow me on Twitter on @Commonscience.

(1)   Although the North Carolina General Assembly recently voted to make it illegal for a citizen of the Tar Heel State to disclose the identity of chemicals used in fracking here in the southern part of heaven, as I explained in Fracking Gag Rule Part I, everyone already knows what they are.