PrintUnless you've been hiding under a rock for at least the past 10 years, you have heard about natural gas in the news. If you have heard about it, it was most likely in relation to hydraulic fracturing, or simply "fracking." This is a VERY controversial topic at the moment, and with good reason (as we'll see below). Because of this, you have to be careful where you get your information (good thing you are taking this course!). Our old friend Hank provides a pretty clear and unbiased description of fracking in the video below.
In case you hadn't heard, we humans use a lot of oil and gas these days. Just a couple of sorts of hydrocarbons, organic compounds made out of hydrogen-carbon atoms. They are a magnificent source of stored energy running a car engine or a fighter jet or a weed whacker or a power plant. Hydrocarbons are pretty useful. A lot of the world's precious petroleum comes from the Middle East, but that puts a few of the world's countries in the position of having all of the useful oil and gas. So, of course, the rest of us are interested in hunting down some domestic sources. Actually turns out the Middle East doesn't have the hydrocarbon market cornered, they just have a lot more liquid petroleum than most places. But a lot of the rest of the world has reserves of natural gas. Gaseous hydrocarbons like methane, propane, and butane.
Usually found deep underground in giant beds of shale, rock that was formed from the floors of ancient oceans, natural gas is likely how your water gets heated and maybe even your air. Burning it for electricity is cleaner and more efficient than coal and unlike oil when it spills, it just vents into the atmosphere instead of spreading out in huge slicks over the ocean. The problem with natural gas has always been how do we get at it? We know it's there, but we can't get it!
Since the forties, oil companies have known that breaking up the rocks in deep underground formations can increase the productivity of wells. See it's not just one big pocket of black gold down there; oil and gas can occur in thousands of little pockets, and by fracturing the rocks around these pockets the gas is released and can be collected. Usually, this fracturing involves pumping millions of gallons of chemically treated water into deep shale formations. We're talking a mile or more underground at extremely high pressures. This fluid cracks the shale or widens existing cracks freeing the hydrocarbons and making a path for them to flow toward the well. So that's how it's done basically, and some people are so unbelievably pumped about this technology they're building little graven images to it, going to natural gas wells on Sunday mornings.
But then, some scientists are like not so fast you guys, cuz fracking isn't all butterflies and cupcakes. For starters, it uses a whole lot of water. It takes up to seven million gallons to frack a single well, and at least 30 percent of that water is trapped in the shale thousands of feet below the groundwater aquifer so it's gone for good. Fracking fluid isn't just water, it's sand which helps keep the cracks open once they form but also chemical additives which can vary from well too well and are often confidential. These additives do things like thicken the water to help suspend the sand or prevent mineral buildup in the pipe and some are things might find under your kitchen sink. Others like benzene in methanol are pretty toxic.
Some concerns about the contents of these fracking fluids not to mention radium, corrosive salts, and other stuff that comes back up from a mile underground, have led places like Pennsylvania to prohibit fracking outfits from sending their wastewater to local treatment plants, and although fracking when done correctly shouldn't contaminate drinking water aquifers, that doesn't mean it hasn't happened.
Subterranean systems are mysterious, and it's impossible to tell how interconnected the shale deposits might be with groundwater. If the fracturing is too effective, groundwater aquifers and shale deposits containing newly injected fracking fluid can mix. Although it's hard to say how many cases of contamination have been caused by improperly installed or maintained fracking wells, improperly bored or sealed wells have contaminated drinking water in several sites in the US resulting in energy companies being fined for polluting water supplies. While natural gas is a far cleaner fuel than coal, the fact that it doesn't spill and instead vents to the atmosphere is also problematic for climate change. Methane is a potent greenhouse gas and if it isn't burned as it vents from fracking wells, it can contribute even more to global warming.
And finally earthquakes. It's crazy, but some US states like Oklahoma, Texas, and Colorado have been experiencing a significant rise in seismic activity, which seems to be corresponding to the fracking boom. Some studies are suggesting that the disposal of wastewater back into used wells are causing the pressurized water to seep through cracks onto old fault lines causing many more earthquakes than normal even in places where seismic activity is rare.
So fracking is creating a new oil and gas boom in the US, sure, but it might not be all it's fracked up to be. Sorry, we didn't make any Battlestar Galactica jokes. So, if you want you could put those down in the comments. If you have any questions or comments or just want to argue about it, the comments are there for that as well. There are also sources. If you'd like to check those out, that would be good. And if you want to keep getting smarter with us here at Sci Show, you can go to youtube.com/scishow and subscribe.
One popular misconception is that fracking has only been around since the early 2000s or so. As Hank explains, this is simply not the case. Hydraulic fracturing has been known to increase the output of gas (and oil!) wells since the mid-1900s. The main innovation that has caused the recent fracking boom is directional drilling (sometimes called horizontal drilling). Until relatively recently, oil and gas wells were generally drilled in a straight line. But directional drilling allows operators to change the direction of the drill bits so that they can trace the path of underground rock layers (which are rarely straight up and down). This allows for significantly more gas output per well and is what mainly facilitated the fracking boom.
Supply
Like coal, it is impossible to determine the amount of natural gas reserves available in the U.S. or worldwide. Most of the data you will see are based on "proved reserves," which the EIA defines as "estimated volumes of hydrocarbon resources that analysis of geologic and engineering data demonstrates with reasonable certainty are recoverable under existing economic and operating conditions." (Credit: US EIA). Basically, proved reserves are a reasonable estimate of the amount of natural gas that is believed to be in the ground that can be recovered given current technology, and for a profit.
Because the proved reserves are based partially on technology, as technology has advanced - especially with fracking - the proved reserves have generally increased. This is clear in the chart below. The upward trend in available gas would seem odd to the uninitiated since it is a finite resource. But it's important to keep in mind that the chart reflects proved reserves, not the actual amount in the ground.
I'm sure you noticed the dramatic drop in proved reserves from 2011 to 2012 and 2014 to 2015. 2015 has a somewhat simple explanation. The price of natural gas dropped significantly from 2014 to 2015, which "(caused) operators to revise their reserves downward", according to the EIA.
In the chart above, shale gas refers to gas that is locked up in the pores of shale in underground layers, as described in the fracking video above. Tight gas refers to gas that is locked up in other formations like low-permeability sandstone. For a full explanation of the terms, see this EIA website.
So how much gas do we have left? The EIA provides the following analysis and explanation:
At the rate of U.S. natural gas consumption in 2016 of about 27.5 Tcf per year, the United States has enough natural gas to last about 90 years. The actual number of years will depend on the amount of natural gas consumed each year, natural gas imports and exports, and additions to natural gas reserves.
Optional Readings
- "How Much Natural Gas is Left? US EIA.
- "Just How Long Will U.S. Gas Supplies Last?" Peter Kelly-Detwiler, Forbes Magazine.
Feasibility and Sustainability Issues
Like coal, the natural gas infrastructure is well-established, including wells, pipelines, and power plants. As you saw previously, natural gas is relatively cheap. The recent boom in natural gas production has provided a lot of high-paying relatively low-skilled jobs and has generated millions of dollars in royalties for landowners. Increased use and cheaper (up front) cost of natural gas has allowed the widespread replacement of coal-fired power plants, which has resulted in natural gas increasing its share of U.S. electricity production from 18% in 2005 to 32% in 2015. During the same period, coal's share has dropped from 51% to 34%. This is a major change in just over a decade!
One major benefit of this is that it has contributed to reduced CO2 emissions that come from electricity generation in the U.S. These emissions are at their lowest level since 1993. The EIA explains that: "A shift in the electricity generation mix, with generation from natural gas and renewables displacing coal-fired power, drove the reductions in (CO2) emissions." This is a major benefit of natural gas. As indicated previously, burning natural gas results in approximately half of the emissions from an equal amount of coal energy.
But this is not the whole story regarding emissions. Remember that while natural gas emits about half of the CO2 as an equivalent amount of coal when burned, natural gas itself is about 30 times as powerful as carbon dioxide in terms of greenhouse effect impact over a 100 year period and about 80 times as powerful over a 20 year period. One result of this is that methane leaks throughout the natural gas supply chain (from the well to the end user) counteract some of the positive impacts of natural gas being a relatively clean-burning fuel.
Some other considerations regarding natural gas, mostly from this article by John Wihbey include:
- Regarding fracking and contamination of water: Widespread water contamination was not found, but there are verified cases of water supplies being tainted.
- Up to 5-7 million gallons of water are used per well, much of which is unrecoverable; the water that is recovered is often contaminated with hazardous chemicals and substances;
- The disposal of fracking wastewater by injecting into the underground formations, including oil wells, is almost without a doubt causing earthquakes. Usually, this is not serious, but some fracking operations have been shut down due to earthquake risk.
- It is certain that there are fugitive emissions coming from oil and gas operations, but how much is up for debate. It does appear that most of the total leakage is from a few major emitters, but overall it can be difficult to monitor all leaks because of the huge number of wells in the U.S.
- Natural gas-fired power plants can also be energy to supplement renewable energy like wind. Natural gas-fired power plants can increase and decrease output quickly, much more so than coal or nuclear. So, if energy generation from solar or wind drops suddenly, natural gas can make up the difference through increased output.
- Whenever batteries or other forms of electricity storage become economic, the above-listed benefit of natural gas will no longer be relevant.
In short, natural gas is really a mixed bag of sustainability implications, especially with regards to hydraulic fracturing. The primary benefits from a sustainability perspective are that there is no doubt that it has reduced CO2 emissions, but to what extent natural gas leaks have counteracted that is in question; and also that it has created an economic boom, at least in the short term. There are many downsides, particularly with regards to environmental damage (water, air, land), but also with regards to quality of life for some people near wells.