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| Fig. 1: A natural gas flare. (Source: Wikimedia Commons) |
In the process of oil extraction, natural gas and other mixtures of volatile hydrocarbons are produced. Pockets of these gases pose a large safety risk to the extraction operation and are either burned off, called "flaring" and shown in Fig. 1, or pumped to the surface to dilute, called "venting". Both of these practices introduce pollutants to the air, depending on the chemical composition of the gas. Venting produces the most air pollutant. Flaring pollutes based on the temperature and efficiency of the flare. There are "green completions" to these pockets of stranded, natural gas where the natural gas is liquified on site and then pumped to market to be sold. [1]
If green completions create a byproduct that can be sold to market, one might expect all oil extraction operations to also become natural gas extraction operations, too. In reality, 286,668 million cubic feet (8.12 × 109 m3) of natural gas were vented and flared in the United States in 2021. The cost of selling the natural gas can eclipse the value of the resource when the pockets are far from market. "Stranded" natural gas refers to natural gas that is economically unrecoverable, meaning the price of preparing and shipping it to market exceeds its cost. [2] The average price of natural gas in the United States, between 2001 and 2022 was $9.76 per thousand cubic feet ($0.345 m-3) but the price can drop as low as $1.5083 per thousand cubic feet ($0.0533 m-3). [3] This makes the economics of green completions fickle as it tracks market conditions. Permanent equipment such as (1) piping to well head, (2) dehydrators, (3) compressors and separators, (4) lease meters, and (5) stock tanks are required on-site before green completions can take place.
In 2011, The EPA published a report on Reduced Emission Completions, another term for green completions. In this report, they detatil that third party REC vendors will foot the burden of owning, setting up, and maintaining REC equipment, at a cost as high as $6000 per day per well. Yet still, they claim that at 10,800 thousand cubic feet (3.05 × 106 m3) per completion this is profitable. In the case of owning and operating the REC equipment, a company would need 270,000 thousand cubic feet (7.6 × 106 m3) of natural gas in a REC to be profitable within the year. High-pressure wells are the best use case for REC, due to their density of natural gas. Most wells are not high pressure, however, meaning that the time to recoup investment on medium-pressure or low-pressure wells will take longer, if possible to recoup cost at all. [4]
The gas expended during these flaring and venting events could otherwise be burned as fuel. By bringing the gas to market, it can be used to heat or power homes, not to mention reduce the emission of greenhouse gases to the atmosphere. We can calculate just how much potentially captured energy is lost through natural gas flaring and venting.
First, let's look at our units. In the United States, natural gas is measured in Btu (british thermal units), MCF (thousands of cubic feet), or MMCF (millions of cubic feet). Furthermore, these units are assuming that the gas is at standard conditions which is 60°F and 14.7 psi, or 1 atm. Under these constraints we can calculate the energy stored. There are 1027 Btu per cubic foot of natural gas. [5] Every Btu is equivalent to 1055 Joules. This works out in SI units to
In the United States in 2021, measurements of total Natural Gas Flared range in the billions of cubic meters, as shown in Table 1.
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| Table 1: Measurements of natural gas flared in the United States in 2021 by different sources. |
We can calculate the amount of energy uncaptured in the United States in 2021 using the above numbers. We will use the BP measurement as our high estimate and the U.S. EIA measurement as our conservative estimate:
| High Estimate: | 9.7 × 109 m3 × 3.826 × 107 J m-3 | = 3.71 × 1017 J | |
| Low Estimate: | 8.12 × 109 m3 × 3.826 × 107 J m-3 | = 3.11 × 1017 J |
The BP 2022 Statistical Review of World Energy reports that, globally, the amout of natural gas flared and vented in 2021 was 152.7 billion cubic meters (1.53 × 1011 m3). The flaring of 9.7 billion cubic meters in the United States only accounted for 6.3% of the global natural gas flaring. The Middle East accounted for 30.8% of all global flaring. Russia and Iran led the globe with 26.4 billion cubic meters and 18.5 billion cubic meters of natural gas flared, respectively. These two countries accounted for 29.4% of the global natural gas flaring in 2021. [8]
Russia accounts for 37% of EU-27 countries' natural gas imports. Russia's immense natural gas flaring can be attributed to Europe's process of extricating itself from depedence on Russian gas. Yet still, the price of Natural Gas quadrupled in 2021. European natural gas imports declined by 6.6% in 2021 and Russian exports declined by 4.9% despite Russian production growing by 10.4%. [8] There we see an economic disconnect in the market supply and demand. Russia is producing more natural gas and exporting less of it, along with its largest buyer taking less. Natural gas, an economically fickle resource, becomes quickly economically unrecoverable from Russia's far-flung wells in Siberia. Still, with natural gas prices quadrpuling in Autumn 2021, with an average price of $16 per million Btu, there was market incentive for Russia to limit its flaring and bring more resource to market. This was in the months leading up to Russia's invasion on Ukraine, subsequent EU sanctions, and the September 2022 sabotage of the Nordstream pipelines. In any case, we can calculate the amount of energy uncaptured in Russia's 26.4 × 109 m3 natural gas flared in 2021. This amount is 1.01 × 1018 Joules.
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| Table 2: Value of natural gas vented in the United States and Russia in 2021. |
This natural gas that is vented and flared into the atmosphere could be captured and used on market as fuel. Power plants in the United States use natural gas as a clean, low-emission hydrocarbon to generate electricity with turbines. Natural Gas can be converted to electricity through combined-cycled power plants at a rate of 7,146 Btu kWh-1 (0.197 m3 kWh-1). Residential daily consumption of electricity in the United States is estimated 12 kWh per person per day. [10] If all stranded natural gas were brought to market, it could provide electricity for over 1.3 million Americans for an entire year. This figure, however, is ignoring the market effects by increasing the supply of energy with sources that are already economically unrecoverable. Still, according to the EIA, the present retail price of natural gas is about $20 per 1000 ft3 or $0.7062 m-3. Were the middle measurement of gas, by The World Bank, able to reach market its value would be over $6 billion. In the case of Russia, if their 26.4 × 109 m3 of natural gas could reach market in 2021, where the price of natural gas was $16 per million Btu ($0.5802 m-3) it would have been valued at $15.32 billion. Both of these scenarios are shown in Table 2.
© Dominic Terrones. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] J. A. Jacobs and S. M. Testa, Environmental Considerations Associated With Hydraulic Fracturing Operations (Wiley, 2019).
[2] C. Hammond, S. Conrad, and I. Hermans, "Oxidative Methane Upgrading," ChemSusChem 5, 1668 (2012).
[3] "Monthly Energy Review, October 2022," U.S. Information Administration, DOE/EIA-0035(2022/10), October 2022.
[4] "Reduced Emissions Completions for Hydraulically Fractured Natural Gas Wells," Environmental Protection Agency, 2011.
[5] S. Berdikeeva, "Turkmenistan's Energy Policy: Risks and Opportunities," Insight Turk. 9, 123 (2007).
[6] "2022 Global Gas Flaring Tracker Report," World Bank, 2022.
[7] "Natural Gas Annual," U.S. Energy Information Administration, 2021.
[8] "BP Statistical Review of World Energy 2022," British Petroleum, June 2022.
[9] "Electric Power Annual 2020," U.S. Energy Information Administration, March 2022.
[10] "U.S. Energy System Factsheet," University of Michigan, September 2022.
