Hydrogen as a sustainable solution to gas flaring

Hydrogen is seen all over the globe as a sustainable solution to tackling climate change, clean manufacturing, and transport. Apart from this long-term goal hydrogen is also seen as a solution to reducing flaring gas emissions which has turned into the biggest threat to climate change globally. This article gives you a summary of what gas flaring is. Why is it done? And how can hydrogen solve the problem of flaring gas emissions?

What is gas flaring?

In general gas flaring refers to the process of controlled burning of natural gas from oil wells as a disposal method or as a safety measure. Though it seems like wasting the natural energy source gas flaring is done for the following reasons:

1. Absence of infrastructure: Crude oil extraction also releases natural gas which is normally found above the oil reserve. when there isn’t enough infrastructure to handle this release of natural gas, it is flared on a routine basis. This infrastructure includes a natural gas reinjection system, power generation facilities, gas storage tanks, and oil/ gas separators.
2. Safety: sometimes even when there is enough infrastructure these off-gases are flared to ensure the safety of the entire oil production facility. This includes flaring when the natural gas released exceeds the storage or processing capacity of the gas distribution infrastructure. This is done to prevent the overpressure in the system that could lead to an explosion.
3. Economic aspects: Most of the oil fields are in remote areas that are hard to access. These oil fields are mostly small and therefore, building natural gas distribution, storage, or processing infrastructure in such areas would be economically challenging. Hence the gases are flared.
4. Technical and Geological challenges: When the gases produced couldn’t be utilized or flared they can also be conserved by re-injecting the gases back into the reservoir. However, this comes with greater technical and geological challenges.
5. Complicated legislation: Sometimes even when the capture and utilization of these associated gases are technically and economically feasible the local regulations might make it difficult for efficient use of these off-gases. Hence the companies are left with no other choice other than burning them.

Hydrogen as a sustainable solution

It is clear that flaring is internationally dangerous and at the same time, the released natural gas from oil fields cannot also be set free because, methane, the major constituent of natural gas is a major greenhouse gas that speeds the warming of the globe. Though the lifespan of this gas is less (12 years) compared to CO₂ (can last for centuries) it has a greater global warming potential (GWP) compared to CO₂. Global Warming Potential is the measure of greenhouse gas emission in CO₂equivalent. According to The Intergovernmental Panel on Climate Change (IPCC), the GWP of methane is between 84-87 for a 20-year timeframe i.e., methane over a 20-year timeframe warms up the atmosphere 84 to 87 times more than CO₂. Hence the energy contained in this natural gas can be stored efficiently in the form of hydrogen for emission-free usage.

One of the promising methods to do this is through methane pyrolysis. Methane pyrolysis is an anaerobic endothermic reaction in which methane undergoes thermal degradation at high temperature (>500°C) and pressure (30 bar) with or without the presence of a catalyst to form hydrogen gas and solid carbon.

CH₄ —> C + 2H₂ Δ_RH°= 74.91 kJ/mol

The pyrolysis of methane can be done in the following ways:

1. Thermal degradation: This involves the pyrolysis of methane without the presence of a catalyst. Hence this process requires a temperature of above 1000 °C for higher reaction rates.
2. Catalytic degradation: This method involves the use of a metal (nickel) or carbon catalyst and hence has an operating temperature of about 800 °C. However, due to solid carbon deposits, the active catalytic layer gets deactivated.
3. Plasma degradation: This method is also known as plasmalysis which uses a plasma torch to split the hydrogen and carbon from methane. The temperature of this plasma could reach temperatures up to 2000 °C and hence requires continuous circulation of gas in order to stabilize the plasma.

Though this method is not much efficient in hydrogen generation compared to conventional steam methane reforming it does not produce CO₂ and hence the implementation of complex carbon capture technologies is not necessary. The solid carbon produced can then be used as a raw material for climate-neutral steel and tire production. Though storing energy in the form of hydrogen seems like a more sustainable solution it also would face the same challenges discussed above for gas flaring. However, hydrogen could solve the following major environmental problems of gas flaring:

1. Global Warming: According to the world bank, oil fields all over the globe flared about 144 billion m³of natural gas in the year 2021 which when calculated annually results in a greenhouse gas emission equivalent of about 400 million tones of CO₂¹. Compared to coal and diesel, natural gas can be used in an eco-friendly manner by converting it to hydrogen and solid carbon.
2. Melting of the Artic: Another pollutant released from gas flaring is soot (black carbon) which is formed as a result of incomplete combustion of the gases. This soot doesn’t remain in the atmosphere for a long time (a few days or weeks) like carbon dioxide or methane but gets easily carried away by the circulating wind currents. This solid carbon then gets deposited in the artic region resulting in a further increase of the snow melting rate. Research by the European Geosciences Union on black carbon from gas flaring shows that about half of the black carbon deposits annually in the artic result from gas flaring ².

Note from the author:

Though hydrogen without a doubt is a sustainable solution to tackling climate change will it save our planet? The answer is still ‘NO’. Hydrogen may solve the harmful emission problems but there are many other forms through which we humans harm the planet. However, there is something that could help better than hydrogen in saving our planet. It was taught to me at school, and I still believe in it. The triple R (RRR) principle. Reduce Reuse and Recycle.
- Afrin Hewitt Alban

References:

1. Methane and climate change – Methane Tracker 2021 – Analysis. (n.d.). IEA. Retrieved October 24, 2022, from https://www.iea.org/reports/methane-tracker-2021/methane-and-climate-change
2. Stohl, A., Klimont, Z., Eckhardt, S., Kupiainen, K., Shevchenko, V. P., Kopeikin, V. M., & Novigatsky, A. N. (2013). Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions. Atmospheric Chemistry and Physics, 13(17), 8833–8855. https://doi.org/10.5194/acp-13-8833-2013
3. Gas Flaring. (2022, March 3). AMAP. https://eua-bca.amap.no/gas-flaring
4. Emam, E.A. (2015) Gas Flaring in Industry An Overview. Petroleum & Coal, 57, 532-555. - References - Scientific Research Publishing. (n.d.). Retrieved October 24, 2022, from:https://scirp.org/(S(351jmbntvnsjt1aadkposzje))/reference/ReferencesPapers.aspx?ReferenceID=1985966
5. Schneider, S., Bajohr, S., Graf, F., & Kolb, T. (2020). Verfahrensübersicht zur Erzeugung von Wasserstoff durch Erdgas‐Pyrolyse. Chemie Ingenieur Technik, 92(8), 1023–1032. https://doi.org/10.1002/cite.202000021
6. What is Gas Flaring? (n.d.). World Bank. Retrieved October 24, 2022, from https://www.worldbank.org/en/programs/gasflaringreduction/gas-flaring-explained