Natural gas is promoted as a “transition fuel” or “bridge” between fossil fuels and renewable energy. Even though natural gas burns cleaner and releases less carbon dioxide per unit of energy than other fossil fuels like coal and oil, it is still a fossil fuel, which gives room for doubt on its importance in the energy transition.
Natural gas is a hydrocarbon mixture consisting mainly of methane. It is found in rock formations associated with other hydrocarbons. In natural gas production from conventional reservoirs, the gas usually floats easily up and then is sent to the processing plant to separate it from NGL and remove nonhydrocarbon compounds and water vapor. The processed natural gas is the consumer-grade/pipeline-quality gas.
Consumption of natural gas followed a long-term pattern, at least in the U.S., that was similar to that of oil but at a lower level. Its share of the total energy consumption increased from 17% in 1950 to 32% in 1970, to later decline to about 20%. But thanks to a technological breakthrough in the late 1980s consisting of pairing hydraulic fracturing with horizontal drilling, its share came back up booming in the 1990s to take part of coal’s share. In 2018, natural gas represented 31% of the total energy consumption in the U.S. Globally, its contribution to the energy market for the same year stood at 23% while the contributions for oil and coal were 32% and 26% respectively; the balance consisted mainly of hydroelectric, wind, solar, nuclear and other minor sources.
According to a DNV GL report from this year, natural gas is projected to overtake oil’s share as the single largest energy source by 2026. That comes as no surprise as this energy source touches our lives in many ways. The electricity in our homes, heating systems, vehicles and many daily products like plastic and detergent are fueled by natural gas. It is easily capturing oil’s already declining market share in power generation; but is the transportation sector the one that is more interesting. Countries like the U.S., Iran, Pakistan, and Argentina (where I have seen it personally in 2005) are already using compressed or liquefied natural gas for their vehicles. It is just logical to convert cars to natural gas as it is cheaper, more efficient and emits 15-20% less greenhouse gases than gasoline.
Now, let us go back to the transition fuel claim. The increased use of natural gas has been found mostly in electricity generation. Electricity is produced by an energy mix which is a group of different primary energy sources. This mix is currently dominated by fossil fuels, which includes natural gas. There is a big global movement to increase the installed capacity of both solar and wind as they are renewable and cleaner than fossil fuels. As it is well known, renewables like wind and solar are intermittent; meaning that they are not always available. That is where natural gas comes to the rescue and takes over the load these cleaner energies cannot carry at some point of the day to make sure electricity keeps flowing.
Some of the advantages of natural gas include its affordability, high calorific value, lower carbon intensity and vast availability. A disadvantage, and this is a big one, is that it emits CO2 and other heat-trapping gases when burnt. Leakage of natural gas in addition to flaring and venting at production sites also mean great amounts of methane and other compounds are entering the atmosphere.
This disadvantage does not mean natural gas cannot be a bridge when moving toward cleaner energies; it already has been for many years and has played a key role in reducing CO2 emissions. The issue is that when the oil and gas industry started marketing natural gas as a “transition fuel”, solar and wind were not at the competitive prices they are now and battery technology was much more expensive.
Battery technology to use as backup for wind and solar is not quite ready to be deployed at the massive scale necessary to fully transition to renewables today. So, the question is: does natural gas as a transition fuel makes a difference compared to transitioning directly to renewables?
That is the question that a study from 2013 by M. Levi tried to answer. Several models with several assumptions were made. The first conclusion is that replacing coal for natural gas can substantially lower peak temperatures. The second is that in scenarios where natural gas was used as a bridge fuel, CO2 concentrations were the same and had similar warming rates as scenarios where the transition to a zero-carbon energy is direct and sooner. The study does not mention why that happens. It could be that producing massive amounts of solar panels, wind turbines and batteries require enormous amounts of energy and battery prices should go down even more, which is going to take some time. Meanwhile, natural gas would still be needed to satisfy that extra energy demand.
The truth is that the contribution of renewables to the energy mix has been less than half that of natural gas since 2017; although, renewables growth has been greater. It is also true that governments need to support policies that promote the use of renewables and do not prioritize the use of fossil fuels instead – like some governments do.
Energy experts seem to agree that coal will remain as part of the energy mix for at least a decade. If we want to achieve the goal of the Paris Agreement, we have to leave coal behind much sooner. Almost immediately. This is unlikely to happen because the infrastructure for renewables with batteries as backup at nice price points is not ready yet; the only choice there is while there are still fossil fuels in the energy mix is carbon capture and storage. Although the technology keeps evolving, it is an option that is available today. Meanwhile natural gas will continue being a bridge toward renewables.
R. F. Aguilera and R. Aguilera. Revisiting the role of natural gas as a transition fuel (2019), M. Levi. Climate consequences of natural gas as a bridge fuel (2013), IHS Markit, Forbes, Bloomberg, Enerdata
Featured image: Semana Economica