Is natural gas actually cleaner than coal?

News Excerpt:

A new research indicates that natural gas, which has long been hailed as a good stepping stone for a world looking to replace coal with renewable energy, isn’t as climate-friendly as once thought.

Natural Gas:

  • Natural gas is a fossil fuel energy source. It contains many different compounds. The largest component of natural gas is methane (CH4). 
    • Methane is a highly flammable gas; it burns easily and almost completely and emits little air pollution. 
  • Natural gas is neither corrosive nor toxic, its ignition temperature is high, and it has a narrow flammability range, which makes it an inherently safe fossil fuel compared with other fuel sources. 
  • In addition, because of its specific gravity (density of a substance in comparison to the density of water) (0.60), which is lower than that of air (1.00), natural gas rises if escaping, and thus dissipates from the site of any leak.

Natural gas as a ‘bridge fuel’:

  • Natural gas has been called a ‘bridge fuel’ for countries looking to transition away from coal and oil dependency, and as they pursue a pathway towards renewable energy. 
    • As solar arrays and wind farms are being built, natural gas can be a stand-in for “dirtier” fuels, like coal and, in some cases, oil.
  • It is hailed as a cleaner energy source than other fossil fuels, especially coal. 
    • Natural gas has a lesser climate impact than coal because it emits 50% less CO2 into the atmosphere.

Coal vs Natural Gas:

  • From a climate standpoint, coal and gas are compared by assessing their life cycle greenhouse gas (GHG) emissions.
    • A “life cycle assessment” evaluates all the emissions throughout the coal and gas supply chains from extraction, processing, and transportation to end use.
    • Comparisons based only on end-use combustion might be limited in their purview and paint an incomplete picture of the total GHG emissions.
  • Carbon emissions from power plants:
    • A coal-fired power plant in Europe emits GHG emissions of 970 tonnes of carbon dioxide equivalent (CO2e) per gigawatt-hour of electricity over its lifecycle. 
    • An oil-fired power plant emits 720 tonnes of CO2e per gigawatt-hour.
    • A gas-fired power plant emits 440 tonnes of CO2e per gigawatt-hour of electricity over its lifecycle.

Methane:

  • Methane is an invisible but strong greenhouse gas.
    • A critical driver of climate change: When it comes to trapping heat inside Earth's atmosphere, methane is over 28 times more powerful than carbon dioxide.
    • Methane is the second-most abundant GHG after CO2. Although methane dissipates faster than CO2 in the atmosphere, it has a much stronger planetary warming effect.
    • According to the UNEP, methane has 80 times the warming power of carbon dioxide during the first 20 years after it is released into the atmosphere.
    • Methane is responsible for 30% of global heating since the Industrial Revolution.
  • Methane has a strong near-term warming effect, unlike the long-term potency of CO2. Traditional climate models measuring the effects of methane over 100 years could end up overlooking its immediate heat-trapping potential, possibly skewing policy conclusions of natural gas versus coal emissions.

Methane Leaks and Climate Change:

  • Unintentional” methane leaks can occur during drilling and well completion, aside from those stemming from faulty gas equipment during production and processing.
  • “Intentional” methane releases occur from venting and flaring. 
    • Flaring involves burning off excess natural gas at the production well using a flare, releasing methane and CO2. 
    • Venting is the direct release of small quantities of natural gas into the atmosphere. 
    • Venting and flaring can cause pollution as well as wastage of resources.
  • Methane leaks result in fugitive emissions, with varying estimates depending upon measurement methods.
  • As little as a 0.2% leakage rate of gas can be worse for the climate than coal in terms of net GHG emissions. 
  • The global average natural gas leak rate is said to be between 2% and 3%. 
  • Methane plumes have also increasingly been detected by satellites and sensors.

Is natural gas a cleaner alternative to coal or oil in terms of emissions?

  • Natural gas is a cleaner fuel in the sense that burning it produces fewer conventional air pollutants, like sulphur dioxide and particulates, than burning coal or oil.
    • Burning natural gas also produces less carbon dioxide per unit of energy – about half compared to the best coal technology – and by this measure, it’s better from a climate perspective.
  • Research indicates that emissions of methane that occur during its extraction and transport mean natural gas isn’t as climate-friendly as once thought.
  • Methane emissions undermine Natural Gas’s credentials as a better fossil fuel and  “cleaner” is probably not the best word to describe it.

Isn't some improvement over coal better than nothing?

  • To limit the rise in average global temperatures to 1.5C - the most ambitious goal of the 2015 Paris climate agreement - scientists say emissions must be reduced to net zero by 2050, which leaves far less room for the use of fossil fuels of any kind.
  • Emissions globally need to fall by about 7.6% a year between now and 2030 to meet the 1.5C target.
  • But emissions from the natural gas industry are now growing so rapidly that the sector "is quickly becoming one of the biggest challenges to address climate change.”
  • A U.N.-backed team of researchers has found that the world was on track to produce 70% more natural gas in 2030 than would be compatible with the 1.5C goal.

Way Forward:

  • The oil and gas industry emissions can be cost-effectively mitigated through “ready-to-implement” measures which include tackling methane emissions, eliminating all non-emergency flaring, and electrifying upstream facilities with low-emissions electricity, among others. 
  • A report by the Climate Policy Initiative highlights that the fossil fuel sector, particularly oil and gas, holds the highest methane abatement potential (34 metric tonnes of CH4 per year) through cost-effective measures, yet it receives less than 1% of tracked methane abatement finance.
  • In the pursuit of cleaner energy, evaluating the true climate impacts of natural gas and coal remains crucial for informed decision-making in the transition away from fossil fuels.