[Paper Review] De-carbonization of global energy use during the COVID-19 pandemic

Zhu Liu, Biqing Zhu+16 more|arXiv (Cornell University)|Feb 5, 2021

Energy and Environment Impacts4 citations

TL;DR

This study analyzes the de-carbonization of the global power sector during the COVID-19 pandemic using near-real-time emissions data from 30 countries (70% of global power generation). It reveals a historic low in carbon intensity—414.9 tCO2eq/GWh in 2020—driven by a 6.1% decline in fossil-fuel power generation and a 6.2% rise in low-carbon sources, with renewables and nuclear exceeding coal and oil for the first time in May 2020.

ABSTRACT

The COVID-19 pandemic has disrupted human activities, leading to unprecedented decreases in both global energy demand and GHG emissions. Yet a little known that there is also a low carbon shift of the global energy system in 2020. Here, using the near-real-time data on energy-related GHG emissions from 30 countries (about 70% of global power generation), we show that the pandemic caused an unprecedented de-carbonization of global power system, representing by a dramatic decrease in the carbon intensity of power sector that reached a historical low of 414.9 tCO2eq/GWh in 2020. Moreover, the share of energy derived from renewable and low-carbon sources (nuclear, hydro-energy, wind, solar, geothermal, and biomass) exceeded that from coal and oil for the first time in history in May of 2020. The decrease in global net energy demand (-1.3% in the first half of 2020 relative to the average of the period in 2016-2019) masks a large down-regulation of fossil-fuel-burning power plants supply (-6.1%) coincident with a surge of low-carbon sources (+6.2%). Concomitant changes in the diurnal cycle of electricity demand also favored low-carbon generators, including a flattening of the morning ramp, a lower midday peak, and delays in both the morning and midday load peaks in most countries. However, emission intensities in the power sector have since rebounded in many countries, and a key question for climate mitigation is thus to what extent countries can achieve and maintain lower, pandemic-level carbon intensities of electricity as part of a green recovery.

Motivation & Objective

• To quantify the changes in global power sector carbon intensity during the COVID-19 pandemic using near-real-time emissions data.
• To assess the shift in energy mix toward low-carbon and renewable sources during 2020, particularly the first-time surpassing of coal and oil by low-carbon sources.
• To examine how changes in electricity demand patterns influenced the performance and integration of low-carbon generators.
• To evaluate the sustainability of pandemic-era emission reductions and their implications for long-term climate mitigation strategies.
• To investigate the rebound in carbon intensity post-2020 and the feasibility of maintaining low-emission power systems in a green recovery.

Proposed method

• Utilized near-real-time energy-related greenhouse gas (GHG) emissions data from 30 countries, representing approximately 70% of global power generation.
• Calculated the carbon intensity of the power sector as total CO2-equivalent emissions divided by total electricity generation (tCO2eq/GWh).
• Tracked the share of electricity generated from low-carbon sources (nuclear, hydro, wind, solar, geothermal, biomass) versus fossil fuels (coal and oil) on a monthly basis.
• Analyzed diurnal electricity demand patterns across countries to assess how changes in load curves affected the dispatchability and performance of low-carbon generators.
• Compared pre-pandemic (2016–2019 average) and pandemic-era (first half of 2020) energy demand and supply trends to isolate the impact of reduced activity.
• Monitored temporal trends in carbon intensity and renewable shares to identify inflection points, such as May 2020, when low-carbon sources surpassed fossil fuels.

Experimental results

Research questions

• RQ1 To what extent did the COVID-19 pandemic lead to a de-carbonization of the global power sector in 2020?
• RQ2 When did low-carbon energy sources first exceed fossil fuels in global power generation, and what factors enabled this shift?
• RQ3 How did changes in electricity demand patterns during the pandemic affect the operational efficiency and dispatch of low-carbon power plants?
• RQ4 To what degree did the reduction in fossil-fuel power generation contribute to the observed decline in carbon intensity?
• RQ5 Can the pandemic-era carbon intensity levels be sustained in post-pandemic energy systems, and what policy implications does this hold for climate mitigation?

Key findings

• The global power sector achieved a historic low carbon intensity of 414.9 tCO2eq/GWh in 2020, representing a significant de-carbonization of electricity generation.
• The share of electricity from low-carbon sources (nuclear, hydro, wind, solar, geothermal, biomass) exceeded that from coal and oil for the first time in May 2020.
• Fossil-fuel-burning power plants experienced a 6.1% reduction in supply during the first half of 2020, while low-carbon generation increased by 6.2%.
• Global net energy demand decreased by 1.3% in the first half of 2020 compared to the 2016–2019 average, masking deeper reductions in fossil fuel use.
• Diurnal electricity demand patterns shifted, with a flatter morning ramp, lower midday peak, and delayed load peaks, favoring low-carbon generation in most countries.
• Carbon intensity in the power sector has since rebounded in many countries, indicating that pandemic-driven reductions were not sustained without policy intervention.