Abstract

SCHERNIKAU, L.  and  SMITH, W.H.. Climate impacts of fossil fuels in todays electricity systems. J. S. Afr. Inst. Min. Metall. [online]. 2022, vol.122, n.3, pp.133-145. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/1874/2022.

Oil, coal, and gas account for approximately 80% of global primary energy, but only a portion of total airborne CO₂^eq (approx. 35% at GWP₂₀ to 65% at GWP₁₀₀), even though they account for 95% of total measured CO₂ emissions. The benefits of these energy sources, as well as their related costs, are not all incorporated in current energy policy discussions. Global greenhouse gas policies must include documented changes in measured airborne CO₂^eq to avoid spending large amounts of public funds on ineffective or sub-optimal policies. The authors examined airborne CO₂, which is less than half of emitted CO₂, as well as reported CH₄ emissions and the global warming potential of CH₄ as published by the IPCC for coal and natural gas. The surprising conclusion is that surfaced-mined coal appears 'better for the climate' than the average natural gas, and all coal appears beneficial over LNG. Therefore, current CO₂-only reduction policies and CO₂ taxes are leading to unintended consequences and the switch from coal to natural gas, especially LNG, will not have the desired impact of reducing predicted future global warming; in fact, quite the contrary. A large portion of anthropogenic global warming is attributed by the IPCC and IEA to CH₄, but it must be noted that CH₄ emissions from natural sources and from agriculture account for approximately 40% and 25% of annual global CH₄ emissions respectively. Energy accounts for about 20% of documented CH₄ emissions. CO₂ contributes only approximately 35% of annual airborne anthropogenic GHG emissions after accounting for CH₄, over a 20-year horizon. At a 100-year horizon, the contribution of CO₂ increases to approximately 60%. Energy policies that do not consider all GHG emissions along the entire value chain will lead to undesired economic and environmental distortions. All carbon taxation and CO₂ pricing schemes are incorrect and need to be revised. At IPCC's GWP₂₀ an approximately 2%¹ higher loss of CH₄ across the value chain prior to combustion of natural gas versus coal will lead to 'climate parity' of coal with natural gas. According to public data, natural gas value chains have high CH₄ and undocumented CO₂ losses. On a global average, using only IEA-documented CH₄ data, natural gas emits approximately 15% more CO₂^eq than surface-mined coal, over a 20-year horizon. This difference will increase as the use of shale gas and LNG expands. Investors should support all energy systems in a manner that avoids an energy crisis, including intermittent renewable energy systems where they make sense. If CO₂ emissions need to be reduced, one of the most effective ways would be to install ultra-supercritical power plants with CCUS technology. However, the undisputed benefits of increased CO₂ concentrations in the atmosphere because of its promotion of photosynthesis and plant growth effects (fertilization) need to be considered in energy policy decisions as well. The authors suggest that future research and development should concentrate on reducing net emissions from fossil fuel power plants and providing cost-effective and reliable new conventional power generation capacity, utilizing clean coal and clean natural gas technology.

Keywords : fossil fuels; GHG; greenhouse gases; energy policy; climate change potential; clean coal technology.

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