SOIL CARBON SEQUESTRATION
Photo courtesy of Harvest To Table
“Energy cost money, and taking CO₂ out of the air uses more energy than emitting it in the first place.”
Genrvieve Guenther “The Language of Clime Politics”
Human caused greenhouse gase (GHG’s) emissions are contributing to the global warming of the Earth. Average global temperatures have risen 1.3°C / 34.34°F hotter since pre-industrial times. Increased temperatures are causing climate change related extreme weather events sparing no-one along with no geographic safe havens. Although the northern hemisphere of the Earth is the main contributor of GHG emissions, with temperatures rising more than 5°C / 41°F higher in some cases, it is the populations that contributes the least in the global south that suffers the most due to poverty & a lack of remedial resources.
The Paris Agreement, an international treaty on climate change, adopted by 195 countries, at the U.N. Climate Change Conference (COP21) in Paris, France, on December 12, 2015 and coming in to force on December 12, 2025 aims to halt GHG emissions attributable global warming temperatures to 1.5°C / 34.3°F above pre-industrial levels, by the end of the century; in the worst case scenario, well below 2°C / 35.6°F.
At 1.5°C / 34.3°F of global warming increase, 14% of humanity is likely to be exposed to life threatening climate induced heat related illnesses and at 2°C / 35.6°F the percentage increases to almost 37%—approximately 3 billion people. 3°C / 37.4°F of global warming is projected to exasperate existing heat and drought conditions which will negatively impact agriculture production.
The only practical solution to halting climate change is to stop GHG emissions by: changing the way we produce energy away from carbon based fossil fuels (oil, coal & natural gas), change material production towards sustainable consumerism and the cultivation of crops & livestock through regenerative agriculture. Once net-zero of GHG emissions is achieved, environmental studies show the inertia of global warming should stop within 3 to 5 years.
Regenerative agriculture is the most “effective” natural low cost measure of atmospheric carbon sequestration. Regenerative farming mitigates CO₂ emissions by creating a natural ecological carbon sink in the soil. Regenerative agriculture involves, but is not limited to, crop diversity, minimize soil disturbance (No-till), reforestation, nitrogen fixing cover crops (Peas, clover & beans . . ) during the dormant season, rotational livestock grazingIt, composting & no use of chemical fertilizers & herbicides.
Plants and trees absorb atmospheric CO₂ (carbon in a gases state) and sunlight through photosynthesis, along with water (H₂O) absorbed through the roots, to create the glucose fuel plants and trees needs to grow biomass in its leaves, flowers, stems and roots. The byproduct of photosynthesis is oxygen (CO₂ minus C = O₂); while carbohydrates and sugars are excreted through the plant roots as exudates where a symbiotic relationship with mycorrhizal fungi convert the plant exudates in to water soluble mineral nutrients like nitrogen. The nutrients are then absorbed through the roots of plants & trees. The microbes also form soil organic carbon throughout their lifecycle. Soil microbes have an affinity with carbon because carbon is the primary component of all life known on Earth. The carbon in plants, trees and soil dwelling organisms detritus, along with biochar from fires, creates the dark soil matter called humus which helps retains moisture & nutrients like nitrogen in the soil. The humus structure is less dense and helps aerate the soil.
Depending on how the soil is treated, the sequestered soil carbon can be retained in the soil for a millennia. However, carbon can be naturally lost through natural plant & tree respiration and organic decomposition. Plants do have a limit on the amount of sunshine they can metabolize known as light saturation point. Once a plant reaches this maximum rate of photosynthesis the plant starts evaporating water to cool itself. Agrivoltaics reduce the amount of elevated levels of CO₂ & water loss of crops. Crops benefit from the shade provided by the ground mounted solar array and are shielded from heavy rains, hail and sun stress.
Industrial farming damages the soil by tilling and erosion which disturbs the soil releasing sequestered carbon. Industrial farming also causes the loss of the precious nutrient rich top layer of soil annually. Since the beginning of industrial agriculture, 50% of topsoil has been degraded. In order to compensate, synthetic fertilizers, which are petroleum based, are used and do not benefit the growth of beneficial soil microorganisms.
While soil carbon sequestration may be the most efficient, the ocean are the Earths ”largest” carbon sink. Unfortunately, the ocean attempts to balance its levels of sequestered carbon with atmospheric levels. Also, since carbon is acidic, it lowers the pH of the oceans leading to ocean acidification. The increased oceans acidification threatens the calcium building blocks of coral & crustaceans.
CARBON SEQUESTRATION TECHNOLOGY
“Carbon Capture & Sequestration” (CCS) along with “Direct Air Capture” (DAC); the latter, a perceived climate solution promoted by the oil & gas industry, are considered technological solutions to the climate crisis. CCS has a dismal CO₂ capture rate, less than 18%. Pre-atmospheric CO₂ is captured at the source —smoke stacks— from industry and carbon based energy generation; then stores the concentrated CO₂ deep underground in impermeable geological formations for —a theoretical— permanent storage. Studies show there maybe a causation between fugitive CO₂ emissions and contaminated ground water and / or pressurized sequestered CO₂and increased seismic activity.
With DAC, already existing atmospheric CO₂ is captured & injected in to low performing oil wells to boost their productivity. The CO₂ aerates the viscous oil making it less dense and easier to pump-up for extraction; a process called “Enhanced Oil Recovery (EOR).” The extracted oil is then refined and used to continue the vicious cycle of carbon fuel combustion contributing to GHG’s emissions and pollution. According to the Institute for Energy Economics & Financial Analysis, 70% of DAC projects are inevitably EOR projects. In 2023, over 1.7 million tonnes of CO₂ was used for enhanced oil recovery. Another profitable option is to combine the captured CO₂ with Hydrogen (H₂) to create hydrocarbon jet fuel which returns the CO₂ to pollute the atmosphere through combustion. The pursuit of DAC is not altruistic because it serves as a distraction to the real climate solution. The fossil fuel industry motives for DAC are to create profits by turning the captured carbon in to a commodity.
Studies have shown that most DAC projects do not capture a significant amount of CO₂ to even off-set operational cost. The technology of DAC is environmentally & financially inefficient because the large amounts of fossil fuels required to power the machinery along with the heat and chemicals needed to extract atmospheric carbon is at a rate that is not commensurate with the dismal productive return in investment. It is far more economical to invest in renewable energy technology and battery storage than to initially generate fossil fuel CO₂ emissions, then attempt to remove it from the atmosphere using tech. Solar panels and wind turbines are the most economical forms of energy production in the history of the world; while Lithium ion battery storage cost has fallen by 90% since the early 2000’s.
The main energy requirements (coal, oil or gas) used to power carbon capture machinery makes this climate technology non-sustainable and a distraction. Even if renewable energy was used for carbon capture, the renewable energy would be more environmentally effective if it was used initially to replace carbon based fossil fuels for energy generation. Even with the incorporation of new technology and scaling the cost of CCS makes it an expensive investment. Between 1995 and 2018, 2/3 of large scale CCS projects were put on pause or terminated. Most CCS projects failed to meet projected goals. Chevrons’ Gorgon liquefied natural gas plant in Australia has a capacity to store up to 4 million tonnes of CO₂ ; yet, since its’ inauguration in 2019 it has never reached that aspirational goal. This underperformance is consistent with most CCS plants.
A December 2023 forensic study published by the University of Oxford states relying on Carbon Capture & Storage can be highly economical damaging, costing $30 trillion dollars more than pursuing emission reduction through renewable energy dominance and natural soil carbon sequestration.
A decline in soil health, called soil degradation, is due to poor agriculture management or industrial misuse. Modern industrial agriculture has a negative impact on soil health in the pursuit of profits over human nourishment. According to the U.N. Food & Agriculture Organization 33% of the world arable farmland is experiencing soil degradation due to monocroping of cash crops, like corn, and soil tillage; resulting in the need for oil based synthetic fertilizers.
No amount of technological innovations or personal carbon footprint mitigation can reduce GHG emissions from the continued use of coal, oil & natural gas for energy generation. The ultimate solution is to adopt a nature based approach of renewable agriculture and end the use of fossil fuels for energy generation.
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