A multipronged mitigation strategy is necessary but many techniques such as carbon dioxide removal must be approached with caution
The era of global warming has ended; the era of global boiling has arrived,” the UN chief recently remarked. The Intergovernmental Panel on Climate Change (IPCC) highlighted in its recent report that projections based upon stated policy commitments fall short of containing the global warming levels at 1.5°C or even 2°C. So, when emissions mitigation is not happening at the pace desired and extreme climate events indicate an earlier-than-expected tipping point, carbon capture may offer a pathway to the solution.
Challenges to Net Zero
The developmental imperatives demanding equity and justice, sub-optimal technology readiness levels and challenges related to lifestyle adaptations make the net zero road, a difficult terrain to tread on. Food, energy, transport and materials like cement & steel contribute significantly to emissions but are such fundamental necessities that they cannot be wished away overnight from our lives. Take the case of food, the global population has increased nearly eightfold since the early 19th century. Quite obviously, it is the fertiliser-intensive farming without which it is estimated that half of the world's population cannot be fed. These fertilisers are synthesised using fossil fuels which contribute to emissions.
Regarding electricity, renewable sources come with intrinsic uncertainties and only reliable storage solutions can fully replace fossil fuels. This necessitates mining significant amounts of lithium which has its commercialised mining predominantly concentrated in the South American lithium triangle and notably it has a high water footprint. Additionally, mining cobalt, a key element in Li-ion batteries, is associated with ethical issues concerning child labour. Pumped hydro, an alternative to battery storage, also has environmental concerns.
The Concept of Carbon Dioxide Removal
Carbon dioxide removal involves capturing CO2 at various sources of generation or directly from the atmosphere and securely storing it to prevent escape. Natural systems such as forests, rocks, and oceans act as carbon sinks, absorbing and sequestering carbon. However, a warmer climate diminishes the capacity of these systems to absorb CO2. To augment the capacities of these natural systems, conservation efforts and engineered techniques for enhanced absorption are necessary.
These include afforestation, increased rock weathering which enables rocks to absorb more CO2, and enhanced ocean fertilisation which is a geoengineering technique that may result in higher organic growth in ocean systems thus implying higher carbon absorption and bioenergy with carbon capture and storage (BECCS), which introduces circularity in the emissions balance sheet. Technology-based solutions involve capturing CO2 emissions during production processes or electricity generation using fossil fuels predominantly using chemicals called amines which can absorb and release CO2 upon temperature regulation. The captured CO2 is stored in deep geological formations, preventing its release. The pumping of CO2 in the oil reservoirs for enhanced oil recovery is an established practice in the oil and gas industry. Another technology namely Direct Air Capture, involving CO2 capture from air surrounding us instead of a concentrated point source is also gaining traction however it has cost concerns.
The Pros and Cons
The fact that certain techniques are already practised in the industry, builds a certain amount of confidence towards the feasibility of the proposition. However, there is scepticism over its large-scale adoption, particularly in terms of potential interference with oceans and other natural systems. Additionally, increased afforestation and adoption of BECCS may have adverse impacts on our food supplies as well. The possibilities of CO2 leakage from geological formations too cannot be ignored. Also, it is argued that excessive reliance on carbon removal pathways may lead to complacency in emissions mitigation and adaptation efforts.
The world needs to act swiftly on climate change and undoubtedly, a multipronged mitigation strategy is necessary. However, considering the uncertainties associated with carbon removal, its deployment should be approached with caution and a gradual scaling up as we learn more about it.
(The writer is Deputy Chief Mechanical Engineer, North Western Railway and UK Commonwealth Scholar; views are personal)
