Offsetting carbon for Livable globe
Climate change is one of the most arduous challenges experienced at global level. It has already increased the risk of severe heat waves in Haryana and other states of country besides other extreme weather conditions in the offing. Climate change is undeniable to inflict irreversible impacts” on globe, unless carbon emissions are reduced. There are many mechanisms for transformation of carbon dioxide into carbon storage. Enhanced terrestrial carbon stocks through plantation forestry for greenhouse gas mitigation option are identified by United Nations Framework Convention on Climate Change (UNFCCC). Afforestation may also conserve soil organic matter by contributing to forest floor carbon. Large parts of India offer congenial conditions for fast growth of trees. The annual planting rate is 4.5 million ha, with Asia and South America accounting for 89%, still a chunk of degraded and non-forest lands needs to be put under forests for carbon storage in India. Considering a variation in the carbon sequestration potential of different plantation species may not lead to junk estimates of the carbon sequestration rates .For understanding the potential of additional carbon sequestration by afforestation for mitigation strategies of carbon dioxide, carbon storage in forest biomass, soil and wood products is necessary for offsetting carbon entering atmospheric. Soil organic matter plays a very significant role in the global carbon cycle by converting atmospheric carbon into terrestrial carbon pool. As per conservative estimate, other sources for carbon storage of manageable carbon are about 183 Mg C ha in the forest soil ecosystem.
Although reforestation and new agricultural practices could trap carbon to slow global warming, but direct removal will still be imperative for capturing of CO2. Carbon Capture and Storage (CCS) with the advantage of being flexible to secure and reliable; while substantially reducing emissions of greenhouse gas to the atmosphere also facilitates continuous using of fossil fuels. Intergovernmental Panel on Climate Change (IPCC) expects global CO2 emissions to dwindle by 50-80% by 2050, to prevent the most disastrous repercussions of climate change. Paris Agreement in 2015 recognizes need for CCS to meet the global climate. As the world is switching to a low-carbon economy by adopting the innovative new technologies with CO2 capture, utilization and storage, paving an important path for pursuing capturing technology and is now accepted as an appropriate emissions reduction technology to offset CO2 emissions for development of alternative energy sources. Technology of CO2 capture and storage over the last decade has considerably progressed .CO2 sequestration (CCS) – represents a set of technologies involved in capturing carbon dioxide emitted from the different sources before it accesses the atmosphere, compressing it, and injecting in subterranean to secure geological formations, and ensuring its perennial existence. Rationale behind undertaking CCS is to emphasize cost-effective solutions to tackle the global issue of climate change by reducing global CO2 emissions for a low-carbon energy future. Comparing huge amounts of CO2 emission on global scale, carbon storage by injecting into geological formations seems more justified. One conservative estimate indicate 11,000 Gt CO2 can be injected into formations like deep saline aquifers, depleted oil and gas fields and silicate formations (e.g., basalt) which can sink the annual CO2 emissions rate of 30 Gt of CO2/year, with objective that CO2 remains trapped underground as a fixed source with a long-term safety from induced seismicity which is an important aspect of risk assessments of geologic storage. In this realm, there is an opportunity for India to become a global technology leader for CCS with a significant opportunity to deploy CCS in industry, not only to reduce emissions, but to improve productivity and the competitiveness of our industrial centers.
Briefly, CCS mechanism involves collection of Carbon dioxide and transported to store or sequestered in geological formations. When the carbon dioxide is deposited deep below ground, having a high porosity and the temperature and pressure are enough to keep it in its liquid phase till injected until it reaches impermeable rock or cap rock that ensures no escape of carbon resulting in structural storage. With a passage of time the stored carbon dioxide become soluble into the brine solution, results water heavier and it sinks down in the formation. This process is known as dissolution storage; finally carbon dioxide in the mineral storage formation binds chemically with the surrounding rock. Blue Planet’s technology companies that specialize in carbon removal needs to devise cheaper technologies and best sites needs to be delineated by government agencies for CO2 storage viz geological formations between 1 and 4km beneath the sea‐bed in many different layers of rock; exhausted oil and gas fields can also be used as places to store this carbon dioxide, consequently, can result in more oil being recovered. Presumably, deep saline aquifers could also be used to store carbon dioxide.Ultimately global warming can be regulated by adopting carbon storage via different mechanisms.
Prof A K Bhat, FAPS
Additional Dean FASC