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Climate change and future options for carbon sequestration
Abstract
With the threat of climate change increasing, carbon sequestration could be expected to play a significant role in alleviating this problem. Unfortunately, the technology is not well understood and good literature overviews of the options in carbon sequestration are lacking. Hence, policy and research priorities are made without full understanding of the state of scientific knowledge, impacts, and policy trade-offs. This paper contributes to the literature, providing a basic picture of the technological options for futurists and policy advisors to begin to address this need.
... Kolawole et al. [197] found that shale formation microorganisms could enhance the cover's long-term integrity and the security of CO2 storage. The ocean is the most significant carbon dioxide sink [203], with a carbon dioxide absorption capability of 1,000 gigatons and a carbon dioxide content of around 40,000 gigatons. The natural sinking process involves the formation of fossil fuels through photosynthesis and rock weathering. ...
The introduction of the idea of “carbon neutrality” gives the development of low carbon and decarbonization a defined path. Climate change is a significant worldwide concern. To offer a theoretical foundation for the implementation of carbon reduction, this research first analyzes the idea of carbon footprinting, accounting techniques, and supporting technologies. The next section examines carbon emission reduction technologies in terms of lowering emissions and raising carbon sequestration. Digital intelligence technologies like the Internet of Things, big data, and artificial intelligence will be crucial throughout the process of reducing carbon emissions. The implementation pathways for increasing carbon sequestration primarily include ecological and technological carbon sequestration. Nevertheless, proving carbon neutrality requires measuring and monitoring greenhouse gas emissions from several industries, which makes it a challenging undertaking. Intending to increase the effectiveness of carbon footprint measurement, this study created a web-based program for computing and analyzing the whole life-cycle carbon footprint of items. The practical applications and difficulties of digital technologies, such as blockchain, the Internet of Things, and artificial intelligence in achieving a transition to carbon neutrality are also reviewed, and additional encouraging research ideas and recommendations are made to support the development of carbon neutrality.
... Soil Carbon sequestration is the process of capturing CO 2 from the atmosphere into the soil through crop residue and other organic solids for a longer period and in a form that cannot be immediately re-emitted. In India, agriculture contributes 18% to the total emissions of greenhouse gases (Das, 2020). In Indian agriculture, livestock and rice production are the top emitters of GHGs. ...
Carbon neutrality means having a balance between emitting
carbon and absorbing carbon from the atmosphere in carbon
sinks. This can be achieved by balancing emissions of carbon
dioxide with its removal (often through carbon offsetting) or by
eliminating emissions from society (the transition to the “post-carbon
economy”). In order to achieve net zero emissions, all worldwide
greenhouse gas (GHG) emissions will have to be counterbalanced
by carbon sequestration. The main natural carbon sinks are soil,
forests and oceans. Carbon neutrality delivers climate action now
and prepares our business for a low carbon transformation. Although
the term “carbon neutral” is used, a carbon footprint also includes
other greenhouse gases, measured in terms of their carbon dioxide
equivalence. Carbon-neutral status can be achieved in two ways like
carbon off-setting and reducing emissions, although a combination
of the two is most likely required.
... We are left with carbon capture and storage (CCS), either by capture of CO 2 from large power stations and industrial plants, or directly from the air. The three methods for CO 2 capture from large plants include: using absorbants such as amides to extract CO 2 from the exhaust gas stream (the most developed method and the only one that can be retrofitted); combusting the fuel in pure oxygen; and gasifying the coal fuel into H 2 and CO 2 , followed by separation of the CO 2 [30,31]. It is even possible that coal gasification could proceed in the absence of CCS [30], given the energy efficiency advantages of combined-cycle gas turbines. ...
This study explores global energy demand, and hydrogen's role, over the 21st century. It considers four illustrative cases: a high (1000 EJ) and a low (300 EJ) energy future, and for each of these conditions, a high (80%) and low (20%) fossil fuel energy share. We argue that neither high energy future is probable, because of resource limitations, and rising energy, environmental and money costs per unit of delivered energy as annual energy demand rises far beyond present levels. The low energy/low fossil case is most likely, followed by the low energy/high fossil case, although both require large cuts in energy use, and most probably, lifestyle changes in high energy use countries. Hydrogen production would be best favoured in the low fossil fuel options, with production both greater, and implemented earlier, in the higher energy case. It is thus least likely in the low energy/high fossil fuel case.
Carbon neutrality is described in four groups, including "carbon neutral", "climate neutral", "carbonfree",
and "carbon clean" which means not to release any carbon dioxide (CO2) into the atmosphere.
According to the European Parliament, carbon neutrality is reached when the same amount of CO2
is released into the atmosphere as is removed by various means, leaving a zero balance, also known
as a zero-carbon footprint. Whereas carbon footprint is defined as the total amount of GHG
emissions caused by an individual, organization, service, or product. It also means recognizing the
problem and gradually reducing its impact. We are only considering CO2 and carbon-neutral, but
there are several other greenhouse gases, which are even more damaging which are methane (CH4)
and Nitrous oxide (N2O) produced by agriculture. Many initiatives (carbon neutrality coalition,
greenwise, climate neutral network, caring for climate, greenlife) seek to assist individuals,
businesses and states in reducing their carbon footprint or achieving climate neutrality.
Purpose
This study aims to examine the sequestration of carbon dioxide (CO 2 ) in abandoned geological formations where leakages are permitted up to only a certain threshold to meet the international CO 2 emissions standards. Technically, the author addresses a Bayesian experimental design problem to optimally mitigate uncertainties and to perform risk assessment on a CO 2 sequestration model, where the parameters to be inferred are random subsurface properties while the quantity of interest is desired to be kept within safety margins.
Design/methodology/approach
The author starts with a probabilistic formulation of learning the leakage rate and later relaxes it to a Bayesian experimental design of learning the formations geophysical properties. The injection rate is the design parameter and the learned properties are used to estimate the leakage rate by means of a nonlinear operator. The forward model governs a two-phase two-component flow in a porous medium with no solubility of CO 2 in water. The Laplace approximation is combined with Monte Carlo sampling to estimate the expectation of the Kullback–Leibler divergence that stands for the objective function.
Practical implications
The injection duration given by the reservoir capacity is extended while the environment is preserved despite the leakage.
Carbon sequestration has been proposed as an important means for mitigating
climate change, particularly in the medium and longer term. Three approaches have been
proposed: biological sequestration in trees and soils; capture from the flue gases of large
fossil fuel-using plants, particularly for electric power generation, followed by transport
and burial; capture directly from the air, followed by burial. Although biological
sequestering in soils and biomass is a natural process, and is seen as the cheapest option,
the annual potential is small, and storage may reverse later in the century. Carbon capture
and sequestration is probably limited to about one third of annual fossil-fuel related
emissions, and will have high energy and money costs if plants are not ‘capture-ready’.
There are no limits on air capture, but it may need more energy than the energy content of
the input fuels, and in any case is a high cost approach. Sequestration can be in geological
reservoirs such as disused oil and gas fields, or saline aquifers. (Many researchers rule
out ocean burial, both because of its adverse environmental effects and because of the
temporary nature of storage.) There is however, great uncertainty in the total safe
capacity of geological reservoirs. Perhaps even more importantly, the time for absorbtion
mechanisms to act varies from immediate to hundreds or even thousands of years, so that
annual limits on safe disposal may be the limiting factor.
Fertilizing the ocean with iron has sometimes been proposed as a mechanism for reducing atmospheric carbon dioxide. The key feature of ocean biogeochemistry that drives this strategy is the presence of unutilized nutrients in the surface ocean. A vertical cross-section shows that this “preformed” nutrient represents a substantial fraction of the nutrients found in the global ocean. Nutrients that are not preformed participate in the carbon cycle, becoming associated with carbon as they are taken up by organisms in the surface layer and returning to solution in tandem with the carbon as the sinking carcasses of these organisms, dissolve at depth. Fertilization can reduce atmospheric carbon dioxide insofar as some amount of preformed nutrients becomes associated with carbon. Initially, this carbon will come out of the large reservoir available in the surface ocean, resulting in a reduction of the partial pressure of carbon dioxide in surface waters, and a flux of carbon dioxide from the atmosphere to the ocean. A number of simulations have been performed in which the impact of large-scale, long-term of nutrient drawdown associated with iron fertilization on carbon dioxide have been performed using general circulation models coupled to simple models of biological cycling. The results raise some significant questions about the verifiability and impacts of ocean fertilization as a strategy for carbon sequestration.
This chapter presents an overview of the research work that is currently underway and provides an analysis of the current state of knowledge on geological storage of CO2. The analysis will be broken down to address the key geological storage options—deep coal seams, depleted hydrocarbon reservoirs, and deep saline aquifers. In each case, areas of uncertainty and areas where it is considered that further work will be needed will be highlighted . If deep reductions in greenhouse gas emissions are required to meet the UNFCC goal of stabilization of anthropogenic greenhouse gas emissions, then one method to use would be CO2 capture and storage. The technology would be used in combination with the other mitigation measures, such as fuel switching, energy efficiency and renewable energy. CO2 can be captured from a variety of anthropogenic sources such as power and large industrial plants and either stored in the oceans or in geological reservoirs. Currently, because of uncertainties about the science and the attendant legal issues ocean storage is unlikely to be promoted as a mitigation option. There are a number of potential geological reservoirs that can be used to store captured CO2. These geological reservoirs include depleted and disused oil and gas fields, deep saline aquifers and deep unminable coal seams. The capacity estimates for these reservoirs show that geological storage of CO2 can make a substantial impact on CO2 emissions reduction. From a capacity perspective, deep saline aquifers offer a significant potential.
We have conducted a detailed analysis of costs associated with today's technology for CO2 separation and capture at three types of power plants: integrated coal gasification combined cycles (IGCC), pulverized coal-fired simple cycles (PC), and natural gas-fired combined cycles (NGCC). The analysis was based on studies from the literature that analyzed the economics of cap turing CO2 emitted at power plants. In this paper, we present a composite cost model and perform a sensitivity analysis to identify the cost-drivers for capture. We conclude that with new developments, CO2 capture and sequestration can become a cost-effective mitigation pathway.
New technologies could reduce carbon dioxide emissions to the atmosphere while still allowing the use of fossil fuels
The goal of carbon sequestration is to take CO 2 that would otherwise accumulate in the atmosphere and put it in safe and permanent storage. Most proposed methods would capture CO 2 from concentrated sources like power plants. Indeed, on-site capture is the most sensible approach for large sources and initially offers the most cost-effective avenue to sequestration. For distributed, mobile sources like cars, on-board capture at affordable cost would not be feasible. Yet, in order to stabilize atmospheric levels of CO 2 , these emissions, too, will need to be curtailed. This paper suggests that extraction of CO 2 from air could provide a viable and cost-effective alternative to changing the transportation infrastructure to non-carbonaceous fuels. Ambient CO 2 in the air could be removed from natural airflow passing over absorber surfaces. The CO 2 captured would compensate for CO 2 emission from power generation two orders of magnitude larger than the power, which could have instead been extracted from the same airflow by a windmill of similar size. We outline several approaches, and show that the major cost is in the sorbent recovery and not in the capture process. Air extraction is an appealing concept, because it separates the source from disposal. One could collect CO 2 after the fact and from any source. Air extraction could reduce atmospheric CO 2 levels without making the existing energy or transportation infrastructure obsolete. There would be no need for a network of pipelines shipping CO 2 from its source to its disposal site. The atmosphere would act as a temporary storage and transport system. We will discuss the potential impact of such a technology on the climate change debate and outline how such an approach could actually be implemented.
Deep saline aquifers were investigated as potential disposal sites for CO2. The capacity of deep aquifers for CO2 disposal in the U.S. is highly uncertain. A rough estimate, derived from global estimates, is 5-500 Gt of CO2. Saline aquifers underlie the regions in the U.S. where most utility power plants are situated. Therefore, approximately 65 percent of CO2, from power plants could possibly be injected directly into deep saline aquifers below these plants, without the need for long pipelines.
Transitioning away from fossil fuel use will be difficult, but Massachusetts Institute of Technology scientist Howard Herzog says that by reducing CO 2 emissions, carbon capture and sequestration could allow fossil energy use to continue, while buying time to make the transition to other energy sources. He discusses storage options, commercial successes, costs, and the technology's possibilities and limitations.
Carbon Sequestration Technology Road-map and Program Plan
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