Chapter 1- Introduction

Understanding the Concept

The terminology of Carbon Dioxide removal or CDR is also recognized as negative Carbon Dioxide emission, and is considered as a procedure in which the carbon dioxide is removed or extracted from the environment and is stored for long period of time. In the similar pattern, there is another concept known has Green House Gas Removal (GGR) or Negative Greenhouse gas emission is considered as a procedure which responsible for removing greenhouse gases, this is done mainly by deliberate human actions or activities which is inclusive of the removal that would happen by natural carbon cycle and procedures associated with atmospheric chemistry. Considering the content and target of Net Zero greenhouse emissions, the conceptuality of Carbon Dioxide removal is highly integrated towards the policies associated with the climate and is considered as a new concept or element of the mitigation tactics. Both the methods of Carbon Dioxide Removal and Greenhouse Gas Removal are considered as negative emission technologies or NET and is considered cheaper in comparison to the prevention of various agricultural gas emissions. The conceptuality of Carbon Dioxide removal is inclusive of different tactics which is inclusive of afforestation, different agricultural practices which are responsible for sequestering carbon that is found in soil, bio-energy that is responsible for the capturing and storage of carbon, fertilization of the ocean, enhanced weather and direct capturing of the air when it is merged with storage. It is essential to consider the functionality of comprehensive life cycle analysis to make an assessment on the probability of net negative emissions obtained through a particular procedure. There was a report that was published in 2019 by the United States National Academies of Sciences, Engineering and Medicine that made comprehensive conclusions that with the utilization of existing Carbon Dioxide Removal Methodologies at scales can allow safe and economical deployment of this concept. The potential suggested in this study was the removal and sequestering up to 10 gig tons of Carbon Dioxide on an annual basis.

 This will have a massive offset when it comes to the emission of greenhouses gases by a fifth of the rate at which these gases are currently being produced. Another research which was published by the Intergovernmental Panel on Climate Change which suggested the fact that the usage of the Carbon Dioxide Removal can lead to a massive decrement in the presence of carbon dioxide in the air by the year 2100. The definition set up for Carbon Dioxide Removal by Intergovernmental Panel on Climate Change is Anthropogenic activities which are responsible and directed towards the removal of Carbon Dioxide by storing it in different components inclusive of different products, terrestrial,  gical and even ocean reservoirs. The functionality of Carbon Dioxide removal is also inclusive of already existing and potential anthropogenic betterment of biological and geo chemical sink. The definition provided by Intergovernmental Pannel on Climate change excludes the fact that natural Carbon Dioxide uptake is not a direct cause due to human involvement or activities. One of the educational institute known as National Academies of Sciences, Engineering and Medicine considers the definition of Carbon Dioxide Removal the same as Negative Emission Technology. In most scenario, the concept involve deliberate reduction of Carbon Dioxide in the air is taken as solar radiation management which is something completely different and is a form climatic engineering which is considered intrinsically very risky. The Terminology of Carbon Dioxide Removal is much broader than Solar Radiation Management where it addresses all the issues inclusive of the root cause and involves creation of strategies and tactics which will help in the mitigation of net emissions. The concept of Carbon Dioxide Removal also manages all the risks which are associated with the elevated atmospheric Carbon Dioxide levels. Carbon Dioxide Removal is also confused with another conceptuality known as Carbon Capture and Storage, which is a procedure that involves collection of Carbon Dioxide from various sources of point such as power plants that are gas-fired and the smokestack caused by these power plants are responsible for the emission of Carbon Dioxide in a concentrated stream. That Carbon Dioxide is then gathered, compressed and availed in the concept of Carbon Capturing and Storing. When this concept is utilized to sequester the carbon dioxide which is being released from the gas-fired plant, it automatically has a massive reduction on the carbon dioxide which is coming out of the power point. However, this conceptuality does not have a reduction on the amount of Carbon Dioxide which is currently present in the air.

Potential for Climate Change Reduction

There has been a growing need for the conceptuality of Carbon Dioxide Reduction, and is now being publically expressed by different individuals, organisations and countries that are actively involved with the issues of climatic changes including well known people such as Dr. Hoesung Lee who is the chief of IPCC, Christiana Figueres who is the executive secretary of UNFCCC and also the World Watch Institute. There are various institutions that are actively involved in the introduction of major programs having focus solely on Carbon Dioxide Reduction including Earth Institute, Columbia university which is also the Lenfest Center for sustainability energy, and the Climate Decision Center which is one of the international collaboration which is functioning out of the Engineering and Public policy department of the Carnegie-Mellon University. With the utilization of Carbon Dioxide Removal alongside other efforts to have a reduction in the emission of greenhouse gases such as deployment of renewable energy, will be less expensive and disruptive in nature in comparison to using a single effort or method. Research conducted by NASEM in 2019, suggested the fact that apart from ocean fertilization all other efforts of Carbon Dioxide Removal can be deployed safely and economically with the utilization of modern day technologies. Additionally, a recent published estimation also showed that the deployment of such practices can remove more then 10 gigatons of Carbon Dioxide annually if all these practices are deployed everywhere in the world. Approximately ore than 50 gigaton of carbon dioxide is produced every year by human activities and usage of such practices can have a reduction of one-fifth of the total carbon dioxide being produced. In 2018, the company Intergovernmental Panel on Climate Change made an analysis which suggested various ways to mitigate climate change, all of these analysis suggested mitigation pathways that would aid in the prevention of above 1.5 °C of climatic warming inclusive of all the measures associated with Carbon Dioxide Reduction. Some of the suggested mitigation pathways suggest that if only one technology is deployed on a massive level then it can help in achieving higher rate of Carbon Dioxide removal, however, this is not efficient considering the fact that this pathway suggest that majority or billion of hectares of croplands are transformed into biofuel crops. Additional research on different areas such as geological sequestration of Carbon Dioxide, direct capturing of air and carbon mineralisation could formulate better technological advancement which can aid economic feasibility of Carbon Dioxide Removal on a much higher rate. Another research published by Intergovernmental Panel on Climate Change in 2018, also suggested the fact that if large scaled deployment of Carbon Dioxide Removal Is considered then it can impose serious threats to achieving the long-term goal of having less then 1.5 °C of climate warming, this is mainly because of the uncertainties which suggest that how quickly Carbon Dioxide Removal can be implemented or deployed. The strategies that are more inclide

Growth of the Concept

There were various target goals that were outlined under the Paris 2015 Agreement, and out of those goals there was one goal which was to meet 2°C target goals. In addition to this goal, the agreement was also responsible for ameliorating different concerns related to viability of pledges, and options related to the removal of carbon dioxide which are mainly responsible to offset the emissions of Carbon Dioxide. The conceptuality of Carbon Dioxide Removal is very different in comparison to other strategies associated with climate mitigation, this is mainly because the strategy of Carbon Dioxide Removal is responsible for the increment of negative emission which helps in achieving “Beyond Carbon Neutral. This is a better strategy rather than having a reduction net GHG emissions to a complete zero which also helps in achieving the state of just being Carbon Neutral. The conceptuality of Carbon Dioxide Removal can be done in various ways inclusive of natural procedures such as Weathering of the silicate rock, usage of photosynthesis and absorption that is made the sea or ocean. In addition to that, it is essential to have the enhanced version of natural procedures and the development of  various other options that can aid in the capturing and sequester or make use of Carbon dioxide is of utmost importance because it will allow to have a massive reduction in the rate of Carbon Dioxide removal and also help in reaching negative carbon emissions in the future. To complement and put in the efforts of removing carbon dioxide and other greenhouse gases, one of the educational instituition known as the University of Michigan Energy institute is making initiative associated with the same conceptuality of Beyond Carbon Neutral and the main purpose of this initiative is solely based on developing various policies, options, and procedures which will increment the effect or deployment of the Carbon Dioxide Removal, which in itself is considered as one of a comprehensive approach towards climate change. Another important part of the initiative that was taken by the University of Michigan School of Natural Resources and environment was based on the compilation of literature review that was based on existing researches on financial cost of different Carbon Dioxide Removal options.

Carbon Dioxide Removal Options

Based on the suggested literature there are approximately eight options which are selected for this discussion involving afforestation and reforestation (AR), Soil Carbon Sequestration, Acceleration of weather, Biochar, Direct Capturing of the Air, Aquatic Bioenergy with capturing and storage of Carbon, Terrestrial Bioenergy with Capturing and Storage of Carbon, Storage in the ocean, and Fertilization of the Ocean. The existing literature provides an estimation of economic and technical feasibility of all these options, where the literature also suggest the fact that these options are on different levels in terms of readiness, that is identified as highly speculative, demonstrated and well established. Out of them, the options which are considered as well established suggest the projects which are in abundance of the projects which are properly scaled and applied. Additionally, these options also have a cost measuring and well-defined sequestration procedure, but some regional application may lead to technological problems. There are many firms and governments that are actively involved in the initiative of Afforestation and Reforestation which are responsible for the creation of new forests. On the other hand, the conceptuality of carbon utilization as also been used a lot in the field of oil for many decades, both Afforestation and reforestation, and Carbon utilization are considered as established in the field of Carbon Removal. Furthermore, there have been many integrated pilot system in the functioning environment of some regions which would suggest that other options such as sequestration, biochar, Terrestrial bio energy with the capturing and storage of carbon are all the in demonstration stage. Apart from these options, Direct Capturing of the Air, Aquatic Bioenergy with capturing and storage of Carbon, acceleration of weather, Storage and fertilization of ocean are all considered as speculative, this means that all of these options are in their initial stages of development and need more time to find out or research on their feasibility, where it is suggested that all of these options require additional studies and continuous lab measurements. From the provided discussion it is quite evident that more than half of the Carbon Dioxide removal and storage options are speculation, which is mainly because they are highly based on model and major assumption.

Chapter 2- Afforestation and Reforestation

Introduction

The conceptuality of Afforestation and Reforestation is considered as one of the established option of Carbon Dioxide removal, where there many commonly used land management methodologies that are inclusive of intentional management of the forest that would in the sequestering and storage of Carbon Dioxide over long period of time. The foresting procedure of Afforestation includes adding forest to the land that does not have any, or the forest from this land was removed more than 50 years ago. Reforestation on the other hand, is considered as a procedure which involves restoring of the land back to its forested station which was deforested few years back. Both of these conceptualities massively aid when it comes to Carbon Dioxide Removal With the utilization of the Photosynthesis procedure, the tree can acquire Carbon Dioxide from the Air and then store it in their different components such as stems, roots, trunk, leaves and branches. When these forests have acquired Carbon Dioxide from the air, they then release massive loads of Oxygen from their leaves. Both Afforestation and Reforestation are considered as commonly referenced methodologies that based on land management and are responsible for sequestering or mitigating Carbon Dioxide from the atmosphere with the utilization of biomass growth in different plants and trees. Both of the conceptualities have a minimum difference between them in terms of carbon dioxide removal, however this report will be collectively discussing both of the conceptuality. The World’s area which was assigned to forest has been slowly declining over the past 25 to 30 years which is mainly because of the high birth rate which leads to more and dense population. In addition to the population growth, there are other factors which are leading to the decline of the forests such as growing demand of the agriculture, market policies, institutional lacking, trades and various other cultural factors.

Figure 1: Decline in the Forest Area throughout the World

The figure 1 showcases a graphical depiction in which the forest area throughout the world is declining at a massive pace. The forest area occupied approximately 31 per cent of the total world’s land which was way less in comparison to 38 per cent which was occupied by the agricultural sector worldwide. The forests have declined massively over the past few years, where in 2015 it was estimated that there are approximately 4000 million hectares of total forest area, which declined from 4150 million hectares back in 1990. In the recent times the conceptuality of planted forest has been incrementing by more than 120 million hectares, as the natural forests continues to deplete. In between 2000 and 2009, the forestry and other lands contributed more than 13 per cent of the total Green House Gases which was produced worldwide. To ensure proper climate change mitigation and intervention strategies it is quite important to consider the conceptuality of Afforestation and Reforestation alongside having proper channels of monitoring and preserving. These forests are considered as natural sink when it comes for Carbon dioxide, however if this tactic of Afforestation and Reforestation is neglected or reversed then they it easily become a contributing source to Carbon Dioxide emissions. The massive amount of deforestation that was done in 2010 contributed approximately 40 million tonnes of global annual Carbon Dioxide emissions, however the green house gases which are being released from the deforestation has been declining in the recent times. Having such a reduction in Carbon Dioxide alongside the creation of additional Carbon Dioxide sinks will aid in the reduction of global net missions of Green House Gases.

It is critical to know that this chapter associated with Afforestation and Reforestation will not be providing a discussion on the forests which are preexisting alongside their yearly sequestration ratio and carbon stocks. The discussion will also be exclusive of the Carbon Dioxide that it being produced as a result of deforestation. The discussion in this chapter will solely be based on Sequestration and storage potential that is associated associated with the conversion of non-forest land to forested land. It will also be inclusive of maintenance of the forested land with the utilization of defined management techniques over long period of time.

The Procedure of Afforestation and Reforestation

The conceptuality and functionality of Afforestation and Reforestation is considered as one of the established option of the Carbon Dioxide Removal, where the trees have been actively involved in the removal and storage of Carbon Dioxide for millions of years. In addition to this there are several substantial empirical research that provides methods and discussion to document potential offering made by Afforestation and Deforestation to mitigate the carbon sequestration. Both of the concepts Afforestation and Reforestation are Carbon Dioxide Removal approach that is responsible for forming a combination of capturing and storage of Carbon Dioxide in a single procedure that is occurring in the same geographic location. This conceptuality is inclusive of a form of transformation of a land which had farmlands, pastures, industrial factories, or any other usage to forests that will aid in the reduction of Carbon Dioxide in the air. The whole transformation of converting non-forest land to a forest land can be done with the utilization of a passive approach through a secondary success or with the usage of active restoration procedure that involves plantation of local or native species of tree plantation. With the usage of passive restoration more abandoned or barren land has been transformed into forest. However, it is essential that the functionality of active restoration is considered in various complex situations such as areas of drought, high growth of weed plants that would outcompete the native plans or foresting lands where seed dispersal is a major issue and can no longer happen.

There are various studies that provide an indication associated the initial transition towards Afforestation or Reforestation can bring an output of short-term net emission of Carbon dioxide where it is quite evident that the forests which are properly managed will aid massively when it comes to the reduction of net Carbon Dioxide, this is mainly because the carbon dioxide is stored for an indefinite period of time within the biomass of the forest. The rate at which the carbon dioxide depends upon the specie and biological structure of the plan. The research also highlighted the fact, that the tree intakes more carbon dioxide in its early decades, then as the time progresses the ability of the tree to absorb Carbon Dioxide slowly declines. For instance, if the tree known as Loblolly pine is taken into consideration, then it takes carbon dioxide in very quickly in its initial years, however when Loblolly reaches the age of 70 then it the intake reaches zero. On the flipside, another tree known as ponderosa tree takes in a steady flow of Carbon Dioxide in its initial years of functionality, but its intake reaches its peak when the tree reaches the age of 65. For most of the trees, it is researched that they take in less carbon dioxide because most of their energy is then utilized in the maintenance of sapwood respirations. The reliance of afforestation and reforestation is solely based on the natural sequestration of Carbon Dioxide in the biomass of tree for long duration of time. With the usage of Photosynthesis, the trees take in carbon dioxide which is stored in their different component and then they release oxygen through the process of respiration. Various factors such as ambient of Carbon Dioxide concentration, history of the forest site, specie of the tree and age of the tree that is growing within the forest using different temperatures, geology, and precipitation. For instance, the forests which are growing in the region of Southeast have a faster recovery pace then other forests such as the Douglas-fir Forest which is found in the region of Pacific Northwest. In addition to that, there are several other factors that affect the intake of the Carbon Dioxide such as the climatic condition, for instance in the region of Southeast, South Central and western pacific northwest region, the weather is quite warm and moist due to rains which allows the regional forests growing there to have a faster pace of  Carbon intake. However, in the Rocky Mountains, the weather there is very cold and dry which ultimately slows the pace of carbon intake of the local and regional forests that are growing there.

These forest can also be a major cause of carbon dioxide production, when the trees are uprooted to extract minerals or due to deforestation. When these forests are burnt due forest fires or human activities, the natural process of decomposition also releases lots of Carbon Dioxide in the air which is detrimental to the environment. Both of these scenarios highlight the importance of land management which is responsible for the prevention of forest to become a part of Carbon Dioxide emission and also have an increment in the forest areas that will be acting as carbon sink. The land management also aids massively in the development of carbon sink, by having an increment in the forested areas. With the utilization of one of the option Carbon Dioxide Removal known as “Afforestation and Reforestation” can help in the restoration of the natural climate by having  massive reduction in the presence of Carbon Dioxide from the air. However, the rate at which the removal will take place will be varied which might multi-decade or with extended time scale. This will be mainly dependent on the management tactics, strategies and practices which are being utilized in the prevention of various risk such as fire, or other diseases.

Even though there are many procedures in place associated with the afforestation and reforestation, but the highly agreed up by different scholar based on effectiveness is comprised of five main steps;

Selection of Site

Selection of Siteis the first step of the Afforestation and Reforestation procedure which is responsible for choosing a land. The land is selected based on availability, native and existing species of the ecosystem, and the history of the land and how it was previously being used.

Establishment if the seedling

Establishment if the seedlingis the second step of the procedure which involves planation of seeds or seedlings in the land which was selected in the previous step for the purpose of Afforestation and Reforestation. The seeds are selected based on the rate at which they would grow and their status as a native species. Usually in such artificial foresting which is to reduce carbon dioxide, only those trees are considered that have a faster and longer duration of carbon intake.

Growth and Survival of the Planted Sapling

Growth and Survival of the Planted Saplingis the third step which suggests that when the seeds starts to germinate or the seedling start to grow, then they slowly start in taking Carbon Dioxide from the air. It is well reported that a fair percentage for these seedlings or seeds end up not surviving due to wide range of reasons inclusive of different biotic and abiotic factors.

Management of Plantation 

Management of Plantation s the forth and important step that is directly associated with the management of the forest. This is mainly because that the ecosystem of the forest has to be managed with the utilization of fire suppression and occasional thinning procedures, which ultimately allows the plantation of the forest to be more healthy in terms of their growth which leads to longer duration of carbon stage on both above and below ground levels.

Intake of Carbon Dioxide by Forest

This is the last step of the Afforestation and Reforestation procedure which is responsible for having a reduction in the Carbon emissions. In this step after the seedlings or seeds are turned into proper trees, shrubs and plants, then they are properly managed to ensure that they use the procedure of Photosynthesis to intake carbon dioxide from the air and in return release more oxygen in the environment.

Restrictions based on Geology

In the theoretical terms, it is quite evident that the functionality of Afforestation and Reforestation can be adopted on any kind of land that has the ability of supporting the growth of the trees and is currently not under any use. This kind of land is inclusive of the terrestrial portion of the planet’s surface which is not too steep for the plantation of the trees and is not over the treeline limit. In 2012, the land which was allocated to the World’s forest was 31 per cent which was fairly less in comparison to the land given to the agriculture sector at 38 per cent (See Figure 2).

With the increment in the level of forest through the usage of Afforestation and Reforestation provides implications based on tradeoffs with other potential uses of the land. The potential uses is inclusive of various functionalities such as development of the urban areas, growing agricultural crops and consideration of other Carbon Dioxide Removal such as Terrestrial Bioenergy with the Capturing And Storage of Carbon, or Soil Carbon Sequestration, where all of these uses poses a massive competition to the conceptuality of Afforestation and Reforestation. It is essential for the governments of different countries to make an analysis of the impacts that are directly related to the functionality of Afforestation and Reforestation in comparison to the other suggested land usage, due to the growing competition associated with land in the recent times. For instance, if the government decides that the suggested land must be utilized for the purpose of agriculture, then estimations and analysis must be made on different factors such as food security in the regions, effect on the biodiversity of that land and livelihood of the communities.

Figure 2: Forest Area in Percentage back in 2015

Implications of the Policy

There are various global policies that have been formulated and implemented over the past few decades which are responsible for the protection of areas in which there are forests. These policies prevent forests from different disasters such as deforestation, forest fires and make sure that expansions are made in the forest land within the suggested boundaries. There are various countries that have had massive success when it comes to implementation of Afforestation and Reforestation to have a reduction in the levels of Carbon Dioxide in the air, these countries include Vietnam, Gambia and Bhutan. Not only in these countries, the level of Carbon Dioxide has been decrementing for the past years throughout the world, which is mainly because of the reduction in deforestation. A research conducted in Brazil showed that it had decreased 60 per cent deforestation rates ever since 2008, with the utilization of different programs such as Amazon Protected Areas Program which is responsible for providing protection to the land and makes sure that the registration of these lands is protected and sustainable in terms of their usage. Additionally, there are different programs such as Reducing Emissions from Deforestation and Forest Degradation Program (REDD+) that are actively involved in supporting developing countries to have a reduction in the levels of deforestation. Apart from Reducing Emissions from Deforestation and Forest Degradation Program (REDD+) , the United Nations also provides encouragement and all kind of support to those countries that are striving to have a reduction in the emissions of the deforestation alongside those countries that are considering enhancement of their forest carbon stocks.

If any country wants to promote higher level of carbon sequestration with the utilization of Afforestation and Reforestation, then it is very important to have all the policies that are associated with it to be fully enacted. This will ultimately help in the reduction of competition associated with land based on their usage such as developing forest or farms, especially when prices of food commodity increments. However, if the limitation of forces is overlooked or neglected then it could lead to higher level of deforestation, therefore it is essential for the countries to consider the ecosystem services provided by the forests. A model known as EU Biodiversity is created by The European Union for the solely for this practice in terms of making spatial assessment of the ecosystem. The selective harvesting is another are for consideration that is responsible for extracting economic benefit from the forest management which ultimately leads to increment in carbon sequestering with the utilization of management techniques that are responsible for mimicking natural forests. If periodical harvesting is allowed then the conceptuality of reforestation and afforestation can be implemented with a much lower cost. All the suggested policies are very beneficial for the conceptuality of Afforestation and Reforestation, as it helps in its protection from different conditional changes.

Benefit, Challenges and Tradeoffs

Apart from the Carbon Dioxide Removal, the conceptuality of afforestation and reforestation is also responsible for providing the ecosystem with different important services that is inclusive of enhancement of biodiversity, prevention against floods and moderation of local climate. Having forests, be it natural or artificial also provide rich matrix and habitat for different animals or plants to survive and live in. In addition to that, these forested areas helps in the decrement of range of temperatures in the surrounding environment. However, it is also important to note that the advantages which are acquired from afforestation and reforestation through the usage of Carbon Dioxide removal and related ecosystem services can also become a trade. It is quite evident that the areas which are naturally reforested will have more native species of plants and animals, and will also look much like the original forest. Additionally, if the conceptuality of afforestation and reforestation are properly managed then they will bring about high level of carbon sequestrations which would result in selecting either Carbon Dioxide Removal or Biodiversity. The main challenge or drawback of using the conceptuality of afforestation and reforestation is directly associated with permanence of Carbon Dioxide storage, where Afforestation and reforestation depend primarily on the carbon storage in the biomass of the plants, these living organisms have expected lifetime. So, when they die, they can also be cause of future emissions of Carbon Dioxide.

Further Research

It is quite evident from the provided discussion that the conceptuality of Afforestation and Reforestation is an established option which is responsible for the reduction of Carbon Dioxide in the air. This an established concept because there are many theoretical and empirical researches that have been done on it related to its viability, economical cost structure and the potential of this concept moving forward. However, the research associated with Afforestation and Reforestation still lacks when it comes to wide-scale implementation, it is important to place an importance on determining the actual cost of the whole procedure alongside the determination of species that would be more beneficial to reduce the carbon emissions. In addition to this, it is also important to consider the effects of the climatic changes, where an additional research should be considered related to likelihood of permanence, which forces such as natural or anthropogenic can easily affect.

Conclusion

In conclusion it is quite fair to say that the conceptuality of Afforestation and reforestation is an important and effective option of Carbon Dioxide removal. In addition to being affective, it is also an established option which is actively being considered by different countries and has massively aided in bringing down the level of carbon dioxide. Having more forest not only help in the reduction of Carbon Dioxide but also includes many other benefits such as prevention against floods, giving living space to wildlife and moderation of local climate. The main drawback of using this conceptuality is directly associated with permanence, where this concept utilize living organisms for the storage of energy, which are expected to die at certain time and would be a cause of carbon release. There are many empirical and theoretical studies done on this concept, however further researches are needed to properly back the large scale implementations.

Chapter 3- Soil Carbon Sequestration

Introduction

The conceptuality of Soil Carbon Sequestration is a method that is responsible for the removal of carbon dioxide and relies heavily on the intentional land management which is directly targeted towards the increment of storage of carbon with the utilization soil organic matter, which is present in both labile and an inorganic forms. It is well known that any kind of soil can act like a carbon sink, this report will be providing a discussion that will be solely based on the conservation management of different pastures and croplands. The discussion will also be highlighting various ways which can be utilized to convert different agricultural land to different carbon sinks. Just like the conceptuality of afforestation or reforestation, the conceptuality of Soil Carbon Sequestration is also dependent on various natural procedures that can be amended with the utilization of different management practices. For example to achieve lower carbon sequestration in soil the conceptuality involving switching crop variety can be considered, this is mainly because the plants that are new and young in age do not shed a lot. Fertilizers also play a contributing role when it comes to emit greenhouse gases such as Nitrogen, therefore different management choices can be considered that involves utilization of less Fertilizers to avoid further emissions.

The procedure of Soil Carbon Sequestration

Being the component of global carbon cycle, all plants take in the Carbon Dioxide from the air with the utilization of photosynthesis and then incorporating it into their biomasses. The biomass can be harvested if it is growing in a certain cropland, eaten by a herbivore or with the utilization of the conceptuality ‘Above ground Biomass’ can be stored over long duration of time, where all three of these situations form a barrier in the absorption of carbon dioxide in the soil. The part of the plant which is present underground or below ground contains as much as half biomass of the plant which allows immediate predisposal of that portion to remain under the ground or in the soil. In addition to this, the yearly deposition of deceased organic material in the layer of the leaf either becomes a component of the topsoil or goes back in the environment through the procedure of decaying and respiration of the soil. A research shows that in an estimation, 10 per cent of the carbon which is released from different organic matter remains for the next 25 years, if it is able to enter into the leaf layer. The carbon which is stored in the soil annually and the amount released in the atmosphere is something that the conceptuality of Carbon Sequestration is based on. The management practices forms the basis of whether the net soil carbon sequestration will be negative or have wide fluctuation that differs every year. The location in which carbon is present in the soil, is responsible for the determination of ease at which the Carbon can be released in the environment.

There are three forms of soil carbon which are named as Stabilized organic matter, slow organic matter and labile organic matter. The first form known as Labile organic matter makes the entry in the soil by going through the leaf layer of the plant or through its root system in past 2 years or less and that is how it can easily be released into the environment. On the other hand, the slow organic matter is usually below the surface level for 20 years or less. These organic matter are usually present in the lower level of soil horizon, where there is less availability of oxygen for the decomposition procedures. This type of slow organic matter is less likely to be released in the environment and is available to different microbes and plants for vital nutrients. In the last, the stabilized organic matter which is inclusive of different types such as humus are present and dissolved in the soil for the past 100 years or less and without the interference of humans are less likely to be released in the environment.

Figure 3: The Procedure of Soil Carbon Cycle

There are different agricultural practices that have traditionally cultivated the soil because the actual plantation of the new crops or plants, where the whole procedure can easily break up the old roots which are present in the soil and also helps with the burial of plant material which is of no importance. The whole procedure makes the procedure of plantation of crops very easy and is also beneficial when it comes to yield of the crop because it softens up the soil for the new plants to spread their root system. The downside of this tilling process of soil, is that it exposes various layers of organic matter which are present in the soil especially the soil carbon named as slow organic matter which is responsible for locking in carbon in the soil. Having such a functionality in place initiates the whole decaying procedure which produces lots carbon in the air.

There are two practices which are well known in the cropland for making sure that the soil in the agricultural landscapes acts as carbon sink rather than being a source of it. The first practice involves plantation of crops, but for non-economic purposes. Such crops can easily be planted in the growing season in areas that are present between the rows of cash crop which would otherwise be barren ground during the seasons of autumn and winter. This practice is responsible for the provision of soil cover to lock in different nutrients that are present in it, if these nutrients are not extracted then they are expected to erode overtime. At the end of the growing season, this conceptuality can also allow a massive increment in the amount of carbon that is present in the soil organic matter. The second conservative agricultural procedure is known as no-till and it is inclusive of planting the crop directly in the harvest of the last year, without having the need to till the soil. This has a massive decrement in aeration of the soil, which would other wise enhance the microbial activity that releases lots of Carbon Dioxide in the air through the procedure of respiration.

The process of storing Carbon in the soil comprises of four main parts, in the first part the plant goes through the procedure of photosynthesis to collect all carbon dioxide from its surroundings. In the second part the as the move towards its harvesting or dying stage, then its biomass or some components are left on the surface to decompose. The biomass which is left on the surface usually comprises of litter of leaves that are present above the ground level and below the ground level the biomass comprises of the plant’s root system. In the third step, the biomass of the plant will decompose in the presence of the oxygen. However, the process will be at a slower pace or will completely shut off if there is limited level of oxygen present in its surroundings. This usually happens if the biomass of the plant is covered with some type of additional material such as leaf litter in the forest or roots which are present deep in the soil. The whole decaying or decomposing procedure is greatly facilitated by microbial activities, and these microorganisms end up respiring Carbon Dioxide back in the air. In the last step, the decaying or decomposing process is completed or stopped and carbon which was present in the biomass of the plant is stored in the soil.  

Potential of Soils to Remove Carbon Dioxide

The elements or divisions such as Regions, type of soil and the management tactics which are employed can be utilized for Soil carbon sequestration on a global level. In the United States alone, the conceptuality of Soil Carbon Sequestration, tillage management and cropping systems can be utilized to store around 0.2 to 4.7 gigatons of carbon dioxide equivalent annually. The methodologies which are included in Soil Carbon Sequestration such as planting cover crops, usage of conversation reserve programs and winter crops cover can further provide contributions in mitigating an extra 0.015 to 0.030 gigatons equivalent annually. Furthermore, if additional nutritional elements and supplemental irrigation system is considered then it has the potential of sequestering around 0.010 to 0.030 gigatons of Carbon dioxide equivalent annually.

The land which is mostly utilized for grazing different animals such as sheep, cows, buffalos, and other domesticated herbivore animals is known as Pasture Land, which also provides a massive opportunity to employ the conceptuality of Soil Carbon Sequestration, this is mainly because there is lack of disturbance in these lands, which are because of tillage and high root density of the plants that are present there which makes it an effective option for carbon mitigation. One of the estimations made in the United States suggested the fact that using pasture lands can allow mitigation of approximately 0.02 to 0.11 gigatons of Carbon Dioxide every year.

Apart from the Pasture Lands, there are other lands which are massively gaining the attention of acting as potential carbon sources and its sinks such as Wetlands. An estimation suggested the fact that there are more than 600-700 gigatons of Carbon Dioxide which are stored in these lands throughout the globe and the growing consideration of the world to transform these lands for agricultural purposes can end up releasing lots of carbon dioxide and other greenhouse gases which were stored in these lands for many years or even centuries. If these lands can be properly restored then they can be very beneficial when it comes to returning coastal and inland areas back to their natural role which is to act as carbon sinks and provide regulations to the terrestrial water cycles. Even though these Wetlands are considered as a sink for Carbon Dioxide, but they are still responsible for being a major source for the production of methane gas which is twenty eight times more dangerous then Carbon Dioxide.

Restrictions based on Geology

The rates and holding capacity of Soil Carbon Sequestration are closely related to all the natural factors that are also the characteristics of that geographic location. The climate is more closely related to the absolute amount of soil organic carbon than any other factors such as the vegetation type, which suggests the act that the climate plays the role of limiting factor in the potential of the soil to remove carbon dioxide from the environment. Through different activities such as geochemical weathering or different plant activities, all kinds of soil could have an increment in their organic carbon content.

Implications of the Policy

Different government throughout the world can utilize the legislation that is associated with ‘Land Use’ to promote the conceptuality of Soil Carbon Sequestration, especially on the lands that are bring used for agricultural purposes. In the United States, The Department of Agriculture is responsible for administering different land conservative programs which includes both Environmental Quality Incentive program or EQUIP and Conservation Reserve Program or CRP, both of these programs are responsible for the provision of payments that is utilized for better agricultural practices such as removal of marginal agricultural land from production, creation of buffer strips and ensuring windbreaks to have a reduction in both runoffs and decompositions. When the conceptuality of Carbon Dioxide Reduction was introduced, it did not contain the procedure of Carbon Dioxide Sequestering as an original intent. However, this program now performs the most useful functionalities inclusive of monitoring mitigation of different greenhouse gases alongside emissions that are avoided as result of reduced fertilizer and fuel usage. With the utilization of this program inclusive of subsidies will have a massive decrement in financial aspect associated with the conservation farming practices. This would ultimately allow more farms to consider implementation of procedures that would lead to the increment of  soil carbon, disregarding the fact that this concept is a stated concern.

Benefit, Challenges and Tradeoffs

Even though that the reliable data associated with the cost of carbon sequestration with the utilization of this methodology is very limited, the cost associated with the conceptuality of soil carbon sequestration is estimated to be a positive or benefit. During the consideration of cost associated with the lifecycle, the conceptuality of soil carbon sequestration is expected to get into the lower half of the cost structure once the value of incremented crop yield and cattle sales is taken into account. Even though the cost structure of the suggested concept is increasingly variable, the conceptuality soil carbon sequestration will be relatively inexpensive compared to other and technical options of Carbon Dioxide Removal, this is mainly because Soil Carbon Dioxide Removal is inclusive of cultivation of product accompanied by the market value. There are unique constraints associated with different cropland or pastures, that go through changes in different moments due to different natural disaster or consideration of different decision such as to till a selected field. In consideration of these elements, there has been very few efforts that have been placed towards the quantification of net cost and benefits associated with soil carbon sequestration which might be for a specific location or as an estimate.

The main challenge in this scenario is associated with the arable land, which is utilized for conservative farming, should be balanced with other options of Carbon Dioxide Removal that are mutually exclusive such as terrestrial based accelerated weather, and Afforestation and reforestation. There are other options of Carbon Dioxide removal such as Biochar and Aquatic Bioenergy with the Capturing and Storage of Carbon that can be considered in combination with soil carbon sequestration which would ultimately result in the need of complex analysis, that will be utilized to make estimation on what percentage of carbon mitigation attribute to each of the suggested methodologies. Elements such as concerns for foods production and biodiversity must also be balanced with the element of soil carbon sequestration. Most of the suggested goals might not be mutually exclusive, however optimization for carbon sequestering often leads to a decrement in yields of the crops which are growing on the farmland but in terms of cultivated land there is a reduction in biodiversity in comparison to other uses of land. With the implementation of management tactics which are targeted solely at the increment of net soil accumulation gives an opportunity that is directed towards the removal of carbon from the environment through natural means alongside achieving complementary goals such as better health of the soil and high productivity of the agriculture.

Further Research

Even though the soil will continue to store carbon naturally, however it is utmost importance that further research are done to understand how to have an increment in the permanence of the soil organic matter and how different types of soils effect on overall storage potential. Additional research is also required, which is to make comparison on the relative potential and cost structure of soil sequestration with other types Carbon Dioxide Removal options such as Afforestation and reforestation, Biochar and Bioenergy with carbon capturing and storing. In economical terms, there is a major lacking associated with the clear data on implementation cost by different management tactics, regions and crops. More detailed analysis must be done to find out the cost related to mitigation of carbon in soils, which would help in the demonstration of how this concept can be beneficial to the farmers and their agricultural land.

Conclusion

From the above discussion it is quite fair to say that the conceptuality of Soil Carbon Sequestration can help massively when it comes to the reduction of Carbon Dioxide in the air. However, there are many areas of lacking associated with this option of Carbon Dioxide removal and further researches are needed related to the implementation impacts such as yield of the crops, the economical cost of implementing such a concept and Carbon Dioxide Removal potential is compulsory for mass implementation.

Chapter 4- Biochar

Introduction

Biochar is a simple conceptuality that involves creation of a charcoal with the utilization of plant biomass or other material, through the procedure of pyrolysis. This procedure involves heating of the biomass of the plant in an oxygenated environment, with a  relatively low temperature that is between 300 to 900 degree centigrade. The usage of the oxygenated environment helps in the prevention of combustion and after such prevention a thermochemical decaying of organic matter starts to occur which leaves behind a charcoal which is carbon rich. Biochar can be produced as a main or primary product or as a secondary byproduct in the scenario of energy production. The conceptuality of biochar has been actively used in the soils of agriculture for millions of years, the main reason of doing such a thing was to have an improvement in the retention of water and other vital nutrients. On a molecular level, Biochar is also responsible for providing more surface area to different nutrient and providing beneficial microbes. The conceptuality of Biochar also has the ability raise the pH level of the soils, which can beneficial for the soils that are acidic. There are many researches conducted that showcase the fact, that if the conceptuality of Biochar is considered then it can leach out 60 per cent nitrogen from the soil. Other researches also show that inclusion of biochar in the soils have incremented the yields by an approximation of 37 to 46 per cent. This suggests a saving of 20 percent in the usage of fertilizer and more then 10 per cent in the usage of irrigation or seeds. In the today’s world the main primary uses of biochar is inclusive of abatement of soil, industrial manufacturing and the usage in chemical, and in the recent times a methodology to extract carbon from the environment

The Procedure of Biochar

The simple definition of the conceptuality of photosynthesis means a process in which the plants gets the energy from the sun and utilize it to take different elements such as carbon dioxide, and water, then converts them to form sugar or carbohydrate. This would suggest the fact that the element of carbon is a building block of all components of plants. Thermal decomposition start happening as the plant is heated, the chemical bondage begins breaking down and the bonds of the carbon are the last one to break inn a low oxygenated environment. If these are properly controlled and managed, then a carbon-rich char will be made and left behind. The procedure involving the formulation of biochar and its ability to improve the condition of the soil is something that as been widely used for many years. The procedure to produce biochar is very simple and involves setting the crop field on fire. However, if a properly controlled methodology is considered then it involves burning the biomass of the plant in some kind of kiln or a enclosed container which ultimately leaves behind a biochar and this biochar is expected to decay way slower than the organic material around it. Burying, Adding or Applying Biochar to the ground or soil is a prevention method, that forbids carbon from returning to the environment in the form of Carbon Dioxide. This kind of procedure would normally occur in decaying or decomposition through respiration of different organism in the breaking of simple organic material.

The production of Biochar is based on three major steps, the first step is responsible for the collection of plant material which is also called as biomass. The biomass can be in several different types such as waste of agriculture, crops and even woody material of the plant. In the second of producing biochar, the biomass which was previously collected will be heated in a temperature of 300 to 800 degree centigrade in a controlled environment having low oxygenation. This process is also known pyrolysis which is a procedure that can take place in conjunction with the formulation of bioenergy products such as bio-oil or syngas and biochar. All these elements can be utilized in the form of energy sources for the generation of electricity and heating application. According to Processing temperature, there are two classifications of slow and fast provided for the pyrolysis procedure, and the residence time of biomass. If the conceptuality of fast pyrolysis is considered, then there will be more bio-oil and less biochar produced in comparison to slow pyrolysis. In the last and third step, the carbon rich biochar that is left can be slowly incorporated into the soil by burying or by spreading it over the agricultural land which would lead to a better soil quality.

Figure 4: The Procedure of Fast Pyrolysis

The figure 4 provides an explanation on the mass and energy flow balance of the biomass which then undergoes a conversion process with the utilization pyrolysis to yield different kinds of solid products alongside other elements such as sand, bio-oil, and biochar. To fuel the whole procedure involving pyrolysis procedure, sand furnace and biomass treatment, the syngas is utilized which also produced in the process and is transported subsequently. However, it can be seen that the bio-fuel is moved directly to the storage tank.  

Potential of Biochar to Remove Carbon Dioxide

Even though the conceptuality of Carbon Dioxide Removal and its potential is primarily dependent on different variables, and are utilized in the production and application of Biochar. It is well researched that the conceptuality of biochar has the ability to store in between 0.02 to 1.05 gigatons of Carbon dioxide equivalent annually across different regions throughout the world. The feedstock of the biomass are inclusive of different elements such as switch grass energy crop, waste of the yards and even corn stover, where such feedstock also provide an insight to the impacts of climatic changes alongside economic cost that is present between the usage of waste resources of the biomass and such crops are solely used for the production of bioenergy. The suggested storage variation of 0.02 to 1.05 gigatons of Carbon dioxide equivalent annually related to Carbon Dioxide Removal potential is mainly due to various assumptions that are utilized by different studies. There are various key variables that are responsible for affecting the potential reduction of Carbon Dioxide which includes feedstock elements, presence of bio, the temperature in which the procedure of pyrolysis took place and incentives included in the incentivized application. Furthermore, it is well known that the element of biochar is formulated with the utilization of biomass and there are certain limitations related to the collection of biomass in a single time within a radial distance from where the whole procedure of pyrolysis is taking place. According to certain estimations, it is also known that around 40 per cent of the biomass is mainly made up from carbon and this percentage also suggests the theoretical limitation to extract the carbon from the biomass.

Restriction based on Geology

The conceptuality of producing biochar is extremely simple which can be done and applied in essential every part of the whole world. Different factors such as the type of the biomass and the temperature at which the pyrolysis procedure took place, can be utilized to understand the level of biochar and carbon that can be made from that biomass. It is well known that the biochar that has been formulated from different kinds of biomasses have varied properties in comparison to Abatement of the soil, which would suggest imposing restriction on the kind of biomass such as coconut shell, risk husk, corn husk and corn remains which are being utilized to create biochar in different parts of the world. The composition of soil is also responsible for playing a large part in the effectiveness of the intended soil abatement properties of biochar. In Addition to all this, it is also found that that the soil types which are coarse to medium are found to benefit the most with the usage of biochar, but the other kinds of soil are expected to be affected adversely with the usage of biochar. This shows that the type of the soil in different region also has a major affect on whether the usage of biochar would be beneficial or not. 

Implication of the Policy

 As per the research done back in 2016 on Google.com it showed that the market price for biochar is in around 1500 dollars per every tonne. The application rates also ranges in between 1 to 60 tonnes of biochar/ha, which have become very unaffordable for most of the farmers. It is well known that the biochar is also produced as a byproduct as a result of increment in the production of bioenergy, therefore having an increment in the supply would ultimately bring the price of biochar down. Having such a functionality in place will bring down high costs related to the application of biochar, but this will still not help the farmers address the uncertainties associated with the adverse effects that biochar might have on the soils which is used to grow agricultural crops. It is very essential to have a better and more relevant information related to the effects of biochar from different feedstocks and the effects that they might have on the soil being used, which would ultimately encourage the farmers to consider the advantages of biochar in their agricultural functionalities and grown. On top of that, organic farms which are a part of industrial agriculture are also actively involved in using less fertilizers. To solve such a problem related to organic farms, the usage of biochar is an attractive option provided that the information and subsidies related to biochar are available.

Benefits, Challenges and Tradeoffs

The conceptuality of biochar has many well-known benefits inclusive carbon mitigation, enhanced fertility of the soil, production of both biofuel and bioenergy and disposal of organic waste. However, it is also important to know that the positive associated with the biochar can also turn into negatives, which is mainly because of the uncertainty which surrounds overall emissions of Greenhouse gases. The uncertain factors is inclusive of various factors such as lifecycle carbon emission of transporting and collecting biomass or biochar, the risks of health and environment  related to primitive methodologies of pyrolysis procedure alongside the potential of biochar having a reduction in the crop yield if added inefficiently.

Out of all the suggested trade-offs associated with biochar, two of them are of most importance. The first one is associated with the usage which suggests whether the land should be used for the production of agricultural goods such as food crops or should be facilitating the production of biomass. Even though the second option of producing biomass seems to be more appealing considering the fact that biomass can be converted to biofuels which gives biochar as a byproduct. However, with the utilization of such concept, the land which is currently being used for the production of foodcrops will end up declining. On the other hand, there has been a growing influence in using the crop waste as an ultimate source of biomass feedstock which will be utilized for the production of biochar. Usage of such a conceptuality will bring about equilibrium in the tradeoff between using the land for biomass or for agricultural purposes and also extract the benefits from the production of biochar.

The second concern is related to the lifecycle emissions of many facets related to the production of biochar, this is inclusive of transportation of the feedstock, pyrolysis and harvesting, which may offset the carbon mitigation done by the procedure of biochar. Even though the energy made in the in the procedure pyrolysis can be utilized for the replacement of fossil fuels, the energy required to initiate the pyrolysis system usually come from carbon intensive fuels or coals and is of special importance in the countries that are currently in their developing stage, which could ultimately offset the carbon r was captured in the whole procedure. Taking the lifecycle perspective into account, it is quite evident that minimal trade off will exist if the pyrolysis procedure as an appropriate and an efficient energy source alongside other factors such as distance of transportation, storage and biochar pyrolysis systems.

Further Research

Compared to the other options of Carbon Dioxide Removal that will be covered in this report, the procedure of biochar has an existing, important and first hand research associated with its benefits, viability, cost structure and potential associated with Carbon Dioxide Removal. However, it is still quite evident that further research is still required for the identification and understanding of many variables that are utilized in the biochar production and usage, and if such a concept becomes viable then it is quite evident that carbon mitigation from the atmosphere will be more efficient. The additional researches that are needed should be laying focus on adoption a model which is more systematic and involves reduction in tradeoffs through the production of sustainable biochar. This sustainable biochar will also aid in the improvement of soil conditions as per the application.  For the procedure of biochar to be scaled up, it is essential to produce biochar from a feedstock that is more sustainable. Furthermore, appropriate temperature levels for the pyrolysis procedure is also important which can be acquired through sustainable fuel source. It is essential for the relationship between the production of biochar and other related bioenergy industries to be properly accessed alongside their potential policy issues, which will help massively when it comes to mass implementation of this concept.

Conclusion

The conceptuality of Biochar is of utmost importance when it comes to the reduction of Carbon from the air. The potential associated with Biochar is mainly dependant on the variables that go into the production and application of Biochar but can easily be applied to any part of the globe. This is a simple concept and if certain elements such as feedstock, temperature and proper management tactics are researched then it could help with the implementation of this concept on a mass level.

Chapter 5- Acceleration of Weathering

Introduction

The conceptuality of Accelerated Weathering or Acceleration of Weather is speculative option of Carbon Dioxide removal that is responsible for enhancing, or accelerating chemical weathering procedure that naturally occur in everyday life. The carbon dioxide is extracted from the atmosphere with the utilization of a reaction involving different elements such as water, calcium, iron silicate minerals, limestone and so on. The whole procedure involving accelerated weathering is still in its development phase, however there are various laboratories in the United States and Finland that have tested the theoretical assumptions which are underlying the potential of Carbon Dioxide mitigation with the usage of acceleration of weathering. The functionality of Accelerated Weather encompasses all the general conceptualities which are responsible for enhancing natural chemical procedure, there are many specific ways to apply accelerated weathering as a Carbon Dioxide Removal option. The provided discussion will be highlighting the exact procedure of weathering acceleration, the potential of this conceptuality to remove the carbon dioxide in the air and various restrictions based on geology. In the end, implication of policies followed by different benefits, challenges and tradeoffs which can be expected from acceleration of weathering.

The procedure of Acceleration of Weathering

The phenomenon of Accelerated weathering is primarily based on chemical reaction that can easily be carried out with the usage of several different reactants in ex situ or in situ settings. The potential sources for this concept is inclusive of different minerals such as calcium, magnesium, water, limestone and iron silicate minerals, where most of these suggested minerals are inclusive of other minerals having similar chemical composition such as serpentine, calcium carbonate and even olivine. There are various industrial waste products such as coal fly ash, kiln and steel making slab which are usually found rich in magnesium and calcium containing silicates that are also considered in the functionality of Accelerated Weathering. Wet carbon mineralization is one of the most well studied concept associated with the accelerated weathering procedure and is demonstrated in figure 5.

Figure 5: Carbonation of Minerals

This procedure of wet mineral carbonation is mostly comprised of five major steps, the first step is known as the pretreatment step in which the source minerals that might have been acquired from mining or industrial waste is grounded to an optimal size and is then heated to a certain level of temperature which leads to purification and pressurization of Carbon Dioxide gas. The second step is known as slurry pumping in which the pretreated mineral is mixed with a saline solution or even water on the basis of optimal pH level and is then added to the reactor. Reaction is the third step of the wet mineral carbonation that involves mixing of pressurized stream of Carbon Dioxide gas with the mineral slurry that happens in an agitator which results in carbonation of minerals. During the fourth stage of separation, there are solid and liquid separators used which are responsible for separating out unused Carbon Dioxide gas for reuse and separate the liquid such as water for further purification and reuse from the carbonate residue or product. The last step involves the storage, which involves both carbonate and solid residue to be transported to a storage location.

Potential of Acceleration of Weathering to Remove Carbon Dioxide

The projections made on the potential of Accelerated weathering to remove Carbon Dioxide is primary dependent on the procedure being use and the underlying assumptions associated with it. This conceptuality is highly dependent on large areas of water or land to disperse silicate mineral which is limited by geographical extent. The procedure of Wet Mineral Carbonation that utilizes raw materials extracted from silicate based industrial byproducts are highly dependent on the quantity and quality of the product that is available. Being speculative, the conceptuality of Accelerated Weather which is an option of Carbon Dioxide is still in its developmental phase where all the estimations on these options are based on specific regions and are not on a global level or potential. There is no study that has been reviewed in this discussion that would provide an estimation of the whole world, either for single type or all applications for accelerated weathering. The application for all the accelerated weathering procedure are not mutually exclusive and it is quite evident that all four of these options can be utilized to some degree for the removal of Carbon Dioxide. In the same manner, the differences in the procedure, input requirement and land requirement lead to variable magnitudes of implementational potential of this concept. Based on the data or information that is available, the mitigation and storage potential of Accelerated weathering is in between 0.001 gigatons to 18 gigatons of Carbon Dioxide every year.

Restrictions based on geology

The geographical areas where the conceptuality of accelerated weather can be adopted primarily adopted depends on the procedure being used. The basalt or peridotite rock is naturally available in the coastal regions where the seawater injection must occur. The mineralization of the soil is mostly recommended in remote river basins and as per various research the Congo and Amazon rivers are also a potential option for adoption.

Implication of Policies

The Policies which are directly related to the cost of water being used and the requirement associated with the industrial waste disposal can affect the implementation of accelerated weather which is mainly because the cost of water would eventually have a drastic impact on the ability to adopt a low-cost Carbon Dioxide Removal option of accelerated weathering. However, if the governmental policies associated with free access to ocean water for accelerated weather is favored then it would ultimately lead to the concepts such as mineral carbonation being more economically affordable or feasible. In the same manner, if the dumping cost of industrial waste is incremented then it would create a market for the utilization of ideal raw materials such as coal fly ash, cement kiln dust and steel making slab. Other approaches of Accelerated weather such as soil mineralization and seawater injection are unproven in terms of their usage and are dependent on governments for approval. Spreading elements such as olivine and other important minerals over a region that is large enough to have high and measurable Carbon Dioxide Removal result would also require permission from the government. In a similar manner, even the usage of basalt salt in tidal areas requires a legal approval.

Benefits, Challenges and Tradeoffs

The conceptuality of accelerated weather can easily provide broader benefits apart from the Carbon Dioxide Removal potential through the usage of its byproducts and low impact of some of its approaches such as wet carbon mineralization. Most of the forms of weather acceleration is inclusive of carbonation of water which results in the creation alkaline bicarbonate solution which can then be injected in the ocean. Many researches and studies have suggested the fact that to cater the dilemma of ocean acidification, the element of alkaline bicarbonate can be used. In terms of the land, solid byproducts which are extracted from wet carbon mineralization can be utilized as a backfill for the mining operations. In such a way, all these procedures related to Accelerated Weathering all can be utilized in the restoration of natural land contour and also to avoid the insertion of additional materials in the landfills. It also has a massive reduction in he industrial waste, considering the fact that these industrial byproducts are being used as raw material to operate these procedures.

There are many procedures associated with the accelerated weathering which are not yet tested, therefore there are still many concerns regarding the negative impact of these practices, especially for the options that are based on land. Furthermore, the conceptuality of accelerated weathering has an increment in the level of alkali in the water or land where it is being plotted, where some areas might reap certain benefits but other areas might face terrible consequences due to drastic increment in pH levels. Some of the researchers suggest spreading an olivine over the area of 37 billion meter square in the Congo river and 60 billion meter square for Amazon river. It would be a major challenge to cover such a large area, the studies also show the probability of raising pH level to  around 6.7 in both these areas would have a drastic affect on the wildlife residing there.

Further Research

The additional research on accelerated weathering should be considered, that should lay its focus on the determination of scalability of laboratory based wet mineral carbonation procedure and factoring economical aspect to find out the minimum efficient scale for siting an accelerated weather plant near a place where it can acquire raw materials from such as industrial factories.

Conclusion

In conclusion it is quite fair to say that the conceptuality of accelerated weathering is in its development phase and as per the various test conducted on this form of Carbon Dioxide removal, it is quite evident that it has lots of potential moving forward. This concept is inclusive of various other approaches, where some of them are mostly not tested. Therefore, it is essential to find out their negative impacts before considering their implementation on larger scale. Neglecting such additional researches can have serious detrimental effects on the planet in the long run which could further boost carbon emissions.

Chapter 6- Direct Air Capture

Introduction

The Carbon Dioxide Removal option of Direct Air Capture is inclusive of the removal of carbon dioxide from the ambient air with the utilization of various technologies and mechanical devices. The other terminologies that have been used for Direct Air Capture is artificial trees which is mainly because in this concept, the air is forced through the Direct Air Capture systems which extracts Carbon Dioxide from the air and then concentrates it to easily stored form. Just like the accelerated weathering concept, the Direct Air Capturing is also in its developmental stage. Therefore the estimation provided in this part of the discussion must be recognized as estimate based on limited models and project data.

The procedure of Direct Air Capture

Primarily there are two main methods to capture an store Carbon Dioxide, one is with the utilization of aqueous chemical sorbent and the other one utilizes a solid sorbent which then acts like a filter. When the carbon dioxide is extracted and stored with the help of the filter, it can the be used as a raw material for other industries or can stored geologically. The method to capture the air directlyinvolves four main steps, in the first step utilizes a big fan which is responsible for forcing the air through the contractor unit in the Direct Air Capturing system, this is when the carbon dioxide binds itself to the liquid or solid sorbent. In the second step, the sorbent and carbon dioxide mixture is transported to a device known precipitator which adds an additional element of calcium that separates the Carbon Dioxide from the sorbent. In the third step the mixture of calcium and Carbon Dioxide solution is heated up to 800 degrees centigrade, to separate both calcium and carbon dioxide. In the end, the carbon dioxide is compressed into a concentrated stream ready for usage or storage.

Figure 6: The procedure of Direct Air Capture

Potential of Direct Air Capture to Remove Carbon Dioxide

In comparison to other methods of Carbon Dioxide Removal, the Direct Air Capturing has very few elements to consider, when evaluating its sequestration potential. The direct air capturing is primarily dependent on two factors for Carbon Dioxide removal. The first factor is the capturing system being used which is inclusive of solid or chemical sorbent and the second factor is based on the type of sorbent being used. As per various estimations it is known that Direct Air Capturing has the potential of storing in between 0.0005 and 16 gigatons of Carbon dioxide annually. However, it is important to know that most of these estimations were primarily based on a single Direct Air Capturing Unit, where only the highest two were mainly based on complete Direct Air Capturing activity for the provided year. In the case of single unit, it as estimated that more than one unit would be utilized in a single year. It is very essential to have more than 1000 such operational units in a year, which would help with the Carbon Dioxide Removal.

Restrictions based on geology

The conceptuality of Direct Air capturing is not bound to any specific region, geography or emission source, which is one of the most promising aspects of this functionality. These systems used in Direct Air Capturing can be utilized or placed anywhere as long as there is sufficient energy sources to power p the whole system. As these systems are flexible and can be placed anywhere throughout the world, therefore they can be placed in location which are ideal for carbon storage or other facilities that can utilize it. Even though the systems of Direct Air Capture require less space in comparison to other options of Carbon Dioxide Removal, they can still get very large and become eyesore for the general public. Therefore, the machinery used in this system should be placed away from the populations. Considering the fact that this concept is in its development stage therefore there are no distinct limitations, there could also be performance differences in Direct Air capturing based on temperature and humidity of different locations.

Implication of Policies

With the implementation of direct air capturing gives more leeway to the society to fight against the climate change. Utilising concepts such as Direct Air Capturing also gives the general public the flexibility to use fossil fuels in a limited capacity for the everyday needs or for industrial usage. This Carbon Dioxide Removal option has the ability to be sited in most location, having less geographical footprint then any other option when it comes to addressing climatic changes. The systems of Direct Air Capturing are responsible for removing carbon dioxide directly from the air, which highlights a question that how may of these systems should be built and which countries should consider them. This is mainly because developing such systems may lead to conflicts between different countries, where one country might be cleaning up the carbon of other countries that do not themselves have these systems in place to cover their own emissions. Even if the countries are able to cover their own emission, these systems are very expensive to build and most of the developing countries will not be able to implement these on a large scale. Therefore, it is quite essential to know who pays for these systems if cost impose restrictions for Direct Air Capturing to be commercially viable. Additionally, as mentioned before these systems are expected to be extremely large and can be considered as an eyesore for the general public if they are built close to the residential places.

Benefits, Challenges and Tradeoffs

There are numerous benefits when it comes to the adoption of Direct Air Capturing procedures. This Carbon Dioxide Removal option is independent of large scale input for its functionality besides energy. The amount of area which will be covered by this system will be less in comparison to other options of Carbon Dioxide removal. The major challenge associated with the implementation of this system is directly associated with the expense of adopting it. Such a cost is not justifiable from the economic point-of-view and for most countries the financials of commercially scalable system is not feasible

Further Research

It is essential to have further researches in this area which will help in finding more efficient ways to collect carbon dioxide from the atmosphere. The additional research will also aid in the refinement of many component of the Direct Air Capturing systems. The size of the contractor which is responsible for administering the bond of sorbent and Carbon dioxide is limited in terms of its size. The size and performance of the contractor can be enhanced with the utilization of a strong chemical that strongly attracts Carbon Dioxide and can easily be separated with minimal force or energy. The part of the Direct Air Capturing in which the air is forced through the contractor is also an area for consideration, where improvements has to be made to further improve the performance and make system more efficient in terms of energy consumptions. Additionally, the research should also be focusing on the materials being utilized in the shell and packing of Direct Air Capturing system, which will help in the reduction of cost and energy of the some components of the system.

Conclusion

In Conclusion it is quite fair to say that the conceptuality of Direct Air Capturing is one of the most desirable one based on its functionality, less carbon footprints and land coverage. This can allow different countries to have a massive reduction in the levels of carbons which is present in the air. However, the main sticking point of this Carbon Dioxide removal option has to do with affordability, if such a project be made economically then it would be very beneficial in the long run.