Becca Hedges
Geo 3010-01/Geo 4070-01
Dr. MacLean/Dr. Kaiser
17 Apr. 2017
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Summit 4
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Carbon is an important element within our universe. It is a fundamental part of carbon based life. Living things like humans are not only partly made of carbon but it is consumed every day in things like our food, building our homes, and in our vehicles for transportation. Carbon is the fourth most abundant element within our universe. The nuclear processes involved with the formation of carbon occurred after the Big Bang. The formation of first generation stars came from helium and hydrogen created from the beginning. Once these stars have lived their course, explosions occur creating cosmic dust that produced elements with larger atomic numbers, carbon being one of them (Faure, 1998). While there is carbon found throughout the universe, the amount of it we have on Earth is roughly 65,500 metric tons. Carbon is mostly stored in our rocks with about 80% of the carbon on earth, the other 20% is found in the ocean, atmosphere, plants, soil, and fossil fuels (Riebeek, 2011). The need the world has for carbon is extensive and as scientific data shows us, our need for energy is creating a serious problem for all inhabitants of the earth; Global Climate Change. The scientific community is in consensus that while the earth has seen naturally warmer periods within its history, the recent warming of the Earth is directly related to human activities.
The Carbon Cycle
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Figure 1: Cartoon image of the global carbon cycle. Illustration courtesy NASA Earth Science Enterprise.
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Some important knowledge of the effect human activities have on the earth is to understand the natural process of the carbon cycle. This cycle existed long before humans showed up. In general the carbon cycle comes full circle between the many different reservoirs where carbon is found. These reservoirs are the atmosphere, biosphere, geosphere, and the hydrosphere as figure 1 shows us (Harrison, 2003). Through various processes carbon flows in and out of everything and repeats while experiencing various reactions along the way. In the atmosphere the carbon attaches to free oxygen creating carbon dioxide. In the biosphere carbon is part of living things such as humans, animals, and vegetation. The geosphere holds carbon through minerals and magma. The hydrosphere is intertwined between all processes. This global cycle can be described further into two subsets; the biochemical carbon cycle, which is considered to be a fast process and the geological carbon cycle, which is considered to be a slow process. Because this is an overall global cycle these two subsets will always have some overlap (Harrison, 2003).
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Biochemical Carbon Cycle
This cycle involves the carbon movements within living organisms, vegetation and is represented on a timescale of days to thousands of years. Biology has an important role with the interaction of carbon between land, ocean, and the atmosphere through the processes of photosynthesis and respiration (Riebeek, 2011). Movement, growth, and reproduction processes need and release energy. Plants take in carbon dioxide from the atmosphere during photosynthesis, and release CO2 back into the atmosphere during respiration. An example of a photosynthesis reaction is: energy (sunlight) + 6CO2 + H2O → C6H12O6 + 6O2. This is what allows the intake of CO2 from the atmosphere to create the sugars and oxygen products. During growing seasons more CO2 is taken from the atmosphere so the concentration decreases (Harrison, 2003).
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Another form that takes place is through a metabolic breakdown process called resporation. An example of this reaction is: C6H12O6 (organic matter) + 6O2 → 6CO2 + 6 H2O + energy. It takes carbohydrates and releases energy and carbon dioxide back into the atmosphere. This type of reaction occurs when plants or animals die so there were be more CO2 in the atmosphere (Harrison, 2003).
Oceans see a combination of geologic and biologic cycles. Marine organisms like phytoplankton uses carbon to create calcium carbonate in the form of shells. When the plankton dies the shells will sink to the ocean floor and then become buried by additional sediments. Over time they become compressed creating limestones as well as carbon bearing fuels like coal and oil. Through these events the amount of time it can take for carbon within this cycle cane be seen over a lifetime. It is estimated that 1,000-100,000 million metric tons of carbon is cycled per year by ways of these faster processes (Riebeek, 2011).
Geological Carbon Cycle
This cycle involves, atmosphere, oceans, rocks, and soils and is represented on a timescale of millions of years. This begins with the interaction of geological components and carbon through weathering, dissolution, precipitation of minerals, burial, subduction, and volcanic events. It may help to think about the rock cycle of the earth (Riebeek, 2011). The atmosphere sees a reaction of CO2 and water to form carbonic acid. What we see from this reaction is slightly acidic rain. This in turn reacts with minerals on the Earth’s surface. Once weathering occurs the sediments travel through water flow and can eventually precipitate out minerals like calcite. Through additional processes of deposition and burial, calcite sediments can also form limestone (Harrison, 2003).
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Additional geologic movements such as seafloor spreading, subduction, other tectonic forces moves the carbon deeper into the Earth. The heat associated with depth allows the carbon to “melt” and rise. This will release the carbon in the form of CO2 back into the atmosphere. Volcanic events both on the surface from volcanic eruptions, hot springs, and other vents as well as on the bottom of the ocean from black smokers will release CO2 back into the atmosphere (Harrison, 2003).
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Tectonic uplift exposes previously buried limestone exposing the formations. This allows erosional forces to take place again releasing carbon dioxide into the atmosphere. One example of this occurs in the Himalayas where some of the world's highest peaks are formed of material that were once at the bottom of the ocean. Through these events carbon can take 100-200 million years to cycle the various process. It is estimated that 10-100 million metric tons of carbon moves within the systems each year by ways of these slower processes (Riebeek, 2011).
Other Natural Processes
The earth has experienced various shifts between naturally hot and cold periods. Without the human component these varying cycles can maintain a steady amount of all the carbon found on Earth. When there has been shifts in concentration is when a noticeable change in the climate is observed. One such way this can happen is through the Milankovitch cycles. There are three categories of these cycles; eccentricity, tilt, and precision. The eccentricity is the shape of the Earth’s orbit around the sun. It is constantly changing from 0 to 5% over a period of 100,000 years and is directly related to periods of glaciation. The Tilt is the inclination of the Earth’s axis and will vary between 21.5° to 24.5° over a period of 41,000 years. Today we are at 23.5° and is the reason we see four different seasons on Earth. Precision is the Earths wobble as it spins. It can be pictured by thinking of a top toy. It’s spinning and wobbling changes through a period of 23,000 years. This is what dictates at what times of the year we experience the seasons of summer and winter. These variations are also causes of some ice ages.
As we can see the Earth is a very dynamic environment, because of this many different factors are at play. Now that we know more about the natural events that take place and can see what effects have been created. Some questions that come to mind are; how do we know this, why is this important, and why should we care? We will now explore these questions further.
How
Scientists who study this global phenomena have provided solid data that when understood correctly cannot be ignored. One way this data is displayed is using the Keeling curve. Instruments at the Mauna Loa observatory in Hawaii show that human activities like the burning of fossil fuels have increased the CO2 in the atmosphere since the industrial revolution about 150 years ago. Since this time our world has already increased by 1°C by releasing CO2 into the atmosphere at higher and faster rates then natural processes within the carbon cycle. Humans are creating a devastating imbalance. This occurs because CO2 is a greenhouse gas which increases the atmospheres ability to hold in heat. Unless we incorporate changes to decrease things like our dependence of fossil fuels (the number one emitter of greenhouse gases), incorporate more renewable power options, and be mindful of the removal of vegetation these warming trends could see an increase up to 13°C by the end of the century (Davies, 2016). An Intergovernmental Panel on Climate Change (IPCC) was created that consists of thousands of international and interdisciplinary climate experts working together to combat this problem. This group set a cap of a 2°C maximum temperature change and a carbon budget. This budget only allows for us to emit 860 ppm more of CO2 before we would surpass a 2°C increase. The current estimates of fossil fuel resources left on our planet would equal 7,100 ppm.
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Techniques that are used to gather data include the analysis of gas bubbles trapped in ice, tree rings, and sediments from ocean and lake floors. These analyses provide us a glimpse of what the past climates looked like. Understanding and mitigating negative impacts of atmospheric CO2 enrichment are the most vital challenges that residents of the planet face.
Importance
The importance in understanding the way the earth works on its own can give a baseline data that we can compare to what effects human kind has on our planet. The world emitted roughly 38.2 billion tons of CO2 in 2011 alone (Rosenbauer, 2012). With the natural increases of the global temperature in the past we can see that we have not reached temperatures like we saw in the Paleocene-Eocene Thermal Maximum (PETM). Paleoclimate data from about the same time shows us a large carbon dioxide increase. This is attributed to a massive die off of phytoplankton within the oceans (Scott, 2014). During this time the average global temperature rose roughly 5-8°C (9-14°F) over about a five million year period. The average global temperature was aproxamently 73°F. That could mean that it took about roughly 625,000 years for the temperature to increase 1°C if it was risen to the full 8°C difference. The current global temperature is not quite 60°F. Keeping in mind we have seen a 1°C increase in just 150 years! We are releasing so much CO2 into the atmosphere it is rapidly increasing our global temperatures at rates much faster than any natural process.
Why
We should care because if the Earth’s temperature continues to increase, we risk the possibility it will be too hot to grow food. Our fresh water supply with hotter temperatures could see increased evaporation. Storm systems like tornados and hurricanes have already seen an increased intensity which can have devastating consequences. They could occur in locations where they are typically not experienced. Our polar ice caps are shrinking quickly. This is noticed by the rise in sea level. If all the ice at our poles is melted we will lose not only some major coastal regions, but lives in the process. It simply means that it will be too hot for most of the life on earth to survive. Global climate change does not discriminate, it will affect every single living thing by way of devastating changes (Davies, 2016).
Carbon Dioxide Sequestration
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This is not just a concern for industries that emit CO2, it is also something that each individual person needs to understand. If each person on the planet makes even a little change, it can make a difference. However, people do not like change, they also do not like being told what to do, or have regulations placed on them. Even with the advancements of alternatives like, solar, wind, geothermal, and hydrothermal power have been made, there are little incentives to move in that direction. Anything that threatens their way or quality of life is viewed as a personal attack. For this reason different ways to combat this issue have arose. The thought of this option is to capture CO2 before it reaches the atmosphere or even be able to capture it for removal. Several different methods have the capability to accomplish this.
Basalt and Mineral Capture
The idea behind Basalt sequestration is taking excess carbon dioxide and initiating natural reactions between the elements contained in basalts. Basalts with high permeability trapped between other layers with lower permeability are optimal. This allows for the injected CO2 to stay in the desired layer and mimics the natural geologic carbon cycle processes. Once mineralization has taken place the CO2 cannot be released back into the atmosphere unless natural processes takes place. As discussed above this will not happen for millions of years. Figure 2 shows by injecting CO2 underground into ancient basalt lava flows with water a chemical reaction occurs creating various carbonate minerals such as calcite. The addition of water acts as a catalyst with the production of carbonic acid thus aiding in the dissolution and promoting mineralization (Rosenbauer, 2012). In 2006, Icelandic, U.S., and French scientists began testing this option via the Carbfix project. They injected 220 tons of CO2 into basalt flows in the subsurface within 400 to 800 meters. They also added a heavy carbon component to monitor the results. Samples were collected from wells located near the injection site. The pH, geochemistry, and other characteristics were routinely analyzed. According to computer simulations they expected the results from these reactions to take upwards of a decade. What they found a year and a half later is that 95% of the injected CO2 had already mineralized. A similar study near the Columbia River near Wallula, Washington is reporting similar results (Kintisch, 2016).
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In similar studies injections around 3000 meters have determined that injected CO2 in a supercritical state will convert into various carbonate minerals. They report that the best results are when temperatures are around 100°C. This can also have positive results from reactions that are noted between 50°C to 200°C. The results will differ based on the exact chemistry of the basalt itself. It was noted that the best results were achieved when the basalts had a higher magnesium concentrations. One example of this reaction is Mg2SiO4 þ 2H2CO3 ¼ 2MgCO3 þ 2H2O þ SiO2 ð7Þ. Ferroan magnesite is the major carbonate product produced. These studies suggest that 1.2 million tons of CO2 can be converted within basalts of 1km3 under optimal conditions (Kintisch, 2012). Surface basalt flows are not the only option. There are also studies into deep-sea basalt sites. Figure 3 shows seafloor areas with large potentials of 4.1 Tt-C capture (Golberg).
Another form similar to basalt sequestration is general Mineral Carbonation. This process takes CO2 and chemically reacts it with metal cations like calcium and magnesium containing materials to form stable carbonate minerals (Sanna, 2014). This ex situ mineralization reaction occurs above ground in separate facilities or other industrial operations. One main advantage of this process is that the reactions are thermodynamically favored and the processes can be controlled, manipulated, and results in more stable products (Romanov, 2015). Another favored outcome is that some of the products created by this process can be used for building material. In 2013 a company named Orica teamed up with Mineral Carbonation International (MCi) to do this. They produced cements and plasterboard in Australia. The products are to be sold to China (Smith, 2017). This allows some of the cost of producing these carbonate minerals to be gained back. Marcus St John Dawe, a CEO with MCi says that “these technologies could store away millions of tons of CO2”. These processes are mostly completed by magnesium oxide or calcium oxide, both are and exothermic reaction and also occur naturally. Some example reactions of these are CaO + CO2 → CaCO3 and MgO + CO2 → MgCO3. Typically magnesium and calcium are found in silicate forms such as forsterite and serpentinite. Manmade reactions can still be controlled in this process. Some reaction examples are: Mg2SiO4 + 2CO2 →2MgCO3 + SiO2 and Mg3Si2O5(OH)4+3CO2→5MgCO3+2SiO2+H2O. These processes have estimates that 27.5 Gt can be easily be achieved by sequestering 10% of the global CO2 emissions (Sanna, 2014). Much of the data with carbon mineralization and basalt sequestration overlap as they are similar processes. A downside to both ways is the overall cost of the processes.
Wetland Restoration and Forest Restoration
As we know from the biologic carbon cycle there are natural increases and decrease of CO2 with the living and dying of carbon based life forms. Wetlands and forests have similarities on the earth. Taking that into consideration it is not hard to imagine that removal or changes of the wetlands and forests vegetation and animals will have an adverse effect on the planet. If we decrease our vegetation this will emit more CO2 via the resporation process. However, if we are able to plant more or protect our wetlands the natural processes can continue. These are relatively new options. Ecological issues and physical limitations need to be kept in mind. It is harder for there to be wetland restoration than forest restoration simply based on location. These processes take time to implement and they may not always work (Kentula, 2002). With these restoration projects it is important to keep in mind is the local fauna, hydrologic conditions, buffer zones and long term management, and the site selection. Some attempts have been made in Oregon and Florida. Results are expected to be seen within two to five years. Invasive species can complicate this option. The amount of CO2 sequestration with these options have variable results that are not really know yet (Aerts, 2011). This area is within the 20% range of the earth’s carbon storage, so though the results may be small they will still have a positive impact.
Ocean Iron Fertilization
Ocean iron fertilization attempts to promote phytoplankton growth is also a newer method. This technique is controversial due to limited understanding of its complete and long term effects. As we discussed earlier the PETM is attributed to the massive die off of phytoplankton which resulted in increased release of CO2. We wouldn’t want that to happen again. There is also growing concerns that enriching the oceans could throw off its natural balance even more than ocean acidification has. In 2004 a European company conducted an experiment called EIFeX just off the coast. There conclusions were the deeper they placed the enrichment material the higher the results were. It was noted that they only reported these results in the last few days of monitoring. They added two tons of acidified iron sulfate into the ocean using a method of drizzling a slurry in a zig zag pattern. They used the slurry to eliminate immediate sinking of the iron so that it would photosynthesize. This was expected to neutralize up to seven tons of carbon dioxide. They looked for areas with high nutrients and low chlorophyll (HNLC) in which to release the iron. It has been determined that ocean areas near the poles should have the best results. Like other methods discusses the long term results are largely unknown and there is some skepticism that these attempts will even stay in the system long enough to see a change (Powell, 2008).
Enhanced Oil Recovery
The last option we will discuss is the ability to pump CO2 into the sites of and oil and gas operations. The thought behind this is to achieve extraction of as much of the resource as possible. This procedure is used in reservoirs with heavy oil, poor permeability, and irregular fault lines. The use of CO2 is thought to be the best option. Not only are they able to get more of the substance out then using traditional methods but also “safe” storage of the greenhouse gas. The major drawback of this option is the fact that it is only furthering our dependence on fossil fuels. There are two other ways of completing and EOR operation but the CO2 sequestration ways is the most popular. This method is projected to increase up to 60% of oil within the reservoirs in the US. This procedure is highly used within the Permian Basin which has produced about 180,000 barrels of oil per day (Melzer, 2012). Other attempts in Canada have been done and they have established some criteria for optimal locations. The site must be at a depth of 1000 meters or more, Strong confining seals minimally faulted, strong harmonious sedimentary sequences, adequate volume and permeability for storage, and no significant diagenesis. A problem here is that not every oil and gas site will provide this criteria. The current CO2 injection associated with EOR in the US claim to have sequestered 3 billion cubic feet (Melzer, 2012).
Conclusion
While the scientific community is trying to find solutions and quickly, it is important to know that there is more than one viable option. Every person needs to make individual changes that will impact the future. We need to invest more into solar, wind, and geothermal power options to decrease our dependence on fossil fuels. However, changes made for the future now does not cover what we have already done to our atmosphere. With the different sequestration techniques there are also more than one option, like most things there are always benefits and downsides. Basalt and mineralization techniques cannot be competed where basalt flows are not present. Ocean iron fertilization can only occur in the oceans where it is viable. Wetland and forest restorations are also highly location dependent. The enhanced oil recovery can only be completed within extraction sites and in my opinion is the one option that should not be utilized. EOR still aids in our dependence of fossil fuels. Even though they are all cost intensive options and results are not immediate they are all viable. With most of the world’s carbon already being stored within our rocks, it make sense to utilize this natural phenomena? In the long run it is better to do a little here and a little there until we reach a point where everything is working for the same goal. That goal, is leaving a planet for future generations to thrive.
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Works Cited
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Aerts, Raf. Honnay, Oliver. “Forest Restoration, Biodiversity and Ecosystem Functioning”. BMC Ecology. 24 Nov. 2011. https://bmcecol.biomedcentral.com/articles/10.1186/1472-6785-11-29. Web. 20 Apr. 2017.
Davies, Robert. “Iceberg. Dead Ahead”. Southern Utah University Convocation. 6 Oct. 2016. Cedar City, Utah.
Faure, Gunter. Principles and applications of geochemistry: a comprehensive textbook for geology students. Upper Saddle River, NJ: Prentice Hall, 1998. Print.
Goldberg, David, Angela Slagle. “A Globas Assessment of Deep-Sea Basalt Sites for Carbon Sequestration”. PDF. http://www3.imperial.ac.uk/pls/portallive/docs/1/53155696.PDF. Web. 12 Apr. 2017.
Harrison, John Arthur. “The Carbon Cycle: What Goes Around Comes Around”. Visionlearning. Vol. EAS-2 (3), 2003. Web. 17 Apr. 2017.
Kentula, Mary E. “Wetland Restoration and Creation”. USGS. 29 Jan. 2002. https://water.usgs.gov/nwsum/WSP2425/restoration.html. Web 20 Apr. 2017.
Kintisch, Eli. “Underground Injections Turn Carbon Dioxide to Stone”. Science Online. 10 Jun. 2016. http://www.sciencemag.org/news/2016/06/underground-injections-turn-carbon-dioxide-stone. Web. 11 Apr. 2017.
Melzer, Stephen L. “Carbon Dioxide Enhanced Oil Recovery: Factors Involved in Aiding Carbon Capture, Utilization and Storage (CCUS) to Enhanced Oil Recovery”. GoogleScholar. Feb. 2012. http://neori.org/Melzer_CO2EOR_CCUS_Feb2012.pdf. Web. 20 Apr. 2017.
Powell, Hugh. “Will Ocean Iron Fertilization Work”? Oceanus Magazine. 7 Jan. 2008. Vol 46, No 1. Web. 20 Apr. 2017.
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Rosenbauer, Robert J. et.al. “Carbon Sequestration via Reaction with Basaltic Rocks: Geochemical Modeling and Experimental Results”. Science Direct. Isu: 89. 116-133 (2012). Web. 12 Apr. 2017.
Sanna, A. et.al. “A Revew of mineral Carbonation Technologies to Sequester CO2”. Chemical Society Reviews. Isu 23 (2014). Web. 20 Apr. 2017.
Scott, Michon, Rebecca Lindsey. “What’s the Hottest the Earth’s Ever Been”? Climate.gov.12 Aug. 2014. https://www.climate.gov/news-features/climate-qa/whats-hottest-earths-ever-been. Web. 20 Apr. 2017.
Smith, Jez. “Mineral Carbonation International”. http://www.orica.com/About-Us/Innovation---Technology/mineral-carbonation-international#.WPmnjNIrLIU. Web. 20 Apr. 2017.