The Prospective Approaches to Limit Global Carbon Emissions and the Adverse Effects of Gaseous CO2

Rapidly increasing CO2 gas emissions generated from human activity is one of the world’s leading environmental concerns because of its negative impact on the environment, ranging from water to air pollution, global warming, and biodiversity deterioration. Consequently, many people are seeking ways to protect the environment. The use of alternative energy sources to generate electricity, instead of burning fossil fuels, showcases a positive change in the industry to pursue an environmentally conscious yet economic mindset. The primary modern sources of alternative energy are wind, solar, and nuclear energy. Shifts in the industry, driven by strict environmental regulations on carbon emissions, are resulting in the decreased use of fossil fuels. Also, new methods and materials have been developed to lessen and capture industrially produced CO2. Many scientists and engineers are also working to limit CO2 emissions by either decreasing the consumption of fossil fuels, using less energy, or improving the efficiency of energy production. In this paper, we will be discussing the latest ways on how to decrease, capture, and measure CO2 emissions and the importance of regulating carbon emissions.

CO2 can either be captured through physical or chemical means. Bioenergy capturing carbon and storage (BECCS) is representative of a physical process. BECCS involves extracting bioenergy from biomass and then using this energy to separate CO2 into carbon and oxygen. This carbon is subsequently captured and stored to prevent its direct release into the atmosphere. Through chemical means, CO2 can be decomposed into carbon monoxide and oxygen, though the decomposition reaction must be driven by supplied energy. There is a diverse set of methods to physically remove CO2, chemically break it down, and ultimately store it. These methods range from improved agricultural practices, optimized decomposition reactions for CO2, advanced instrumentation, conversion of gaseous carbon into solid carbon, and using large bodies of water to serve as carbon storage sites. There are many carbon capture, utilization, and storage technologies that need to be tested at global and international scales, in order to satisfy increasingly stringent emissions regulations and energy goals. In addition, a variety of instruments exist to measure CO2 in the environment. Gauging CO2 levels is essential for identifying of areas that are producing an excess of CO2, which would consequently require the implementation of regulations to limit these emissions. Additionally, maintaining optimal levels of CO2 helps to optimize plant yield, growth conditions for specimens, and work environments. New test methods and instrumentation are constantly being developed in response to growing interest in global environmental preservation.

Human activity generates about 84% of total excess CO2 gas emissions, ranging from using light energy to burning fossil fuels [1].

Effects of CO2 emissions on the environment and industry

Since the Industrial Revolution, CO2 emissions have been rapidly increasing each year due to increased fossil fuel consumption and energy demands. Today, about 84% of CO2 gas emissions are attributed to the burning of fossil fuels for transportation and electricity generation. Also, increased CO2 levels are a driving factor for climate crises and ocean acidification, resulting in oceans being 30% more acidic on average [1].
Power plants that burn fossil fuels, like coal, oil, and natural gas, are the main contributors to rising CO2 emissions. Although fossil fuels are our primary source of energy today, burning them causes many problems, which necessitates the discovery of new and more sustainable alternatives, like biofuels, nuclear energy, and solar energy.
Power plants are industrial facilities that generate electric power through the combustion of fossil fuels and are responsible for releasing the largest quantities of CO2 into the atmosphere, comparatively to any other human activity [2].

There are many negative effects CO2 can have on the environment. The major consequences are global warming and flooding induced by rising ocean levels. As global warming increases, we are experiencing less snowfall and more flooding in coastal and low elevated areas. Another consequence is biodiversity deterioration, meaning that more species are becoming extinct due to habitat destruction, caused by increasing temperatures or rising sea levels. In addition, as CO2 gas levels rise globally, the acidity of oceans continues to increase [3]. For terrestrial animals, the inhalation of excess quantities of CO2 can easily cause respiratory problems. Also, increased CO2 levels can cause the occurrence of acid rain, which can negatively affect natural vegetation and corrode buildings and infrastructure. Due to these harmful effects, switching to alternative energy sources has been a primary objective in the industry.
The most viable alternatives to burning fossil fuels for energy revolve around the harnessing of wind, solar, and nuclear energy. Wind energy currently contributes to 7% of the US’s electricity production and is a clean, abundant, and renewable source of energy [4]. There have been recent developments in wind turbine components, primarily for pitch control technologies and bearings. Pitch control systems are vital for controlling blade spins and preventing strong winds from uncontrollably rotating these blades [5]. Meanwhile, bearings reduce the overall weight, size, and manufacturing costs of wind turbines. Additionally, they can bear thrust loads, providing optimal and normal performance during harsh weather conditions and high wind speeds [5]. Also, solar energy has been on the rise, with more solar panel installations and increasing conversion rates of heat to electrical energy. Experts predict that the largest impacts on the energy sector will result from developments in solar technology. “Floatovoltaics” are solar power systems created for floating on bodies of water, offering greater efficiency and more space for solar energy production without using valuable real estate [6].
The water below keeps the solar panels clean and minimizes energy waste. This image was taken in California, Napa Valley [6].
Additionally, building-integrated photovoltaics (BIPV) enables people to save on building material and electricity costs. BIPV also offers benefits including increased energy efficiency, high thermal and sound insulation, and zero carbon footprint [6]. In addition to this, solar fabrics, which incorporate solar panels in each fiber, are being developed by researchers. These solar filaments in clothing help keep people warm, power phones, and help save on solar power mounting and costs [6]. Researchers estimate that overall solar energy will increase by 600% from 2020 to 2050 [4]. Nuclear energy, which involves the generation of heat for use in steam turbines to produce electricity, is currently looking like the best alternative to fossil fuels. Nuclear energy operates at much higher capacity factors than conventional renewable energy sources and fossil fuels, resulting in more efficient energy displaced and leading to safer environments with more available fresh water, food, and shelter. Additionally, two new innovations, fuel cells, and small, single-cycle gas turbines offer an immense advantage over large, centralized power plants, with both experiencing increasing popularity in the industry. These local generations are fueled by natural gas, which can both reduce transmission losses and improve air quality [4]. Many researchers also state that if these new innovations can be adopted in vehicles, emissions from small gas turbines and fuels will plummet as a result [4].

Latest Methods of decreasing, containing, and measuring CO2

Currently, there are many methods for reducing global carbon emissions. Using better engine oils and replacing old, worn-out engines with newer and more energy-efficient ones can help limit total emissions. For example, substituting conventional light bulbs with LEDs, can increase energy efficient and preserve energy expenditure [7]. Moreover, in 2016, China substituted cars with bikes for transportation by 10% due to traffic issues and growing air pollution [8]. Also, new cars have been made to decrease excess CO2 emissions, like the electric vehicles (EVs) manufactured by Tesla. Tesla states that their EVs can save up to 600 more pounds of CO2 per year compared to the average amount of CO2 emitted by conventional petroleum-powered vehicles [9].  Also, in 2019, scientists have developed a new method that involves the collection of gaseous CO2 and its subsequent conversion into a useful organic polymer. [10]. Using X-rays, researchers found that the coordination polymer (PCP) structure rearranges as CO2 molecules come to it, so that the CO2 can be trapped. Once the material has accumulated enough CO2, it is able to be reused as an organic polymer, which is primary used in clothing or for packaging. This newly developed method does not expend too much energy while suctioning out CO2 from the air. By using this PCP containing zinc ions, CO2 can be attracted to the zinc with “10 times the efficiency of other PCPs (with other elements)” [10]. This PCP is also reusable and durable, meaning that it can function at the same speed for up to ten reaction cycles.
Furthermore, there have been technological developments and changes in the automotive industry, with the main ones being innovations that can decrease carbon dioxide gas emissions significantly [11]. These include a triple-junction solar module sunroof with an efficiency of 31.17%, the world’s highest conversion efficiency of 26.33% achieved in a crystalline silicon solar cell, a water splitting-biosynthetic system with CO2 reduction efficiencies exceeding photosynthesis, and the world’s tallest wind turbine integrated with pumped storage hydro. The sunroof has the highest photovoltaic conversion efficiency and can be an alternative to burning fossil fuels. The new world record for thin-film solar cells is a project that has achieved the highest PV conversion efficiency in a thin-film solar cell, and with the advantage of them having a low cost, they should significantly reduce greenhouse gas (GHG) emissions [11]. The world’s highest conversion efficiency achieved in a crystalline silicon solar cell is 26.33% and is anticipated to lead to the more widespread use of PV power generation in residences with little installation space. The water-splitting biosynthetic system has a solar energy conversion efficiency of 10% or can capture 1/10 of the energy from sunlight and turn it into fuel [11]. The tallest wind turbine integrated with pumped storage hydro is the first major wind turbine to put water in its turbine to generate its power and has a big possibility of contributing to future wind power penetration. In additional, American multinational oil and gas corporation, ExxonMobil, is currently projecting that CO2 levels will decrease by as much as 20% by 2025. ExxonMobil is planning to invest in newly developed/efficient carbon-capturing machines, while placing greater significance on maximizing energy efficient and minimizing production waste.
Carbon capturing is a process that involves the removal of excess CO2 from the air, which is then either stored underground, in concrete, or in the soil, so that it does not enter the atmosphere immediately [13]. There are five primary ways to store or break down CO2 in the atmosphere. By managing and restoring forests, photosynthesis can decrease the levels of CO2 in the atmosphere, which has the added benefit of being relatively inexpensive compared to other methods. Another effective way is to use more agricultural soil for carbon storage instead of limiting more than 900 million acres of land solely for agricultural purposes. Although the quantity of carbon that agricultural soil is able to store is finite, the crops grown on the soil additionally contribute to lessening CO2 emissions. Also, environmentalists found that putting carbon in soil can increase the health of the soil and the plants that grow on it, while installing trees can help shade and forage livestock [14]. A third and currently risky way to store CO2 is through the process of BECCS. For example, in Switzerland, the world’s first commercial plant (The Climateworks AG) for capturing CO2 at an industrial scale directly from the air was built. The developers estimate that 900 tons of CO2 will be captured annually and that creating 250,000 more copies would capture the equivalent amount of CO2 released by most cars in the world [15]. This process uses biomass for energy to capture emitted gases, before storing it underground or in long-lived substances, like concrete [14]. However, since BECCS relies on bioenergy from crops, BECCS could displace food production or natural ecosystems, erasing climate benefits and exacerbating food insecurity and ecosystem loss. Carbon mineralization is another option for combating carbon emissions.  Mineralizing carbon or converting gaseous carbon into solid carbon naturally takes more than a hundred years, but scientists are now figuring out ways to allow these minerals, naturally occurring silicate rocks, to encounter CO2 in the water or air in order to accelerate the process. Also, by injecting CO2 into rocks, CO2 can be stored manually. The fifth and final way is by using ocean-based concepts. Instead of solely using the land for carbon capture, the large bodies of water can also serve as a place for carbon storage. However, these ocean-based solutions are in their early stages of development and still need additional testing to validate their efficacy. Improper implementation of this method can result in the deaths of many aquatic organisms from CO2 inhalation. Besides this, each approach to these concepts aims to speed up carbon cycles in waters, capitalize on photosynthesis in coastal plants, and add minerals to increase the storage of carbon dioxide [14].
In addition to capturing CO2, there are multiple ways of measuring CO2 levels and pollution. Measurements are typically taken using a wide range of meters and sensors, with gases being measured in parts per million (ppm). The safe range of CO2 is typically measured to be between 250-400ppm, outdoors, and 400-900ppm, indoors. Furthermore, maintaining optimal levels of CO2 optimizes plant yield, growth, or chambers for biological samples and specimens, while in colder climates, it saves energy and improves the work quality inside schools, hospitals, and businesses.

Table showing the safe levels of CO2 measured in ppm on land [16]:  
CO2 levels can be determined using non-dispersive infrared light (NDIR) sensors and various CO2 meters. An NDIR has a detector, measuring the amount of infrared wavelength that is absorbed by the surrounding air and with this measurement, the concentration in ppm of a specific gas is calculated [17]. The key components of NDIR sensors are an infrared source, a light tube, an interference (wavelength) filter, and an infrared detector. It functions through the diffusion of a gas into the light tube, while the electronics measure the absorption of the light.
Infrared lights are beamed into a tube with two openings for letting gas particles in and out, has a filter so when gas particles hit the filter the wavelength of light is absorbed goes to a detector which measures the concentration of any specific gas, in this case, CO2 [18].
Optimizing the CO2 levels of interior spaces, greenhouses, and incubators allow for greater production. Facilities, such as offices, hospitals, and schools have automated systems that control CO2 levels, which increases air quality and saves energy in colder climates [19]. In greenhouses, it is integral to maintain CO2 levels at around 400 ppm to optimize yield [19]. CO2 incubators for biological specimens, which uphold elevated CO2 levels, are critical for cultivating cells and ensuring the optimal growth of the specimens [19].                        

Discussion and Conclusion
As CO2 levels continue to rise, environmental concerns, such as global warming and ozone deterioration, are becoming increasingly important to address. As a result, there have been new environmental regulations implemented to restrict GHG emissions. In June 2019, the US Environmental Protection Agency (EPA) issued regulations regarding emissions from fossil fuel-fired power plants, as stated in the Affordable Clean Energy Rule (ACE) [20]. ACE establishes emission guidelines for the coal-fired power plants in each state and identifies the best system of emissions reduction for CO2 that can be implemented at individual facilities. By 2030, the ACE rule is projected to reduce CO2 emissions by 11 million tons from 2019 [20]. In 2018, the EPA proposed regulations for restricting the amount of GHG emissions in new, changed, and rebuilt power plants. These proposed regulations would set emission rate performances for reconstructed power plants to be equivalent to that of newly constructed units which normally have emission rates close to 2,200 lbs. CO2/MWh. This rule would also make quality and refined emission reduction systems that are equal to or equivalent to supercritical steam generators (coal power plants). They have emission rates of “1.900 lbs. CO2/MWh and would set the best system of emission reducwtions for small units to 2,000 lbs. CO2/MWh” [21].
Additionally, professions related to environmental safety are forecasted to increase worldwide.  ExxonMobil predicts that CO2 emissions can be reduced by 15% in four years by taking measures like continual investments in products that create lower emissions; increased support and strictness of sound and public policies regarding CO2 emissions and increased cogeneration capacity at manufacturing facilities [12]. But, by not taking measures like these and not considering technological improvements, the US Energy Information Administration (EIA) predicts that after 2030, energy usage will increase—predominantly in transportation and industrial—and will cause CO2 emissions to increase [22]. However, they also project that by 2050, the US will have 4% less CO2 in the atmosphere than in 2019 [22]. So, researchers and energy administrators are not sure what will happen in the future with excess CO2 levels going down due to more people using more fuels to generate energy and electricity. But jobs are projected to grow, according to the Bureau of Investigation, by 3% between 2018 and 2028 about the average growth rate of all occupations [23]. As CO2 emissions increase yearly, more meters and sensors will need to be installed in third world countries and other areas that produce significant GHG emissions. After measuring CO2 concentrations in these areas, capturing, and storing CO2 can become a crucial step to reduce emissions to a regulated level.  

About the Authors

Dr. Raj Shah is a Director at Koehler Instrument Company in New York, where he has worked for the last 25 years. He is an elected Fellow by his peers at IChemE, CMI, STLE, AIC, NLGI, INSTMC, The Energy Institute and The Royal Society of Chemistry. An ASTM Eagle award recipient, Dr. Shah recently coedited the bestseller, “Fuels and Lubricants handbook”, details of which are available at https://www.petro-online.com/article/analytical-instrumentation/11/petro-industry-news/astmrsquos-long-awaited-fuels-and-lubricants-handbook-2nd-edition-now-available/2792
A Ph.D in Chemical Engineering from The Penn State University and a Fellow from The Chartered Management Institute, London, Dr. Shah is also a recipient of the prestigious an Eagle award from ASTM International. He is a Chartered Scientist with the Science Council, a Chartered Petroleum Engineer with the Energy Institute and a Chartered Engineer with the Engineering council, UK. A volunteer adjunct professor at the Dept. of Material Science and Chemical Engineering at State University of New York, Stony Brook, Raj has over 300 publications and has been active in the petroleum and alternative energy space for the past 3 decades. More information on Raj can be found at
https://www.petro-online.com/news/fuel-for-thought/13/koehler-instrument-company/dr-raj-shah-director-at-koehler-instrument-company-conferred-with-multifarious-accolades/53404
Mr. Stanley Zhang and Mr. Andrew Kim are students of Chemical engineering at SUNY, Stony Brook University, where Dr. Shah is the chair of the External Advisory Committee in the Dept. of Material Science and Chemical Engineering.

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