Background
The report titled "AR6 Synthesis Report: Climate Change 2023" by the Intergovernmental Panel on Climate Change (IPCC) clearly shows that human activities have caused a significant rise in global temperatures, reaching 1.1°C[1]. It is widely acknowledged that as global temperatures increase by every 0.5°C, extreme climate events like scorching heatwaves, heavy downpours, and regional droughts become more frequent and severe. Moreover, recent data from the World Resources Institute reveals that carbon dioxide levels on our planet have reached their highest point in almost two million years. In the past decade alone, Earth has experienced warmer conditions than any other time in the last 125,000 years[2].
Fig 1. Illustration of the Current Status and Trends of Global Warming
Due to the continuous rise in temperature, approximately half of the global population will face severe living challenges, such as acute water scarcity, debilitating heatstroke, desertification. Coastal regions will also be plagued by catastrophic natural disasters like unprecedented floods and tempests triggered by escalating sea levels. Furthermore, elevated temperatures will precipitate a decline in global food production and exacerbate the proliferation of vector-borne diseases such as malaria, West Nile virus, and Lyme disease, thereby further imperiling human safety and well-being.
The combustion of fossil fuels and their low energy efficiency have emerged as the primary culprits behind the multitude of climate crises, exacerbating global warming. According to the Greenhouse Gas Bulletin released in 2021 by the World Meteorological Organization (WMO)[3], the burning of fossil fuels continues to be the predominant source of carbon dioxide in our atmosphere. The report further emphasizes that "reducing greenhouse gas emissions from coal, oil, and natural gas" ranks as the third most promising mitigation measure, following closely behind "harnessing solar energy" and "generating electricity from wind power". Lastly, in its policy recommendations to governments worldwide, the report advocates for a substantial reduction in overall fossil fuel consumption while simultaneously implementing carbon capture and storage technology within existing fossil fuel systems, alongside enhancing energy efficiency. These measures are deemed indispensable for humanity's future response to combatting global warming.
Fig 2. Analysis of Different Emission Reduction Methods and Their Effectiveness
Target users
We expect our users to consist of three main groups: thermal power plants, carbon sequestration research teams, and other iGEM teams.
1. Thermal power plant
According to the latest data, China currently possesses over 3,000 thermal power plants. In 2022, the actual carbon emissions resulting from thermal power generation in China amounted to 4.85 billion tons, constituting approximately half of the nation's total CO2 emissions for that year. Therefore, in the current situation where it is difficult to rapidly reconstruct China's energy structure, how to address the great amount of carbon emissions from thermal power generation has become a key issue that our project aims to improve.
In reality, thermal power plants initially remove pollutants such as sulfur dioxide from the exhaust gases before releasing them into the atmosphere. Our project introduces strain Synechocystis sp. PCC 6803, which efficiently absorbs and utilizes carbon dioxide through photosynthesis. Moreover, by incorporating the omcs gene, this project enhances the conversion efficiency of CO2 within Synechocystis sp. PCC 6803 cells, thereby promoting carbon sequestration in these organisms. Consequently, this application expects thermal power plants to redirect their waste gases into our meticulously designed fermentation tanks before the emissions. Within these tanks, Synechocystis sp. PCC 6803 will effectively absorb CO2, thus reducing the carbon dioxide content in industrial emissions and playing a pivotal role in carbon sequestration and purification.
Moreover, the ldhA-lldP genes in this project possess the remarkable ability to convert carbon dioxide into lactic acid within Synechocystis sp. PCC 6803 and efficiently transport it to the culture medium. Subsequently, this culture medium serves as an invaluable carbon source for S. oneidensis MR-1. By introducing genes including ycel, pncB, nadM, nadD*, and nadE*, S. oneidensis MR-1 adeptly use lactic acid to generate electricity, effectively compensating for power losses caused by inadequate coal utilization. This groundbreaking approach not only enhances energy utilization efficiency but also significantly mitigates carbon emissions while revolutionizing the overall energy utilization structure.
Fig 3. Final industrialization
Moreover, it is gratifying that the waste heat generated by thermal power plants can effectively fulfill the temperature requirements for fermenting tanks. Empirical data confirms that the unemitted exhaust gas temperature from a thermal power plant typically falls within the range of 80-100°C. Our innovative design seamlessly incorporates this high-temperature waste gas into our system through advanced heat exchange pipes, harnessing the remarkable synergy between the waste gas and culture medium to consistently maintain the desired fermentation temperature. This not only guarantees an optimal growth environment for our strains but also maximizes energy utilization by capitalizing on the invaluable waste heat resources offered by thermal power plants.
In our visionary outlook for the project, we have incorporated resilient genes such as gshA, gshB, sodA, and dsup to counteract the deleterious effects of a small amount of gases like sulfur dioxide in exhaust emissions on bacteria. This endows the bacterial strains with formidable antioxidant and DNA damage resistance capabilities, ensuring their survival and fulfilling carbon sequestration requirements.
2. Research centers
As thermal power plants primarily serve as applications for existing products, it limits their capability to upgrade and develop the functionalities of these products. Therefore, the application upgrades are mainly undertaken by domestic and international carbon capture laboratories and other research institutions. Hence, we have decided to collaborate with relevant scientific research institutes in order to further develop our products.
The plasmids and strains we have already constructed, along with our design plans, will be bestowed upon the research teams or scientific institutions. Researchers may then enhance the efficiency of our target genes or vectors, or imbue them with additional functions. Alternatively, they may utilize our pre-constructed strains to explore novel forms of carbon source supply for S. oneidensis MR-1 in order to improve biomass power generation structures. Furthermore, our tracking teams shall be dispatched to monitor the progress of these strains and provide guidance and communication on cultivation environments, hardware facilities, and other conditions.
We have already had communications with the Tianjin Industrial Biotechnology Research Institute of the Chinese Academy of Sciences (refer to the HP section for more details). This esteemed research institute is devoted to advancing carbon development and enhancing carbon sequestration efficiency. We eagerly anticipate further communication and advancements for this project in the future.
3. Other iGEM teams
Not limited to the initial project design, our genes engineered for S. oneidensis MR-1, such as ycel, pncB, nadM, primarily aim to augment intracellular NADH levels in order to expedite electron transfer and enhance S. oneidensis MR-1's electricity production efficiency. Should other teams aspire to improve S. oneidensis MR-1's electricity production efficiency, they can refer to our meticulously crafted project design.
Additionally, we have integrated GshA, GshB, SODA and Dsup systems into the bacteria to fortify their resistance against DNA damage. If other teams also require bacterial stress resistance capabilities, they can draw inspiration from our comprehensive stress resistance system.
Lastly, we have developed a compact fermentation tanks that enables us to simulate supplementation of culture materials while precisely controlling temperature, pH level and oxygen concentration under laboratory conditions. Henceforth, if other iGEM teams seek simulation of industrial cultivation requirements as well, they can derive insights from our innovative hardware design.
Safety
Firstly, the two strains used in this project are considered safe as they are included in iGEM's whitelist of strains. The likelihood of contamination by other bacterial species is extremely low. Additionally, we plan to use nutrient-deficient strains in the later stages of the project to further ensure safety. Moreover, our hardware only has gas inlet and outlet connections with the external environment, and UV sterilization devices are installed at these points to prevent any potential release of bacteria into the surroundings, thus guaranteeing the safety of the project.
In terms of regulations and policies, according to Article 5(1) of the Agreement on the Application of Sanitary and Phytosanitary Measures (SPS) by the World Trade Organization (WTO), it states that Members shall ensure that their sanitary or phytosanitary measures are based on an assessment, as appropriate to the circumstances, of the risks to human, animal or plant life or health, taking into account risk assessment techniques developed by the relevant international organizations[4]. When conducting cross-regional exchanges and collaborations in this project, it is necessary to re-evaluate the safety of bacterial strains based on local quarantine and hygiene requirements. At the same time, efforts should be made to prevent any leakage of bacteria in the local area, thereby reducing the risk of cross-regional contamination. According to Article 13 of the "Regulations on the Safety Management of Agricultural Genetically Modified Organisms" issued by the State Council of the People's Republic of China, before conducting productive experiments and industrialization plans for our project, it is necessary to conduct preliminary small-scale "intermediate trials" and medium-scale "environmental release experiments" in different pilot areas[5]. This means that during the process from laboratory experimentation to industrialization, we need to select different trial sites in various environmental regions for field experiments in order to ensure that this genetically modified product will not contaminate the environment and is truly effective.
Future design
1. Commercial analysis
In order to facilitate the practical application of our ideas in business production and daily life, we conducted a commercial analysis of this project utilizing the SWOT framework from the field of economic management. This was executed with the aim of establishing a robust theoretical foundation for the successful implementation of the project.
Fig 4. SWOT diagram (commercial analysis for industrialization of this project)
Regarding the opportunities and advantages of the project, we firmly believe that in the context of global warming, low-carbon emissions reduction has become a topic of paramount concern for all nations. Simultaneously, China's recent policies have placed significant emphasis on carbon neutrality and environmental friendliness. While coal-fired power generation remains an integral component of China's energy structure, this design holds immense potential for widespread application. Not only that, but with carbon trading market prices steadily rising year after year, instead of expending substantial funds to procure carbon credits, we can leverage our energy-saving and emission-reducing projects to curtail operational costs for businesses, thereby rendering our designs more extensively utilized.
Moreover, the selected strains for this project are commonly found and possess minimal requirements for culture medium, further diminishing the company's operational expenses. Additionally, this project exhibits exceptional carbon fixation efficiency while generating a substantial amount of electricity; thus offering vast prospects within the realm of power applications and yielding a considerable profit conversion rate for the enterprise.
Furthermore, it significantly enhances the innovative competitiveness of the company by showcasing high originality and patentability. As for the shortcomings inherent in this project, we acknowledge that its demanding hardware equipment requirements stem from isolating and cultivating two distinct strains within it. Furthermore, continuous cultivation has emerged as a pivotal cost consideration. It is also crucial to note that as improvements are made in our energy structure over time,the proportionate reliance on thermal power plants will inevitably diminish,resulting in reduced dependence on support systems provided by this particular project.
In response to the deficiencies and challenges of the product, we have analyzed and proposed the following solutions: for strain cultivation, a co-cultivation system can be designed utilizing Synechocystis sp. PCC 6803 and S. oneidensis MR-1 to streamline device complexity and operational costs. Moreover, regarding the cultivation medium, an industrial mechanism for purification and recycling can be developed to effectively reduce long-term expenses for businesses. As for system reliance, this project has the potential to transform into a waste gas treatment park that not only addresses emissions from power plants but also efficiently manages greenhouse gas emissions from chemical factories, landfills, residential areas, etc., thereby offering extensive application prospects in comprehensively enhancing carbon sequestration efficiency. Furthermore, as previously mentioned within this document, with further technological advancements, this project could find applications in future urban development and play a pivotal role in subsequent space exploration endeavors.
Fig 5. Improved version of SWOT diagram (commercial analysis for the industrialization of this project)(X is the part that will be eliminated later, O is the part that will be added later)
2. Industrialization blueprint
To fulfill the application requirements of our project, we have meticulously crafted the corresponding hardware component, comprising two fermentation tanks for solid carbon fixation and electricity generation utilizing microorganisms. Nevertheless, in practical production and daily life scenarios, colossal thermal power plants discharge thousands of tons of carbon dioxide on a daily basis. The current simplicity of our devised apparatus renders it inadequate to meet prevailing industrial demands. Consequently, we hereby present our comprehensive blueprint for industrialization.
Fig 6. Power generation device for laboratory
We envision the establishment of a waste gas and wastewater recovery center surrounding the thermal power plant, utilizing our project as the technological foundation. The above-ground area of the park will serve as the designated zone for transparent photobioreactors containing Synechocystis sp. PCC 6803, with multiple reactors employed to ensure optimal growth conditions for each strain. Furthermore, we will adjust the inclination angle of these reactors based on solar altitude at different latitudes to maximize light absorption and further enhance photosynthetic efficiency.
At the same time, a corresponding heat dissipation and transfer system will be established to provide the waste gas heat to the fermentation tanks of Synechocystis sp. PCC 6803 and S. oneidensis MR-1, replacing the current electric temperature control system, reducing power consumption, and enhancing energy utilization efficiency.
The park will also feature a dedicated area for the fermentation tanks of S. oneidensis MR-1, complete with an underground facility and energy storage system. The substantial amount of electricity generated by these bacteria will greatly contribute to supplementing the park's power supply as part of its comprehensive electrical supplementation strategy. As power generation increases, it will gradually be harnessed to meet the entire park's electricity demands, including replacing cultivation medium devices and providing essential industrial power. Once the efficiency of electricity generation by S. oneidensis MR-1 reaches a sufficiently high level, surplus power from the park can be transmitted through a grid to supply nearby industrial or residential areas. This presents an innovative avenue for biomass-powered electricity and further optimizes energy utilization structures during the dynamic process of enhancing or even replacing conventional thermal power plants.
3. Vision of the future
As the clean energy process accelerates, we envision a gradual reduction and eventual replacement of thermal power plants in the energy sector. In anticipation of this future scenario, we present our "vision for the future."
With the introduction and progressive development of "future cities", we propose that our " Synechocystis sp. PCC 6803- S. oneidensis MR-1" system can be integrated into future power systems. One prominent application is its incorporation into "future streetlights": replacing the pole component with a transparent cultivation box containing Synechocystis sp. PCC 6803, connected to an appropriate ventilation system. Simultaneously, S. oneidensis MR-1 fermentation tanks are seamlessly integrated into the lighting body section as energy storage units. This innovative approach allows Synechocystis sp. PCC 6803 to utilize roadside exhaust through the ventilation system during daylight hours for carbon sequestration and emission reduction while also providing acid for electricity generation by S. oneidensis MR-1. The stored electrical energy in these batteries can then be utilized to illuminate streetlights at night, thereby expediting the transition towards cleaner cities.
Furthermore, as humanity embarks on its preliminary exploration of the universe, our ' Synechocystis sp. PCC 6803- S. oneidensis MR-1' system can also be applied in future spacecraft. We envision deploying our dual-bacterial system within fermentation tanks aboard forthcoming space vessels and stations. The Synechocystis sp. PCC 6803 strain would efficiently absorb the carbon dioxide generated by astronauts, while simultaneously generating oxygen to replenish the respiratory systems of both the spacecraft and space station. In parallel, harnessing the electricity produced by S. oneidensis MR-1 could provide vital power for essential operations in space engineering. This innovative approach not only enhances the well-being of astronauts but also effectively addresses energy scarcity issues prevalent throughout the vast expanse of our universe.
Challenges
Currently, the successful integration of resistance genes into the project design has not been achieved. Therefore, we will redesign the plasmid construction for resistance components and continue to promote testing in this area, aiming to reduce the harmful effects of exhaust gases on bacterial strains.
Meanwhile, in terms of research and development, this project aims to explore a co-cultivation system between Synechocystis sp. PCC 6803 and S. oneidensis MR-1, with the goal of reducing the complexity of hardware construction and making the cultivation environment easier to achieve, thus further lowering costs.
Lastly, we hope to collaborate with thermal power plants for experimental testing on-site, in order to assess the feasibility of our current hardware design and microbial strains, address any shortcomings, and use this as a experiment foundation for the ultimate industrialization of our project.
