Section 1: Topic Selection: Climate Crisis Awareness

At present, a trend of rising summer temperatures is apparent, impacting not only tropical and subtropical regions but also extending to the Arctic, where the average temperature has reached an astonishing 30°C in summer. This phenomenon is a clear component of the broader issue of global warming, prompting HUST-China to launch an investigation within the field of global warming and gradually intensify our efforts to identify key contributors to this pressing issue.

According to the Intergovernmental Panel on Climate Change (IPCC) AR6 Synthesis Report: Climate Change 2023, the global surface temperature has already increased by 1.1°C above 1850–1900 in 2011–2020. The IPCC states that the observed global warming is primarily caused by human activities, particularly the emissions of greenhouse gases (GHG), especially CO2. Simultaneously, the latest data from the World Resources Institute indicates that the current concentration of CO2 on Earth is the highest it has been in nearly two million years. Over the past decade, Earth has experienced warmer temperatures than at any point in the last 125,000 years. Due to rising temperatures, around half of the global population faces severe water scarcity for at least one month annually. The 950 million people residing in arid regions worldwide will confront a suite of challenges, including water stress, heatwaves, and desertification. Furthermore, elevated temperatures will result in a reduction in global food production, exacerbating the proliferation of diseases such as malaria and viral infections. Thus, addressing the greenhouse effect is an urgent imperative.

Furthermore, the World Meteorological Organization (WMO) highlighted in its Greenhouse Gas Bulletin 2021 that fossil fuel consumption is the predominant source of CO2 emissions in the atmosphere. Notably, China's heavy reliance on coal for electricity production has played a significant role in contributing to this issue. According to the China Energy Statistical Yearbook 2022, coal consumption accounted for 55.9% of the country's total energy consumption. Furthermore, in the production and supply of electric power and heat, coal consumption constituted 55.8% of the total consumption. This substantial reliance on coal has led to significant CO2 emissions from coal-fired power plants.

Therefore, our team has directed its attention towards coal-fired power plants, with the expectation that our project can offer practical applications and address on-site challenges.

Section 2: Background Investigation: Current CCUS Landscape Navigation and Project Shaping

To gain a deeper understanding of the current state of carbon emissions, we consulted Professor Cong Luo from the State Key Laboratory of Coal Combustion at HUST, who is at the forefront of research to support China's National Carbon Neutral Strategy. His work encompasses both carbon capture and carbon utilization, with a focus on absorption capture, adsorption capture, oxy-fuel combustion capture and chemical utilization. Furthermore, Professor Cong Luo is a pioneer in developing low-carbon technological innovations in sectors like thermal power generation and alternative fuel vehicles.

Fig 1. Professor Cong LUO

In our discussion with Professor Cong Luo, we delved into the various methods currently employed for carbon fixation, which primarily encompass physical, chemical, and biological approaches.

Traditional physical methods for CO2 capture involve the use of physical adsorbents. These methods depend on adjusting operational parameters like temperature and pressure to facilitate the fixation of CO2. While they have the advantage of simplicity and the ability to reuse adsorbents, they also come with certain drawbacks, such as the need for a significant quantity of adsorbents and potential limitations in achieving the desired level of selectivity. Chemical methods involve converting CO2 into solid compounds through chemical reactions. However, they face challenges such as high energy consumption, often necessitating high-temperature and high-pressure conditions, as well as limited selectivity.

Both physical and chemical methods exhibit limitations in terms of environmental sustainability and CO2 selectivity. Hence, biological approaches emerge as a promising alternative. We intend to employ synthetic biological approaches to tackle these challenges.

Professor Cong Luo also provided us with a detailed introduction to Carbon Capture, Utilization, and Storage (CCUS) technology. CCUS involves the capture of CO2, generally from large point sources like power generation or industrial facilities that use either fossil fuels or biomass as fuel. If not being used on-site, the captured CO2 is compressed and transported by pipeline, ship, rail or truck to be used in a range of applications, or injected into deep geological formations such as depleted oil and gas reservoirs or saline aquifers. CCUS technology plays a crucial role in supporting carbon-neutral initiatives and achieving Net Zero emissions by effectively reducing greenhouse gas CO2 emissions.

According to the Special Report on Global Warming of 1.5 °C (SR15) released by IPCC, by 2030 and 2050, global CCUS capacity will reach 100–400 million tons yr–1 and 3–6.8 billion tons yr–1, respectively. Furthermore, data from the 2021 Annual Report on CO2 Capture, Utilization, and Storage (CCUS) in China shows that 40 CCUS model projects are now in operation or under construction in China, with a CCUS capacity of 3 million tons yr–1.

Fig 2. Geological distribution of CCUS projects in China

Professor Cong Luo mentioned that most of the current CCUS projects involve separate methods for CO2 capture and utilization. This inspired us to explore the possibility of integrating CO2 capture and utilization in our project, thereby innovating and making meaningful contributions in the realms of carbon neutrality.

Additionally, Professor Luo guided us through a tour of the State Key Laboratory of Coal Combustion, where we observed experimental equipment for oxy-fuel combustion capture. He explained that this method enables the enrichment of CO2 in flue gas, making its separation and capture more feasible. Nevertheless, he also pointed out the downsides of oxy-fuel combustion capture, notably the high costs and energy consumption. We brainstormed the idea of addressing this challenge by using synthetic biology approaches, offering the advantage of low microorganism cultivation costs. Moreover, synthetic biology approaches enable the construction of high-yield strains, significantly improving production efficiency. This approach might provide a novel solution to the climate crisis.

Fig 3. Experimental equipment for oxy-fuel combustion capture in HUST Fig 4. HUST-China members with Professor LUO in Wuhan, China

In addition to gathering background knowledge from academia, we have established connections with various government agencies, including the Department of Ecology and Environment in Hubei Province, as well as cities like Wuhan, Yichang, Sanmenxia, and Zhengzhou. Through these connections, we have gained valuable insights into the current air quality in these regions and the strategies being employed to reduce CO2 emissions. This information has deepened our understanding of the project's background.

Furthermore, we have consulted iCarbonMap, a nationally recognized carbon accounting institution established under the lead of teams from the Chinese Academy of Sciences. This tool provides professional services to both national and local Departments of Ecology and Environment, supporting carbon neutrality efforts. Through this exchange, we have acquired CO2 emissions data for over 400 cities in China, spanning from 2000 to 2021. This data serves as a crucial foundation for our comprehensive assessment of CO2 emissions levels and their changing trends across different regions.

Section 3: Project Initial Design: Functional Concept and Pathway Establishment

After gathering sufficient background information, we initiated the project design intending to provide a solution to address the climate crisis issue. Following a thorough literature review, we chose the Synechocystis sp. PCC 6803 and S. oneidensis MR-1 as our engineered microbial strains. We intended to use cyanobacteria to absorb CO2 and produce lactate, which would then serve as the carbon source for electricity generation by Shewanella.

Through genetic engineering, we aim to enhance lactate production by cyanobacteria and improve Shewanella's electricity-generating capacity. For cyanobacteria, we introduced the LdhA gene. An extensive literature review confirmed that introducing the LdhA gene enabled lactate production, a concept validated in previous studies. Additionally, we introduced the LldP gene to facilitate the transport of lactate from the intracellular to the extracellular space, making it accessible for uptake by Shewanella. Furthermore, we incorporated the Omcs gene, encoding an electron transfer protein. This protein redirects electrons from PQ to Cytb6f, reducing NADH consumption by repressing the electron transfer chain RET, ultimately increasing lactate production. For Shewanella, we introduced five genes—ycel, pncB, nadM, nadD*, and nadE*—to enhance its electricity generation capabilities. Additionally, the Oprf protein was introduced to assist in the transport of riboflavin, enhancing electron transfer efficiency. Detailed design specifics can be found in the Design section.

After finalizing our selection of cyanobacterial strains, we reached out to the Institute of Hydrobiology, Chinese Academy of Sciences, seeking their support in obtaining Synechocystis sp. PCC 6803. They graciously shared their cultivation methods and experience with this cyanobacterial strain.

Professor Yunjun Yan, from the School of Life Science and Technology at Huazhong University of Science and Technology, is an expert in cyanobacteria research. After reviewing our project, he acknowledged the feasibility of our design and provided valuable suggestions to enhance production efficiency. Specifically, he recommended the use of AuNPs (Gold Nanoparticles) during cyanobacterial cultivation to expedite electron transfer and improve photosynthetic efficiency.

Fig 5. Professor Yunjun YAN

Our instructor, Xiaoman Xie, who specializes in enhancing Shewanella's electricity generation capabilities, recommended the incorporation of rGO to form a 3D structure with the biofilm. This would increase the local riboflavin concentration and facilitate electron transfer, ultimately enhancing Shewanella's electricity generation.

Fig 6. Instructor Xiaoman XIE

We decided to incorporate their advice into our project after a thorough literature review and consideration.

Section 4: Project Design Refinement: Functional Optimization and Component Enhancement

After recognizing the importance and viability of our project, we engaged in discussions with Professor Abdelghani Sghir from Université d'Évry Val-d'Essonne(UEVE), Université Paris-Saclay. Recognizing the potential presence of emissions such as SO2 and nitrogen compounds in coal-fired power plants, which could harm our engineered microorganisms, we sought guidance from Professor Abdelghani for advice to refine our design. He recommended the incorporation of resistant genes to enhance the survivability of our engineered strains.

After conducting a thorough literature review, we decided to overexpress the GshA and GshB genes in cyanobacteria to enhance their antioxidative capabilities. Additionally, we introduced the SOD gene into Shewanella to mitigate cellular damage caused by ROS. Furthermore, we introduced the Dsup gene into both engineered strains to protect their DNA from damage.

Fig 7. HUST-China members with Professor Abdelghani Sghir in Wuhan, China.

After making further improvements to our project design, our team members met with Professor Abdelghani again in France. We updated him on our project's current progress, and he acknowledged the feasibility of our resistance component design. During this meeting. Professor Abdelghani recommended we seek solutions to improve the efficiency of CO2 absorption, offering valuable insights for our hardware development in the upcoming phases.

Fig 8. Project design presentation to Professor Abdelghani Sghir in Paris, France

While conducting a literature review, we recognized the Tianjin Institute of Industrial Biotechnology(TIB), Chinese Academy of Sciences as an institution with extensive expertise in carbon capture and utilization. As a result, we reached out to Professor Lingling Zhang and her team with the hope of seeking their guidance and insights.

Fig 9. Professor Lingling ZHANG

In our online meetings, we shared our project design with Professor Zhang. She advised us to determine the optimal cultivation ratio of the two bacterial strains, offering valuable insights for our hardware development. Moreover, she emphasized the importance of assessing biological compatibility after introducing AuNPs and rGO. Professor Zhang recommended avoiding the use of rGO to prevent potential disruptions in microbial growth balance, suggesting the use of photosensitizers and exogenous riboflavin as alternatives to enhance performance. Her suggestions provided us with clear guidance for our forthcoming expression experiments.

Fig 10. Online meeting with Professor Lingling ZHANG

After our online discussions, we visited TIB to gain deeper insights into ongoing research related to microbial CO2 fixation, which is the institute's primary focus and aligns with our project’s goals. In comparison to other approaches for microbial CO2 fixation, we recognized an advantage in our project design. Unlike other microbial CO2 fixation products that can be consumed by bacteria, the lactate produced by our engineered cyanobacteria cannot be consumed by the bacteria themselves. This strategy ensures more product availability for electricity generation. Furthermore, we maintained the advantages of microbial CO2 fixation over other biological approaches. These advantages include the high metabolic activity and short lifecycle of microorganisms, the feasibility facilitated by mature technologies, and the sustainability achieved through waste-free biological processes.

Fig 11. Team members discussed with members of ZHANG’s team Fig 12. HUST-China members with Professor Lingling ZHANG in Tianjin, China

These interactions with experts have enhanced the robustness and effectiveness of our project design, reinforcing our ability to tackle the challenges of CO2 fixation and electricity generation for more sustainable use.

Section 5: Hardware design

5.1 Initial Hardware Design For Coal-Fired Power Plants

Considering the practical cultivation needs of our engineered microorganisms and the energy generation process in coal-fired power plants, we explored the possible utilization of waste heat and created an initial draft design of our hardware. In light of this, we initiated contact with Professor Yunze LI from Beijing University of Aeronautics and Astronautics(BUAA), who has expertise in Power Engineering and Engineering Thermophysics, Aircraft thermal management, and Thermal Design of Electronic Equipment.

Fig 13. Professor Yunze LI

During our discussions with Professor Li, he explained that the heat produced by industrial facilities can be categorized into high-quality heat that can be efficiently utilized and low-quality heat that cannot. Many existing applications predominantly make use of high-quality heat while neglecting the potential utility of low-quality heat, whereas our specific need for a cultivation temperature of 30℃ aligns with the potential utilization of low-quality heat. Professor Li suggested that we explore the use of low-quality waste heat from coal-fired power plants, such as waste heat from cooling towers, to maintain the required temperature for our microbial cultivation. This suggestion provided valuable inspiration for our hardware design.

Professor Li expressed his strong support for our project, particularly in the context of coal-fired power plants. He emphasized that traditional coal-based electricity generation cannot be entirely substituted by renewable energy sources due to their limitations, such as the intermittent nature of wind power generation, which predominantly occurs at night. Therefore, conventional fossil-fuel-based power generation, including coal-fired plants, will maintain a substantial role in fulfilling our electricity needs in the future. In other words, our project design is in demand and can serve a critical purpose. Additionally, he highlighted the innovative aspect of efficiently using low-quality waste heat, as its release can be detrimental to aquatic life, highlighting the environmentally conscious aspect of our approach.

Fig 14. HUST-China members with Professor LI in Beijing, China

Inspired by Professor Li's insights, we subsequently updated our device design to make it more adaptable to the operational environment of coal-fired power plants.

5.2 Hardware Design Refinement

Following the completion of our project design, we turned our attention to the refinement of hardware design tailored to our engineered microorganisms, incorporating the valuable guidance provided by professors.

Building upon Professor Li Yunze's guidance, we explored the layout and configuration of coal-fired power plants. This exploration led us to focus on cooling towers, a significant source of low-quality waste heat generation. Subsequently, we designed pipelines in our device to facilitate the inflow of water rich in thermal energy, ensuring the maintenance of our desired cultivation temperature. Additionally, following Professor Lingling Zhang's guidance, we designed two separate cultivation tanks tailored to accommodate each bacterial strain, thus optimizing overall efficiency. Furthermore, our hardware design also required careful consideration of factors such as the placement, shape, and size of the cultivation tanks to ensure that cyanobacteria receive an adequate amount of light for maximum growth. Detailed Hardware design specifics can be found in the Hardware section

Fig 15. Hardware design

5.3 Design for miniature fermentation tanks

To seek for more inspiration in hardware design, we interacted with representatives in Hubei Guangji Pharmaceutical Co., Ltd, our fellow practitioners in the field of synthetic biology. During our exchange, we identified a significant disparity between microbial cultivation in laboratory shake flasks and the in real-world industrial applications. This disparity is primarily attributed to the substantial differences in the controlled laboratory environment compared to the complex conditions found in industrial production settings. As a result, many of the techniques developed in the laboratory face challenges when transitioning to industrial-scale applications.

To address this issue, we designed a miniature fermentation tank specifically tailored to simulate the actual conditions encountered during large-scale industrial cultivation. This innovative solution enables us to use a device that processes the same volume as laboratory flasks while carrying out tasks essential for industrial fermentation. These tasks include supplementing culture materials and maintaining precise control over critical factors like temperature, pH, and oxygen levels.

By implementing this miniature fermentation tank design, our engineered microorganisms can transition from the laboratory to practical industrial environments.

Furthermore, we have refined this miniature fermentation tank system drawing upon extensive experience in the field of fermentation. We are making this system available to the broader synthetic biology community, facilitating its adoption and promoting the transition of engineered microorganisms from laboratory research into industrial applications.

Detailed Hardware design specifics can be found in the Hardware section

Fig 16. Modular parts of Miniature Fermentation Tanks

Section 6: On-site Research and Public Evaluation

As our project progressed, our team did deep on-site research on Datang Sanmenxia Power Generation Co., Ltd.

Fig 17. Team members at Datang Sanmenxia Power Generation Co., Ltd, Sanmenxia, Henan, China

We conducted a comprehensive investigation into the plant's layout, meticulously recording essential data such as temperature and gas concentrations. These data played a crucial role in determining the optimal location for our project implementation. One of our primary focuses was the investigation of the cooling tower's conditions and its water temperature. With guidance from the plant engineers, we found that during the winter, the water temperature inside the cooling tower hovered around 18°C, which was lower than the 30°C required for cultivating our engineered microorganisms. As a result, our initial plan to install our hardware near the cooling tower and utilize its water for maintaining our cultivation temperature proved unfeasible.

Fig 18. Team members conducted detailed investigations into the cooling tower

Facing this challenge, we revisited the power plant's layout in search of a more suitable location. Ultimately, we selected a spot between the desulfurization absorption tower and the exhaust towers for our hardware installation. At this position, the waste gas temperature remained at approximately 45°C throughout the year, and with proper temperature control, we could effectively utilize the waste heat to cultivate our engineered microorganisms.

Fig 19. The spot between the desulfurization absorption tower and the exhaust towers

Surprisingly, we discovered that the flue gas emitted by the power plant, after undergoing desulfurization treatment, had an SO2 content of less than 30 mg/m³, and nearly all nitrogen compounds were removed. This meant that our initially designed resistant component might not be effective in practical production applications. After careful consideration, we decided to allocate more of our efforts to testing and enhancing lactate production and electricity generation.Nonetheless,our resistant component design could inspire future iGEM teams.

Furthermore, we engaged in extensive discussions with the plant's engineers, gaining firsthand insights into the company's emissions reduction goals and current environmental policies. Inquiring about their perspective on our project, we discovered that the plant's primary concerns were the efficiency of our device and the investment required for its implementation.

Fig 20. Team members discussed with the plant’s engineer

Additionally, in terms of CO2 emissions, they encouraged us to explore the current Carbon Exchange Market, where the rights to emit CO2 are openly traded. This inspired us to approach our stakeholders from a new perspective.

Our on-site research proved highly valuable, leading us to make substantial modifications and enhancements to both the experimental and hardware designs. These changes were aimed at better aligning our project with practical applications.

After concluding our on-site research at the coal-fired power plant, we reached out to the China Biodiversity Conservation and Green Development Foundation and received their feedback. While they did raise certain questions about the project's short-term potential for widespread and rapid adoption, they recognized the innovative and practical aspects of our project design. Importantly, they expressed confidence that our project will play a significant role in addressing the climate crisis.

Section 7: Market Research: Stakeholder Target and Project Prospects Understanding

After finalizing our project, we sought further guidance from Professor Cong Luo. His expertise in projects closely linked to power generation corporations offered valuable insights into the emerging Carbon Exchange Market in China.

Professor Luo provided us with a comprehensive overview of the current Carbon Exchange Market, highlighting its potential for substantial growth in the coming decades. As emissions quotas for factories decrease, the prices within the Carbon Exchange Market are expected to soar. This presents a valuable opportunity for technologies related to carbon capture and utilization, signaling a promising future outlook.

Our products can deliver substantial benefits to businesses, encouraging enterprises to actively engage in environmental protection efforts and contribute to environmental conservation. By maintaining our focus on further enhancing our device’s CO2 capture capabilities in the future, we have the potential to distinguish ourselves from existing CCUS technologies.

Furthermore, Professor Luo introduced innovative potential applications for our product, including the modification of our engineered bacteria to produce methanol and other fuels. These modified bacteria could be strategically placed at vehicle exhaust emission sites, where they would not only capture CO2 emissions but also convert them into fuel for use, effectively contributing to a green, low-carbon, and circular economy.

Fig 21. Team members discussed with Professor LUO

At the end of our conversation, Professor Cong Luo showed his confidence in our project's potential and looked forward to our progress.

Section 8: Positive Feedback: Achievements and Industry Prospects

After completing our project, we presented a brief report to Professor Lingling Zhang. We expressed our gratitude for her valuable suggestions, which greatly contributed to the refinement and improvement of our project. Her feedback was highly positive.

In our experiments, we successfully focused on enhancing the lactate production in cyanobacteria and the electricity generation in Shewanella. We made a choice not to introduce resistance genes into our engineered microorganisms. We integrated our experiments with hardware, enabling the cultivation of cyanobacteria and Shewanella within the specialized hardware device we designed, allowing us to simultaneously capture CO2 and generate electricity..

We once again contacted Engineer Du from Datang Sanmenxia Power Generation Co., Ltd. and shared with him our project's finalized hardware design. Throughout our discussion, he underscored the importance of refining the cultivation methods within our device to maximize CO2 absorption efficiency. Nonetheless, he also conveyed his strong belief in our project and eagerly anticipates its performance in potential industrial applications.

Fig 22. Show our hardware to the plant’s engineers

Section 9: Explore Future: Alternative Application

Our team members established contact with Professor Sylvain Fission from the Université d'Évry Val-d'Essonne(UEVE), Université Paris-Saclay. He acknowledged our project and engaged in creative discussions with our team regarding potential future applications. We discussed the possibility of using our design as an alternative road lighting system that absorbs CO2 and at the same time illuminates the city. Detailed specifics can be found in the proposed implementation section.

Fig 23. HUST-China members with Professor Sylvain Fission in Wuhan, China

Section 10: Integrating Human Practice with Synthetic Biology Education and Communication

10.1 Identifying the Lack of Synthetic Biology Knowledge Among Non-Biology College Students

During our visit to the State Key Laboratory of Coal Combustion, we had the opportunity to meet several college students majoring in Energy and Power Engineering. They were surprised by our approach of using synthetic biology to address CO2 emissions and expressed their limited familiarity with the field. This inspired us to consider organizing an educational debate on synthetic biology to raise awareness among college students.

10.2 Exploring Opportunities for International iGEM Team Communication

We learned from Professor Abdelghani that iGEM Team Evry Paris-Saclay has consistently achieved impressive results in their annual iGEM competitions. We obtained their contact information and saw it as a valuable opportunity for mutual learning and collaboration. Following that, we engaged in an exchange with iGEM Team Evry Paris-Saclay in Paris.

10.3 Identifying the Lack of Synthetic Biology Knowledge Among the General Public

During our investigation in the coal-fired plant, we discovered that both the workers and engineers found our project, which utilizes synthetic biology to capture CO2, to be utterly novel. Additionally, we noticed that our communication was sometimes not as smooth due to their limited understanding of synthetic biology. This prompted us to contemplate organizing educational activities for the general public, with a particular focus on primary and middle school students. We believe that educating younger generations is the most effective way to foster a long-term understanding of synthetic biology.

Detailed activities can be found in the Education and Communication section.

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