Does it make sense to implement a carbon capture and storage project to store carbon dioxide permanently? What are the uncertainties associated with such a project? Can I quantify the net CO₂ emissions I remove from the gross? All these questions can be answered thanks to MRV and LCA.
Below are the basic criteria of the Limenet MRV.
Criteria for a CO₂ capture and storage project
In the context of CO₂ capture and storage (CCS), the concept of “additionality” refers to the amount of CO₂ emission reduction that can be attributed specifically to the CCS project.
A CO₂ capture and storage project is considered “additional” if the CO₂ emission reductions achieved through the project would not have been achieved without the project.
In other words, additionality implies that the project has a real impact on the reduction of emissions compared to the baseline situation without the project. To establish the additionality of a CCS project, it is necessary to consider the so-called “baseline scenario”.
This scenario represents the situation where the project is not implemented and takes into account existing activities, available technologies and implemented policies.
Additionality can be assessed in several ways, including:
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Physical additionality: it concerns the actual amount of CO₂ that is captured and stored by the project compared to the amount of CO₂ that would have been emitted in the baseline scenario. This can be determined by calculating the difference between the actual emissions of the project and the estimated emissions if the project was not carried out.
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Time additionality: consider when CO₂ emission reductions occur thanks to the CCS project. If the project anticipates or delays emission reductions compared to the baseline scenario, it can be considered additional.
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Market additionality: refers to the impact of the project on the carbon emissions market. If the project reduces the demand for emission credits or affects the price of carbon credits, it can be considered additional.
A high quality CO₂ capture and storage project is considered “measurable” if it can accurately and reliably demonstrate the amount of CO₂ captured and stored during the process. Measurability is essential to ensure transparency and traceability of the CO₂ emission reductions achieved by the CCS project. Here are some key aspects of measurability in a high-quality CO₂ capture and storage project:
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CO₂ capture measurement: it is important to have reliable measurement systems to quantify the amount of CO₂ effectively captured by the CCS process. This can be achieved using accurate measuring instruments and techniques, such as gas analysers and flow meters, which allow monitoring of CO₂ concentrations and gas flows in the capture system.
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Measurement of CO₂ storage: the amount of CO₂ that is stored underground must be reliably measured to demonstrate effective emission reduction. This can be achieved through monitoring techniques such as measuring pressure and temperature in the storage tank and using chemical tracers or isotopes to track the movement of CO₂ underground. Measurability (Ability to accurately and reliably quantify the CO₂ emission reductions achieved through the project. Industrial sensors that measure the removed CO₂.)
A high-quality CO₂ capture and storage project shall be considered “verifiable” if it can be subjected to an independent verification process to confirm the accuracy and reliability of the reported CO₂ emission reduction results.
Verifiability is essential to ensure the credibility and integrity of CCS projects. Here are some key aspects of verifiability in a high quality CO₂ capture and storage project:
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Independent verification: Verifiability requires an independent third-party body, such as a certification or external auditor, to conduct a detailed project assessment. This independent verification process ensures that the data, measurement methodologies, and project results comply with applicable standards and regulations.
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Complete documentation: a verifiable project requires complete and accurate documentation detailing the activities carried out, the measurement methodologies used and the results obtained. The documentation should be easily accessible and include detailed information on the CO₂ capture and storage process, the measurements made, the traceability of emission reductions and the steps taken to ensure data integrity.
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Reliable and transparent data: verifiability requires that the data collected and used in the CCS project be reliable, accurate and representative. The data should be subject to quality controls to detect and correct any errors or inconsistencies. In addition, it is essential that the data and results are transparent, accessible and understandable to stakeholders and the public.
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Compliance with standards and regulations: A verifiable design must comply with relevant standards and regulations in CO₂ capture and storage. This may include international standards, such as UN guidelines or national reference standards, which define best practices for implementing and verifying CCS projects.
A high quality CO₂ capture and storage project can claim to have a “negative carbon footprint” when considering the entire project lifecycle (LCA) the CO₂ emission reductions achieved exceed the carbon footprint associated with CO₂ capture, transport and storage activities.
To achieve a negative carbon footprint, Limenet adopts the following characteristics:
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Energy efficiency: the CO₂ capture, transport and storage process is designed to minimize energy use and CO₂ emissions. This is achieved through the optimization of energy flows and heat recovery.
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Use of low-carbon energy sources: Limenet uses renewable or low-carbon energy sources to fuel CO₂ capture and storage activities. The use of renewable energy is essential to minimize the total carbon footprint.
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Capture from carbon-intensive sources: Limenet preferentially captures CO₂ from carbon-intensive sources, such as industrial plants, which reduce CO₂ emissions directly at the source.
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Life cycle emission balance: To affirm a negative carbon footprint, Limenet considers the entire life cycle, including capture processes, transport, storage and emissions associated with raw material extraction and infrastructure construction. The CO₂ emission reductions achieved must exceed all these indirect emissions. For more information, see LCA.
A high-quality CO₂ capture and storage project requires a permanent CO₂ storage of at least one thousand years to ensure the effectiveness and integrity of CO₂ emission reductions in the long term. Here are some key points to understand the importance of permanent storage in the context of a high quality CO₂ capture and storage project:
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Long-term emission reduction: Permanent storage of CO₂ is essential to ensure that CO₂ emission reductions are maintained over time. If captured CO₂ is not stored permanently, it could be released back into the atmosphere, nullifying emission mitigation efforts. Permanent storage (>1,000 years), therefore, offers a solution to maintain emission reductions over the long term.
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Safety and monitoring: CO₂ must be stored securely and monitored carefully to prevent leaks or releases over time. Unlike the geological storage facilities, which are designed to provide a physical and geological barrier that prevents CO₂ from escaping into the atmosphere or infiltrating groundwater, Limenet uses calcium bicarbonates which, dispersed in the sea, ensure permanent storage.
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Laws and regulations: CO₂ capture and storage projects are subject to laws and regulations that require permanent CO₂ storage. These regulations set standards and guidelines to ensure storage is made safely, reliably and permanently. Permanent storage is an essential requirement to achieve legal compliance for high quality CO₂ storage projects.
A high quality CO₂ capture and storage project must be environmentally friendly and environmentally friendly, which can be achieved through different measures and strategies. Calcium bicarbonates as a permanent storage solution, as in the case of Limenet, can help ensure the project’s environmental sustainability.
Here are some key points to consider:
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Minimisation of environmental impacts: an environmentally friendly CO₂ capture and storage project should be designed to minimise environmental impacts. This can be achieved by adopting clean and efficient technologies, reducing energy consumption, controlling emissions and responsible management of materials used.
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Safe storage: the permanent storage method, such as calcium bicarbonates, must be safe and reliable. It is important that CO₂ is safely trapped in the storage system without risk of leakage or release into the atmosphere or groundwater. Constant monitoring and evaluation of the integrity of storage is crucial to ensure that CO₂ remains permanently trapped.
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Side benefits: an eco-friendly project can try to offer side benefits to the environment or society. In the case of Limenet, the use of calcium bicarbonates not only aims to store CO₂, but also to combat ocean acidification. Ocean acidification is a serious environmental problem that can adversely affect marine life and marine ecosystems. Using calcium bicarbonates to counteract ocean acidification can offer an additional advantage in marine conservation.
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Regulatory compliance: An environmentally friendly CO₂ capture and storage project must comply with relevant environmental laws and regulations. It is important to comply with local and international regulations governing the management of CO₂ emissions, storage and environmental protection. This helps ensure the project is aligned with the required best practices and environmental standards.
The use of calcium bicarbonates as a permanent storage solution in the case of Limenet is an interesting approach that not only allows CO₂ to be trapped but also helps to mitigate ocean acidification.
This approach can provide added value to the eco-compatibility and sustainability of the CO₂ capture and storage project, helping to protect the environment and its ecosystems.
The uncertainties to consider are:
Biomass
Electric
Raw materials
- Calcium Carbonate
Indicates calcium carbonate, as it is extracted and ground before being processed to make calcium hydroxide and negative CO₂ emissions.
- Biomass
Indicate the biomass. How it is retrieved, used and restored.
- Storage of carbon in biomass
It indicates that if the biomass that is used to produce energy or negative emissions, the biomass waste process must be considered whether a permanent storage or not. If the same biomass is used to release CO₂ into the atmosphere, it must be subtracted from the total amount of gross CO₂ removed.
- Biomass replacement
These are the emissions related to the replacement of biomass if it is produced specifically by this project. Limenet will only use waste biomass. No replacement of the raw material will be made if waste is used. When Limenet will use biomass produced on purpose, this will be counted in the LCA.
- Indirect use of land
Limenet will not use biomass that contributes to the use of arable fields. Limenet will initially use only waste biomass. Subsequently, if it uses specific arable fields, it will count consumption in the LCA.
Project activity
- Calcination
Limenet uses an indirect calciner powered by electricity or biomass. Being indirect, the CO₂ from the chemical breakdown is directly conveyed into the transport and then stored permanently.
The CO₂ from biomass oxycombustion is also conveyed to be transported and stored.
- Transport
Limenet transports CO₂ from the calciner to storage through the use of sealed systems to the outside world. From a transport perspective, Limenet accounts for transport emissions in its LCA.
- Formation of Bicarbonates
Limenet uses its proprietary technology to store CO₂ in the form of calcium bicarbonates. Through a complex system of sensors, it is possible to quantify exactly how much CO₂ is removed, with how much calcium carbonate and water.
Dilution of calcium bicarbonates in the sea
Limenet has modeled the plume of its CO₂ storage facilities to understand the variation in the concentrations of calcium bicarbonates (Omega Aragonite) in the exhaust.
This allows you to understand how best to introduce the same bicarbonates into the sea avoiding any abiotic precipitation.
Storage
- Abiotic precipitation
Secondary precipitation can be controlled and reduced to negligible if the right process parameters are chosen: experiments conducted by Politecnico di Milano with Limenet to the TR6 prototype and scientific articles confirm that the abiotic precipitation of carbonates can be avoided if the dilution in the plume of the ionic alkaline solution released with the surrounding marine waters allows to reach a Ωar of 5-7 within a few hours. The Limenet process can achieve this condition within minutes of the release of the ionic solution at sea and the experimental results confirm that with a 10:1 dilution ratio between seawater and the Limenet ionic alkaline solution, abiotic precipitation does not occur during the next 3 months. The fluid dynamics simulations of the plume to ensure the optimal dilution of the ionic solution in the seawater are performed by the Aerospace Engineering Department of the Politecnico di Milano.
- Biotic precipitation
Biotic calcification is still our highest uncertainty. Biological tests with marine biologists of Milano Bicocca University such as Daniela Basso, Politecnico di Milano with Arianna Azzellino, Geomar with Ulf Riesbersell will be carried out in mesocosms to emphasize and quantify biotic precipitation under conditions of sea water with high balanced alkalinity (same pH). A new idea to minimize biotic calcification is to inject from a ship the ionic alkaline solution well below the photic depth: this solution will be tested and studied in the TR7 plant in Limenet.
- Marine carbonate precipitation
It is known that calcium bicarbonates in seawater last between 10k and 100k years. It is also known that if Ωar in seawater is kept below 5-7, no precipitation of marine carbonate will occur: storage of CO₂ in the form of calcium bicarbonates in marine waters can be considered a stable carbon deposit. This uncertainty can be considered negligible.