Background

The IMO introduced the CII as part of its comprehensive strategy to reduce greenhouse gas emissions from ships, in alignment with global climate change initiatives. This regulation is embedded within MARPOL Annex VI, focusing on minimising air pollution from maritime operations. The CII serves as a metric to evaluate the efficiency of a vessel's carbon emissions, taking into account the cargo capacity and distance travelled.

The Emission API’s role

The Emission API provides year-to-date estimates for CII, which is an additional tool to make it easier to assess the state of the fleet for the current year. Thus, it helps navigate legislation for actors that want to engage with a given vessel, whether in chartering in other ways. It is not intended to help ship owners with reporting on CII. 

The methodology of the Emission API product to calculate year-to-date (YTD) CII scores utilises the official guidelines set by the IMO. By doing so, the aim is to ensure transparency and accuracy, enabling our partners and users to effectively assess the environmental performance of vessels and make strategic choices that align with sustainability goals and regulatory compliance.

Key definitions

• Carbon Intensity Indicator (CII): A measure used to quantify the carbon emission efficiency of a ship's operation, calculated as the mass of CO2 emitted per unit of transport work.
• Attained CII: The actual carbon intensity performance of a ship over a year, calculated based on its fuel consumption, distance travelled, and cargo carried.
• Required CII: The target carbon intensity level that a ship is expected to achieve, set by the IMO and adjusted over time to promote continuous improvement in carbon efficiency.
• CII Ratings: A classification system from A (most efficient) to E (least efficient), assigned based on how a ship's Attained CII compares to the Required CII, guiding operational adjustments and policy compliance.
• CII estimate: the CII rating calculated by the Emission API to gauge the year-to-date performance of a given vessel.

The CII initiative underscores the maritime industry's commitment to transitioning towards more sustainable and environmentally friendly practices. By monitoring and improving their CII ratings, ship operators can significantly contribute to reducing the sector's overall carbon footprint, and charterers can make informed decisions on which vessel to select.

Emission API setup and operation

Setup

In order to use the API, a valid API token is required. Reach out to your ZeroNorth contact for more information.

Operation

The Emission API product runs the estimations for the global fleet on a weekly basis. In order to guarantee completeness and correctness of data, new dumps are made available with a 14-day delay. For example, the data dump for the first week of January 2024 would be available latest the night of January 21st 2024. For more information on the specifics of the API, refer to the technical documentation here: https://api.public.zeronorth.app/charter-emissions-api/docs/index.html#/Dumps/get_v1_dumps_weekly_emissions

The Emission API utilises the latest infrastructure and methods available in the ZeroNorth environment for any given week. This means that if there are updates to the fuel model, data cleaning methods and algorithms, data will be corrected going forward but not retroactively. Only in exceptional circumstances will existing data be recalculated.

• Units of measure throughout the API
• Fuel consumption: metric ton [mt]
• Speed: nautical mile per hour [kn]
• Distance: nautical mile [nm]
• CII: gram CO2 per deadweight tonnes times nautical mile [gCO2/dwt.nm] // Calculated estimate

Data collection for CII calculation

For our product to accurately calculate the Year to Date (YTD) Carbon Intensity Indicator (CII) for vessels, it relies on a robust data collection process that aligns with the International Maritime Organization's (IMO) guidelines. This section outlines the types of data our tool gathers and how it's utilised in the calculation of CII scores.

AIS positional data

At the core of our data collection is the use of Automatic Identification System (AIS) positional data. AIS data provides real-time information about a vessel's location, speed, and navigational status, which are crucial for estimating the distance travelled by the vessel. This data serves as the foundation for our calculations, enabling us to assess a vessel's operational efficiency and carbon footprint with a high degree of accuracy.

Machine learning fuel model

To estimate the fuel consumption of each vessel, the Emission API employs the sophisticated zero north fuel model, built using machine learning. This model is designed to predict fuel consumption based on various factors, including vessel type, size, speed, and operational patterns.

The fuel model is built on millions of data points, including noon reports, weather data and vessel characteristics. The data is processed using state-of-the-art machine learning enhanced with naval architecture principles, to make it possible to predict the expected  consumption of any vessel.

Furthermore, as new data flows in, the model is continuously refined and enhanced to adjust dynamically to the changing conditions. This ensures that ZN always provides a high quality fuel consumption estimate, for any vessel, at any time, anywhere in the world.

Emission estimates

The calculated fuel consumption figures are then used to estimate CO2 emissions. Our methodology assumes conventional fuel types based on the vessel's location and operational characteristics, aligning with the IMO's categorization of fuel types and their respective carbon emission factors. This approach allows us to derive an accurate estimation of the CO2 emissions for each vessel, which is essential for determining the CII score.

Noon reports not used for vessel activity insights

In gathering and processing data, our product adheres to any data protection and agreements. No directly reported data from ship owners or operators is used as part of the product. The entire process is designed to ensure compliance with international agreements and data protection laws and regulations, safeguarding the confidentiality and integrity of business data.

For example, although the fuel model is trained on noon reports, the noon reports are not used in the assessment of the CII for any vessels. Instead, the CII is calculated with the estimations output from the fuel model. This means that noon reports are not necessary for the Emission API, and that when the noon reports are available, they are still not used directly by the product.

Summary

The data collection process for CII calculation within our product is carefully crafted to ensure accuracy, reliability, and compliance with IMO guidelines. By harnessing AIS positional data, leveraging advanced machine learning models for fuel consumption estimates, and accurately estimating emissions, we provide maritime actors with a powerful tool to assess and improve their environmental performance. This data-driven approach empowers our users to make informed decisions, optimise operational efficiency, and navigate the complexities of regulatory compliance with confidence.

Calculation methodology

Our product utilises the International Maritime Organization's (IMO) guidelines to calculate the Year to Date (YTD) Carbon Intensity Indicator (CII) for vessels. This section breaks down the step-by-step methodology applied in our calculations, ensuring transparency and adherence to the established standards.

Gathering vessel activity data

The process begins with collecting and cleaning AIS data for each vessel. This data provides insights into the vessel’s movements, speed, draft, and operational patterns over time. We also gather weather information for the particular vessel at the particular location. Note that we do not use data from noon reports for vessel activity assessment even when the data is available. For vessels in port, the consumption is based on an assumption of adherence to best practices in the industry for auxiliary engine consumption in port.

Estimating fuel consumption

The model considers various factors such as vessel type, size, and activity level to predict fuel usage accurately. The machine learning model's output gives an estimation of fuel consumed by the vessel. This estimate takes into account the type of fuel likely used based on the vessel's operational area. It is assumed that vessels use conventional fuels. The assumption of fuel type is crucial as different fuels have varying carbon intensity values, which impacts the overall CII calculation.

Disclaimers

The calculations do not take deduction factors into account that are allowed for CII. For example ice sailing, ship to ship operations, reefer consumption for container ships, cargo heating for tankers and other types of deduction factors. For affected types of vessels, this can affect the rating.

Furthermore, port consumption is estimated based on best practices in the industry. Prolonged port stays with a different operating mode may skew the results.

Calculating CO2 emissions

With the estimated fuel consumption figures, we proceed to calculate the CO2 emissions for the vessel. This calculation multiplies the amount of fuel consumed by its carbon emission factor, which is determined based on the assumed fuel type. The emission factors used are in line with those specified by the IMO, ensuring that our emission estimates meet the required regulatory standards.

The fuel types used are the following:

• Low sulphur fuel oil when sailing outside of SECA zones | Conversion factor 3,151
• Ultra low sulphur fuel oil when sailing inside SECA zones | Conversion factor 3,114
• Marine diesel oil in ports | Conversion factor 3,206

Determining transport work

Transport work is a measure of the vessel’s operational efficiency, calculated by multiplying the distance traveled by the vessel’s carrying capacity over the period in question. The carrying capacity is considered in terms of deadweight tonnage (DWT) for cargo ships, which allows for a standardised measure of the vessel’s service output.

Calculating the CII score

The final step involves calculating the CII score by dividing the total CO2 emissions by the transport work done by the vessel. This ratio gives us the carbon intensity per unit of transport work, aligning with the IMO's formula for the CII. Later this result is compared against the IMO's CII rating scale, which classifies vessels into categories from A (most efficient) to E (least efficient) based on their carbon intensity.

Adjustments and anomalies

The methodology includes mechanisms for adjusting calculations based on feedback and detected anomalies in data. Maritime actors are encouraged to report any discrepancies, which are then analysed to refine the accuracy of our estimates. This iterative process ensures that the CII scores provided by our product remain as accurate and reliable as possible.

Summary

This calculation methodology offers maritime actors an accurate, standardised way to gauge the environmental performance of their vessels. Through the integration of advanced data analysis and adherence to IMO guidelines, we provide a tool that not only aids in regulatory compliance but also supports the maritime industry’s journey towards sustainability.

CII rating determination

The determination of the Carbon Intensity Indicator (CII) rating is a critical step in assessing a vessel's environmental performance. This section outlines how the Emission API assigns CII ratings to vessels based on their calculated carbon intensity, following the International Maritime Organization's (IMO) guidelines. The IMO categorises vessels into five CII ratings, from A to E, with A representing the highest level of efficiency and E indicating the least efficient. These ratings are determined by comparing a vessel's calculated CII against predefined thresholds that reflect varying degrees of carbon efficiency.

Determining the vessel's CII rating

After calculating the CII score for a vessel, as outlined in the previous section, the Emission API compares this score to the IMO's CII rating scale. The scale is created based on a required CII.

All vessels have, for a given year, a CII target – a required CII. Achieving exactly this target will result in a moderate performance – a “C”. Emitting less than this target can put the vessel at better ratings (A, B), and emitting more than this target can result in a lower rating (D, E). The required CII is different for different types and sizes of vessels, and also is progressively stricter every year for a given vessel. This is in view of the IMO’s aim to continuously improve the fleet's overall carbon efficiency.

The scale is structured as follows:

• A (major superior): Significantly lower than the required CII level.
• B (minor superior): Moderately lower than the required CII level.
• C (moderate): Close to the required CII level.
• D (minor inferior): Slightly above the required CII level.
• E (inferior): Significantly above the required CII level.

If you see any discrepancies in the required CII, please contact us for assistance, as this may indicate errors in third party data.

Rating scale adjustments

The IMO periodically adjusts the CII rating scale to align with global carbon reduction goals. The Emission API product incorporates these adjustments to ensure that the ratings provided reflect the most current standards. This dynamic approach ensures relevance and accuracy in the rapidly evolving regulatory landscape of the maritime industry.

Feedback and anomaly correction

We encourage users to report any discrepancies or anomalies they observe in the CII ratings assigned to vessels. Our system includes mechanisms for reviewing and adjusting ratings based on credible feedback, ensuring that our product remains accurate and trustworthy. Reach out to us here.

Summary

By adhering to the IMO's guidelines and incorporating user feedback, we ensure that our ratings are both accurate and up-to-date, supporting the maritime industry's efforts towards sustainability and regulatory compliance.

Frequently asked questions

Q1: What is the Carbon Intensity Indicator (CII)?

The CII is a metric developed by the International Maritime Organization (IMO) to measure the carbon emission efficiency of a ship's operation. It calculates the amount of CO2 emitted per unit of transport work (distance * capacity).

Q2: How is the CII calculated?

The CII is calculated by dividing the total CO2 emissions of a ship (in a year) by its total amount of transport work. Transport work is typically measured as the product of the cargo capacity and the distance travelled. For regulatory use, it is calculated retroactively for a year. The Emission API helps anticipate the resulting CII rating by providing a year-to-date CII estimate.

Q3: What do CII ratings mean?

CII ratings classify ships based on their environmental performance, ranging from A (most efficient) to E (least efficient). These ratings help stakeholders assess and improve their ships' carbon efficiency.

Q4: How can I find the CII rating for a specific vessel?

CII ratings can be determined using the ship's total CO2 emissions and transport work data, often calculated through specialised software or tools that adhere to IMO guidelines. The ZeroNorth Emission API is one such specialised software that calculates the CII for the year-to-date for specific vessels – or if you prefer, the whole global merchant fleet.

Q5: Will the CII requirements change over time?

Yes, the IMO plans to gradually tighten CII requirements to encourage continuous improvement in the fleet's carbon efficiency, aligning with global goals to reduce greenhouse gas emissions.

Q6: How can maritime actors improve their CII ratings?

Improving CII ratings can involve operational changes, such as optimising routes for efficiency, investing in more fuel-efficient technologies, or adopting alternative, lower-emission fuels. Charterers can transport with better CII by selecting better vessels.

Q7: Are there penalties for poor CII ratings?

Ships rated D for three consecutive years or rated E must submit a corrective action plan outlining how they will improve their rating, as per IMO regulations. Penalties for non-compliance can vary by flag state and may involve restrictions or additional scrutiny.

Q8: Where can I access official documents and guidelines on CII?

Official documents and guidelines on CII are available on the IMO website. Visit IMO MARPOL Annex VI and IMO's GHG Strategy for more information.

Q9: Can the CII be used for vessels of all sizes and types?

The CII applies to ships of 5,000 gross tonnage and above, covering a wide range of vessel types that operate internationally. Specific calculations may vary based on the ship's characteristics.

Q10: How frequently is the Emission API estimating CII?

The Emission API calculates CII weekly, with a two week delay, for YTD CII. It's important to regularly monitor and adjust operations to maintain or improve CII ratings. Using tools such as the ZeroNorth Emission API, maritime actors can act proactively to course correct performance within years, make efficient chartering decisions and monitor market trends.