4 options for measuring ship carbon emissions

The shipping industry has welcomed the decision by the International Maritime Organization (IMO) and the European Commission (EC) to develop an accurate measurement of CO2 emissions from ships.

Previously, most of the greenhouse gas research in charge of IMO was based on top-down data. The data was based on one year as a reference time, and the fuel consumption estimates of ships of different ship types were collected as the main data source.

Although such data is obviously inaccurate, from the current point of view, these data are still worthy of reference, and are widely cited by people in the industry in various debates about the contribution of ships' carbon emissions to environmental protection.

The third wave of research currently underway will use real-world data from each ship voyage. In this way, the reliability of the data will be enhanced, but this requires finding a surefire way to measure and organize this data. In addition, in order to achieve the purpose of continuously monitoring the carbon emissions of ships, the data collection plan should also consider including multiple sets of specific time data.

In other words, the purpose of this research is to make the excess emission capacity contribute more to the climate fund under the guidance of the market mechanism.

Four existing options are likely to be used for this study and to prepare first-hand data on ships' fuel consumption emissions. In addition to monitoring the accepted mandatory fuel delivery documents, monitoring the ship's fuel tank, engine fuel flow meter and the amount of direct exhaust gas emitted by the ship's engine is feasible.

The ship's fuel tank monitoring process is similar to the daily fuel readings that most ships perform to control and evaluate voyage efficiency. Similar to the way bunker delivery notes are used, the above method has become part of the prescribed procedure for assessing fuel consumption during a ship's voyage. However, this data still needs a new framework to ensure that the data is actually curated and used.

A third solution principle is to use a flow meter to assess the amount of fuel flowing directly into the ship's engine. This approach requires each vessel to have a flow meter, which inevitably increases the owner's cost, and the owner also has to spend time and effort to calibrate the instrument. In addition, the cost of maintenance and replacement of flowmeters is likely to be borne by ship owners and operators.

While this approach is more accurate than judging a vessel's fuel consumption through fuel delivery notes and tank reports, not all flow meters are accurate and not all suitable for installation in marine environments.

In addition, the volumetric flowmeter does not take into account variables such as fuel temperature and density, so the data read by the flowmeter needs to be further corrected. Only in this way can the actual fuel consumption and resulting carbon dioxide emissions be calculated.

Similarly, direct measurement of ship CO2 emissions according to the fourth scheme also requires technical input, data calibration and verification, and professional information technology support to ensure accurate data collection, storage and transmission.

Given the relative backwardness of related technologies, carbon dioxide emission monitoring systems are still out of reach. However, the above four monitoring schemes do provide options for accurate calculation of CO2 emissions from ships.