Carbon capture and storage (CCS) is one of the measures the United Nations’ Intergovernmental Panel on Climate Change believes will be necessary in order to sufficiently reduce greenhouse gas emissions.  In 2020, the Longship CCS project was approved by the Storting (the Norwegian Parliament) as the first project of its kind in the world. This however led to challenges when it came to laws and regulatory frameworks. A regulatory framework has not been applied to this sort of industry in Norway or in the EU.

Through working on Longship, aspects of this regulatory framework have been put into place, and agreements have also been signed between the Norwegian state and each industrial operator involved in Longship. The report Regulatory lessons learned from Longship was put together by Gassnova, and examines the regulatory challenges and problems encountered in Longship and how these have been addressed.

Measuring CO₂

One of the areas the report examines is how CO₂ can be measured in the transport chain. The transport chain covers CO₂ being transferred from the capture operator’s tanks over land to specially designed ships up to the CO₂ being transferred to the storage site on the Norwegian Continental Shelf. 

In Longship’s transport chain, both the quality and the quantity of the CO₂ were measured through a number of measuring points. In addition to measuring the total volume of CO₂ twice between being captured and being stored, the point of using multiple measurements is to monitor the processes in the transport chain.

The first measurement is carried out when the CO₂ is transferred from the capture operator’s temporary storage tanks to the tanker ships. When the CO₂ is transferred from the tanks at the quay to the ships, the amount of CO₂ transferred is calculated from the measurements inside the ship’s tanks at the start and at the end of the transfer. The measurements are taken in this way because the amount in the temporary storage tanks is impacted by fact that the system continues to capture CO₂ supplied to the tanks at the same time as it transfers it from the tanks to the ship. There are also some gas returns from the ship. That is why it is the volume of CO₂ on the ship before and after the transfer which forms the basis of the measurement of the amount of CO₂ that capture operators report to the state.  According to the agreements between the state and the industrial operators, this will constitute the formal volume of CO₂ that will be transferred between the capture operator and Northern Lights.

The second measurement of CO₂ in the transport chain is carried out when the CO₂ is transferred from the ship to the reception terminal in Øygarden. The measurement of the total volume of CO₂ is measured twice to ensure that no CO₂ has leaked out during transportation.

Compensation for the volume of CO₂

The agreements between the Longship capture operators and the Norwegian state specify that the capture operators will be compensated for the volume of CO₂ that has been measured during transfer to the ship. The ship to which the CO₂ has been transferred has a specially designed system to measure changes in the CO₂’s liquid level in the ship’s tanks, adjusted for the composition of the CO₂, pressure and temperature.

The agreements between the state and the capture operators require an operator to measure the density of the liquid CO₂ in order to calculate how much liquid CO₂ has been loaded on board the ship. The accuracy of the measurement system has been estimated to be well under the 2.5% margin of error required by the EU’s Monitoring and Reporting Regulation. The principle behind this type of measurement is similar to the system used in business to measure other types of liquefied gas, such as LPG.

You can read more about measuring the amount of CO₂ in the transport chain in chapter 5 of the report.

This article was adapted from Gassnova’s report “Regulatory lessons learned from Longship”, which is based on the experience gained from working with laws and regulatory frameworks in the Longship CCS project. Longship consists of the two capture operators, Heidelberg Materials and Hafslund Oslo Celsio, as well as the transportation and storage provider Northern Lights.