Cost-effective solutions in maritime transport
The CO2 LOS project aims to reduce the costs of transporting CO2 on ships.
“TODAY’S CONCEPTS FOR CO2 CAPTURE are based on the assumption that much of the transport will occur through pipelines to the storage location,” says project director Martin Hay at Brevik Engineering.
“There has been less focus on solutions for ship transport, partly because this area has been considered a mature technology, and partly because the costs have been seen as low in comparison with the total costs for CCS-technology. However, as the costs of capture and storage are reduced, transport costs become relatively higher.”
Northern Lights – the infrastructure part of the planned Norwegian fullscale CCS project – has chosen ship transport for the project’s first phase, based on the current practice for CO2 transport. This is technology equivalent to what is used for small scale transport for the food and beverage industry.
DIFFERENT SOLUTIONS FOR SHIP
CO2 LOS sees beyond the first phase of Northern Lights. The project evaluates different transport solutions from an onshore export terminal to an onshore import terminal, for example a process plant on the western coast of Norway, where the gas is compressed and pumped through a pipeline and out to the storage location under the sea.
The project is also considering two options for offshore unloading. Option one is to load CO2 to a “storage tank” at sea, a Floating, Storage and Injection Unit (FSI), which injects the gas into the geological storage formation.
The other option is to do the injection directly from the shuttle tanker. This solution requires additional equipment onboard the ships.
The selection of method is determined mainly by whether the storage formation requires a continuous injection of CO2 or if batch-wise injection is possible.
“The advantage of offshore unloading is that there is no need for an onshore installation and an expensive pipeline from land,” says Hay.
CO2 requires low temperature and high pressure to remain in a liquid form. The Norwegian full-scale project has decided to utilize the same pressure and temperature (approx. 15 bar/-28°C) that is currently used on ships transporting CO2 in smaller scale for industrial purposes.
The gas pressure defines the maximum size of the tanks onboard ships. If pressure and temperature is reduced, larger tanks and, consequently, larger ships can be built.
Larger ships mean reduced transportation costs per tonne of CO2, since the
CO2-volumes for transport and the distances increase.
However, use of bigger ships presents a challenge. This solution requires larger intermediate capacity ofthe onshore facility. And the CO2 must be kept liquid for a longer period of time.
“We have to strike a balance. If we only consider ship transport, bigger ships are cheaper,” says Hay. “But it’s not straight forward. We have to consider the entire transport chain.”
CO2 LOS is evaluating four concepts for ships.
One possibility is to equip existing dry cargo ships with new CO2 tanks. This is the cheapest solution. The project also considers barges for the water ways in Europe, which can bring CO2 from industrial plants in the lower parts of the Rhine.
The second concept entails building a new ship, which will transport the gas at low pressure (approx. 7 barg).
The third concept is an autonomous ship that can give significant cost reductions.
The fourth concept consists of design of large ships for transport over large distances.
“All work packages are conceptual,» says Hay. «And we hope to be able to continue this work and create concrete technical solutions
Project owner: Brevik Engineering AS
Project period: 2019–2020
Total budget: 14.5 MNOK
Support from CLIMIT: 6.25 MNOK
Partners: SINTEF, Equinor, Total, Gassco, Air Liquide, Sogestran