Carbon Capture and Storage (CCS) as a Necessity
In order to reduce the effects of global warming, strategies such as increased efficiency and investments in renewable energy sources have been implemented. However, in order to make a significant impact on carbon emissions, experts agree that carbon capture and storage (CCS) is essential. According to the DNV Pathway to Net Zero Emissions, CCS is a “must” if the world is to meet the 1.5°C limit.
Efforts to increase the amount of carbon capture have already been initiated. Currently, there are 16 large-scale carbon capture facilities that are able to capture over 30 million tonnes of carbon annually from fertilizer, steel, hydrogen production, and natural gas processing plants. Additionally, the storage of CO2 is a well-established technology, as energy companies have been using pressurized CO2 to push oil to the surface for many years. Furthermore, the transportation of CO2 is safe and flexible.
Erik Mathias Sørhaug, Business Development Leader of DNV’s Maritime Advisory, states that transporting large amounts of CO2 from the capture site to storage can be done through pipelines, ships, or a combination of both. He adds that shipping is a secure, dependable, and adaptable way to transport over shorter distances and in lower to moderate amounts.
"In our view, scaling up global CCS capacity will require a fleet of specialized tankers with the ability to collect CO2 from capture sites operated by many different industrial segments."
Martin Cartwright, DNV’s Business Director Gas Carriers & FSRUs, states that to move CO2 on an industrial scale, the industry is exploring different methods of transportation, such as high, medium, and low-pressure solutions, which could help incorporate shipping into the CCS value chain. However, there are some technical issues that need to be addressed.
“DNV has offered class services to CO2 carriers since 1988,” he says. “Through our work with various partners, we have developed expertise specific to vessels design, specialized tanks, piping and refrigeration systems for the transportation of liquified CO2.”
Exploring Low-Pressure Solutions for Transporting Liquified CO2: Risks and Challenges
Johan Petter Tutturen, Vice President of Special Projects – Gas at DNV, states that current experience with transporting CO2 is with medium-pressure solutions. He adds that low-pressure solutions would enable larger cargo tanks, thus increasing the capacity of the vessel and allowing for more CO2 to be transported per unit volume.
Despite the potential benefits of transporting liquified CO2 through low-pressure systems, it is essential to conduct a thorough investigation of the associated risks and challenges to guarantee safe and dependable operation.
”Unlike natural gas, CO2 must be pressurized to reach a liquid state. Pure CO2 has a ‘triple point’ at 5.12 bara and ÷56.6°C. For temperatures below the triple point, CO2 will only exist as gas or in solid states.”
Tutturen states that the current method of transporting CO2 is done at a medium pressure (13-15 barg) and a temperature of -20 to -30°C on smaller vessels for the food and beverage industry. However, the industry is looking into other pressure options. He adds that DNV is involved in several Joint Industry Projects that are assessing the feasibility of transporting CO2 at both high and low pressures.