Geological storage of CO2 in the Baltic States

Jānis Krūmiņš
Ph.D., Leading Researcher
University of Latvia
Latvia

Māris Kļaviņš
Professor
University of Latvia
Latvia

If greenhouse gas emissions are allowed to continue without implementation of mitigating measures, then changes to the climate will endure on the timescale of centuries with consequent frequent and devastating natural disasters. Alas, the climate change due to growing CO₂ emissions is now inevitable, even if tomorrow the humanity moves to a complete carbon neutrality, because the change has already begun and because CO₂ has exceptionally long lifetime in the atmosphere. However, if immediate action in this climate crisis follows, then the transition to new conditions may be more gradual and thereby give people more time to adapt to the change.

The Baltic States recognize climate change as topical issue and look for mitigating measures, which include halting anthropogenic emissions and eventually reaching complete carbon neutrality. Strategies to achieve carbon neutrality involve the expansion of renewable energy and phasing out fossil fuel. In this regard, CO₂ capture, and consequent storage are one of the most promising approaches without immediate transformation of the industry. In addition, it can be applied not only for industrial decarbonization but also for the green growth of the energy sector.

In general, carbon capture and storage technologies involve separating CO₂ from flue gases and capturing it after the combustion of fossil fuels. Among the most common capture methods are the absorption, use of CO₂ for microalgae cultivation, membrane separation, adsorption, and cryogenic separation. The captured CO₂ is then transported, injected, and stored in geological reservoirs for exceptionally extended periods of time with minimal risks of leakage. However, in order to avoid any impact on climate, CO₂ must remain isolated for at least 10 000 years, which therefore requires safe and predictable storage settings. The geological structure of the Baltic States offers such storage conditions with an adequate CO₂ storage capacity and dense surrounding sediments, which work as natural insulation to prevent CO₂ leakage – in general, these are porous sandstone structures deep underground. One of the most promising geological formations for CO₂ storage in the Baltic States and in the entire Baltic Sea region is the Baltic Sedimentary Basin. It contains structures with porous Cambrian terrigenous sediments within the temperature and pressure regime that allows to store CO₂ in a supercritical state. Currently, some of such structures are used for natural gas storage, for example, Inčukalns gas storage in Latvia.

The optimum geological conditions that meet the requirements for CO₂ storage are in Central and Western Latvia and the Baltic Sea. Even if it is possible to store CO₂ in structures in Lithuania, they are too few and have a low overall storage capacity. In addition, in Estonia there are no prospective Cambrian structures for CO₂ storage.

Based on the seismological research and evaluation of the reservoir properties, 15 onshore sites can potentially be used for CO₂ storage in Latvia, with total estimated storage capacity exceeding 400 Mt CO₂. Those are Dobele, Northern Blīdene, Snēpele, Southern Kandava, Degole, Lūku-Dūku, Kalvene, Vērgale, Ēdole, Northern Kuldīga, Viesatu, Aizpute, Usma, Liepāja, and Northern Līgatne. Two additional potential offshore sites are established in the Baltic Sea near the coastline of Latvia: E6 and E7. The capacity of the 15 reported onshore structures could support storage of the national emissions for at least the next 200 years, and the additional offshore structures can increase the CO₂ storage lifespan even more. Notably, that scientific observation suggests larger (up to 1 000 Mt CO₂) than estimated storage capacity because these structures have not been studied in high detail and no recent data are available about them. However, to prove higher storage capacity, it is crucial to perform new in-depth geophysical and seismological research, and it is expected that the results will indicate much longer lifespan for the CO₂ storage. Nevertheless, among the Baltic States, Latvia is the only one with a practical potential for CO₂ storage in geological formations. The high CO₂ storage potential of the Latvian structures is related to the intense structuring of the Baltic Sedimentary Basin and effective reservoir properties of Cambrian sedimentary rocks. Thus, use of carbon capture and storage in these unique geological structures can support the aims of the Baltic States climate policies to achieve climate neutrality.

E-mail: krumins.janis@lu.lv, maris.klavins@lu.lv

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