Publications

Microalgae are single-celled organisms that thrive in both saltwater and freshwater, using light as their primary energy source. These photosynthetic microorganisms can rapidly generate biomass by utilizing solar energy, CO₂, and nutrients from aquatic environments.

In the oil and gas industry, acid gases such as H₂S and CO₂ are often produced. These gases are classified as waste and are typically combusted in a flare system. At the Central Processing Plant (CPP) Donggi, an Acid Gas Removal Unit (AGRU) is used to remove acid gases from feed gas, specifically 4% mole CO₂ and 0.4% mole H₂S, through amine solvent absorption. The removed H₂S is treated in the Biological Sulfur Recovery Unit (BSRU), where it is converted into elemental sulfur (S₈) using bacterial absorption. However, CO₂ cannot be processed in the BSRU and is instead released as waste gas, which is combusted in a thermal oxidizer. This CO₂ waste gas has the potential to be utilized by microalgae for biomass production.

As part of a pilot project at CPP Donggi, 0.17% of the CO₂ feed to the thermal oxidizer—approximately 0.0005 MMscfd—will be redirected for contact with microalgae. The selected microalgae contain 5% fat, 15–20% carbohydrates, 55–70% protein, and 10% other components. Microalgae have the capability to absorb CO₂ at a rate of 1.83 kg of CO₂ per 1 kg of microalgae. Through photosynthesis, microalgae process CO₂ and produce biomass, which has potential applications as fuel, animal feed, supplements, and other uses.

This pilot project has demonstrated biomass production of up to 2.7 kg per year, CO₂ capture by microalgae of up to 0.03 tons CO₂ equivalent per year, and a reduction in fuel gas combustion from the thermal oxidizer by up to 510 tons CO₂ equivalent per year.