Galdieria, Co., Ltd. successfully conducted cultivation experiments of the microalgae Galdieria utilizing boiler exhaust gas, in collaboration with Mitsui Mining’s Takehara Smelting Plant.
- Release
- 2024/02/02
〜Simultaneously Achieving CO₂ Emission Reduction and Improvement in Precious Metal Recovery Efficiency, Driving Contributions to Circular Economy〜
Galdieria Inc. (Headquarters: Chuo-ku, Tokyo; CEO: Tadashi Tanimoto; hereinafter referred to as “the Company”) is pleased to announce the successful cultivation experiment of the microalgae Galdieria utilizing boiler exhaust gas at the Takehara Smelting Plant operated by Mitsui Mining Co., Ltd. (Headquarters: Shinagawa-ku, Tokyo; President: Takeshi Nao; hereinafter referred to as “Mitsui Mining Takehara Smelting Plant”).
To achieve carbon neutrality, the Company has been developing a cultivation method using the photosynthesis of Galdieria by utilizing the waste heat and CO₂ contained in the boiler exhaust gas, an underutilized heat source with support from Hiroshima Prefecture.
In this successful proof-of-concept experiment with Mitsui Mining Takehara Smelting Plant, we have achieved photosynthetic cultivation of Galdieria using boiler exhaust gas directly, which is rare globally.
The Company conducted photosynthetic cultivation experiments of Galdieria utilizing the facilities of Mitsui Mining Takehara Smelting Plant from November to December 2023 and confirmed favorable growth. The experiment utilized boiler exhaust gas generated in the plant’s processes, containing approximately 200 times the atmospheric concentration of CO₂.
Galdieria, which inhabits acidic hot springs, possesses exceptional growth capabilities even under extreme environmental conditions. In this experiment, we achieved photosynthetic cultivation in a solution with increased CO₂ concentration and acidity due to boiler exhaust gas, demonstrating higher efficiency compared to atmospheric conditions.
In photosynthetic cultivation of microalgae, increasing the CO₂ level in the culture medium can enhance cultivation efficiency. However, purchasing high-purity CO₂ for this purpose is cost-prohibitive, and using exhaust gas could potentially inhibit growth due to other components besides CO₂. Galdieria, as an extremophile inhabiting acidic hot springs, possesses characteristics such as acid resistance, survival in 100% CO₂ atmosphere, and resistance to nitrogen oxides (NOx) and sulfur oxides (SOx), enabling it to utilize exhaust gas efficiently.
Galdieria: Cultivation Status Utilizing Exhaust Gas
Galdieria, a sulfuric acid hot spring red alga, is a type of microalgae ranging from 3-16 μm in size. It possesses a unique property of selectively adsorbing valuable metals such as gold (Au) and palladium (Pd) on its spherical cell surface. It can thrive in extreme environments of high temperature, high CO₂ concentration, and low pH.
Globally, there are very few examples of full-scale microalgae cultivation utilizing exhaust gas, and to the best of our knowledge, no examples have reached practical stages. Building on the success of this experiment, the Company will scale up cultivation and contribute to the reduction of CO₂ emissions at Mitsui Mining Takehara Smelting Plant.
Furthermore, by utilizing cultivated Galdieria and manufacturing precious metal adsorbents using our technology, we aim to recover trace amounts of precious metals from the effluent discharged from the recycling process at Mitsui Mining Takehara Smelting Plant, which were previously unrecoverable.
Collaboration with Mitsui Mining Takehara Smelting Plant: Future Outlook
Innovation Promotion Team, Commercial and Industrial Labor Bureau, Hiroshima Prefectural Office
We recognize the results of the experiment conducted by Galdieria and Mitsui Mining Takehara Smelting Plant as a significant achievement and look forward to their continued success.
Hiroshima Prefecture formulated the “Hiroshima Prefecture Carbon Circular Economy Promotion Concept” in 2022 to achieve a sustainable carbon-circulating socioeconomic system. We aim to strengthen the demonstration research on carbon recycling-related technologies and promote the “localization” of carbon recycling, aiming for the formation of new industrial clusters centered on carbon recycling.
As part of our specific efforts, we initiated the unique subsidy program “HIROSHIMA CARBON CIRCULAR PROJECT” for research on carbon recycling in fiscal year 2022, and we have been supporting the initiatives of Galdieria and Mitsui Mining Co., Ltd., Takehara Smelting Plant.
The success of this cultivation experiment is considered a splendid result that contributes to the development of carbon recycling technology and the reduction of CO₂ emissions by companies in the prefecture. We look forward to further technological development, including scaling up the process.
Mitsui Mining Co., Ltd., Metal Business Headquarters, Technical Supervision Department, Nakayama
Though it is a small step, we are satisfied with the results achieved this time.
Our company has been conducting experiments on CO₂ fixation using our own exhaust gas with Galdieria.
We consider environmental impact reduction initiatives as one of the most important management issues and have been working on reducing environmental burdens such as increasing recycling raw materials, waste treatment, water pollution, and reducing plastic usage towards the realization of a circular society.
This time, we successfully cultivated Galdieria using waste heat and CO₂ contained in the boiler exhaust gas emitted from our factory.
As Galdieria has the characteristic of adsorbing precious metals, if we can recover trace amounts of precious metals contained in the effluent from the recycling process using this microalgae, it is expected to increase the recovery rate, making it a case that contributes to resource circulation.
We hope to continue promoting environmental impact reduction initiatives through joint development with Galdieria and even utilizing Galdieria for precious metal recovery.
Galdieria is committed to addressing global societal issues through research and development of the microalgae Galdieria, which inhabits hot springs. Leveraging its exceptionally efficient cultivation capabilities and the unique property of adsorbing precious metals acquired in extreme environments, the Company aims to contribute to achieving a circular economy, improving the global environment, and solving food-related challenges through safe and highly efficient precious metal recycling in urban mines, replacing mercury in natural mines, utilizing the high-quality content components in food applications, and reducing CO₂ emissions.