Seasonal storage of solar thermal energy through supercooled phase change materials (PCM) offers a promising solution for decarbonizing space and water heating in winter. Despite the high energy density and adaptability, natural PCMs often lack the necessary supercooling for stable, long-term storage. Leveraging erythritol, a sustainable mid-temperature PCM with high latent heat, we introduce a straightforward method to stabilize its supercooling by incorporating carrageenan (CG), a bio-derived food thickener. By improving the solid-liquid interfacial energy with the addition of CG the latent heat of erythritol can be effectively locked at a very low temperature. We show that the composite PCM can sustain an ultrastable supercooled state below −30 °C, which guarantees no accidental loss of the latent heat in severe cold regions on Earth. We further demonstrate that the common ultrasonication method can be used as the key to unlocking the latent heat stored in the CG-thickened erythritol, showing its great potential to serve as a high-performance, eco-friendly PCM for long-term seasonal solar energy storage.

The aim of the interpretative phenomenological analysis is revealed, in particular, the investigation of one’s personal life experience from the perspective of the narrator as well as the impact of its parts ‒ phenomenology, hermeneutics, and ideography ‒ on its procedure and contents. Experience as one’s internal world, the unity of its aspects (desires, feelings, motivation, assumptions, etc.) that are meaningful for them based on which they construct their actions are defined as an object of the research in IPA. Experience is considered as a phenomenal, but not objective reality; the importance of investigating one’s experience within their specific social and cultural context is stressed. The narrator acts as an experiential expert. The subjectivity bias of the researcher is inevitable; the author offers to focus on the way the latter shapes research as well as consider it when processing empirical data both as the system of values of the respondent and the researcher. IPA foresees “disciplined spontaneity” of the researcher that includes following both the structure and the demand of a free scientific inquiry. The synthesis of meaning-making of research participants and the researcher is postulated. IPA poses a question of relationship between the processes of cognition, the contents of narratives, and one’s behavior. Contemplating on a meaningful event is understood as a part of the being-in-the-world but not as a mere cognitive activity. IPA methodologists see people as those who existentially reveal the world. When speaking on life events that make sense to a person, they simultaneously realize a big number of tasks but not only picks up words-carriers of meaning available in the culture. The stress is done also on the aspects of life world experiencing: temporality, spaciality, embodiment, self, sociality, discourse, and project. Interviews is named the basic method for getting empirical evidence (repeated interviews are allowed), but multi-mоdal forms of data collection are also acceptable. The researcher carries out profound, thorough analysis of a case (n=1...30), on the basis of which constructs a way to universal laws and structures. As a result, the research conducted on the grounds of IPA, often investigate existential issues and contain descriptions of transformational experience bringing change, touching upon one’s identity and feelings of the self.