Norway is widely perceived as a global frontrunner in environmental responsibility and sustainable development. Yet, tensions arise when national green ambitions translate into local land-use decisions shaped by competing values and aims. This thesis explores such a conflict on Askøy, an island near Bergen. Despite several objections and years of local resistance, a proposed sustainable urban development project called Kildn has been dominating the municipal planning debates. Kildn is promoted by the developers “as a new way of thinking” to become the world’s first zero-emission cruise harbour and fjord metro hub. However, the project is planned to be built on Askøy’s last untouched coastline, raising concerns about nature conservation, local identity and democratic participation. To explore how this debate unfolds, the study applies a critical planning perspective and analyses how different actors – including politicians, citizens, and developers - discursively construct their aims and mobilise support through texts, discursive strategies and engagement with social practices in multiple public arenas. Through a qualitative discourse analysis of interviews, social media, and documents, the research formed a nuanced and in-depth understanding of how underlying power and contextual dynamics shape the knowledge, legitimacy and influence of the discourses within the planning process. The findings reveal that planning is far from a neutral or purely technical process. Even in a democratic, consensus-oriented society with embedded participatory practices like Norway, hidden power dynamics and contextual dynamics determine whose voices are heard and whose knowledge is perceived as legitimate. However, the study also shows that marginalised groups can influence planning debates by organising strategically, building alliances, demonstrating dedicated leadership and creating visibility across various platforms. This thesis highlights the need for urban planners to recognise how discourse and power operate within complex contexts to shape planning outcomes, and to develop more inclusive decision-making processes that respond effectively to public value conflicts.