One of the challenges of energy transitions is implementing governance schemes able to frame socio-technical transformations. This involves aligning the views and interests of diverse actors, guiding and intervening as a means of realizing a long-term vision. Backcasting is a technique often used in sustainability transitions, but its use is relatively new to emerging and developing countries. This paper follows Energy 2050, a long-term policy design exercise developed in Chile. In a country with few mechanisms for energy planning, Energy 2050 was to produce a long-term policy with social legitimacy; a roadmap of interventions leading the transition to a sustainable energy system. We analyse the introduction of novel, future-oriented methods in the Chilean context as a "policy innovation", focusing on the trade-offs between long-term thinking and the instrument's immediate value. Focusing on the role of consensus-building, visioning and scenario building, and participation, we show the reflexive relation between promises and expectations, and the process that shapes them, highlighting how expectations about policies shape and limit the way in which futures are imagined and articulated. In this respect, we stress the importance of designing backcasting exercises which consider the political cultures in which they are embedded.