Future utility services’ (un)knowns framework: Knowledge existence and knowledge reach

•We create a framework using principles from risks, uncertainties and futures studies.•We look at long-term futures in critical utility infrastructure.•We use mixed methods and multiple expert opinions.•We apply the framework to a vignette (a possible future infrastructure).•We evaluate two contrasting scenario contexts.

This paper presents a framework for assessing risks and uncertainties in the domain of utility services in futures up to 100 years hence. A nine-step process framework is presented following a review of extant literature. The framework provides a way to quantitatively and qualitatively evaluate one or more vignettes (potential future utility infrastructure solutions) by examining: 1. Alternative scenario contexts; 2. User utility service requirements; 3. Technologies’ readiness; 4. Knowledge of each technology life cycle stage; 5. Criticality of technologies to user requirements; 6. Interdependencies between technologies. The framework is based on collecting multiple expert contributions in order to arrive at a comparative evaluation. We use the ‘city blood’ vignette, which represents an infrastructure system delivering hydrogen enriched water, to apply the framework to two radically different scenario contexts.