A new quantitative life cycle sustainability assessment framework: Application to integrated energy systems

There are two dimensions to “sustainability” as it applies to an engineered system: (i) it needs to be designed, operated, and managed such that its environmental impacts and costs are minimal, and, (ii) it ought to be designed and configured in such a way that it is robust to extreme disruptions and shocks posed by natural, manmade, or random events, i.e. be resilient under extreme events. These somewhat conflicting attributes call for a multi-criteria analysis framework. This paper proposes such an assessment framework for engineered systems involving three new location and circumstance-specific sustainability indices that monetize the economic, environmental and resiliency characteristics throughout the lifecycle of the system components. The proposed framework, thus, allows translating sustainability goals into engineering practice, and is applicable to: (i) the design of new systems, (ii) assessing performance of an existing system, (iii) day-to-day scheduling and operation of the system, and (iv) future growth planning. A novel presentation method, called “Sustainability Compass”, is also proposed which allows decision-makers to visually track the direction and magnitude of changes in the individual sustainability indices of different scenarios; this would also allow easier communication with other stakeholders. The proposed methodology and the usefulness of the Sustainability Compass diagram have been illustrated using end-use monitored data for a whole year of operation of a university campus integrated energy system. The results of five alternative energy development scenarios involving a combined heat and power system and solar photovoltaic systems with different penetration levels have been investigated and are reported in this paper.