Making consistent scenarios for LCA on new technology - using OTEC as a case study

Life Cycle Assessment is an approach for collecting the entire scope of environmental impacts generated by a product, technology or service, in order to find solutions for reducing its environmental burdens. However, the... [ view full abstract ]

Life Cycle Assessment is an approach for collecting the entire scope of environmental impacts generated by a product, technology or service, in order to find solutions for reducing its environmental burdens. However, the application of conventional LCA methodology is difficult to apply to the assessment of environmental impacts of emerging technologies.

Scenario-based LCA’s aim to model future technological developments through the identification of influential parameters, which are quantified and used to determine the potential future environmental impacts of a technology. While various of such scenario methods aim at predicting a likely future situation, they face significant issues with uncertainty of both inventory data and results. Normative scenario development, however, aims at generating a desirable instead of a likely future, in which uncertainty regarding the likelihood this future outcome is not regarded as an obstacle.

A structured way of developing consistent normative scenarios is found in General Morphological Analysis (GMA). GMA consists of several iterative steps. First, all parameters relevant to the future development of a technology are identified, after which values for each of the defined parameters are formulated. The resulting morphological field is used to generate a field configuration, a set of specifically chosen scenario variables that represents a particular future state of the assessed technology. Finally, the generated field configuration is assessed on its internal consistency. All steps of the GMA are participative, meaning they are completed in conjunction with the technology developer.

In order to incorporate the described method of normative scenario development into an LCA framework, adjustments to the Life Cycle Inventory phase were proposed. The addition of a Relevance Analysis to the LCI benefits the identification of influential technological parameters and obtains inventory data on the current best-practice of the emerging technology. The addition of a GMA ensures the generation of consistent normative scenarios while the quantification of the scenarios provides inventory data on future versions of the assessed technology.

The proposed normative prospective LCA approach was applied to a case study, Ocean Thermal Energy Conversion, to uncover its practical implications and values. In the case study the functional unit was defined as 1kWh of electricity generated at the plant gate. Two normative future scenarios regarding an OTEC plant in the year 2050 were developed, resulting in qualitative descriptions of a 25MW offshore OTEC plant and a 100MW grazing OTEC plant. The quantification of the scenarios resulted in sufficient LCI data to conduct an impact assessment of both future plants. The results were used to identify potential improvements regarding the environmental performance of OTEC and to compare the performance of the two hypothetical future OTEC plants with that of the current state of development, as well as with that of a 2MW offshore wind turbine. Relevance and limitations of the case study and proposed assessment method are discussed before drawing conclusions and making recommendations.