Engineered nanomaterials (ENMs) are increasingly incorporated into clean energy technologies due to observed improvement in technological and system performance. Though these materials could revolutionize many products and technologies, increased use of ENMs can also introduce uncertainty and risks that are difficult to predict. Increase in ENM use could significantly increase ENM releases to the environment across their life cycle, from material synthesis to end-of-life. To address knowledge gaps and uncertainties, this work assesses a portfolio of ENMs from a systems perspective. First, characterization and quantification methods were developed for three carbonaceous ENMs, fullerenes (C60, C70, and derivative PCBM), which have promising application in solar technologies. Empirical ecotoxicity assays and predation studies were performed to determine ecotoxicity and predation effects. Next, an integrated model predicted potential risks of ENM accumulation by estimating potential manufacturing locations, spatial concentrations, and potential ecological risks. This was followed by an adaption of portfolio optimization, a model traditionally used to optimize investment performance, to model potential environmental and economic risks and simultaneous performance benefits and inform safe nano-enabled design.
Ecotoxicity findings demonstrate differences among fullerenes where organisms exposed to fullerenes also experienced significantly increased predation risk, underscoring the need to consider potential system-level effects. Based on manufacturing locations, potential ENM exposure may be within buffer distances of sensitive ecosystems. However, modeled ENM accumulation would only reach levels associated with ecotoxicity risk under extreme scenarios. Future ENM use-patterns can be informed by the portfolio optimization approach, where optimal portfolios are determined by the materials-mix that yielded the greatest overall performance return while minimizing the portfolio risks. These novel methods and tools contribute to the knowledge of the benefits and risks of ENMs, which will help to guide more responsible and proactive policy and planning around ENM development and use
