Assessing how non-carbon co-priorities affect zero-carbon electricity system development in California under current policies

Abstract

While many electricity resource mixes can facilitate a zero-carbon electricity system, different pathways can vary significantly in their contribution to environmental impacts. Many current assessments focus on tradeoffs associated with monetary cost, neglecting these wider impacts. Here, electric grid dispatch modeling and electricity mix optimization is combined with data on resource consumption and electricity technology costs to compare five different approaches for developing a 100% zero-carbon electricity system in California: minimum critical metals use, minimum solid construction materials mass, minimum land use, minimum freshwater consumption, and minimum monetary cost under present-day policy goals and constraints. The modeled scenarios show that prioritizing minimum solid construction materials mass in developing such systems also achieve near-minimal monetary cost and land use and did not exhibit the worst performance on either freshwater consumption or critical metals use. In contrast, the strategy that prioritized minimum freshwater consumption exhibited the largest land use and materials use of the five strategies. The minimum monetary cost strategy exhibited near-minimal freshwater consumption, but large land use and the highest demand for critical metals. The modeled monetary unit cost of electricity was lower than the 2030 reference for all zero-carbon electricity system scenarios. The results highlight tradeoffs between contributions to different types of environmental impact in developing a zero-carbon electricity system. Notably, prioritizing certain metrics can result in electricity systems that balance these tradeoffs better than others given the existing suite of zero-carbon options. More broadly, the results show that the planning of zero-carbon electricity systems should more explicitly incorporate non-carbon environmental externalities as co-priorities in their development.