Integrating Land Conservation and Renewable Energy Goals in California: Assessing Land Use and Economic Cost Impacts Using the Optimal Renewable Energy Build-Out (ORB) Model.

There is a lack of understanding of the environmental impacts and economic costs of potential renewable energy (RE) siting decisions that achieve ambitious RE targets. Such analyses are needed to inform policy recommendations that minimize potential conflicts between conservation and RE development. We use the state of California's rapid development of utility-scale RE as a case study to examine how possible land use constraints impact the total electricity land area, areas with conservation value, water use, and electricity cost of ambitious RE portfolios. We developed the Optimal Renewable energy Build-out (ORB) model, and used it in conjunction with the Renewable Portfolio Standard (RPS) Calculator, a RE procurement and transmission planning tool used by utilities within California, to generate environmentally constrained renewable energy potential and assess the cost and siting-associated impacts of wind, solar photovoltaic, concentrating solar power (CSP), and geothermal technologies. We find that imposing environmental constraints on RE development achieves lower conservation impacts and results in development of more fragmented land areas. With increased RE and environmental exclusions, generation becomes more widely distributed across the state, which results in more development on herbaceous agricultural vegetation, grasslands, and developed & urban land cover types. We find land use efficiencies of RE technologies are relatively inelastic to changes in environmental constraints, suggesting that cost-effective substitutions that reduce environmental impact and achieve RE goals is possible under most scenarios and exclusion categories. At very high RE penetration that is limited to in-state development, cost effectiveness decreases substantially under the highest level of environmental constraint due to the over-reliance on solar technologies. This additional cost is removed once the in-state constraint is lifted, suggesting that minimizing both negative conservation impacts and electricity costs at very high RE penetration will require California to utilize a combination of in-state and out-of-state RE resources.