With growing concerns about climate change, efforts to invest in low-carbon alternatives to conventional fossil-fuel-based products are on the rise globally. As more low-carbon products are developed, current systematic methods for optimizing supply chain expansion and operations need to be redesigned due to differences in consumer preferences between sustainable and conventional products. In this work, we investigate how the choice of traceability method (i.e., the chain of custody model), which governs a consumer’s claim to a sustainable product, impacts decision-making in the expansion of low-carbon ammonia supply chains. We propose a mixed-integer nonlinear programming formulation that applies the mass balance and book-and-claim models, the two most relevant chain of custody models in the chemical industry, to an ammonia supply chain. We then present a comprehensive case study spanning 25 years that includes nine U.S. states and highlights differences in solutions between the two models, such as the extent of renewable technology expansions, ammonia distribution decisions, demand met, and the breakdown of different costs under various ammonia price scenarios. Moreover, we make key observations in the solutions provided by a rolling-horizon simulation to cases with uncertain ammonia demand. This work highlights the critical role of chain of custody models in evolving low-carbon ammonia supply chains, laying the groundwork for future research into their application and impact on other sustainable supply chains.

中文翻译：

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评估产销监管链模型对低碳氨供应链长期规划的影响


随着对气候变化的日益关注，全球范围内投资传统化石燃料产品的低碳替代品的努力正在增加。随着更多低碳产品的开发，由于可持续产品和传统产品之间的消费者偏好存在差异，当前用于优化供应链扩展和运营的系统方法需要重新设计。在这项工作中，我们研究了管理消费者对可持续产品的要求的可追溯性方法（即监管链模型）的选择如何影响低碳氨供应链扩张的决策。我们提出了一个混合整数非线性规划公式，该公式将质量平衡模型和账簿和索赔模型（化工行业中两个最相关的监管链模型）应用于氨供应链。然后，我们提出了一个跨越 25 年的综合案例研究，其中包括美国 9 个州，并强调了两种模型之间解决方案的差异，例如可再生能源技术扩展的程度、氨分配决策、满足的需求以及各种氨价格情景下不同成本的细分。此外，我们还对滚动视距模拟为氨需求不确定的情况提供的解决方案进行了关键观察。这项工作强调了产销监管链模型在不断发展的低碳氨供应链中的关键作用，为未来研究其应用和对其他可持续供应链的影响奠定了基础。