Power-to-X: A review and perspective

In the past decade, producing chemicals from renewable energy for use as fuel has gained considerable interest. Renewable hydrogen production (PtH) is the backbone of this power-to-x concept, while further conversion to methanol (PtM) or ammonia (PtA) serves to increase energy density. In this article, we review production and utilization technologies for PtH, PtM, and PtA in the context of the energy and transportation sectors. Specifically, each technology's basic operating principals, state of development, energy efficiency, dynamic flexibility, and deployment outlook is discussed. We also review recent process systems engineering research of PtH, PtM, and PtA. At the process level, this research largely aims to improve economics through optimal synthesis and design of novel processes as well as coupled real-time optimization and control for dynamic operation. At the facility or supply chain level, combined capacity planning and scheduling to optimally use intermittent renewable resources is the major focus.