Grid-Responsive Smart Manufacturing: Can the Manufacturing Sector Help Incorporate Renewables?

Abstract

Grid-responsive smart manufacturing has the potential to contribute greatly to the use of renewable energy sources in the manufacturing sector. Smart manufacturing includes the use of demand-side management to store energy in various forms as well as schedule operations so that power is used at optimal times. This work presents a case study of a mineral manufacturing site in the United States comparing different methods of smart manufacturing integrated with renewables. Using historical utility bills and various process models, the study seeks to quantify the savings and costs of various schemes in an overall effort to improve the economics of facility operation. The models compare solar arrays, battery storage, smart pumping schemes, and various combinations of those with process-integrated technology as viable ways to reduce energy costs. The study finds that a solar array by itself is prohibitively expensive for this facility. This is due to relatively high peak demand charges and the fact that the solar array's output does not align well with the facility's real-time power usage. The addition of a battery for load shifting helps the economics significantly, bringing the payback period down from 28.4 to 17.0 years. A key finding of this study, however, is that rather than battery storage, the facility can utilize existing process flexibility, namely pumps with variable frequency drives and built-in water storage capacity, to shift loads. The combination of solar with this novel smart pumping scheme brings the payback period for this investment down to 10.2 years. The smart pumping scheme by itself, however, has a near instant payback (0.13 years), demonstrating that enhanced automation can be used to leverage existing process equipment to operate as a “battery”, but at only a fraction of the cost of an actual battery.