Compressed Air Best Practices, Apr. 2017, by Don van Ormer.
http://www.airbestpractices.com/industries/pharmaceutical/fine-tuning-oil-free-air-compressors-and-purification-pharmaceutical-plant

"A pharmaceutical product manufacturer spends an estimated $137,443 annually on electricity to operate the oil-free air compressors in its compressed air system. The compressed air system operates well and is providing the level of purification required.  Our team visited the plant and identified a group of projects which could reduce compressed air demand and reduce energy costs by $42,248 – or 31% of current use. The objective of this article, however, will be to illustrate the review we did of all the supply-side equipment.  This includes the oil-free air compressors, dryers, filters, drains, oil-water separators and breathing air systems."