SimpleFill Gas Pressurization Device

A reliable compact device for efficiently compressing natural gas fuel for automobiles

The Need

Compressed gas is useful in a number of different applications such as propulsion in vehicles. The global Compressed Natural Gas (CNG) market was valued at $14.8 billion in 2016, and is projected to reach $36 billion by 2023, growing at a CAGR of 14.1%. Furthermore, the Natural Gas Vehicle market size was valued at $17.1 billion in 2019 and is projected to reach $28.7 billion by 2027, growing at a CAGR of 6.9%. However, current approaches to compress the natural gas include using direct mechanical compression, a system that can be expensive as well as difficult to repair and maintain. Given the profitability of these sectors, a need exists to find more cost effective, reliable and manageable solutions for compressing natural gas.

The Technology

Researchers at The Ohio State University’s Center for Automotive Research, led by co-inventor Dr. Fabio Chiara, have developed a new method of compressing gas. The Simple-Fill system is based on the concept of using a liquid piston compressor. A pressurized functional liquid is inducted inside a compression chamber, where gas has been previously admitted. The raising “liquid piston” compresses the gas inside the compression chamber while concurrently providing a cooling action and, as needed, a dehydration function. The first application of the technology is for compression of natural gas for vehicular refueling (CNG), even though several other applications are envisioned for compression of industrial gases.

The compression concept, was initially demonstrated in 2014 and 2015 through a full scale two-stage laboratory compressor capable of a flow rate of 4 gasoline gallon equivalent per hour (GGE/hr) and peak delivery pressure of 3600 psig. Simple-Fill Inc., that licensed the IP from the Ohio State University in 2013, further developed the product through an engineering prototype developed in 2015 and 2016, with the same basic specifications of the proof of concept prototype. This prototype was engineered according to ASME and NFPA standards and it was deployed in the field for an actual operational testing, providing refueling services to a Columbus Ohio based commercial fleet of CNG work vans.

Between 2017 and 2018, Simple-Fill further developed the liquid piston compressor by developing a pre-production compressor. This product was fully re-engineered to be a compact single-skid fully integrated compression and dehydration solution able to provide 30 to 40 GGE/hr of CNG at a peak pressure of 4500 psig. The compressor skid is geared toward mid and heavy duty fleets of CNG vehicles and it has achieved the Underwriter Laboratory (UL) field evaluated product mark. Between 2018 and 2019, Simple-Fill was successful in deploying three compressors in the field and serving two operating fleets of heavy duty CNG class 8 trucks. To date (June 2021), the Simple-Fill compressors have accumulated over 13,000 operating hours and they continue to serve operational commercial fleets in the field, while working in environments as cold as 5F and as hot as 100F.

Commercial Applications

● Filling stations for CNG vehicles returning to centrally located base

● CNG consumer vehicle filing stations

● Rapid, high pressure compression of gasses other than CNG


● Up to 30% reduction of lifecycle costs of ownership if compared to conventional CNG vehicles refueling stations of similar size

● Easier system to repair and maintain than direct mechanical compression, due to the absence of costly moving parts inside the compression chamber and the use of heavy duty, commercially available fluid power components

● The compression liquid provides a dehydration action to the CNG, eliminating the need for expensive additional dehydration systems and allowing for overall cost and complexity reduction

● Process can be divided in multiple stages to increase efficiency and reduce energy consumption and it can be made modular to suit different applications, gas discharge capacity and peak delivery pressures

Please see technology T2012-297 for additional patents in this portfolio.


Patent # Title Country
9903355 Method and System for Multi-Stage Compression of a Gas Using a Liquid United States of America
2930851 Method and System for Multi-Stage Compression of a Gas Using a Liquid Canada
10,865,780 Method and System for Multi-Stage Compression of a Gas Using a Liquid United States of America

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