TAKEnergy is pleased to announce that we have recently joined forces with RadMax Technologies Inc., of Spokane Washington, (Read the RadMax press release here) to commercialize the patented RadMax Gas Expander and support the recently announced pilot project co-funded with the Natural Gas Innovation Fund (NGIF) (Read the NGIF news announcement here).

We believe this technology will be a game changer in small scale power generation from natural gas pressure letdown applications.  Some of the features of RadMax technology:


• Low parts count with only two unique moving assemblies, the vanes and rotor, resulting in reduced component, assembly and maintenance costs, increased reliability, and reduced noise

• Device family parts are mirror image parts and are typically interchangeable

• Rotary motion input and output porting does not require complicated valving systems

• Lower speed with high work efficiency that can directly drive off-the-shelf generators without the need for speed changing gearboxes

• Easier field maintenance and repair 


• Continual, smooth rotary motion 

• Compact, lightweight design

• Easily scalable; volume capacity grows geometrically

• Multiple devices in one compact unit

• Agile technology easily modified for multiple devices, uses and applications

• Larger expansion to compression ratio capability results in a longer power stroke and greater fuel efficiency

RadMax Expander Cycle


The RadMax gas expander design is a combination of four distinct sections:  two complete intake and discharge expansion cycles on each cam in the standard two cam configuration. This unique design allows for each of these sections to potentially be configured with different expansion ratios. Different porting options into and between the sections allow for stable expander speed control due to changing gas-flow conditions, or the capability for multi-stage expansion in one device. Additionally, the device has the potential to integrate an electric generator within the unit, creating a compact genset.


The total amount of energy contained in a volume of gas is in two forms: pressure energy (useful work energy) and internal energy. During a free gas expansion process, like that found in a typical air-conditioning expansion valve or a mechanical gas-expanding throttling valve, pressure energy is not captured and is instead converted to internal energy with no actual work accomplished.  

In contrast, the purpose of gas expansion through the use of rotary devices, such as the RadMax positive-displacement gas expander or a turbo expander, is to convert as much of the available pressure energy as possible to output-shaft work instead of it being converted to internal energy. The benefit of using these types of gas-expansion devices over free gas-expansion devices is that the resulting shaft work can be used to generate other types of useful energy (i.e., gas compression or electricity generation) to help offset the cost of initially pressurizing the gas.

RadMax Gas Expansion Cycle


In the RadMax positive-displacement gas expander, the vanes move axially driven by the rotor face and the pressure in each chamber changes when the adjacent vanes extend or retract. During rotor revolution, the ends of the vanes follow a path that approximates a sinusoidal wave. This path is uniquely designed so that during each revolution of the rotor, the chambers’ volumes alternately expand and contract. 

The process is repeated in each of the expander sections, in each chamber, and on each side of the rotor. The rotor spins continuously in one direction rather than violently changing directions as with pistons in a reciprocating device. Because the upper and lower faces of the rotor are 90-degrees out of phase, the RadMax gas expander is always balanced and exhibits minimal vibration.


As a prime mover in standalone or turbine engine configurations, the RadMax gas expander is well suited for power generation, waste-heat recovery, air conditioning and natural-gas system throttling loss recovery, and RadMax turbine engine applications.