How does a Green Turbofan work?

The Green Turbofan does not work like a conventional turbofan (picture 1), which compresses part of the air it takes in, heats this air in combustors and uses this hot and compressed air to drive the turbines of the compressors and turbofan.

Picture 1
Cross section view of a conventional turbofan

For more details on how conventional turbofans work, please visit

The Green Turbofan does not have compressors or combustors, and the turbines driving it are impulse turbines, not reaction turbines. For more details on the difference between impulse and reaction turbines please visit

The impulse turbines can be either fitted on a metal ring connecting the tips of the Green Turbofan itself (pictures 2, 2a and  2b) or on the axis of the Green Turbofan (picture 2c).

Picture 2 Picture 2a
Cross section view of the Green Turbofan Front view of the Green Turbofan
Picture 2b Picture 2c
Tip turbine Green turbofan using impulse turbines
Picture 2d
Dental drill
The way the Green Turbofan is powered can be compared with the dental drill in picture 2d, or with an adapted version of the Pelton wheel, which is designed to extract energy from a high-pressure and low-flow (volume) water source.

Green Turbofans are powered by a compressor (picture 3) placed inside the main body of the air plane, e.g. the hold of the air plane.

The air stream produced by the compressor is channeled through a Laval type nozzle. The compressor can be powered by a diesel/biofuel generator or diesel/biofuel engine.

Video shows how a jet engine is started by using a diesel powered compressor
<<  This video shows how a jet engine is started by a small gas turbine powered compressor.

Unfortunately, it only specifies the PSI (20), but does not specify the air volume.

Picture 3 - Flowchart of the Green Turbofan

Flowchart of the Green Turbofan

Green Turbofan has environmental and safety advantages

Environmental advantages:

Unlike the exhaust of conventional turbofans, the exhaust from the diesel/biofuel generator can be run through a catalytic converter and particle filter, cleaning up the exhaust as much as possible.

Additionally, it is possible to run the exhaust through a chiller (heat exchange), cooling the exhaust (using liquid nitrogen), preventing the creation of contrails, which many scientists believe contribute to global warming.

Safety advantage:

Cooling the exhaust also makes an air planes harder to detect using infra red homing devices like the ones used in heat-seeking missiles. E.g. a terrorist using a shoulder-fired heat-seeking missile might have more difficulty taking down a civilian air plane.

Main disadvantages:

Weight and space (fewer passengers and/or less cargo). Although generator and compressor technology is very reliable there might still be a need for a back up generator and compressor, at least for civilian air planes. This extra weight and space, might reduce or even nullify the advantage of the Green Turbofan being lighter (it has no combustors or compressors and has a simple axis) but probably can be overcome by using composite materials for the compressors. Still, its environmental and safety advantages make it worthwhile to explore the idea further.


Can a stand alone compressor like the CU compressor, power the General Electric GE90-115B high bypass turbofan?

Well, let's compare their main specs.

The GE90-115B

Overall Pressure Ratio: 42:1 = 42 bar.
The primary air stream is ± 150 kg/sec (The total air mass flow of the GE90-115B is approximately 1500 kg/sec. Its bypass ratio is 9:1 (for 1 kg of primary air, 9 kg's of bypass air are generated), so the primary air stream is ± 150 kg/sec and the bypass air stream is ± 1350 kg/sec.).
For full specs click here.

The CU compressor

Maximum working pressure is 351 bar or 5090 PSI (more than 8 x that of the GE90-115B).
Maximum air flow capacity is 1600 nm3/h or 445 l/s (less than 1% than that of the GE90-115B).
For full specs click here.

Suppose the CU compressor's has to power two turbofans, it would capable drive the impulse turbine/pneumatic motor on each of the Green Turbofans with an air stream of 220 liters of air per second. The air stream has a pressure of 175 bar, equaling ± 175 kgf/cm2.

It is easy to spin a Turbofan by hand - click to watch videoGE90-115B video
175 bar should be sufficient, since the GE90-115B is extremely well balanced and calibrated. It needs very little energy to start.

As you can see in the video on the left, you can easily spin it by hand!

Air cylinder rocket- MythBustersMythBuster Air Cylinder Rocket video
Have you watched the GE90-115B video? Please do and next watch the MythBuster Air Cylinder Rocket on the right.

After you have seen this air cylinder rocket bust through a brick wall and damaging another, you will probably understand why 175 bar is probably enough to make the Green Turbofan spin at the same speed as the GE90-115B.

Energy savings

The CU compressor is powered by a 200 kW electric motor. A 1000 kW diesel generator consumes about 300 liters per hour

The average fuel consumption of two GE90-115B is about 4000 liters per hour (a conservative estimate).

Pretty obvious which one is more efficient.

If the air mass flow is not sufficient...

1. Use hydraulics

Michael V. Rodrigues already patented a hydraulic powered turbofan. So please check it out: Gigadron – The Most Powerful Motor to Supplant Jet & IC Engines .

Use a hydraulic pump and hydraulic motor to drive the turbofans. A gearbox can be used to speed up the turbofan.

Flowchart of a green turbofan power via hydraulic motor

It is also possible to use the compressed to drive the Green Turbofan via a hydraulic pump / motor and gear box. Hydraulic pumps can work at 5000 rpm

2. Use a more powerful compressor

1000 bar Siemens STC-SV centrifugal compressor
like the Siemens STC-SV centrifugal compressor

Volume flows from 250 to 480,000 m3/h – 133 m3/sec (full power)
Discharge pressure up to 1,000 bar
7.5 MW electric drive, powered by Siemens SGT 200 gas turbine which consumes about 25 MW.

Final remarks

If it is possible to drive a Green Turbofan the size of a GE90-115B turbofan as described above, it should be able able to power an airplane 70-80% the size of a Boeing 777, for which the GE90-115B turbofan was designed.

Why? The GE90-115B turbofan has a bypass ratio of 9:1, so 9 times more air flows through the bypass duct, producing about 70-80% of the thrust. If the Green Turbofan has the same diameter and spins at the same speed, it should be able to create the same air mass flow and thrust as the bypass air of the GE90-115B turbofan.

Furthermore, I would like to point out that the examples are based on existing hardware. If one would design the hardware for the specific needs and purpose of the Green Turbofan, efficiency would be even larger.

Feedback welcome

Do you think it will it work? Please give some feedback.

Technical specifications of the General Electric GE90-115B High Bypass Turbofan

General Electric GE90-115B high bypass turbofan
Type: Ultra High Bypass Ratio Dual Shaft Turbofan
Bypass Ratio: 9:1
Low Pressure Compressor: Single Stage fan, followed by 4
stage axial booster
High Pressure Compressor: 9 stage axial flow compressor
Burner: Double annular through-flow combustor
Turbine: Dual spool, 2 stage axial high pressure turbine, 6
stage axial low pressure turbine
Exhaust: Coaxial core and bypass jet exhaust
Thrust Rating: 115,300 lbs. of thrust
Weight: 18,260 lbs.
Thrust/weight: 6.3:1
Air mass flow: Approximately 3,000 lbs/sec
Fan Pressure Ratio: 2:1
Overall Pressure Ratio: 42:1
Maximum Turbine Inlet Temperature: 2,700F+
Specific Fuel Consumption: .25 lb/lbt/hr
Fuel Burn at takeoff: 3,750 gallons/hr


CU compressor technical specifications

CU compressor technical specifications