Turboshaft Business Opportunity

[voltech444]

Hello members

This is my first post here, I've been a member on the Yahoo DIY site for about a year now and I finally joined this site.

I see a lot of talent on this site and I am wondering if anyone would like to make this into more than just a hobby; even if it is a cool hobby.

Basically what I am proposing is to build turboshaft engines to run an alternator to power an electric vehicle. This is something I've been researching for the last 3 years and i made some posts about it on the Yahoo forum. After taking the last year to digest all the information I've realized that this is not a project I can do by myself, gas turbines especially turboshaft engines are just too complicated for an automotive mechanic to tackle solo. I am not a big company, I dont have lots of money or any serious investors at this point; but if I had a working prototype I believe I could get all of that.

I got training and got my commercial driver's license and got hired to drive for a trucking company, which is what im doing now, so that i could get hands on experience in the transportation industry and learn more about trucks.

I believe that a gas turboshaft electric vehicle hybrid is the ideal platform for an over the road truck, for several reasons. Emissions, laws are getting stricter for commercial diesel vehicles and in order to meet those we have to use particulate filters and diesel exhaust fluid. DEF is just another operating cost that cuts away from a company's profits. Reliability, modern diesel engines are expensive and the engine and transmission must be serviced regularly. Fuel, the price for diesel will continue to rise making mpg a top priority for all trucking companies. These companies are also looking at alternative fuels such as natural gas and biofuels.

Now I know that it is difficult to build a DIY turboshaft engine that can match or exceed the efficiency of a modern diesel engine. I believe the solution is to use a combined cycle with a steam powered microturbine. A company called Green Steam Turbine is already making and selling these with a 15kw version coming online soon. These are getting a real world efficiency of 30% which has never been done before with a steam microturbine. The unit is very simple, compact and reliable. When paired with a turboshaft we could be looking at efficiencies between 40-60%. Keep in mind efficiency is not the only strong point of this system; when you consider the whole hybrid electric drivetrain we are talking about something that is fuel flexible, has much better emissions, gets way more mpg, has much less moving parts and is thus more reliable.

Keep in mind it is not cheap to buy a new drivetrain for one of these trucks, so although the hybrid system may cost more initially, the payback will be well worth it.

So what do you guys think, anyone interested? I see a business opportunity to build these engines for commercial trucks. I know capstone is already doing this, but I think they're approach is wrong. They wont admit it but they are having problems with the large shock loads on the air bearings inside a vehicle. They're system is cool but in my opinion it's too complicated. What I think we need is a free power turbine with conventional brass and oil bearings. Semi trucks already have air brakes which means we can use compressed air to start the engine; of course we may need a larger or higher psi air tank but there's plenty of room. That way we only need an alternator and dont need all of the complicated electronics for electric start. Im not sure if its less efficient but would it be possible to have a large enough free turbine to eliminate reduction gearing, like 10,000 rpm or so?

I got more ideas ill post tomorrow. I appreciate any input you guys have and look forward to your response.

Thank you!
Jordan

[rexhunt]

Hi Jordan,

I like the idea and if I was in the same country I'd probably like to get involved physically, however I'd be interested in watching from the sidelines at this stage due to other commitments in my life currently.

Are you planning on sharing a lot of the development work publicly?

Cheers,
Rex

[voltech444]

I don't have any problems sharing our work amongst the forum; although that is a decision that would have to be made by the group; however everybody here shares their work already so i dont see that as being too much of an issue.

[cursorkeys]

Hi Jordan,

Thats an interesting proposition. Your intended design would be recouperated?
I do think, in spite of the flexibility, efficiency would seem to be the killer in your application. The control methodology could make a large difference to your system performance (LPV et al.).

I'm currently commited to some turbine consultancy work but I'd love to offer any small assistance on the electronic/control side if it would help you with your project.

Jon

[voltech444]

Recuperation is something I've been thinking about because if we are talking about a combined cycle application that extra heat energy is going to be captured by the steam turbine. So im not sure if it would be necessary; although it may be to get a high efficiency even with a combined cycle. Does a recuperator produce higher egt's or lower; because higher egt will produce more power for the steam turbine.

[cursorkeys]

That's a very good question. It improves engine effiency by off-setting the operating point as less fuel has to be burnt to get the desired temp rise. I haven't done the maths but intuitivly the EGT should remain the same and you simply improve core effiency? Maybe Racket could help here as he's the resident thermodynamics expert!

[finiteparts]

Hi Jordan,

The idea of a combined cycle power plant for a truck is an interesting one, how cool would it be to have a small "power plant" generating electrical power in your truck! What if you could "sell" the power back to the grid when you are sitting in restops...you hook up to a natural gas line and generate power to run your systems, but sell the excess... A few engineers that I used to work with and I were going to build a small natural gas powered turbocharger combined cycle "plant" for teaching kids about power generation. We figured that we could use a alternator, remove the diode trio, to get three phase AC...a large motor to simulate the "grid", etc. But, making one for that power range will be a challenge....

I am not sure that I share your view on Capstone turbines. Compliant foil air bearings have been used in aircraft cycle air machines since the sixties with amazing reliability. NASA and Mohawk Innovative Technology have demonstrated some amazing things with compliant foil air bearings and I think that the potential for reliable use exists. Capstone engines have been in buses for ten years or more with good success.

"December 17, 2001 – Three microturbine-energized hybrid electric Designline buses operating in New Zealand for more than a year and a half have amassed nearly 200,000 miles of public service with only minor microturbine-related problems, such as a failed ignitor/exciter.... The original three have logged 54,000, 66,000 and 71,000 miles of service. The LPG fueled buses each operate an average of more than 14 hours per day."

I think that Capstone has it right. Their engines are little jewels of engineering and if you have had the pleasure of seeing them, you would agree. For a major trucking fleet, even the fact that they don't have to buy oil, urea and can run off of natural gas (thus getting "green" tax credits) is a huge driving factor. The fact that Wal-Mart is buying into it should be a good indicator on the technology readiness of their system. Big corporations hate risk! The other thing is that the viscosity of air is always lower than heated oil...so you will struggle to get a similar mechanical efficiency with oil lubricated journal bearings. But, that being said, it would be super cool to have a portable combined cycle package! So good luck!!!

As for the regenerator and EGTs, you produce lower EGTs if you are meaning exhaust temp from the engine. The temperature coming out of the turbine should be very close to what it is without the regenerator. Since you are adding flow restrictions and losses due to the regenerator, there might be a slight change in the turbine exit temp, but if you think about at the fundamental level, you are not asking the turbine to do any more or less work, you are just recovering the thermal energy from the fuel more effectively. If you recycle the exhaust heat into the compressor discharge air so that you need to put in less fuel to get to the specified turbine inlet temperature, you will be left with less energy in the exhaust stream. That is why combined cycle gas turbines do not use regenerators.

~ Chris

[obilaser]

Hello All,

I am also new to the group but I am not new to turbines. I've been working on this issue for over a decade, I have built hundreds of turbines from a 10 watt hydro-electric generator up to a 400kW turbojet. I am presently developing a 120HP turboprop for experimental aircraft and even at that power level it is hard to beat a piston for efficiency. Unfortunately, less then 20kW is particularly difficult. As you get smaller your relative losses get larger...

Robin Mackay (a Capstone Founder) patented a sub-atmospheric turbine good for ~ 40% eff. but the design has never been built.

Regeneration, or Recuperation, is absolutely essential to achieve good efficiency. Presently this is VERY DIFFICULT in miniature machinery; however, 3D printing in ceramic-metal-composites allows for new designs today.

To achieve > 30% eff. at < 20kW requires an EPR > 6.0; this is also a VERY EXPENSIVE proposition.

To achieve > 40% eff. at < 20kW requires a combined-cycle machine. I don't know of any such build today. Over the years, I have proposed several designs but I have not yet been funded for any such work.

As for Foil-Bearings; It was promised to me: "Give me an order for 40 engines and I will design and build your bearings".

So, if anyone else is interested, I'm working on it...

Best Regards,
ROB

[ripcrow]

I've got a design for a turbine assisted heavy vehicle hybrid stpystem. Getting investors is the hard part.

[madpatty]

Hi Voltech444,

I have been working on combining high temperature fuel cells with gas turbines for cogeneration and also on fuel cell devices that can be retrofitted to existing setups.

I have recently filed 3 patents in the same field.

Combining fuel cells with gas turbines seems a viable solution.
And also i am in US currently so can work on this project.

Thanks.

[voltech444]

Hey yal, I haven't been on here in a while and i'm glad to see there is still interest in this project. I have not been able to go any further with it. I have been looking at other options for powerplants. I have been very interested in building a reverse uniflow compression ignition to use as a generator in a hybrid. I have written about this on physics forums. The reverse uniflow engine is a 2 stroke so it has a high power to weight ratio, it is also very efficient and would cost about the same as a regular diesel to build. I also think it could be used for aviation or any other application. It's possible to build a spark ignited version as well. I have also been day dreaming about making an electric drag racing car with a turbocharged motorcycle engine for the generator, so a smaller and cheaper battery pack could be used. Man the things I would do if I won the lottery!

[raygmurphy]

Thanks for sharing the business opportunity here

[bournaVee]

i love your idea
im currently building a turboshaft engine for a similar purpose. using turbocharger rotor system.
increasing air mass in flow would certainly boost efficiency