I think they include Total Cost of Ownership. The vibration and repair may be outweighed by the simplicity and reliability. You could heat recover with combined cycle in either. The high turbine temperatures might make the final cycle more efficient.

It is interesting to look at up front cost and total overall cost. If the initial cost is high, but fuel is cheap and it is more efficient, then total costs will be lower. Lots of people will choose the lower initial cost and pay more in the long run. City governments may see things differently.

You also factor in price insurance. If the price of diesel keeps going up and who knows where it will be years from now, something that can run on CNG, kerosene or other fuels starts to look better. Which leads to PHEV designs that can add more storage. If all else fails rely more on the grid and charging stations.

Doggydogworld

Very good points. I am also convinced the diesel series hybrid would be more efficient by fuel to wheel and save vehicle cost when compared to the turbine series hybrid although the turbine should be more durable than the diesel engine. I don’t think you can calculate diesel genset wheel efficiency as 0.4*0.8 = 0.32 and compare it to turbine wheel efficiency calculated as 0.25*0.8 = 20%. The reason is that I am almost sure the 25% turbine efficiency is electric efficiency and the 40% is thermal efficiency for the diesel engine so we need an electric generator on the diesel engine to get comparable diesel electric efficiency. Assuming this dynamo is 90% efficient the diesel genset is 0.4*0.9 =36% electric efficiency and the diesel series bus is 0.4*0.9*0.8 = 28.8% which is still much better than the comparable 20% for the turbine fuel to wheel.

You could also be right about the marketing issue about “up to 100% better full consumption” so that the actual standard diesel to wheel efficiency could be better than 10% (0.5*0.2). Mki put the upper limit at 12%. In any case these numbers shows that there is a lot of efficiency gains to be made by the using even a mild series hybrid with no electric grid power when compared to a non-hybrid diesel bus. Longer down the road of time when the price of the lithium batteries has dropped you can simply upgrade the bus to a PHEV by increasing the size of its battery and adding a plug.

As I understand it, turbines are most efficient when fully loaded. I do not know what they do with the high temperature exhaust and noise.

The bus company has a video that shows the factory floor. You can see the buses in various stages of manufacture. I looks like a small company that has found a niche and is doing well.

One could use a SOFC topping cycle with a turbine. The increased operating pressure would greatly increase the current density of the SOFC. As I recall, SOFC/turbine combinations have reached efficiency of 60% at 1 MW on natural gas (don't recall if that was LHV or HHV).

That is true. You can just keep going until there is not enough high grade energy left. I think we might see some SOFC buses at some point. SOFC with gas turbine and rankine final cycle might get more than 60% efficiency. In some ways you are an electric vehicle, but you have taken the power plant along with you.

The best efficiency in series hybrid is when the battery are not in use . In general the battery are 60-97% efficient (more like 80% for most type).
If you could run the bus just on gen set no battery involve you can got around 90% from engine to the wheel.
The brake power recovery also have some issues too. In most case the power from braking is converter to electric power and loaded to battery. The efficiency usually is pretty low 40-60%.
For the brake recovery probably super cap will be the best due to fast energy absorption with assistance of batteries.

Series hybrid with turbine have couple advantages – for gen set. The turbine is small and light and the generator is small and light too. The generator operate at very high rpm so in can be very small light and efficient.
They using air bearing. Clever idea, however I believe it at the cost of overall efficiency. The magnetic bearing (or electro magnetic) might be more efficient.
Some description:
http://en.wikipedia.org/wiki/Magnetic_bearing
and it look like Rolls-Royce using magnetic bearing.

Let compare the type of engine and expected efficiency (best case):

1.Combustion Turbine in series hybrid:

25%(engine)*0.92(gen)*0.87(elec.motor)=20%*0.95(battery Li)*0.87(charger)=16.6%
Engine operation characteristic: ON (full load), idle (low loses), OFF
Hayride system used as torque convener instead of transmission, power time shift thru battery.
High reliability, low cost of maintenance, low weight, low pollution, might be noisy at full load

2.Diesel in series hybrid:

45%(engine)*0.92(gen)*0.87(elec.motor)=36%*0.95(battery Li)*0.87(charger)=29.77%
Engine operation characteristic: ON (full load), Idle (high loses), OFF
High reliability, medium maintenance cost, high weight, high pollution, medium noise level.

3.Otto in series hybrid:

30%(engine)*0.92(gen)*0.87(elec.motor)=24%*0.95(battery Li)*0.87(charger)=19.84%
Engine operation characteristic: ON (full load), Idle (high loses), OFF
Medium reliability, medium maintenance cost, high weight, high pollution, medium noise level.

4.Modern Stem Engine:

36%, no hybrid required, no transmission required.
Engine operation characteristic: ON (variable from 0rpm - highest torque to max rpm ), OFF (no idle cycle), no brake power recovery
High reliability, low maintenance cost, low weight, low pollution, low noise level.

5.Electric motor

87%(elec. motor)*0.95(battery Li)*0.87(charger)=71.90%
High reliability, low maintenance cost, low weight, very low pollution, very low noise level

6.Compress air

60%(engine)*0.60(compressor)=36% , no hybrid required, no transmission required
Engine operation characteristic: ON (variable from 0rpm - highest torque to max rpm ), OFF (no idle cycle), no brake power recovery
High reliability, low maintenance cost, low weight, very low pollution, high noise level.

I stress the usage of lithium ion battery. If this type of battery is not used efficiency will drop by 15-35%.
The NiMH Battery have only 60% efficiency.
The NiCd Battery have 80% efficiency.
The lead acid battery have efficiency of 75-85%.
See the wilki link about energy density.
http://en.wikipedia.org/wiki/Energy_density
Digression: If I am correct Toyota Prius do not used yet Li battery. Just changing the battery to Li could significantly increase the millage.. and price. It might be worth it.

By fare the electric bus look most promising if the capacity and the cost of the battery can be overcome.

Same apply for compress air engine. The compress air engine look very attractive if no for the limited storage of compress air.

For electric and compress air we need some adjustments. In both cases they used grid line a a source.
It highly depended of the greed efficiency. The old coal power plant get 33-35, newer around 45%, and co generative up to 60%. the transmission losses are up to 8%.
So the number for grid efficiency will look like 35-8=27%, 45-8=37% and 60-8=52%

The best case efficiency for electric bus will be 52%*0.719=37.38855%
The best case efficiency for compress air engine bus will be 52%*0.36=18.72%

The diesel hybrid look best from all internal combustion engine configuration. Biggest problem is pollution.

Interesting thing is Modern Steam Engine. It will outperform Diesel hybrid. One of the problem is brake power recover. That will probably required some hybrid system.

Interesting thing is that bus require around 20kW at 25mile hour to overcome rolling resistance and air drag. The acceleration of 10 tone bus required more power..
Conventional bus require 250 hp engine. The transmission loose around 42hp, more then two time then the power that is required to move the bus.

We do not have to look fare to find advance series hybrid system - trains locomotive.
You see lately the advertisement for railroad that they need 1 gallon of fuel per 400miles per tone. Just amazing.

Some other idea that I read lately about.
On the beginning of 20th century there were develop switching steam locomotives that did have a steam boiler as we know. The whole idea was to have a steam storage. Basically they have isolate steam tank . The steam was generated on the refiling station. The whole design was surprisingly save.
See the link about new design:
http://www.internationalsteam.co.uk/trains/newsteam/modern21.htm

very good analisys MKI.. I might quibble a bit with motor efficiency but then the motor controllers are not 100% either..

I would think for a bus the overall fuel cost plus mainteneance and availability are all critical.. just pure electric with lipos may be the best if the range is short enough or the batteries cheap enough. For long range transport over the road fuel cost is king, hard to beat the steam engine if it can be made reliable.

Let me add some more.
I just look on the e-Traction web side and look on power requirement to move the bus.

They are three important numbers;
Total power required to move 9200Kg bus at 40km/h = 20KW
That power consist of: rolling loses (17KW), and air drag (3KW).
I was always on the impression that air drag for bus should have should be much higher then the rolling losses. That not the case.
If the rolling loses can be minimize we can improve the efficiency significantly.

I start thinking lite and ten it stock me; The lowest rolling losses are on trains - metal wheel on metal rail.
I found that the rolling resistance on bus could be up to 60 time higher then on train.
Rolling resistance coefficient for train is 0.0005 where for bus is 0.03!!
See more on roiling resistance in there;
http://en.wikipedia.org/wiki/Rolling_resistance

It look like engineers in 19th century solve that problem, and we just trying to reinvent the wheel.

So may be we forget the buses in the cities (whenever it possible) and return to the old 19th century invention of trolley.

The big tree (GM,Ford and Chrysler) destroy trolley transportation in US that was worth $280 billion. For that the chairmans of that companies pay to government $5000 each in 1946.

You could do regenerative braking with a steam turbine hybrid. The turbine drives an alternator that powers the wheel motor and/or charges the batteries. The motor that drives the wheels becomes an alternator to charge the batteries in regenerative mode.. You could have an SOFC running NG, a gas turbine on the output of the SOFC and a final cycle steam turbine with heat exchanger on the output of the gas turbine.. The efficiency might be quite high for such a power plant.

Some other Capstone powered busses were produced years ago with ZEBRA sodium nickle chloride batteries which are also used in full electric buses. The use of them in these buses would allow cheap plug in hybrid operation. ZEBRA batteries have as good a range as L-Ion in the new TH!NK cars.

The higher mileage is due to the hybrid configuration and diesel engines would be superior in efficiency but have more pollution, sound and maintenance problems.

The low maintenance almost makes up for the high cost. The turbines with their air lubricated bearings can run continuously for about a year without maintenance. These buses should be used on 24 hour per day services as there is no engine wear at all and no lubrication costs.

See PARRY PEOPLE MOVERS and their large flywheel hybrid vehicles for efficient rail transportation.

Super capacitors should never be used in buses except in combination with batteries. While they have high power peaks they have little actual energy and cannot ever on their own move the bus more than a few yards. The slighly lower price of capacitors is not a significant advantage when compared to the full price of the system.

The best configuration would have many ZEBRA batteries and a system for charging from the grid at stops in addition to the turbine. Compressed natural gas operation would allow the use of purified biogases, but diesel is easier to find and fill and transport.

Full electric buses or cars should never be built. At least a three kw electronic HONDA like generator and a few liters of BIO-Butanol should be built into a small free corner for slow emergency operation. Coates Limited rotary valves could be used to get much higher RPM and two or three time the power for emergency situations. Gasoline could be used to refill the butanol tank in a desparate situation.

Capstone turbines have been run on methanol or ethanol. Methanol should become the liquid land transportation fuel of the future because it can be made cheaply from natural gas, hydrogen, biogas, wood, biomass and especially coal. It is the ultimate clean coal technology. Bacteria can be fed hydrogen and CO2 to produce ethanol.

Cities should form a consortium to build and operate methanol production independent from oil companies for their transport operations. Gasoline engines can be converted to methanol or dual fuel operation for less than a thousand dollars. Diesel engines can have up to 75% of their fuel displaced by methanol injected into the input air. Double sized tanks needed for methanol are not as hard to fit as CNG or Hydrogen tanks to get the same distance as diesel. Hybrid operation reduces the size of tank needed...HG....

An excellent thread - I was unaware of the difference in thermal efficiency. I also don't think anyone mentioned the weight difference - the turbines are relatively lightweight compared to a diesel. A hybrid has to cart around lots of things, batteries, electric motors, generators, A/C, pumps, and it all adds up, displacing the humans it is supposed to cart around.

As to the 30kW turbine, Capstone has a 60kW also. When the AC is running at full blast, it can suck 20kW itself (I think). But at $1000/kw, this means the 60kw version is more like $60k (= 40kEuros).

Designline has been doing serial hybrids for 20 years, so they must have a compelling reason for using the turbines, and isn't probably just for marketing.

Anyway, I'm going to look into them more.

A very informative thread, very good analysis MKI.
I am not so sure that magnetic bearings are more efficient than air-foil bearings but at least they don't get worn out on startup and roll down.
So, is this just another sale based on "coolness" and a questionable comparison with a NON-hybrid Diesel ? (Maybe Capstone is a twig from the big tree).
Also a turbine, even with "pottery" turbines and recuperation, has really poor SFC at idle so the batteries should be large enough to allow for non-uniform operation so they can always use max power from the generator.
Maintenance of a Capstone turbine with foil bearings and a recuperator may or may not be less than for a small bullet proof constant speed diesel. Recuperators (it appears to be an air-to-air) can be expensive to replace and may not allow use of some fuels.
And do omnivorous vehicle engines make sense in the long run? If there is any marginally significant amount of "novel" fuels available, does it make sense to design vehicle engines for them, rather than just send them to a more efficient power plant?
All these systems (like compound turbo diesel or sterling cycle hybrids etc) are grist for sophiticated cost studies - research $ - development $ - production $ - support $ - fuel $ - future fuel $.

Anyone know exactly where the new Designline Bus plant in Charlotte, NC, will be located???

Does anyone out there know the location of the new facility in Charlotte NC for the designline company that will be building the hybrid vehicles and etc?

Pleaase advise.

Thanks in advance !

Bill

2309 Nevada Boulevard, Charlotte, NC

http://www.cbre.com/NR/rdonlyres/065CF3EE-C0FF-455D-B1EA-ACD653E97328/681666/2309NevadaFlyer.pdf

"...100,000 square foot freestanding industrial facility consisting of office, manufacturing, and warehouse/distribution space."

"The Property is 100% leased to DesignLine International Holdings, LLC under a triple net lease structure through February 28, 2019. DesignLine is a worldwide manufacturer of fuel-efficient and low emission hybrid buses and coaches, a very high growth industry."

are you taking applications if so where