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Capstone to Demonstrate Heavy-Duty Hybrid Electric Drive System with Major US Truck OEM

Capstone HEV truck solution. Source: Capstone. Click to enlarge.

Capstone Turbine Corporation has initiated a demonstration project with a major US manufacturer of Class 5 through Class 8 heavy duty trucks that will utilize a Capstone 65 kW microturbine as a range extender in a hybrid electric drive system. In June, Capstone released configurations of the C30 (30 kW) microturbine as a range extender meeting California Air Resources Board (CARB) requirements for New On-Road Heavy-Duty Engines for Urban Bus - Hybrid service with no aftertreatment.(Earlier post.)

This truck will be the first to take advantage of the complete Capstone Drive Solution, which includes the Capstone microturbine along with liquid cooled power electronics, permanent magnet traction drive motor and vehicle power control system.

The electric hybrid vehicle market is in a significant growth phase, with essentially every manufacturer of trucks, buses and automobiles looking for the right solution to serve their customers. Capstone’s microturbine technology offers many benefits for these applications, including our extremely low emission levels that meet the most stringent CARB and EPA 2010 requirements without any exhaust after-treatment.

I am pleased that a major OEM in the heavy duty truck market is investing its time and resources to demonstrate the Capstone Drive Solution and that the demonstration will include getting this vehicle in the hands of some of their key customers as well.

—Darren Jamison, Capstone President and CEO

Capstone’s HEV drive system. Source: Capstone. Click to enlarge.

The Capstone Drive Solution will make it easier for vehicle manufacturers to integrate microturbines into a series hybrid electric drivetrain. As part of a recent joint development agreement with CalMotors, the Capstone HEV product offering will now include inverter drives, traction motors and a vehicle power control module that will seamlessly integrate with Capstone 30kW and 65kW microturbines.

The inverters and traction motors are mobile hardened versions of the proven Parker Hannifin industrial motor drive products. (Earlier post.) The Capstone microturbines are able to operate on traditional liquid fuels such as diesel and biodiesel but can also utilize alternative fuels such as natural gas without sacrificing efficiency.

This demonstration project is the first of several vehicle applications we are working on that will use the new Capstone Drive Solution. The other projects include Class 4 commercial trucks and Class 8 tractors and utilize both new OEM applications like this one and retrofits to existing vehicles. We are also pursuing marine applications for both auxiliary power and propulsion. Our new Capstone Drive Solution offering will open a lot of opportunities for electric drive systems where our ultra-low emissions and high efficiency have an advantage over more traditional prime movers.

—Jim Crouse, Executive VP of Sales and Marketing



I was right on all counts BTW. proof is in the pudding. 50% fuel savings and lower O&M costs plus alt fuels. read it and weep. Real world tests in service in real world applications. No I am not a PE I am in Exploration and more profitably in land management. Hence the MSf and the MS Sedimentology English is not my first language BTW


This post clearly states above that there using a 65kw turbine not 154kw, I'm sure that they have done the necessity calculations to know what peak power they need open the pdf file it clearly shows that 30kw is enough to range extend a 30000lb bus class 8 trucks peak out at 80000lbs unless there special wide/heavy load so its not so much to think 65kw would be enough. I have opened the link to the simulations EP posted Capstone would not come to production with a product that was unable to maintain hwy speeds. check out the SUV 80mpg low OM and alt fuels I want one or better yet the super car 75mpg.


The Dunning-Kruger effect is the phenomenon of people who aren't competent in an area nevertheless showing very high confidence in their abilities. I think we have an example here.

Medium-speed diesels exceed 40% efficiency quite easily, while the Capstone C65 is rated at only 29% efficiency (and drops to 27% at 90 degrees F). The power is totally inadequate for OTR use at highway speeds. However, this is not the intended use; hybrid systems are wasted on over-the-road units, which run continuously and brake rarely.

Here's what Tex doesn't get: the hybrid tractor is for urban use. That's why emissions are paramount, 65 kW is adequate, and the lower efficiency can be made up by the lack of idling.



if you read their article carefully, they only claim the demonstrated fuel efficiency improvement over standard diesel engine buses, even though they clearly have other types of hybrids in their fleet. The reality as EP alludes to is that the big efficiency benefit in urban applications is due to regenerative braking and elimination of idle time. these are attributable to the hybrid architecture, not because of the type of heat engine they use. The problem with their approach (as well as other HD electrical hybrid solutions) is that there is a large discrepancy between the average power consumption and max power requirements. The bus may only need 30kw to keep up with average usage, but it will need 150-200kw in order to accelerate at a pace that doesn't make it a road hazard, or to climb a hill when loaded. That power will need to be available on demand and providing the energy storage to support such power levels without exceeding current state of charge limits is neither cost effective nor packaging friendly. Moreover, Capstone has avoided discussing the cost of the technology or the fact that there are not substantial quantities of other fuels for their microturbine to burn which makes that feature relatively valueless. It is for these reasons that most Heavy Duty hybrid solutions are leaning toward pneumatic-hydraulic energy storage rather than electrical, with power coming from conventional diesel engines using aftertreatment to meet emissions. it is simply a result of it being the best solution and most economical, not a conspiracy by the oil industry or automotive engineers worldwide.

In summary, Capstone tries to confuse the issue by parading the benefits of hybridization as the benefits of a gas turbine while completely ignoring the cost of their gas turbine relative to a comparable IC engine or addressing the battery storage issue.

P.S. if you read between the lines, 20 years ago the Rosen brothers understood the issue was more about the batteries than the heat engine which is why they were working on flywheel energy storage.


If 400+ hp is required for only 5% of the time, why not have two power sources? One (100 hp? or so) for cruising + electric motors + e-storage units + genset to supply extra power when required. The cruising ICE and genset ICE could be combined into one ICE.

This would in fact become a PHEV and would be the most efficient in stop and go traffic and could also match or do slightly better than a single 400 hp diesel on flat highways.

City Hybrid Buses are about 30? more efficient when operated with a smaller diesel genset and properly calibrated.

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