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GE testing sodium halide battery/Li-ion battery/fuel cell hybrid system for transit bus

GE’s publication reports that GE engineers have begun testing a transit bus equipped with a new hybrid energy system integrating GE’s Durathon sodium-halide battery (earlier post), a lithium-ion battery and a hydrogen fuel cell.

With this system, we are bringing together a battery that supplies power, a battery that provides a lower amount of energy longer and a fuel cell that creates the base load of electricity to operate the bus. It’s all centered on the system that manages power, energy and the fuel cell all in an intelligent way.

—Tim Richter, Systems Engineer in the Electric Propulsion Systems Lab at GE Global Research

Current fuel-cell-powered buses must include batteries to provide power for acceleration. Up to today, though, hybrid systems have not run as efficiently as they can because they use lithium-based batteries, which often produce more energy than needed and drain quickly. This limits a bus’s range to around 50 miles and increases costs by requiring larger, more expensive fuel cells.

GE has been exploring ways to synergize the benefits of its sodium-halide Durathon technology, which can store a large quantity of energy but isn’t optimized for power, with power-optimized lithium batteries and hydrogen fuel cells.

Richter says the new management system, GE’s Ecomagination-qualified Multi-Energy High Voltage Energy Management Architecture, has been created to manage the bus’s power sources and provide the energy it needs when it needs it.

The energy management technology is a combination of hardware and software all in one box. DC converters boost low-voltage electricity to power the bus’s motor while the software controls the converters to get the best out of the different sources of energy.

Richter suggests that this design approach will allow engineers to scale back the size of costly hydrogen fuel cells, potentially lowering a bus’s initial cost by 50%. Better power management also means long-term savings in operating the vehicle.



I have been advocating the possibilities of fuel cell hybrids for some time, against the predilections of the battery only purists.
Fuel cells are far too good a technology not to be useful.
How all the combinations of them and batteries pan out will await events.

BTW, on the ever-contentious subject of the relative efficiency of batteries and fuel cells, I was alerted by the author to this article of his:

I was surprised to see that he gave the wall to battery and battery storage losses at 19%.

I did not believe that, so I checked.
Here is the information from a Leaf owner:

He puts the figure at 20%!

This not only makes the comparisons with fuel cell efficiency considerably more favourable to fuel cells, but shows that losses from inductive charging are unlikely to be much greater than conventional charging, as indeed the likes of Nissan have always said.


Using a smaller FC as a genset to charge high power (batteries or super caps) and high energy density batteries is a smart idea to provide extended range at a 'potential' lower cost.

However, hydrogen filling stations must be available?


Why not add some supercaps while you are at it (for regen braking).
Sounds good, but rather complex (and expensive ?)
Interesting to make a version which can use an ICE genset instead of a fuel cell.
The fuel cell ones could be used in cities, the ICE ones, for countryside/suburban use.
3 (or 4) power sources sounds expensive, whichever way you look at it.


Filling stations for hydrogen for buses is not really a big issue, as they return to base, whatever the arguments about private vehicle use.

Those arguments are in any case overblown in my view, and the people who are engaged in building them reckon that they will be able to reduce costs to about the same as for a natural gas filling station.

For any alternative to petrol, natural gas, hydrogen or electric, the cost is reckoned to be around 5% of that of the vehicles themselves out to 2050.

Don't forget that if only batteries are used, then provision has to be made for the 50% of cars in the US alone which have no garage to charge in, and that increases costs.

In general for private car plug in hybrids of any sort then a 110v plug should be fine,whilst for very large batteries such as that in the Tesla much more robust charging is needed.

All of that costs money.


There are plenty of ICE hybrids already.
Hydrogen is just fine for country routes, as long as they return to base at some time.
In cold climates waste heat from fuel cells can be used for heating, unlike in pure battery buses.
Unlike an ICE the fuel cell bus is zero pollution at point of use, so you never have a diesel firing up.


The EV1 design 20 years ago had provisions for a fuel cell range extender, this is nothing new. Using energy dense with power dense batteries is an idea we have been talking about on here for years. It started with the lithium air being combined with lithium ion.


Yes has been talked about for 20+ years but has anybody mass produced it?

FCEVs are not dead and they may become competitive in large vehicles.

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