Dept of Energy seeking battery EV’s with fuel cell range extenders to reduce battery pack cost

The US Dept of Energy is seeking information (RFI DE-FOA-0001145) on fuel cells to be used as a range extender in a battery EV.   It’s important to remember that a fuel cell vehicle is an electric vehicle, but with a pathetically small battery pack, and all the energy comes via hydrogen passing through a fuel cell.  But the DoE is envisioning a different model, where the vehicle is a competent battery electric vehicle and a fuel cell is used to extend the driving range.

Think of the two versions of the BMW i3 – one is a pure battery electric vehicle, while the other has the same size battery pack along with a small gasoline engine.  The engineless BMW i3 has an empty space in the rear where the engine goes on the REX version.  Who’s to say BMW couldn’t develop a small fuel cell to fit into the same location?

Maybe, just maybe, a car could be designed such that before heading out on a long trip, you go to the dealer who installs a rental range extender.

Before you get too excited, the target of the RFI is commercial vehicles – delivery vans and the like.  The idea is to develop an add-on fuel cell dohickey to help such commercial vehicles have enough range for daily use in a commercial fleet.

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In 2013 the DoE did a feasibility study, titled Fuel Cells as Range Extenders for Battery Electric Vehicles, which used two vehicles (a Nissan Leaf and a large Navistar truck) to evaluate the potential of a fuel cell paired with a battery EV.  They found it was possible to drastically reduce battery pack size, by 80%, while maintaining range.  Or you could increase total range by adding a fuel cell and not reducing battery pack size.

The slide deck doesn’t discuss the cost of the fuel cell.  If the fuel cell’s price is more than the savings from a smaller battery pack, then you haven’t gained anything.

That is, what they’re looking for is a route to replace a large number of fleet vehicles with some kind of zero emission vehicle.  The combination they’re looking into is to reduce battery pack size by using a fuel cell, perhaps making the vehicle more cost effective.

Reducing battery pack cost is widely seen as a key to battery electric vehicle adoption.  Big trucks require a far bigger battery pack than the family sedan’s we drive around.  A class 8 big rig with a 50 mile range might require a 250 kilowatt-hour battery pack, or 10x the pack size on a Nissan Leaf.  An 80% reduction in pack size means eliminating 200 kilowatt-hours of battery pack, representing gobs of money.

These are interesting ideas but I think there’s a flaw in the reasoning.  Namely – will battery packs always be expensive.

It appears there’s a battery pack cost breakthrough just around the corner – and that it’s for real this time.  There has always been technology just around the corner that promises much cheaper battery packs.  But so far that idea hasn’t panned out.  What’s different is rumors of car makers who are imminently announcing battery EV’s with 200+ mile range at affordable prices.  That combination requires a battery pack cost breakthrough.

In other words, is the Dept of Energy about to optimize away the cost of something whose cost is about to plummet?

For this concept to pan out, the the fuel cell must cost less than the battery pack cost being displaced.   Additionally, it appears that fuel cell refueling stations cost $2 million apiece, while not being as clean as they’re touted to be.  Given that fuel cells are very expensive, the refueling equipment is very expensive, and fuel cells don’t really produce the desired environmental gains, I have to wonder out loud whether this is something the Dept of Energy should be pursuing at all.

About David Herron

David Herron is a writer and software engineer living in Silicon Valley. He primarily writes about electric vehicles, clean energy systems, climate change, peak oil and related issues. When not writing he indulges in software projects and is sometimes employed as a software engineer. David has written for sites like PlugInCars and TorqueNews, and worked for companies like Sun Microsystems and Yahoo.

About David Herron

David Herron is a writer and software engineer living in Silicon Valley. He primarily writes about electric vehicles, clean energy systems, climate change, peak oil and related issues. When not writing he indulges in software projects and is sometimes employed as a software engineer. David has written for sites like PlugInCars and TorqueNews, and worked for companies like Sun Microsystems and Yahoo.

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  1. Pingback: GM’s “range extended EV” fallacy — fast charging is also a range extender | The Long Tail Pipe

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