This is a version of the document that Greg Hanssen, partner at EnergyCS
(the creators of the lithium-ion version of PRIUS+), delivered at EVS21,
the Worldwide International Battery, Hybrid and Fuel Cell Electric Vehicle
Symposium & Exposition), in Monaco April 5. Greg is also co-chairman of the
Production Electric Vehicle Drivers Coalition, an early force in promoting
EVs in California. You can find a link to the PDF version of this document
at http://www.calcars.org/vehicles.html

A Bridge to the Hydrogen Highway
By Greg Hanssen, EnergyCS
greg@...

August 20, 2004 updated March 9, 2005

California has set forth on the ambitious goal of building a network
of hydrogen fueling stations by the year 2010. This clean fuel 'Hydrogen
Highway' is intended to solve the familiar 'chicken and egg' problem of
vehicles and infrastructure. While the vision of a renewably fueled zero
emission vehicle future remains clear, there are still many hurdles to be
overcome before affordable Fuel Cell Vehicles (FCVs) are likely to reach
the public. This paper proposes an enhancement to the FCV platform that
would reduce vehicle cost, increase efficiency and alleviate the consumer
anxiety over a sparse hydrogen infrastructure.

One of the rarely discussed issues is how the Hydrogen Highway could
compete with a ubiquitous gasoline infrastructure. Prototype FCVs have
only half the range of a traditional gasoline vehicle. How accepting of a
medium-range vehicle will consumers be if the nearest refueling station is
10 miles out of their way? A solution: give the consumer access to
refueling capability at home.

While home-based hydrogen generation devices may not be available in
the near future, a hydrogen fuel cell based electric vehicle could easily
gain additional driving range by enlarging the existing hybrid battery and
adding a plug for home recharging. The electric energy gained from a home
re-charge would complement the fuel cell and provide additional daily
driving range beyond that of the hydrogen fuel cell itself. By expanding
the existing fuel cell hybrid battery to a high-energy battery, a
substantial portion of the daily driving could be done directly without the
overhead of hydrogen production. The Hydrogen Highway would then allow
such vehicles to go well beyond the traditional range of a normal battery
electric vehicle. Renewably produced hydrogen would complement renewable
electricity from the battery to allow unlimited range and quick refueling
while also permitting inexpensive and convenient home refueling.

At the moment, fuel cell power comes at a high price. Current fuel
cells approach $3000 per kilowatt although these costs are expected to drop
closer to $1000/kW during the next phase of prototype vehicles. High
energy, low weight advanced lithium batteries can now be purchased for as
little as $200/kW. As long as fuel cell costs exceed that of batteries,
there is a clear advantage to decreasing the fuel cell size and increasing
the onboard hybrid battery. A battery-dominant hydrogen FCV would only
need a fuel cell large enough to keep the battery charged for average
driving as the battery would supply the additional peak power. At $1000/kW
for the fuel cell, reducing an 80kW fuel cell to 20kW could save
$60,000. Adding 50 miles of battery range would add less than $10,000
resulting in a net savings of $50,000 in the near to midterm.

Additional battery range would not only decrease infrastructure
anxiety and vehicle cost, but could ultimately increase FCV
efficiency. Advanced lithium batteries can return up to 80% of the
electricity used to charge them. Using electricity to manufacture hydrogen
and compress it, followed by a conversion back to electricity in a fuel
cell may return as little as 20% of the original electricity. The battery
portion of a plug-in FCV drive cycle would therefore deliver electricity to
the mo://gup to four times more efficiently than through hydrogen. With
renewable electricity at such a premium, great effort should be taken to
use it as efficiently as possible.

Ultimately a plug on a hydrogen FCV could allow the vehicle to sell
back hydrogen produced electricity for peak power needs or provide valuable
voltage regulation services through the battery to further benefit the
California electric grid. In the near term, while fuel cell costs exceed
that of batteries, adding battery power and a plug will clearly increase
the consumer and societal benefits of FCVs.

If the plug-in hydrogen FCV is the keystone in a bridge from gasoline
to the hydrogen future, how do we complete this bridge? A plug-in gasoline
hybrid could take the existing momentum of vehicles like the Toyota Prius
and move us further in the direction of a renewably powered zero emission
vehicle future by replacing more of the gasoline based driving cycle with
renewably produced electricity. While adding a plug to a fuel cell vehicle
reduces the vehicle cost, the same cannot yet be said for a gasoline
hybrid. But this is likely to change in the very near future with fuel
costs rising and battery costs dropping.

The EnergyCS/Valence Technologies plug-in hybrid Prius prototype
demonstrates the viability of the gasoline plug-in hybrid concept. The
ability to displace gasoline with electricity is accomplished by replacing
the stock 1.3kWh NiMH hybrid battery with a 9kWh high-energy, lightweight
Valence Saphion lithium-ion battery pack. The Toyota battery monitoring
controller is also replaced with an EnergyCS lithium monitoring
system. The EnergyCS control package consists of cell monitoring and
balancing for the lithium batteries as well as pack voltage and current
sensing, fan and charger control, user display and SD flash data recording.

The Saphion lithium battery pack can be externally charged with the
on-board 120/240V charger in under 8 hours. While the expanded battery is
sufficiently charged, the control system takes full advantage of built-in
modes of the Toyota hybrid system to use electrical energy from the battery
to displace gasoline. At lower speeds or power demands, the vehicle may
run without burning any gasoline at all. When the expanded battery is
depleted, the control system emulates normal Prius operation and the
vehicle behaves like a normal Prius until the battery is recharged.

The amount of gasoline consumed over a normal daily driving cycle is
dramatically reduced with the introduction of up to 9kWh of electricity
from the grid. Preliminary driving tests over a variety of surface streets
and freeways in Southern California have netted a gasoline efficiency of
between 120mpg and 180mpg for the first 50 to 60 miles of the day. After
50-60 miles the average gasoline consumption drops back to 50mpg under
normal Prius emulation mode.

The environmental as well as energy security implications of
displacing gasoline with electricity could be tremendous. While plug-in
hybrid gasoline vehicles like the EnergyCS/ Valence Prius could eventually
help build a bridge to fuel cell vehicles, in the near term they could also
dramatically reduce our reliance on imported fossil fuels.

As California strives to increase the amount of renewable electricity
on the grid, vehicles that can be powered by this clean energy by way of
batteries and hydrogen must be built to realize this zero emission vehicle
future. The convenience, low cost and high efficiency of batteries
combined with fast hydrogen refueling on the Hydrogen Highway make for the
ultimate zero emission vehicle solution. In order to complete this bridge
however, consumers must first be introduced to clean and inexpensive home
refueling by way of plug-in hybrid gasoline vehicles.