IEEE Electrification Magazine - March 2018 - 10

Hydrogen FCEVs
are considered by
many to be ideal,
no-compromise,
alternative-fuel
vehicles.

optimizing operation strategies, and
utilizing otherwise-curtailed renewable energy. california requires 33% of
the hydrogen sold in the state to be
produced from renewable sources,
and other areas are beginning to
implement renewable hydrogen production and dispensing requirements
for stations receiving incentives.
enabling wide-scale production and
utilization of hydrogen is an objective
of a multilab initiative called Hydrogen
at Scale (H2@Scale). this initiative aims to integrate hydrogen technologies across generation and consumption sectors to reduce cost, diversify feedstocks, enhance grid
flexibility, reduce emissions, and generate jobs. hydrogen
can be an economically viable solution that connects the
grid with the renewable generation, transportation, stationary, and industrial sectors.

current View: Hydrogen Use in Transportation
hydrogen FceVs are considered by many to be ideal, nocompromise, alternative-fuel vehicles. FceVs offer zero
tailpipe emissions while giving drivers the same range
and fueling experience they have come to expect from
gasoline-powered vehicles. Figure 1 shows the current
fueling nozzle and FceV receptacle. despite their many
advantages, these vehicles have been perpetually considered for the future. however, during years when the
attention on alternative-fuel-vehicles shifted solutions
considered closer to market-ready, the r&d of hydrogen
FceVs continued. in the past decade, dramatic technology improvements in the industry have resulted in
many automakers now having commercially available
FceVs, and many others are poised to bring them to the
market soon.
to generate useful work from stored hydrogen, fuel
cells consume hydrogen in an electrochemical reaction
with oxygen (from the air) to produce electricity, water,
and heat. the electricity is then used to power the FceV's
electric motor. the efficiency of a fuel-cell system is

Figure 1. An example of retail hydrogen fueling. (Image courtesy of NREL.)

I EEE E l e c t r i f i c a t i on M a gaz ine / March 2018

typically two to three times higher
than that of an internal combustion
engine, and FceVs have many of the
same attributes-fueling time, range,
power, mass, and size-as today's
conventionally fueled vehicles. Many
of the initial barriers to FceV adoption, including cost, durability, performance in subfreezing temperatures,
volume/mass of on-board hydrogen
storage tanks, and vehicle packaging,
have been reduced or eliminated
through technology advances. Fuel-cell system costs have
dropped from US$275/kW in 2002 to US$50/kW in 2016,
roughly an 80% reduction, while durability has seen a
fourfold increase. Fuel-cell systems in the field have
achieved more than 120,000 mi of operation with less
than 10% degradation in stack voltage. Fuel-cell stacks
and power systems have also made dramatic improvements in power density and system integration. Fuel-cell
system power densities have roughly doubled in the past
decade, allowing greater packaging flexibility.
the automotive industry has settled on 70-Mpa onboard hydrogen storage systems with energy storage densities of ~1.4 kWh/kg and ~0.8 kWh/L, compared to
~0.24 kWh/kg and ~0.5 kWh/L for automotive lithium-ion
batteries. although these energy densities are low compared to liquid fuels, they allow most FceVs to store
enough hydrogen for more than 300 mi per fill. these vehicles can fill at a rate of 5 kg (a full tank) in 3-5 min, and the
energy content of hydrogen is 33.3 kWh/kg (roughly the
equivalent energy content of a gallon of gasoline).
to date, most FceV development has focused on lightduty personal vehicles, but the benefits that hydrogen fuelcell power trains bring to light-duty vehicles can have an
even bigger impact in heavy-duty vehicle applications.
as heavy-duty vehicles are responsible for the majority of
tailpipe emissions in urban areas, electrification of these
vehicles could have significant air quality and health benefits. the volume and weight of the batteries to electrify
many of these heavy-duty applications make batterybased systems very difficult, but hydrogen fuel-cell systems
are a possible solution. the large number of hydrogen fuelcell bus demonstrations shows there is a precedent for the
use of hydrogen in heavy-duty applications. additionally,
there are a number of demonstrations of hydrogen vehicles in other commercial applications, ranging from local
delivery trucks to class-8 tractors.
Successful deployment of FceVs relies on the availability of a widespread and convenient hydrogen refueling
infrastructure. hydrogen infrastructure for fueling FceVs
has progressed in the last decade from individual stations
with specific access requirements and limited operation hours to retail fueling stations. Because of the high
costs of hydrogen infrastructure, planning and optimizing hydrogen fueling system rollout have been key

Table of Contents for the Digital Edition of IEEE Electrification Magazine - March 2018