by Sig Gronich,
Hydrogen Program Team Leader, U.S. Department of Energy
Since I joined the Hydrogen Program, Ive
been personally impressed by the many scientific and engineering accomplishments
that have been achieved. Sometimes we dont stand back to see the real,
steady progress and how it relates to our mission. So, I thought I would
reflect back on a few of the more notable accomplishments that have been
achieved through R&D; activities funded by the Hydrogen Program. Taken as
a whole, these achievements should encourage all of us that progress is
being made.
In a cost-shared effort, the Schatz Energy Research
Center (SERC) has built a 5-kW proton exchange membrane (PEM) fuel cell,
incorporated it into a vehicle, and demonstrated the fuel cell vehicles
use as a transportation provider in a real-life application. Unlike conventional
PEM cell designs, the SERC cell is designed for low pressure on the air
side, eliminating the need for an air compressor and reducing the parasitic
loads to less than 10% of the stack output (compared to roughly 20 to 25%
for a 30 psig system). Presently, a person in the City of Palm Desert, California,
U.S.A., is using the SERC vehicle for his commute to work. Construction
of two additional fuel cell vehicles will be completed over the next several
months.
A hydrogen-fueled internal combustion engine
(ICE) is an on-board power system option with a near-term focus. NOx emissions
were originally viewed as a barrier to the use of hydrogen-fueled ICEs,
but work at Sandia National Laboratories, Hydrogen Components Inc., and
elsewhere has demonstrated NOx emissions that are two orders of magnitude
lower than those of hydrogen-powered ICEs of the early 1980s and that exceed
Californias proposed EZEV [electric zero-emissions vehicle] standards
(i.e., 8 ppm at 60 mpg). In addition, Sandia has built three laboratory-scale
internal combustion engines and, through a systematic development process,
has improved the indicated thermal efficiency from 38% to 46% (LHV basis).
In a cost-shared effort, Air Products and Chemicals
is developing a sorbent-enhanced natural gas reforming process (SERP). They
have developed a proprietary sorbent with acceptable CO2 capacity, selectivity,
and kinetics, and a proprietary process that uses the sorbent and commercial
reformation catalyst to directly produce high-purity hydrogen (95+%). Currently
the process is undergoing rigorous bench-scale testing. The SERP can potentially
lower the cost of hydrogen by 25% compared to conventional steam reforming.
Researchers at the National Renewable Energy
Laboratory (NREL) have shown that hydrogen can be produced through pyrolysis
of biomass, a process that produces valuable chemical coproducts. A detailed
analysis conducted by NREL has shown that the selling price of hydrogen
from this process operated with a coproduct option is US$7.4/MMBtu.
Researchers at NREL have identified a bacteria
that performs the carbon monoxide shift reaction, and have demonstrated
mass transfer rates and lifetimes that make the process commercially viable.
Researchers at the University of Hawaii, U.S.A.,
(working closely with NREL) have built a laboratory-scale photoelectrochemical
hydrogen production unit using multijunction amorphous silicon as the photoelectrode.
Solar efficiencies of 7.8% (LHV) have been demonstrated under natural light,
1-sun condition, which is approaching the Program goal of 10%.
Researchers at Oak Ridge National Laboratory
have proven that a strain of green algae, Chlamydomonas reinhardti,
does not absorb light via the conventional Z-scheme model of
photosynthesis. The algae uses only one of the two photosynthesis steps,
cutting in half the theoretical amount of sunlight energy consumed and thereby
doubling the potential energy conversion efficiency.
Researchers at Sandia have developed a hydride
that has a desorption operating pressure of 1 atm at 190ºC and a storage
density of 3.5 wt%. These results are approaching the Program goal of a
150ºC operating hydride.
Researchers at the University of Hawaii have
developed novel polyhydrides that catalyze the dehydrogenation of saturated
hydrocarbons at roughly 200°C. These compounds form the basis of a hydrogen
storage system with a theoretically achievable storage density of 7.3 wt%,
which exceeds the goal of 5.5 wt% required for vehicle applications.
The Programs success depends on the development
of products for the mid- and far-term marketplaces. The above represent
varied technology areas and are in different stages of development. Importantly,
however, they represent a significant complement of ideas with which to
proceed.
©1997. All Rights Reserved. A Publication of
the National Hydrogen Association.
This material may not be reproduced in any form without permission.