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Co-production of Renewable Hydrogen and Electricity
Presented at Fuel Cell Seminar & Exposition 2008
October 27-30, 2008 Phoenix, Az
Pinakin Patel, Fred Jahnke, Ludwig Lipp - FuelCell Energy, Inc
Frank Holcomb - U.S. Army Corps of Engineers, Engineer Research and Development Center (ERDC-CERL)
Edward C. Heydorn – Air Products and Chemicals Inc.
The continued uncertainty in energy supply has increased emphasis on the energy independence and
sparked interest in the domestic renewable energy. The US-Department of Defense strategy is now
focusing on clean and efficient energy for its bases, distributed generation, and feed stock diversity.
Renewable hydrogen production is of particular interest because it has a minimum environmental
impact, is from indigenous sources, and can be used for transportation as well as power applications.
The development of a hydrogen infrastructure is critical for the widespread deployment of hydrogen
fuel cells for stationary and transportation applications. One of the major techno-economic barriers
to the hydrogen infrastructure is the high cost to deliver hydrogen. On-site generation of hydrogen
will minimize the costs associated with the hydrogen delivery and storage. FuelCell Energy is
developing an innovative solution for cost-effective distributed generation of hydrogen in
collaborative support from the Construction Engineering Research Laboratory of US Army and Air
Products and Chemicals, Inc.
High Efficiency
Hydrogen can be produced from commercially available fossil fuels such as gasoline, natural gas,
diesel, and propane; or renewable fuels such as biogas, bio-diesel, ethanol and waste-derived fuels,
such as anaerobic digester gas. Co-production of electricity and hydrogen using high temperature
fuel cells will provide a low cost option for the hydrogen infrastructure once it is commercialized.
The high temperature fuel cells, such as molten carbonate or solid oxide, can produce hydrogen
internally from these fuels at very high efficiency for use in the fuel cell reaction, as well as for
export. These multi-purpose power plants can produce electricity, hydrogen and heat at an overall
efficiency of 80-85%, with over 65% of the energy going to high value electricity and hydrogen.
This efficiency makes co-production of hydrogen one of the most efficient power systems available
as shown in Figure 1. They also offer ultra-low emissions so can be easily sited where needed, such
as in California where the emissions credits are typically traded at an average value of about
$50,000/ton..
Maximizing Value
The electricity produced on-site can power the local grid or recharge a plug-in hybrid vehicle. In
addition, the co-product hydrogen can be used for fuel cell vehicles, fork lifts, back-up power or
industrial customers. The multiple co-products maximize the overall value proposition and
eliminate the problem of low capacity factor faced by the conventional refueling stations. Use of
waste-derived biogas provides renewable hydrogen and power, and will generate additional emission
credits to further improve the value proposition. At $0.10/kwh, the 300 kw DFC power plant has a
gross annual revenue of about $250,000. This value doubles to $500,000 with hydrogen co-product
assuming $8/kg.
in e
70 ® /Turb
DFC
®
DFC-H2 ed
Combin
ll® Cyc le
FuelCe
EFFICIENCY, %(LHV)
50 Direct
M FC Coal/
PA/PE Engine
s bine s
Ga s Tur Steam
30
es
rbin
ic rotu Average
M
U.S.
Fossil Fuel
10 Plant = 33%
0.01 0.1 1 10 100 1000
SYSTEM SIZE (MW)
Figure 1 – High Efficiency for Distributed Generation of Power and H2
FCE is developing Electrochemical Hydrogen Separation (EHS) systems to recover the hydrogen
from high temperature fuel cell anode exhaust with relatively low energy consumption and without
pressurization. The separation process (and overall system) is virtually emission-free. A 25-cell
sub-scale EHS stack developed by FCE has been operated for over 10,000 hours at the Global Fuel
Cell Center, University of Connecticut. The cell and stack hardware have been successfully scaled to
1000-cm2 and validated in a 6500 hour test. A full-area 100-cell stack has been fabricated and
assembled as shown in Figure 2. The stack has the capacity of 75 lbs/day of hydrogen production.
Figure 2 – 100-cell EHS Stack in Operation at FCE
Page 2 of 4
The acceptance testing of this stack began in mid-summer with very encouraging test results. EHS
cells operated in the laboratory using simulated DFC anode exhaust gases indicate significant
savings in operating costs (30-60%) are possible when compared with today's commercially
available hydrogen separation systems. Further scale-up of the EHS system to integrate with FCE's
DFC300" power plant is underway. For best efficiency, the integration of the EHS with a DFC
power plant requires maximizing the hydrogen and minimizing the carbon monoxide in the DFC
anode exhaust gas. Laboratory scale testing of a DFC and EHS unit with an H2 Booster, which
converts CO to H2 and CO2, has been performed at FCE for over 2000 hours.
The overall system is shown in Figure 3.
Figure 3 – Overall Configuration of Co-Produced Hydrogen and Electricity
This multi-purpose power plant is expected to produce 250+ kW of net electricity and enough
hydrogen to support a fleet of up to 300 fuel cell vehicles and fork lifts, over 500 vehicles if plug-in
battery power is included.
Current Status
The cooling train with water gas shift (H2 Booster) has been built and delivered to Fuel Cell Energy
for testing. Two hydrogen separator systems are currently under construction. Once delivered to
FCE, these units will be tested in preparation for a future field installation. A demonstration of
hydrogen co-production using anaerobic digester gas is being planned for 2009.
Two types of hydrogen purification solutions are being developed. The first system will be based on
an advanced pressure swing absorption (PSA) technology from Air Products and Chemicals, Inc.
PSA technology is well proven, commercially available technology and high performance of the
system had been verified by Air Products in their testing facilities. It is based on separation of CO2
from hydrogen after compressing the conditioned DFC anode exhaust gas to 100 to 300 psig. The
PSA based hydrogen co-production system will be tested at FCE this year and then deployed in
California for long term field testing.
Page 3 of 4
The second purification system based on electrochemical hydrogen separation discussed above will
have its major components tested this year also with field test planned for later next year. EHS
offers a higher efficiency method of separating hydrogen from the low pressure, dilute anode
exhaust stream due to its lower power usage. This system is highly modular and hence phased
expansion of hydrogen capacity is easily achieved.
A comparison of these two separation systems is shown in Figure 4
Comparison of PSA and EHS system operating on
Biogas
Units PSA EHS
Overall Efficiency (without waste heat) LHV 63% 66%
(Net Power + Hydrogen Product) / (Fuel)
Power Efficiency LHV 47% 53%
Net Power / (Total Fuel – Hydrogen Product)
Hydrogen Efficiency LHV 73% 85%
(Hydrogen Product – Purification Power) / Hydrogen Product
Hydrogen Product Nm3/hr ~76 ~70
Net Power w/o & w Hydrogen kW ~300/245 ~ 300 / 271
Biogas (ADG) Flow Nm3/hr ~125* ~120*
DFC performance has no impact from Biogas
* Includes ~70-75 nm3/hr of methane, balance is CO2
Figure 4 – Hydrogen Production Efficiency of up to 85% is estimated
As can be seen in Figure 4, both purification systems offer a unique opportunity to produce
distributed power and hydrogen from renewable fuel with high efficiency and high added value. The
renewable hydrogen and power co-production provides an attractive dual use option for defense and
civilian applications.
Acknowledgements: Financial support from the DOE, DoD, FCE, and APCI is gratefully
acknowledged
Page 4 of 4
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