150W Portable Direct Methanol Fuel Cell Power Supply/Battery Charger Lawrence J. Gestaut Cecelia Cropley Giner Electrochemical Systems, LLC Newton, MA 2005 Joint Service Power Expo Tampa, FL - May 4, 2005

Why Fuel Cells? Fuel cells … can offer quiet operation, a lower heat signature, fuel efficiency, … supporting communications, surveillance and other electronic equipment. - Fuel Cell Today, April 20, 2005

Battery Logistics “Marines reported they were down to less than a 2-day supply” of primary batteries during OIF combat operations. “CECOM officials said they were developing newer, lighter-weight rechargeable batteries…to reduce dependence on disposable batteries.” US GAO “Actions Needed to Improve the Availability of Critical Items during Current and Future Operations”, April 2005, pps. 90,95

Battery Limitations Portable power is critical, but –Batteries can not provide increasing energy demands –Primary batteries are a logistic and cost concern –Secondary batteries require a portable and reliable charger

What is a Direct Methanol Fuel Cell? CH 3 OH + H 2 O → CO 2 + 6H + + 6e - 3/2 O 2 + 6H+ + 6e - → 3H 2 O CH 3 OH + 3/2 O 2 → CO 2 + 2H 2 O No compressed hydrogen– No reformer

Applications Small systems –20 W battery replacements Mid systems –150 to 500 W generators/chargers Large systems –2 to 5 kW diesel generator replacements

Types of DMFC Small Systems Natural air convection Passive water management Passive cooling Low current density >30% methanol possible Generally planar cells

Small System Toshiba 12W/20W peak Photo from Fuel Cell Today

Types of DMFC Mid & Large Systems Discrete components Forced air Active water management Active cooling Moderate current density Dilute methanol water mix

Types of DMFC Large Stacks & Systems 800 W System 1.5 kW Stack

GES Approach to DMFC Bipolar stack, operating at high power density Neat methanol fuel, on-board dilution Operate at 60-70°C Near-atmospheric air supplied by blower

DMFC Schematic

Direct Methanol Fuel Cell (DMFC) 6.8 kg 10 liters

DMFC Operation Transportable Rapid start Load following Low thermal signature

DMFC Refueling Liquid fuel Refuelable “on-the-fly”

Advantages of DMFC High system energy density Safe and easy transport Long membrane lifetime Reactant humidification is not required

Fuel Comparison 1500 W-hr (includes tank) Neat CH 3 OH 2000 psig cylinder Metal hydride canister Volume1.5 liters8.8 liters4.5 liters Weight1.25 kg13.2 kg (80 g H 2 ) 6.8 kg Refillable by User? YESNO

Disadvantages of DMFC Lower cell voltage and lower current density – Larger stack, but light and compact Fuel efficiency – Currently ~17%, – Forecast ~25%

Fuel Cell Performance Comparison

I = 9A Primary Batteries Comparison

GES 150 W DMFC 6.8 kg 10 liter 3 hours operation with stored fuel Rapid start Excellent load following

Future Development Reduce stack weight and volume by > 25% –Increase power density Improve catalysis and structures Improve mass transfer Reduce methanol crossover –Improved Stack Design Lighter/thinner end and bipolar plates

Improve reliability, durability and ruggedness Store and operate over military temperature range Reduce thermal and acoustic signatures Decrease unit size and weight Systems Engineering Issues

Projected Metrics Mass (kg)Volume (l) 150 W W kW18.135

Conclusions 150W DMFC provides >60% weight reduction compared to primary batteries for 72-hour missions DMFCs have many advantages including ease of fueling DMFC could be fielded in the near term

Acknowledgements DARPA Army Research Laboratory Jet Propulsion Laboratory Parker Hannifin