Fuel Cell Nation

Fuel Cells for UAVs, Part 1

Spider Lion       (Courtesy NRL)        Ion Tiger 

Since 2003 the U.S. Naval Research Laboratory has teamed with Protonex Technology Corporation to produce a series of hydrogen-air fuel cell-powered unmanned aerial vehicles (UAV).

In November of 2005, the NRL conducted its first UAV flight with the Spider-Lion, using commercial parts (such as a paintball gun compressed air tank to hold the compressed hydrogen, and aluminum foil and tubing for a radiator). It flew for 3 hours and 19 minutes, without a payload.

  In 2009 the NRL flew the Ion Tiger, a much larger UAV capable of carrying a 5 pound payload. An October flight stayed aloft for a record 23 hours and 17 minutes, while a November flight set a new record of 26 hours and one minute. The Ion Tiger included a number of improvements, such as a more efficient fuel cell, and custom-fabricated compressed hydrogen tanks.

I thought a comparison of the two UAV fuel cell power plants would show how much a technology can change in four years. The following table summarized what I have found:

In 2005 a UAV could fly without a payload for 3 hours; by 2009 a UAV could carry a 5 pound payload for a full day. Furthermore, the 2009 UAV could carry the 2005 UAV as its payload!

Relative to the 2005 UAV, a 2009 UAV weighed six times as much, but also had six times the power (resulting in the same power density), and carried 12.7 times the energy (for a significantly longer flight duration). By using specialized components, rather using generic components (i.e. a paintball gun compressed air tank to hold the compressed hydrogen, and aluminum foil and tubing for a radiator), the 2009 UAV's fuel cell system level power density was twice that of the 2005 craft.

All in all, this shows the rapid progress possible with a motivated sponsor (NRL) and a promising technology (hydrogen-air fuel cells). I wonder what the NRL will prove in 2013, if they keep on this trajectory!

Mercedes Fuel Cell Vehicle PR Tour - Oops!

Image: © 2009 Daimler AG

Bloomberg has a story titled Mercedes 18,600-Mile Trip Parts With Daimler's Century of Strategy Shifts that describes the plans for three B-Class F-CELL cars to circumnavigate the globe. It involves 4 continents, 14 countries, and more than 20 stopovers with their fuel cell vehicles.

Each car includes:

• A fuel cell stack operating at 80 C
• A lithium-ion battery
• 700 bar (10,000 psi) compressed hydrogen storage
• A single front-drive motor

Cold-start capability is promised down to minus 25 degrees Celsius.

All is well until Bloomberg discusses that "Daimler, which packed fuel cells into the back of a delivery van to create the world’s first vehicle using that technology in 1994." I couldn't believe this, so I found the Mercedes press release Zero-emission vehicle sets off on automotive marathon: Starting shot fired for F-CELL World Drive. Somehow, a Mercedes flack says "Mercedes-Benz recognized this potential at an early stage, launching the first vehicle with fuel cell drive, the NECAR 1, as early as 1994." Mercedes, do some fact checking!

It is very easy to find multiple references to the 1966 GM Electrovan, the REAL first fuel cell vehicle. The Electrovan had 32 1 kilowatt alkaline fuel cell "modules," and had a peak power output of 160 kW. Luckily, it never got recycled, and is at the General Motors Heritage Center near Detroit.

First North American Fuel Cell Ship

(UVic Communications)

In a story titled Greener B.C. research ship to use fuel cells, the 1985-vintage Tsekoa II, once used by the Canadian Coast Guard, is discussed being transferred to the University of Victoria, along with its ongoing retrofit with an all-electric, hybrid drive. The propulsion system consists of:

• Batteries
• Hydrogen-air fuel cells and
• "Low-emission" diesel generators.

As such, the Tsekoa II will apparently become North America’s first hybrid fuel cell and plug-in hybrid ship. No word on the vendors supplying the battery and fuel cell systems, or even the battery type. If it is a Lithium-Ion battery, it will likely be one of the largest transportation-based installations in the world, because Kim Juniper, lead scientist on the project. is quoted as saying "When fully charged, the batteries can supply all the ship's power requirements for up to eight hours."

$22 million (CAN) is going to the power plant changeover. An additional $8.8 million (CAN) is going to to expand the Venus undersea observatory in the Strait of Georgia and Saanich Inlet.

So not only is this project developing a hybrid ship, but it involves hybrid funding sources and sinks: a variety of governmental and private sources are being pooled to fund both fuel cell and oceanography work!

Hydrogen for 65,000 Feet

In 2003-2004 Giner Electrochemical Systems, LLC put me in charge of building a MATLAB/Simulink model that automatically optimized the design of a fuel cell-based power generation system for a stated 2-week high-altitude, long-endurance (HALE) aircraft mission. NASA and other government agencies were convinced that an air-breathing, liquid hydrogen fueled engine would provide the lowest-weight HALE aircraft power plant. Accordingly, they hired us to determine the weight and volume of such a hydrogen-fueled proton exchange membrane (PEM) fuel cell-based system. Other firms optimized the design of alternative power plants, such as a hydrogen-fueled internal combustion engine.

AeroVironment is developing both types of aircraft. In 2005 they demonstrated a 1/4-scale version of their Global Observer HALE aircraft that was driven by a liquid hydrogen-based fuel cell engine. Earlier this month (1/11/2011) AeroVironment's full-scale, liquid hydrogen-fueled, internal combustion engine-based Global Observer took its first flight, lasting four-hours. Ultimately, with its 175 foot wingspan, it will operate for up to a week at 65,000 feet.

Global Observer at at Edwards Air Force Base (EAFB) in California (USAF Photo)

Its always good when the theoretical becomes reality!

Too Much Hype About Fuel Cells

I have been working in technology development for years, most recently in electrochemistry and fuel cells, and see fuel cells' promise in the long term. Unfortunately, too much hype in the near term will lead to the public's perception of them as some form of green Snake Oil, as promises are not kept.

Georgia Tasker in the Miami Herald  has a puff piece detailing a Hydrastax 5000 (five kilowatt) residential fuel cell demonstration in Miami. Demos are good, but some rosy claims are quoted from the National Hydrogen Association (NHA). The NHA's Patrick Serfass is quoted as saying "hydrogen powers 200,000 to 300,000 cellphone towers in the United States." Hopefully, Patrick meant to say "could power", and Georgia merely misquoted him. A brief search shows that a total of 200,000 to 300,000 cellphone towers are estimated to be in the US. I don't think that they all are hydrogen-powered.

Not to beat a dead horse, but for years the public has heard some form of "in 10 years automotive fuel cells will be commercially available..."

Just sayin'.