GUIDE TO FUEL CELL TECHNOLOGY

SLIDE 1

Introduction

The concept behind fuel cells is more than 150 years old, but it wasn't until the advent of advanced materials sciences that they became practical.

Modern fuel cells can be found experimentally powering laptop computers, prototype motorbikes and cars, even homes and zoos. This FastTrack tutorial focuses on motor vehicle applications.

• How Fuel Cells Work
• Fuel Cell Challenges
• Fuel Cell Progress

GUIDE TO FUEL CELL TECHNOLOGY

SLIDE 2

How Fuel Cells Work

The heart of most mobile fuel cell systems is the polymer or proton exchange membrane, a highly specialized polymer engineered to allow ion exchange across the membrane and in the process enable the movement of electrons.

As atoms of very pure hydrogen gas pass through the membrane, the electron is stripped off, while the proton passes through. That electron and all that follow, generates a current that can be used to excite an electric motor to propel a vehicle, and in the case of a fuel cell hybrid, recharges its batteries and/or supercapacitors.

GUIDE TO FUEL CELL TECHNOLOGY

SLIDE 3

Complex, Costly Technology

While simple in concept, in reality, fuel cell propulsion systems are highly complex, requiring advanced and costly materials, as well as sophisticated software controls. Currently, polymer membranes have to be coated with platinum, a rare element more costly than gold. Work is being done to find ways to use less platinum or to substitute other materials.

Additonally, one of the biggest challenges in automotive fuel cells is water management. Because water is created during the process of generating electricity, engineers have had to develop approaches that prevent the water from freezing and damaging the stack during cold weather. Both Honda and GM have demonstrated stacks that can operate in sub-freezing temperatures down to -30 degrees C (-22 F).

GUIDE TO FUEL CELL TECHNOLOGY

SLIDE 4

Hydrogen Storage Challenge

As steady progress is made in widening the operating envelop of fuel cells, the hunt continues for more practical ways to store the hydrogen. At the moment, compressing the hydrogen to a phenomenal 10,000 PSI is required to give the vehicle sufficient capacity to allow the vehicle to drive more than 200 miles.

Bulky and expensive carbon fiber tanks are needed to safely contain the few kilograms to hydrogen that typically fuels the vehicle. Ideally, a solid-state storage material that is highly absorbant, light-weight and low cost is needed to move the technology beyond its present compressed hydrogen bottleneck.

GUIDE TO FUEL CELL TECHNOLOGY

SLIDE 5

Fuel Cell Prospects

While there are now several hundred cars and a relative handful of buses and even a river ferry being electrically propelled by energy from fuel cells, the consensus is that the technology will need many years and much more research to reach maturity, especially in terms of stack durability and cost reduction.

Major carmakers like Honda and General Motors, along with Toyota, continue to refine their fuel cell systems, forecasting that the technology could become competitive with the internal combustion engine sometime in the mid-to-late 2010s. If and when that happens, a hydrogen refueling infrastructure will have had to be deployed, itself a costly undertaking estimated in the hundreds of billion of dollars.

GUIDE TO FUEL CELL TECHNOLOGY

SLIDE 6

Fuel Cell Advantages

The advantage of fuel cells is they produce no pollution, only warm water vapor. Their 'fuel' -- hydrogen, which is actually a high-quality energy carrier -- is potentially infinitely renewable, unlike today's fossil fuels, especially when created from renewable sources. The result is an electrically-powered vehicle that operates much like a conventional one today, but with none of the associated environmental and geopolitical consequences of our dependence on petroleum.

While work continues on refining fuel cell technology and solving its problems, parallel research is making modern batteries a serious challenger to fuel cells. How this race will end won't be known for at least a decade.