Just how far are we from the world of hydrogen-powered transportation? The answer is obvious: pretty far. But the good news is that people can finally see some hydrogen-powered vehicles parked in the dealership lot in several U.S. and Japanese cities. It was once considered the “five years down the road” technology. No wonder many enthusiasts have already given up their hope and thought the mass producing personal fuel-cell cars would never hit the road.
The working mechanism of a fuel cell. Credit: Fuel Cell & Hydrogen Energy Association
The ideal of fuel-cell powered machinery dates back to the 1800s. But it wasn’t until the past century that various types of demonstration units proved that these electrochemical devices could reliably produce electric current. The first commercial use of fuel cells came more than a century later in NASA space programs such as the Gemini and Apollo missions in the 1970s to generate power for satellites and space capsules. Since then, fuel cells have been used in many other applications.
The working mechanism of a fuel cell is quite similar to the batteries. Its electrodes, one positive and one negative, connect through an external circuit and extract electricity from reduction-oxidation reactions. When oxidation occurs at an anode and reductions proceed at a cathode, electrons flow through the circuit, powering the device connected to it, in this case, an electric motor that drives a fuel-cell car. But unlike batteries, which store the oxidant and reductant within the electrochemical package, fuel cells draw oxidizers - air and fuel - hydrogen from the outside. So fuel cells don’t need to be replaced (as often as batteries) or be recharged.
The benefit of using hydrogen fuel cell to cars is obvious. The technology is highly efficient in term of energy transformation, makes vehicles much quieter versus traditional combustion engines, emits low-to-zero pollution (depending on the hydrogen-generation process), has a longer lifespan than conventional batteries, and is power grid independent.
The downsides of this technology are also significant. Fuel cells are expensive to build. The use of precious metal like platinum contributes a lot of the cost. Fuel cell vehicles also require dedicated infrastructures like fueling stations and the hydrogen generation plants. The technology, at least in its current stage, is sensitive to climate, meaning that it is not reliable in too hot or too cold ambient temperature. Containment and safety is another outstanding issue: hydrogen is highly flammable – more so than regular fuel, and is harder to contain than oil. The formidable challenges have many including Elon Musk called the technology impractical and unprofitable.
The auto industry continued working away on the technology, as the first generation fuel cell vehicles are delivered auto dealers’ showrooms. They are also expanding the hydrogen-refueling infrastructure in the U.S. and other countries and continuing to find ways to make the vehicles cheaper and more durable. By continuously gaining engineering and manufacturing experience, the car manufacturers are on track to lower production costs.
Meanwhile, researchers have also been busy with improving the efficiency of fuel cells and reducing or completely avoiding the use of platinum. Many have also working on novel hydrogen storage technologies to reduce the reliance on high-pressure storage and improve the volumetric energy density of hydrogen fuel cells. Those advances hopefully will translate to less expensive, smaller, and more powerful devices that make fuel cell vehicles more practical and assessable to customers.
As vehicle sticker prices get lower and refueling gets easier, more and more motorists will have the opportunity to own fuel-cell passenger cars. Maybe, in the end, we are not as far as we think.
How Fuel Cell Vehicles Work. Credit: Fw:Thinking
Source: C&EN
