Hydrogen cars

Last week Tuesday - 27 October 2015, Honda, the Japanese car manufacturer, unveiled the consumer version of its Clarity Fuel Cell sedan, which the company plans to start leasing to the public in March of 2016. In 2013, Hyundai, the Korean car manufacturer, released its ix35 FCEV car, while Toyota released Mirai in 2014. These are not your everyday cars. Instead of using petroleum products (gasoline, diesel) to propel your car (that is, cause your car to move), a hydrogenbased technology is used. Of course, the motivation for wanting to stay away from petroleum is to protect humans and the environment from harmful products of petroleum combustion.

The technology referred to above is the so-called Fuel Cell (FC) technology. Many demonstration vehicles using this technology have also been developed, including Audi A7 h-tron quattroFCEV (2014), Honda FCX Clarity (2008), Honda FCV Concept (2014), MercedesBenz F-Cell (2009), MercedesBenz-F800-(2010), Nissan TeRRA FCV SUV (2012), Roewe 950 Fuel Cell (2014), Toyota FCHV-adv (2008), and VW Golf Hymotion (2014). To appreciate the FC technology, you need to understand how standard, as opposed to Fuel Cell, cars are propelled (moved) by burning petroleum products.

The engine of a standard car is one of the leading technological inventions in human history. It is usually referred to as the internal combustion (IC) engine. The “internal” means that the combustion processes take place inside a chamber - that is cylindrical in shape for the most part. “Combustion” means that something is burned. In the case of a regular car, petroleum and oxygen from the air are brought together, mixed, and made to react and burn when the temperature and pressure of the mixture are significantly raised by compressing the mixture (insider the cylinder) and applying, in the case of gasoline, a spark to the mixture. In the case of diesel, the pre-burn pressure is high enough that you do not need a spark plug to ignite the mixture.

As the fuel-oxygen mixture burns, the high pressure that develops in the cylinder pushes the piston of the engine, which in turn, moves the connecting rod that rotates the crankshaft, causing the tires of your car to also rotate and move your car forward or backwards. Thus, combustion takes place when fuel, most commonly a fossil fuel, reacts with the oxygen in air to produce heat.

As you can imagine, combustion has been with us since the beginning of time, and it is the process used to create fire for cooking your food. In the primitive realm, the fuel that mixes with oxygen to create heat and fire comes from wood, whereas in more modern approaches, the fuel is propane, which is usually contained in a tank before it is released in a controlled manner and made to combine with oxygen from the air, to bring about combustion and the heat needed to cook your food. The engines that drive commercial aircraft also operate on the principle of combustion, except that aviation fuel is more like kerosene.

With petroleum as the fuel in IC engines, the results of combustion, other than heat and water, include carbon monoxide, carbon dioxide, and oxides of nitrogen, all of which are very hazardous to either human health and/ or the ozone layer in the atmosphere. So, you can appreciate the need for “green” technologies that do not generate these compounds.

The FC technology is one of those green technologies. For all practical purposes, it involves an electrical means of moving a vehicle, similar to batterypowered vehicles. With the appropriate means, energy can always be converted from one form to another. Hence, if you have energy in the form of electricity, you can always get mechanical energy that moves, in the current case, the crankshaft and hence the tires of your car. (In contrast, in petroleum-powered vehicles, chemical energy resulting from combustion is converted to mechanical energy for moving the crankshaft.) In FC, the electrical energy comes from decomposing hydrogen into atoms and electrons via some electrochemical process.

The by-products of the hydrogen decomposition process in FC are water and heat; no more, no less. Thus, FC cars do not have tailpipe emissions as do your standard cars. FC vehicles are considered zero-emission vehicles. They are great for indoor applications where air quality is of paramount importance to people; hence, the motivation to use FC to power industrial forklift trucks. On the other hand, for example, petroleum-based cars generate 60% of the carbon monoxide and 20% of the greenhouse gas emission products in the U.S. in 2009. In addition to its zero-emission feature, FC vehicles are known to generate greater power per unit of fuel consumed, and to give longer range and better fuel economy than fossil fuel-powered vehicles.

There are numerous other uses of FC in locomotion, even if only at the demonstration stage, including the Mercedes-Benz FC buses, Yamaha FC motorcycles, Boeing FC demonstrator airplane, the Hydra FC boat, the FC submarines of the German and Italian navies, and the China South Rail Corporation’s hydrogen-fuel-cellpowered tramcar in Qingdao. In aircraft surveillance applications, the low noise, low thermal signature, ability to attain high altitude, and the capability for long endurance, make FC vehicles, unmanned or otherwise, to be very attractive.

Critics of the FC technology are many, as some do not feel it can ever compete with regular fossil-fuel powered technology. Some of the critics point out that the process of creating hydrogen itself generates as much emission of carbon as does today’s gasoline cars, and is anemically inefficient. Also, hydrogen infrastructure (refueling stations) is scarce, and presently FC cars are twice as expensive as standard cars with comparable features.

In closing, be aware that hydrogen is also being tested as the fuel in IC engines.