Hydrogen is a simple atom/molecule and the most abundant element in the universe.
As a physicist it is an an article of faith with me that mankind will eventually make large scale use of hydrogen as a fuel. As a realistic physicist I also acknowledge that such large scale use of hydrogen is a number of years away.
The device that will convert hydrogen into a major energy source is the fuel cell, which is an electrochemical device that combines hydrogen and oxygen to produce electricity, with water and heat as its by-product. First invented in the 19th century, today there is extensive research and a large and growing literature on fuel cells.
In its simplest form, a fuel cell consists of two electrodes – an anode and a cathode – with an electrolyte between them.
When cells are stacked in series the output increases, resulting in fuel cells with power capacities ranging from several watts to several megawatts. A fuel cell system that includes a fuel reformer can obtain hydrogen from any hydrocarbon fuel such as natural gas, methanol, or gasoline. Since fuel cells rely on an electrochemical process and not combustion, emissions from fuel cells are significantly lower than emissions from even the cleanest fuel combustion processes. Fuel cells are also quiet, durable, and highly efficient. They are different from batteries in that they require a constant source of fuel and oxygen/air to sustain the chemical reaction; however, fuel cells can produce electricity continually for as long as these inputs are supplied.
My enthusiasm for hydrogen goes beyond my physics daydreaming: I often refer to it as the ultimate energy storage system. For example, what does a utility do with excess electricity generated by wind turbines at night when the wind is often strongest and consumer demand for electricity is lowest. The simple answer is to store it for delivery during the next day when demand and electricity prices are higher. Of course, storage is not energy- or cost-free, and still expensive today. My attraction to hydrogen is that excess electricity can be used to electrolyze a common substance (water) into hydrogen and oxygen and the hydrogen can be stored and used in fuel cells which transmit their generated electricity to consumers in many locations via power lines. No need to transport hydrogen via pipelines which are inherently expensive and often hard to site, and these pipelines have to be impervious to leakage by the tiny hydrogen molecule, unlike more standard fossil fuel pipelines. The kickers in this game are that water has to be available and the efficiency of electrolysis devices needs to be improved to reduce the cost of hydrogen production.
A fuel cell is a transformative technology that changes the way we generate and use electricity, a characteristic it shares with solar PV. It can be used in small and large sizes, in mobile and stationary applications, and has several technological foundations (proton exchange membrane, phosphoric acid, solid oxide). The hitch in fuel cells is cost reduction, a tough problem to address, and they’re competing as storage devices with lithium ion batteries which are steadily getting cheaper. Flywheels, when mass produced, may also offer some competition.
I’ve been following fuel cell development issues for almost forty years, since arriving in Washington, DC, and cost seems to be the major barrier to their large-scale use. Lots of effort is going into related research, including how to mass produce cheaply. The U.S. Department of Energy is supporting this effort both for mobile applications (i.e., cars) and larger stationary applications.
Considerable effort is also going into development of micro fuel cells that can be used to power cell phones, laptop computers and tablets – all of which can benefit from longer-lasting portable power supplies. These will probably be fueled by replaceable alcohol-water cartridges where the alcohol (ethanol/C2H5OH or methanol/CH3OH) supplies the needed hydrogen. For example, one mixture under investigation is 35% methanol in water. Such a micro fuel cell could provide ten hours of laptop time, although some computer tablets today achieve that goal. The reason for not going above 35% is that methanol interacts chemically with common anode and cathode materials and degrades the fuel cell. Nanotechnology may offer new material options, allowing this percentage to increase. An interesting aspect of alcohol use in micro fuel cells is that alcohol, being flammable, requires a waiver to be brought onto airplanes. Ethanol clearly has such a waiver as witnessed by drink service on most aircraft. Methanol only recently obtained such a waiver.