First published in Cleantech magazine Fuel Cell Special Sept/Oct 2010
Dr Denis Gross reviews the history of fuel cells
Fuel cells have been with us for over 150 years, although for many decades at a time they have slipped into the background. The first attempted application area was as an alternative to the internal combustion engine, with sustained research work carried out in the 1860-1880 timeframe. Well into the 20th century the electric car was seen as a serious contender, until Ford’s mass production of internal combustion engine automobiles dimmed the lights on most forms of self-propelled electric transport. Even at that time there was no fuel cell technology available that could have competed against either the petrol-driven vehicle or battery power. By the 1960s, however, fuel cells were successfully used in manned spaceflight, and they continue to be utilised in aerospace applications. The third wave of fuel cell technologies has been building up since the 1990s, driven by growing global pressure to meet increasingly rigorous environmental requirements.
The first basic fuel cell was built and demonstrated by Sir William Robert Grove, FRS, building upon the work of German chemist Christian Schönbein. Schönbein, who is credited with a number of discoveries, including the ozone molecule, in the course of experiments involving the electrolysis of water, published a paper on the reaction of hydrogen and oxygen in the ‘Philosophical Magazine’ in 1839. Grove called the first device, which he subsequently developed in 1842, a gas voltaic battery – effectively a fuel cell, although it was still not named as such.Swansea-born Grove was for many years Professor of Physics at the London Institution. He developed the Grove Cell, a battery technology that comprised zinc and platinum electrodes exposed to sulphuric and nitric acids separated by a porous ceramic pot. This battery enjoyed a degree of commercial success and was used in early telegraph stations.
The invention of the fuel cell was based on the idea of reverse-electrolysis – i.e. if water can be split into hydrogen and oxygen by means of electricity, then the process of combining hydrogen and oxygen should generate electricity. Using platinum electrodes in two small upturned glass vessels, one containingoxygen and the other hydrogen, and both immersed in an electrolyte (dilute sulphuric acid), a voltage was generated between the two. By linking several of these cells together in a ‘gas battery’, higher voltages could be obtained.
The term ’fuel cell’ did not emerge until 50 years later in 1889. It was first adopted by Ludwig Mond and Charles Langer, two chemists, when they attempted to build the first practical ‘gas battery’ device using air and industrial coal gas.
There followed a hiatus of over half a century with little development taking place in fuel cells while the world saw the mass adoption of the internal combustion engine. However, in the 1930s the Mond/Langer fuel cell concept of 1889 was revisited by Francis Bacon at Cambridge University. Bacon made a number of changes to the design, including the introduction of nickel gauze electrodes and the use of potassium hydroxide as the electrolyte, replacing sulphuric acid which corrodes the electrodes. This ‘Bacon Cell’, developed in 1932, was the forerunner of the alkaline fuel cell (AFC). It took Bacon almost thirty more years to achieve an operational fuel cell, but by 1959 he demonstrated a fuel cell that could generate 5kW of energy.
Interest in fuel cells was revived by the space race that followed the former Soviet Union’s launch of Sputnik in 1957, and by manned spaceflight in particular. NASA used fuel cells in the Gemini Earth orbit space capsules and in the Apollo moon landing missions in the 1960s and 1970s. The AFC technology pioneered by Bacon was licensed by Pratt and Whitney and used for Project Apollo: it remains the standard aerospace fuel cell. Meanwhile, General Electric (GE) developed another fuel cell technology in 1955-1959, the proton exchange membrane (PEM) fuel cell, which was used on the Gemini missions in the first half of the 1960s. Both fuel cell types used oxygen and hydrogen (although liquefied for storage). In addition to supplying electrical power for the spacecraft, these fuel cells also provided drinking water for the space crews.
NASA’s focus on fuel cells was driven by the need to find a solution to the problem of powering the series of manned spaceflights. Batteries were ruled out at the outset owing to weight and reliability considerations. Solar energy was too nascent and thus inefficient and expensive at that time, and nuclear power, while used in satellites, was determined to be too risky in this context. The fuel cell was proposed as a possible solution, and consequently NASA sponsored efforts to develop practical working fuel cells that could be used during these flights.
In 1955, Willard Thomas Grubb, a scientist working at GE, used a sulphonated polystyrene ion-exchange membrane as the electrolyte rather than a dilute acid or an alkali. In 1958, fellow GE chemist Leonard Niedrach devised a way of depositing platinum on to this membrane, which ultimately became known as the ’Grubb-Niedrach fuel cell’. GE and NASA developed this technology together and it was used on the Gemini space project. Pratt and Whitney, the aerospace engine manufacturer, licensed the Bacon patents for the AFC in the early 1960s and significantly improved the original design, developing a fuel cell that demonstrated a longer life than the GE PEM. As a result, Pratt & Whitney won a contract from NASA to supply these fuel cells to the Apollo spacecraft. Alkali cells have since been used on the Space Shuttle.
During the 1970s, the focus of fuel cell technology shifted to systems on Earth, in large part driven by the oil crises in 1973 and 1979. Soaring oil prices focused research efforts on fuel cell technology as the U.S. Government sought ways to reduce dependence on petroleum imports. By 1966, however, the GM Electrovan had already demonstrated the use of hydrogen fuel cells for ground transportation. That vehicle was in essence a 1966 GMC Handivan powered by Union Carbide PEM cells, which were fuelled by super-cooled liquid hydrogen and liquid oxygen. GM’s special engineering team of 250 developed the Electrovan for over two years before attaining a driveable vehicle.
As a consequence of the oil crises, the impetus for fuel cell development grew. A number of companies and government organisations began serious research into overcoming the obstacles to widespread commercialisation of the fuel cell. Throughout the 1970s and 1980s, a large research effort was dedicated to developing the materials needed, identifying the optimum fuel source and drastically reducing the cost of this technology. During the 1980s, fuel cell technology began to be tested by utilities and automobile manufacturers. Technical breakthroughs during the decade included the development of the first marketable fuel cell-powered vehicle in 1993 by the Canadian company, Ballard, using PEM technology.
Today’s interest in fuel cells, as a response to pressures on resources and the associated environmental problems of a hydrocarbon-burning economy, stems from a number of factors, including:
• Their high energy conversion efficiency;
• Their generation of minimal emissions other than heat;
• Their ability to provide a continuous and reliable source of energy.
The challenges of the 21st century – particularly fuel security, climate change and environmental pressures – are opening up a host of opportunities for fuel cells. Thus today, fuel cells are being developed to address three markets: zero emission vehicles, off-grid and distributed power generation and fuel cells for portable consumer and defence electronics.
The hydrogen highway, if successfully rolled out, will create a massive demand for fuel cells in transport. Hydrogen fuel cells have seen applications in a number of vehicle types – cars, vans, buses, forklifts, bikes, scooters, submarines, ferries, electric boats and aircraft.
Although less high profile than their applications in transport, fuel cells are also being used for a broad range of stationary power purposes, including emergency power supplies and UPS, combined heat and power (CHP) and off-grid power for telecommunications – as well as industrial and recreational vehicles. The range of fuel cell technologies has also increased, and includes solid oxide and molten carbonate types with attributes for stationary power.
Fuel cells have been around for a long time and have travelled further than most technologies, but the pace of technology adoption has now reached a critical point and the fuel cell industry is – finally – approaching maturity.
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