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Fuel Cells: Batteries of the Future?

Research has actually shown that in recent years, there are over fifteen billion batteries produced every single year. On the surface, batteries may not appear to be causing any pollution when being used. However, batteries actually do contribute to the overall pollution. If one were to look at the amount of pollution caused by batteries in the context of their entire lifespan — from the time when miners retrieve the raw materials for their construction through their use on applications up to the time when owners haul them to the dump, the amount of pollution produced is significantly high, considering the number of batteries produced each year.

First of all, in the production process, the mining process used to produce the material for the batteries makes them big contributors of lead emissions. Thus, lead pollution stemming from production of the battery will contribute significantly more carcinogens and other toxins to people and the environment.

Next, the disposal process also proves to be harmful for the environment. The metals used in batteries vary considerably and they include mercury, lead and cadmium, which are considered as hazardous waste, as well as nickel, copper, zinc, manganese and lithium. Although nickel, copper, zinc, manganese and lithium are not hazardous, the pollution produced when mining and extracting them from underground does harm the environment already. In the process of incineration, the metals used in batteries contribute to air emissions and pollute via incineration residues. When batteries end up in landfills, the metals contribute to the leach from landfills.

On top of that, battery acid is toxic, and getting the acid into the groundwater causes serious environmental contamination. Disposable batteries can pollute lakes and streams, as the metals vaporize into the air when burned. Heavy metals in the batteries can leach from solid waste landfills, and the environment and water is exposed to lead and acid. Disposable batteries also contain strong corrosive acids.

Additionally, the large amounts of batteries disposed creates huge amount of wastage, in addition to waste disposed every year. Take for example, in 1997 Americans generated 340 million tons of municipal waste, which averaged 1.272 tons per person. Current programmes such as recycling to reduce wastage are already in place and this therefore shows the need for the world to reduce the amount of waste produced, and at the same time shows the need to conserve the environment.

It is near certain that the results would be staggering if one were to study on the effect of battery waste. It would technically not be possible for billions of battery remnants to be easily or safely break down in an environmentally friendly manner. This causes a huge problem to the environment, and therefore makes it a good reason why fuel cells are a much better alternative.

There are current alternatives, and one innovation would be the rechargeable battery. The development of lead-acid, nickel-cadmium, nickel-metal hydride and lithium-ion batteries has led to the invention of the rechargeable battery. However, while this reduces the amount of waste generated every year, many of these rechargeable batteries suffer from a “memory effect”, which means that the power of the battery reduces after every charge.

How batteries work:

Batteries have two terminals – positive and negative. The negative terminal is where the electrons are concentrated. When the two terminals are connected in a circuit, the electrons flow from the negative terminal to the positive terminal. These electrons are produced internally inside the battery through electrochemical reactions, which produce free electrons.

Electrochemical reactions taking place within the batteries produce the flow of electrons, which is also called as electricity. The reaction can only take place when there is a flow of electrons between the two terminals and if that does not happen, there would be no reactions in the battery and thus no power would be produced.

The first battery was created by Alessandro Volta in 1800. To create his battery, he made a stack by alternating layers of zinc, blotting paper soaked in salt water, and silver.

This battery works when acid molecules in sulphuric acid (H2SO4) break up into two H+ ions and one SO4­­2- ion is the presence of the zinc. Concurrently, the zinc atoms on the surface of the zinc electrode lose two electrons (2e-) to become Zn2+ ions. Following that, the Zn2+ ions combine with the SO42- ion to create ZnSO4, which dissolves in the acid. The electrons from the zinc atoms combine with the hydrogen ions in the acid to create H2 molecules (hydrogen gas). These hydrogen gas bubbles form on the zinc rod. The rod and acid will also start to heat up.

Should a carbon rod (or silver rod) be stuck into the acid, nothing will happen to it. However, if a wire connected the zinc and carbon rod, the electrons from the zinc rod would flow through the wire and combine with hydrogen on the carbon rod instead, resulting in bubbles on the carbon rod. Also, there would be less heat, as some of the heat energy is converted to kinetic energy (for electron motion).

The electrons flow to the carbon rod due to the fact that it would be easier for electrons to combine with hydrogen there. In this battery, there is a characteristic voltage of 0.76 Volts. However, once the zinc rod dissolves completely or the hydrogen ions in the acid are used up, the battery ceases to function.

Alkaline batteries, which are our conventional batteries today, use the same principle for producing the electric charge. However, zinc and manganese-oxide are used as electrodes, and the electrolyte is an alkaline instead.

Case Study: United Kingdom (UK)

In 2001 people living in the UK bought 680 million batteries, and 89% of these were general-purpose batteries. It was estimated that in the year 2000, almost 19,000 tonnes of waste general-purpose batteries and 113,000 tonnes of waste automotive batteries required disposal in the UK.

Currently, only a very small percentage of consumer disposable batteries are recycled (less than 2%) and most waste batteries are disposed off in landfill sites. The rate for recycling of consumer rechargeable batteries is estimated to be 5%.  This means roughly means that for the 20,000 – 30,000 tonnes of waste general purpose batteries generated every year, UK recycles less than 1,000 tonnes.

In addition to that, it was found that the average UK household uses 21 batteries a year. Meanwhile, world wide, 15 billion primary batteries are thrown away every year, and almost all of which end up in landfill sites.

As a result from this case study, it is evident of the harm that waste batteries pose to the environment. As such, the fuel cell could very well be a good substitute for batteries. Should every battery-powered device be powered by a fuel cell, the world will have fewer batteries to dispose.

So what exactly is a fuel cell?

Fig. 3b.1 How a Fuel Cell work

A fuel cell is an electrochemical energy conversion device similar to a battery, but differs in that it produces electricity from an external fuel supply of hydrogen and oxygen as opposed to the limited internal energy storage capacity of a battery. Additionally, the electrodes within a battery react and change as a battery is charged or discharged, whereas a fuel cell’s electrodes are catalytic and relatively stable. This means that the fuel cell is a potentially better alternative, in addition to the fact that it is environmentally friendly. Moreover, fuel cells are especially effective in generating electricity in areas not in a power grid, meaning that no electricity is supplied to them. These areas could be remote areas, or even in space.

For the fuel cell to operate, hydrogen is supplied at the anode, and oxygen is taken in from the surrounding air at the cathode. The equation is as given:

2H2 => 4H+ + 4e- ­ (anode)
O2 + 4H+ + 4e- => 2H2O (cathode)
2H2 + O2 => 2H2O (net overall reaction)

The hydrogen atom would be separated into the proton and electron through the help of a platinum coated catalyst. The proton would then pass through the catalyst and electrolyte to the cathode, whereas the electron would enter the cathode through an external circuit, generating a current. The only by-product of this reaction is water, which can be seen from the equation above. This concept is derived from the reverse principle of hydrolysis.

This reaction in a single fuel cell produces an optimal voltage of 1.1 volts. For the voltage to be increased, many separate fuel cells must be combined to form a fuel-cell stack. In addition, several fuel-cell stacks can be connected to create a fuel cell system that can power larger devices due to a higher voltage being produced.

However, the major limitations of the fuel cell technology would lie in the areas of the storage of hydrogen, cost and the public’s acceptance. Moreover, the generation of hydrogen is still quite dependent on power generated by fossil fuels, making the entire fuel cell system somewhat indirectly dependent on fossil fuel, which is an ironic situation. However, new methods of generating hydrogen that are not dependent on fossil fuels are currently being researched into [e.g. solar-hydrolysis]. However, many of these researches are still in their early stages. Research and advancements in technology has resulted in different kinds of storage systems, such as metal hydride tanks, which are certified safe, making the storage much less of a problem. Currently, fuel cells are extremely costly, which makes it less attractive to consumers. The cost mainly arises from the usage of the platinum coated catalyst. Perhaps if more research is put into fuel cell technology, and an alternative to platinum is discovered, the price of the fuel cell would be greatly reduced. Getting the public to accept this energy resource would be rather tricky since the Hindenburg accident, and this would definitely take some time.

In fact, most problems could be solved with the advancement in technology and over time.

Current Applications

There are many different applications of a fuel cell that has already been developed, although the production and development is on a relatively small scale.

Image 3c.2 A Fuel Cell powered laptop by NEC

Image 3c.1 A Fuel Cell Car by Daimler Chrysler

Firstly, fuel-cell-powered cars could start to replace gas- and diesel engine cars in the near future. A fuel-cell car will be very similar to an electric car but with a fuel cell and reformer instead of batteries. However, some companies are hoping to do away with the reformer by designing advanced storage devices of hydrogen. In fact, Daimler Chrysler has already produced such a car.

Secondly, fuel cells are also used for portable electronics like laptop computers, cellular phones and even MP3 Players. In these applications, the fuel cell provides much longer life than a regular battery would, and it is quickly recharged by a liquid or gaseous fuel.

Thirdly, home power generation is a promising application that is already available in some areas. General Electric offers a fuel-cell generator system made by Plug Power. This system uses a natural gas or propane reformer and produces up to seven kilowatts of power that is enough for most houses. A system like this produces electricity and significant amounts of heat, so it is possible that the system could heat water and help to heat the house without using any additional energy.

Lastly, fuel-cell technology has the potential to replace conventional combustion power plants. Large fuel cells will be able to generate electricity more efficiently than today’s power plants. The fuel-cell technologies being developed for these power plants will generate electricity directly from hydrogen in the fuel cell, but will also use the heat and water produced in the cell to power steam turbines and generate even more electricity. There are already large portable fuel-cell systems available for providing backup power to hospitals and factories. In addition, research at National Technological University (NTU) is ongoing to use fuel cell power plants with desalination plants to minimize wastage of any energy.

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