INTRODUCTION
Recently, as you may be well aware (!), there has been a lot of hype surrounding hybrid cars and fuel consumption. This has all been sparked by the discovery of global warming, the idea that releasing CO
2
and other greenhouse gases into the atmosphere causes damage to the earth’s ozone layer which will warm the temperature of the earth’s surface and atmosphere.
Since this breakthrough, all different car manufacturers have been frivolously working to reduce the CO
2
emissions across their fleets of vehicles. Many different methods have been tried and tested for reducing the amount of carbon produced for every kilometre travelled. Some of these methods are:
· Air injection - injecting oxygen into the exhaust system to finish the burning of any unburned hydrocarbons [1].
· Exhaust Gas Recirculation - allows a small amount of exhaust gas back into the combustion chamber which eliminates oxides of nitrogen produced, this has an adverse effect on engine performance [2].
· Catalytic converters - located just above the exhaust pipe, its primary function is to allow another space for combustion to take place. The idea is that any unburnt hydrocarbons with combust here into carbon dioxide and water [3].
· Hybrid/electric vehicles - These use either just electric power, charged up through the mains, or a combination of electric and petrol engines. Some use the electric to keep the car running when idling and other just use the petrol engine to charge the electric ones [4].
There is now a new type of engine uprising: the Hydrogen Fuel Cell!!!
TECHNOLOGY
The Hydrogen Fuel Cell uses simple technology to convert the hydrogen, stored in a pressurised tank, into electricity (stored in a battery) which then turns an electric motor to power the vehicle.
· Hydrogen is fed into the fuel cell and, because of its simple structure (1 proton, 1 electron), is then separated into protons and electrons with the help of a catalyst
· The electrons are then channelled through a circuit as electricity which stored in a battery
· The protons are bypassed around this part, but then join up again with the electrons, which are both then reacted with oxygen in a condenser to produce water
· Heat and water are the only by-products of this series of reactions and so the process is incredibly efficient [5]
One of the main researchers into this technology is Honda. Their first fuel cell was developed in 1999 and since then they have been pioneering to get a hydrogen powered vehicle onto the road and into production [6]. Since these first fuel cells were developed,
Honda has spent a considerable amount of their resources on development and increasing efficiency and safety. Throughout the whole operation, they say that safety was ‘top of mind’ when they decided to put their first hydrogen powered vehicle on the road [7].
BENEFITS
Throughout the use of hydrogen fuel cells, only water vapour is released into the air. This means that it is one of the cleanest methods for transforming chemical energy into

electrical energy. Also the fuel used (Hydrogen) is the most abundant element on earth making up around 75% of all matter by mass [8]. This means that here is no shortage of the fuel needed. At the moment, the main fuel types (petrol and diesel) come from hydrocarbons that make up oil. This means that the earth’s supplies of oil are rapidly decreasing and so there is another major concern for us, who rely on it so much. By using hydrogen as a fuel, we are saving our oil supplies and so are not using the earth’s resources.
DRAWBACKS
Hydrogen exists mainly as a gas in the universe. To be stored, so that it can be used as a fuel, it has to be stored as a condensed liquid. This means that it is under a high pressure and so could cause safety risks. This is hard to do and so this is the main reason why development in this field has taken a long period of time.
The main drawback with using hydrogen though, is safety. This is why Honda put such a focus on it in their development, and the reason why the industry standard for anything using hydrogen is very high. The main safety hazards are:
 Liquid hydrogen is a cryogen and so presents dangers such as frostbite that are commonly associated with cryogenic materials [9]
 Hydrogen has the ability to dissolve many metals and so can leave holes and cracks in fuel lines and tanks that could lead to explosions [10]
 Hydrogen reacts strongly with oxygen in the air and so can spontaneously ignite if leaked out of the fuel tank. Also the flames produced are often invisible and so other hazards are created [11]
 Because of the nature of a vehicle travelling at high speeds, where collisions with other vehicles will inevitably happen at some point in the cars life, there has to be additional safety measures in place. The Honda FXC Clarity has a system controller that automatically shuts off all flow of hydrogen and the electric current in the event of a crash [12]
As you can see, there are many safety issues with using hydrogen as a fuel. This is the reason why years of testing have been carried out at Honda and other major car manufacturers to reduce the risk of any of the above taking place.
REFUELLING
When you come to refuel your hydrogen fuel cell car, it is just the same as refuelling a normal internal combustion engine. You drive up to the pump, and fill the tank up using the nozzled-hose. Hydrogen is stored in a large tank in the fuelling station just the same as any other fuel. It is sold per kilogram rather than per gallon/litre, and the fill-up only takes several minutes. A fuel tank of hydrogen will last for up to 240 miles [13].
Hydrogen filling stations are being introduced in some states of America, where the FXC
Clarity is being tested with various users [14]. The likelihood is that as the industry for hydrogen powered vehicles grows, many more filling stations will come into being.
Again Honda is looking into the future. They have created something that at the moment is being put through the testing phase of development. They call it the ‘Home Energy
Station’. Its aim is to increase the number of accessible fuelling stations for hydrogen. The idea combines the need for Hydrogen fuel for your car and also the need for reduced emissions in the energy used by houses. Honda claim that using the Home Energy Station reduces the carbon dioxide emissions by 30% compared to a house using a car running on petrol and commercial electricity and heat [15]. The Hydrogen used by the system comes from natural gas which is supplied to many houses across the world. The Home energy

system, at the end of its testing and development could, therefore change the way we heat our homes, get our electricity, and power our cars: the future!
[1] http://www.car-emissions-explained.co.uk/2011/01/air-injection.html
[2] http://www.car-emissions-explained.co.uk/2011/01/egr-valve.html
[3] http://www.car-emissions-explained.co.uk/2011/01/catalytic-converters.html
[4] http://www.car-emissions-explained.co.uk/2011/01/alternatives-hybrid-cars.html
[5] http://automobiles.honda.com/fcx-clarity/vflow.aspx
[6] http://automobiles.honda.com/fcx-clarity/fuel-cell-evolution.aspx
[7][12] http://automobiles.honda.com/fcx-clarity/hydrogen-safety.aspx
[8] http://en.wikipedia.org/wiki/Hydrogen
[9] http://www.hydrogenandfuelcellsafety.info/resources/mdss/Praxair-LH2.pdf
[10][11] http://en.wikipedia.org/wiki/Hydrogen#Safety_and_precautions
[13] http://automobiles.honda.com/fcx-clarity/refueling.aspx
[14] http://www.washingtontimes.com/news/2009/aug/24/hydrogen-powered-vehicles-on-horizon/?page=2
[15] http://automobiles.honda.com/fcx-clarity/home-energy-station.aspx