The two ways in which hydrogen can be employed: Honda FCX Clarity Vs BMW Hydrogen 7

At the heart of the FCX Clarity is a fuel cell stack – a device that uses an electrochemical reaction between hydrogen (H2) and oxygen (O2) to convert chemical energy into electrical energy to power a motor that drives the car’s wheels. Honda’s FC stack simultaneously generates electricity and water, emitting no CO2 or other harmful emissions.



A new dedicated fuel cell vehicle assembly line has been established for the production of FCX Clarity, which includes processes unique to a fuel cell car, such as the installation of the fuel cell stack and hydrogen tank.



The fuel cell stack itself is produced at Honda Engineering Co., Ltd. (Haga-machi, Haga-gun, Tochigi Prefecture). In manufacturing fuel cells, exclusively designed automated equipment was introduced to ensure quality of the highest precision while enabling mass production of cells, with several hundred cells required for each fuel cell stack.



As well as its work with hybrid technology and other alternative energy solutions, Honda has been at the forefront of developing fuel cell systems since 1989. Honda was the first manufacturer to receive commercial certification for a fuel cell car and has 10 previous-generation fuel cell vehicles in experimental use around the world – more than anyone else.



And while the start of FCX Clarity production is a significant milestone for Honda, the company’s short-term focus is the continued development of its low emission, petrol-electric hybrid vehicles.



Not all hydrogen cars are the same

In order to inform, educate and dispel some of the myths associated with hydrogen fuel, we've put together the following fact sheet, which compares just two ways in which hydrogen can be employed.

	Hydrogen-fuelled fuel cell technology (as used by Honda FCX Clarity)	Hydrogen-fuelled internal combustion engine (as used by BMW Hydrogen 7)
Concept	Honda’s V-Flow FC Stack combines hydrogen fuel with oxygen to create electricity via a chemical reaction. This powers an electric motor, that delivers drive to the car’s wheels	Hydrogen fuel is burned in an internal combustion engine, which creates power to drive the car. It’s a tried and tested technology that’s been around for 100 years. We know it works
Fuel	Uses only hydrogen as fuel	The BMW H7 can switch between petrol and hydrogen fuel – but that means it is impossible to optimise the engine for petrol or hydrogen, so therefore the engine is never working at its optimum. Also it can run solely on petrol – meaning the user can run the car on petrol the entire time (with CO2 levels of up to 327g/km)
Reliability	Relies on a chemical reaction, not moving parts – but technology is new and further testing needs to be carried out	Continues to use moving parts, but technology is proven
Emissions	A true zero harmful emissions vehicle (only water vapour is emitted from the exhaust)	Zero CO2 emissions, but emits nitrogen oxides (NOx) – albeit low levels) – created by the hydrogen and air mix burned in the engine
Storage	Hydrogen stored as a compressed gas (at 35 MPa in a 171 litre tank)	Hydrogen stored in liquid form stored at -253 Celsius
Storage qualities	The drawback of compressed gas is that energy is used in the compressing of the gas, and in-car storage tanks have to be fairly large in order to carry sufficient amounts of hydrogen	Liquid hydrogen is highly energy intensive as it has to be cooled down to -253 Celsius and therefore it has some storage problems. For example, if left for a period of time without using the car (currently estimated to be 9-14 days), ‘boil off’ takes place, meaning the liquid hydrogen warms up, is vaporised and escapes from the tank. As well as draining the fuel, this also means the car cannot be stored in a contained area for any length of time
Efficiency	When employed as part of a car’s powertrain, fuel cell technology is incredibly efficient at using energy. The V-Flow FC Stack in the Honda FCX Clarity is 60 per cent efficient at using the energy value of its hydrogen fuel. To put that into perspective, a petrol-fuelled hybrid is 28 per cent efficient, while a petrol internal combustion engine is just 18 per cent efficient at using the fuel (all when measured on the LA4 cycle)	Not nearly as efficient as a fuel cell, but we do not have the exact data to provide an exact comparison. It is likely that a hydrogen internal combustion engine is half as efficient as a fuel cell, but that cannot be proven at this time

Source: Honda UK Media Resource