The hydrogen fuel cell is about 50% efficient, double that of a petrol engine. The combination of this efficiency and the new, and much more efficient, architecture creates a vehicle which is more sustainable because it needs far less hydrogen energy.
Further fuel and emissions savings are gained because,unlike an internal combustion engine, the electric motor is not running when the car is stationary in traffic.
The Riversimple technology demonstrator uses a 6kW fuel cell (For comparison, Honda is using a 100kW fuel cell in its FCX Clarity model currently being trialled in California - admittedly in a four seat car). In the Riversimple car, less hydrogen needs to be carried (and less held at the filling stations) and the cost of the fuel cell drops dramatically.
We have been working with Horizon Fuel Cell Technologies of Singapore, who have developed a highly efficient yet simple fuel cell system for our local car. As the output required of the fuel cell is less than in most fuel cell prototypes, Horizon has been able to prioritise cost reduction in the development of the system. This has been the focus of their research since they were founded and gives a natural synergy between their technology and our approach to commercialising hydrogen fuel cell vehicles. Together we are pursuing a combined development programme on the next generation of fuel cell for our production prototype vehicle.
The super-capacitors which store electricity can also be smaller; our cars have just 21kg of super-capacitors, capable of absorbing over 30 kW of
power from regenerative braking, and of delivering 15kW for bursts of acceleration of up to ten seconds, enough time to reach maximum cruising speed.
The result is a car with a fuel consumption equivalent to 300 miles per gallon on petrol, a range of 240 miles, a top speed of 50mph, and greenhouse gas emissions at 31gCO2/km (well to wheel) from hydrogen derived from natural gas - less than a third of the most efficient diesel and petrol-engined cars currently available. If renewable sources of hydrogen are used, the CO2 emissions become negligible.
Note: The 2012 Hyundai i20 CRDi Blue is currently the lowest emission car available at 84gCO2/km but this is only “tank to wheel” – when extraction, refining and distribution of the diesel is included this rises to 100gCO2/km “well to wheel" (using CONCAWE figures).