Hydrogen and Fuel Cells
During recent ages, the energy demand has increased rapidly. Fossil fuels have covered most of this demand. The associated CO2 emissions contribute significantly to the change of our climate. In addition, our society is seriously threatened by a reduction in the security of supply of energy.
The future energy supply.
In the distant future, fossil fuels will play a minor role in the energy supply, renewable energy sources and nuclear energy will be dominant. For most renewable sources, there will be a mismatch in moments of supply and demand, resulting in a need for energy buffering. And except for biomass, renewable sources as well as nuclear power plants do not provide a fuel that is readily usable in transport (What about battery cars?). In these cases, H2 produced by electrolysis of water is a useful intermediate energy carrier.
For the less distant future, fossil fuels will be dominating the energy supply in large parts of our society. CO2-capture and storage have to be introduced in order to reduce CO2 emissions. This can be realised by the conversion of hydrocarbons to separate streams of H2 and CO2, followed by CO2 storage. Here too, H2 will have an important role as an intermediate energy carrier.
In case H2 is available as an energy carrier, fuel cells are the best technology for production of electricity in many stationary and transport applications. Fuel cells offer unparalleled efficiency and modularity in combination with potentially low cost.
Thus, H2 production, CO2 storage and fuel cells will be technologies of paramount importance, not only for the distant future, but also in the transition from our present fossil fuel based energy supply system to a supply system based on renewable sources and nuclear energy.
Hydrogen versus battery electric vehicles
The statement has been made befor: battery electric vehicles will use electricity from renewable sources more efficiently than fuel cell vehicles, as the intermediate step of hydrogen production is avoided. However, battery electric vehicles do by far not give the same performance as fuel cell electric vehicles. This is highlighted by comparing the Honda FCX Clarity (Fuel Cell) with a typical (battery only) electric vehicle, the (Mitsubishi i MiEV). The comparison shows the superiority of H2 + fuel cell technology over battery electric vehicles. The i MiEV is powered by a 47 kW motor and a 16 kWh lithium-ion battery pack. Top speed is 130 kph and the range is up to 160 km under Japanese 10-15 cycle driving conditions. The much bigger and heavier Toyota Clarity has a 100 kW electric motor, a top speed of 160 kph and a range of 434 km on the more demanding EPA combined drive cycle. In a comparison with internal combustion engines, the Clarity shows its efficiency: this fuel cell car has a tank load of 4 kg H2, with an energy content that corresponds to that of 15.4 litres of gasoline. So, the gasoline equivalent fuel consumption is 27.8 l/100km, not at all bad for a luxury sedan. And it is refuelled almost as fast as a gasoline car as well…
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Will you prefer Hydrogen or a wall socket? The Honda FCX Clarity (left) and the Mitsubishi i MiEV (right) | |
