Drive towards home refuelling

Shell is investigating the potential for car owners to fill up their vehicles with hydrogen while parked in their drives.

The energy company’s hydrogen business has formed a partnership with Belgian firm Vandenborre Technologies to develop and market a compact refuelling unit based on electrolysis, where electricity is passed between two electrodes placed in water.

The unit is powered by mains electricity, and converts water from the domestic supply into a slow stream of hydrogen, emitting only oxygen.

Under the agreement Vandenborre, owned by Canadian-based hydrogen technology specialist Stuart Energy, will develop and manufacture the units, while Shell Hydrogen will market the technology, said Stuart Energy’s chief executive Peter Wressell. ‘Shell intends to carry out a study to determine the most appropriate way for the units to be used – at petrol stations or homes.’

The companies plan to begin field testing their first prototype unit within a year. Each unit will produce around 2 meter-cubed of hydrogen an hour, the equivalent calorific value of 3.7 litres of petrol, said Wressell.

‘The idea is that overnight you would fill your car again.’

Questions about the future use of hydrogen power transportation have centred on the difficulty in producing large amounts of the gas in an environmentally friendly way.

There are also problems with transporting hydrogen and storing it at fuel stations. This system is designed to exploit excess power in the National Grid that would otherwise not be put to good use.

Using power from the mains supply to produce hydrogen means the fuel could only be called emission-free at the point of use, as fossil fuels are still used to generate electricity for the National Grid.

But grid systems cannot be ‘turned down’ overnight, when demand for power is low, nor can they store unwanted electricity until it is needed, said Wressell.

‘The intention is to use off-peak electricity at night, a lot of which the grid system simply dumps because it is easier than storing it.

‘So the idea would be to use some of the low-cost electricity already being generated, and already generating carbon dioxide, but put it to good use.’

As the unit itself would not produce carbon dioxide when converting water into hydrogen, the net effect would be a reduction in emissions, he claimed.

Hydrogen and oxygen bubbles generated in the pressurised electrolyser when direct current is applied are collected separately. The gas is then separated from the electrolyte solution before flowing into the outlet connections. The hydrogen and oxygen produced by the units will not contain contaminants such as sulphur that can degrade the performance of fuel cells, according to Stuart Energy.

A spokesman for Shell said the partnership between the two companies is designed to investigate the potential of home refuelling, to determine whether it will be attractive to drivers.

‘We will be testing it in a European market, and obviously one of the things that will determine whether drivers want it will be the cost,’ he said.

In April Shell opened its first hydrogen refuelling station in Reykjavik, Iceland, and later this year the company plans to install a hydrogen dispenser at one of its existing petrol stations in Washington DC.