HYDROGEN STORAGE

The quantity of hydrogen produced is a function of the number of photovoltaic modules and specific irradiance of each location. Depending on the quantity of hydrogen produced from the system there are several storage methods suitable for a dwelling in a residential area. The most feasible of these methods appear to be compressed gaseous hydrogen in a series of cylinders or storage tanks.

The storage of hydrogen cylinders or tanks should be located in a secure, external purpose compound, which should be well vented. The water tank, electrolyser and compressor system components will also be located in this purpose built compound. This will protect the cylinders, tanks and the other system components against corrosion and extremes of weather. In compliance with the Building Standards (Scotland) Regulations 1990, the contained hydrogen must have a minimum separation distance of 4.0m from the dwelling if contained by a barrier. A barrier is defined as 'a wall or screen having not less than 60 minutes fire resistance, located 1m and 3m from the tank and extending:-

(a) longitudinally: so that the distance specified above without a barrier is maintained when measured around the ends of the barrier, and

(b) vertically: 2m or the height of the top of the tank, which is the greater.

Cylinders and tanks of hydrogen should be in a location free from fire risk and away from sources of heat and light. Smoking and the use of naked flames either inside or in the vicinity of the storage area should be prohibited. The amounts of flammable or toxic gases in the storage area should be kept to a minimum. Cylinders and tanks of hydrogen should be segregated from cylinders and tanks of different gases, for example LPG cylinders must not be stored within 3m of any compressed gas cylinders or tanks. Toxic and corrosive gases should be stored separately from all other gases by at least 1m, the use of a fire wall can help to provide the required separation.

In terms of handling and use of cylinders and tanks they should be periodically checked for general condition and leakage using a suitable flammable gas monitor which will alert of gaseous build up in the vicinity.

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