§ Mr. Skeetasked the Secretary of State for Industry, from studies supported by his Department, if he will indicate in reference to lead acid and sodium sulphur batteries relative weights per unit of output, energy produced by each, input cost of basic materials and the cost of the refrigeration requirements of the latter.
§ Mr. Les HuckfieldAlthough the sodium-sulphur battery is not yet fully developed, it is expected that its weight will be approximately one-fifth of that of a lead acid traction battery producing the same power output. Energy produced is proportional to range which for a practical vehicle is predicted as about 150 miles for the sodium-sulphur propelled vehicle as compared with some 60 miles for a lead acid propelled vehicle. The current cost of the basic materials only for a sodium-sulphur battery is 47p per kilowatt hour, which compares with £12.50 for a lead acid battery, but although production costs of sodium sulphur batteries are not yet known it is clear that they will result in a much smaller cost difference than that for basic materials. The sodium sulphur battery does not require refrigeration; on the contrary, thermal insulation is necessary to prevent it from cooling too much during inactive periods.