Move to resurrect convection power scheme

Dr Alan Williams has written to us to draw our attention to a possible way of using natural convection to harness energy from the sun, which he says, was seriously suggested with a British patent granted in 1904

, but never built. There may have been little interest back then to obtain cheap energy from sunlight when coal was cheap and nobody minded burning it but the scheme proposed by H. M. Funke, M. P. Funke and E. G. Funke in British Patent Specification 15,576 looks as if it could work quite well. Their scheme had a large scale solar collector built on a South facing hillside, with the force of buoyancy sucking incoming air through an air engine at the bottom. This avoids most of the costs associated with building possible solar chimneys. Dr Williams calculates that with a funnel shaped intake, air could reach a speed of 50m/s through a throat before being allowed to expand into the collector and the system could generate electricity with an efficiency of greater than 50 per cent.