Introduction

I should like to welcome participants on behalf of the Royal Society to the meeting for discussion on solar energy. To set the scene I can misapply the Shakespearian quotation, ‘A universal largess like the sun His liberal eye doth give to everyone’ and go on to add 'Thawing the cold fear' of energy shortages to come. The Sun’s liberal eye has provided energy for the Earth’s surface at the rate of over 50 x 1012t of coal equivalent per year, that is some 5000 times greater than our present rate of energy consumption. Apart from providing direct warmth, indirect solar energy has been used for many years. The biomass, in the form of wood, was the earliest source of energy. Even now, wood supplies a surprisingly large amount of primary fuel. In North America, for instance, the amount of wood used is about equivalent to the total consumption of primary fuel by Denmark, or some 7 % of U.K. consumption. Later tallow, vegetable oils and the fossil fuels, coal, peat, lignite and some mineral oils came into use for heating, cooking, lighting, pottery making and primitive smelting and manufacturing. Solar heat and fuels were not used for power or work. The first sources of power for man, other than his own and his animals’ muscular power, were provided indirectly by solar energy via the atmosphere, through wind acting on sails and windmills and through rain acting on waterwheels. About 250 years ago the picture was radically and forever changed by the invention of the steam engine. This was done principally and most effectively by Newcomen, who devised a machine that used fuel for producing work.