Professor Stephen Salter

Stephen Salter was born in Johannesburg South Africa in 1938. He served an old fashioned apprenticeship in the aircraft industry with Saunders-Roe on the Isle of Wight as a fitter, tool-maker and instrumentation engineer eventual working on the Black Knight rocket project before reading physics at Cambridge University where he stayed for six years doing research.

His interests have always been on the border of mechanics and electronics. He moved to Edinburgh University to build robots in Artificial Intelligence and then, in 1973, to Mechanical Engineering to work on wave energy. That required the design of new kinds of directional wave tank with absorbing wavemakers and new types of high-power, computer-controlled hydraulic pumps and motors. Small versions are now being installed in the transmissions of road vehicles where they allow improved engine management and the recovery of energy which would have been wasted in braking. These machines may, in future, be used for wind and tidal-stream energy. They enable the design of variable-displacement pumps which despite a low machinery weight can absorb the very high torque needed for multi-megawatt tidal-stream generators suitable for use in the full depth of the Pentland Firth.

Other interests are fatigue reduction in wind turbine blades, desalination using energy from sea waves, improving road-traffic congestion and the capacity of congested bridges, Stirling engines, the mathematics of nuclear disarmament, variable-pitch air turbines, unconventional ways of teaching design engineers and inventors, mine clearance, flood-prevention, the suppression of explosions and the reversal of global warming by increasing cloud albedo.

His research group has its own mechanical and electronic workshops and runs a wide tank with directional absorbing wave-makers. In 1986 he was awarded a Personal Chair in Engineering Design. He is a Fellow of the Royal Society of Edinburgh and an MBE. Rumours of his retirement in 2004 are exaggerated.

What can be done if we cannot reduce CO2 quickly enough or at all?

It is disturbing that, although it is 15 years since Rio and nearly 10 years since Kyoto, there is no sign of any reduction in the acceleration of atmospheric CO2 concentrations, only large profits for carbon traders. The recent DUKES data show that UK emissions have increased every year since 2002 and are higher now than in 1997. They increased by 1.75% in 2006 even though shipping, aviation and the proxy carbon associated with imports from China are not counted. A rising world population with rising energy expectations and a switch from oil back to coal make it unlikely that the necessary world CO2 reductions will be achieved quickly enough.

Ice core records show that there have been many previous, very rapid rises in temperature. We may be close to a number of irreversible and mutually-reinforcing trigger events such as loss of Arctic ice cover, the release of methane from melting permafrost, the release of CO2 from warmer oceans, fires in tropical rain forests and loss of phytoplankton, all of which would give a positive feedback.

The talk will discuss the engineering of one of several possible emergency global cooling-systems which could keep temperature under control until the renewable sources can be fully developed. It exploits a well-known phenomenon known as the Twomey effect. The idea, due to John Latham, is to increase the amount of solar energy reflected from marine stratocumulus clouds by increasing the number of cloud condensation nuclei in the marine boundary layer. For the same amount of liquid water, a larger number of small drops make a whiter cloud than the smaller number of large drops which result from the shortage of condensation nuclei in clean mid-ocean air. The increase can be achieved by spraying submicron drops of sea water. The salty residues are ideal seeds for new cloud drops. The volumes of water needed turn out to be surprisingly small.

Background papers can be downloaded from http://www.see.ed.ac.uk/~shs