Stephen Salter - a celebrated green energy innovator

Prof Stephen Salter, the Edinburgh University-based innovative engineer and wave energy pioneer, has died, at 85. He had an illustrious career. His original ‘Nodding Duck’ wave energy device caused a big stir when he first developed it in the mid 1970's and he more or less put wave power on the map at that point. There was talk of wave energy providing all the power the UK could use and the then Labour government eventually provided around £14m in funding for this and other deep sea wave energy devices. 

Salter was convinced that the way ahead lay in initial tank testing using models, rather than going out to sea with a full scale prototype, as Coventry University (then Lanchester Poly) had done, with mixed results, using a version of his duck. Instead, he focussed on building and using a ‘wide tank’ at the University of Edinburgh in 1977-  it was the world's first multi-directional wave tank equipped with absorbing wave-makers.

Several other wave devices also emerged around the UK and all seemed to be going quite well, with the  incoming Conservative government elected in 1979 also evidently enthused. ‘Whatever other problems our wave energy researchers may face, lack of Government support will not be among them’. So said Energy Minister John Moore in Sept 1980 at the opening of another wave test tank, this one in Southampton. However, it proved to be an unwise promise, with the public sector being squeezed by the Thatcher government, R&D funding came under pressure, and, after a review in 1982, support for deep sea wave power was cut and the rest of the programme was scrapped later.

The demise of the UK wave energy programme, following an adverse (and much disputed) assessment of the potential economics, more or less halted further work on large scale deep sea devices. Salter thought it was all very unfortunate and premature: like trying ‘to decide our aviation policy on the data available in 1910’.  However he, and some others, continued with EU and/or private funding to develop ideas for smaller in shore and shoreline devices. Certainly Salter was not one to give up when the going got tough and he came up with a single duck concept, SOLO, and also, moving beyond wave energy, a circular ring-shaped tidal stream turbine, POLO.  

In evidence to hearings on wave and tidal energy by the Select Committee on Science and Technology in 2001 he said  ‘I think the uncertainties about tidal streams are lower, I think they can take a lot of technology from wind, and I think they are a more predictable environment; so I would expect that would reach commercial viability sooner than wave energy. The problem is that it is not such a large resource, and we can use all of it and still want more, whereas wave energy is such a big resource that it is worth going for, even if it looks hard to start with’.

In its final report, the Select Committee concluded that ‘given the UK's abundant natural wave and tidal resource, it is extremely regrettable and surprising that the development of wave and tidal energy technologies has received so little support from the Government.’ However, although some funding was subsequently allocated to these marine renewables by Labour in the 1990s, and some small tidal stream projects went ahead, as well as a few wave projects, it has mainly been wind power that boomed, first on shore then offshore, followed by solar power. There had been some spectacular wave energy failures (e.g., Osprey in Scotland 1995). Nevertheless, wave power was still seen, like tidal power, as promising for the longer term, although only if cost fell. But for now, wave and tidal power were relatively marginalised- and that seemed likely to remain the case for a while.

Ever innovative, however, in the 2000s, although he carried on supporting  wave and tidal research at Edinburgh (e.g. pushing for their circular flow wave tank),  and acting as a consultant on the Oyster hinged sea bed-mounted wave flap project, Salter started diversifying. He came up with a floating offshore vertical-axis wind turbine-powered sea water desalination system for desert areas, and then, more radically, a system for spraying sea seawater into the atmosphere for whitening clouds- so they reflected solar radiation more, and reduced global warming. He envisioned a fleet of ships power by Flettner wind rotors cruising around the oceans, spaying mist in to air. He said  ‘Maybe 10 cubic meters of water a second as sub-micron drops sprayed in the right place would offset all the damage we've done since pre-industrial times.’ 

This exercise in geo-engineering was evidently seen as a way to buy time while renewables were developed fully. Renewables were clearly his first love in terms of energy technology, even if he had found it hard to overcome bureaucratic resistance to his wave plans. As he had told  a meeting of the Parliamentary Group for Alternative Energy Systems in 1981, ‘I am sure that many people engaged in the work whether from device teams, consultants or administration will agree with me when I point out that improvements could be made to the administrative machinery. So much of it seems designed to delay and demoralise’.  

Nevertheless he had persevered, and then moved on, helping many others to follow suite, often treating us all to wry commentary- he had a wonderfully dry wit. But also a clear vision of the way ahead for renewables. In a paper in the Journal of the Royal Society of Arts in 1981 he had said ‘we are attempting to change a status quo which is buttressed by prodigious investment of money and power and professional reputations. For 100 years it has been easy to burn and pollute. 100 years of tradition cannot be swept away without a struggle. The nearer renewable energy technology gets to success, the harder that struggle becomes’. 

Sadly, that’s still true today. We have done well with wind and solar, although there is still a way to go.  And while tidal stream power is doing a bit better (with 8 projects supported by CfDs), it is still quite marginal, with high costs, and wave power is still struggling to get established at large scale. However, new wave power ideas and projects are still emerging around the world, including one on the Orkneys. And wave and tidal power are being talked up again as key UK options. So the story continues. That, and indeed the wider success of renewables, is thanks in no small part to inspiring people like Stephen Salter. He will be greatly missed.