“It’s too soon to tell” is the somewhat cautious response often ascribed to Chairman Mao when he was asked to assess the impact of the French Revolution. Similar caution is required ingauging the potential of wave and tidal-stream generators as a renewable energy source. Butresearch and development activity in this branch of the renewables has increased dramatically in the past few years. According to a recent survey carried out by AEA Energy & Environment on behalf of Sustainable Energy Ireland (SEI)and the International Energy Agency (IEA),the number of ocean energy devices underdevelopment has doubled over the past four years, and now stands at no less than 81 across thenineteen IEA countries. The majority arereported to be in the early phases, but some 40% have started sea trials.

The burgeoning interest in the area was also much in evidence at a British Wind Energy Association conference in March (which claimed to be the largest event ever held devoted solely to the marine renewables), with several reports of some large scale demonstration projects (at least by wave and tidal-stream standards) underway or about to get started, and some very big “traditional” utility players getting themselves immersed: E.On, Scottish Power, EDF, RWE, to name but a few.

And the pace of activity looks likely to increase considerably, spurred on by the growing political momentum behind renewables. This is exemplified, in the European context, by the recent landmark decision of the European Council of Ministers to go for binding commitments on renewables, setting a Europe wide target of 20% of EU energy consumption to come from renewable sources by 2020 (see this month’s news).

The idea of extracting power from ocean waves and the tides is of course nothing new. Large tidal barrage schemes already exist and there has been talk of building a barrage in the River Severn in the UK for about a hundred years – a scheme now receiving serious attention once more. But the concepts of generating electricity from marine currents and from the motion of the ocean also go back a long way. There are drawings of designs for tidal stream turbines dating from the 1950s (as Vincent de Laleu of EDF showed in his presentation to the BWEA conference). And in the early 1970s, prompted by the oil supply worries of those days, there was Dr Stephen Salter’s ingenious nodding duck.

But as with many immature areas of technology we are still a very long way from any sort ofconsensus on the best ways to generate electricity from waves and tidal currents – although there is of course no shortage of people claiming to have the answer.

The diversity of approaches, particularly in the wave sector, is truly bewildering (as evidenced, for example, in a handy booklet produced by the BWEA providing an overview of developments in the UK, Power & opportunity: a directory of wave and tidal energy devices & UK support).

Currently one of the frontrunners in the wave area would appear to be the Pelamis device – consisting of semi submerged cylindrical sections linked by hinged joints – developed by Ocean Power Delivery (based, like Stephen Salter, in Edinburgh). A 2.25 MWe Pelamis installation is currently under construction off the coast of Portugal, for a consortium led by Enersis, while Scottish Power is planning a 3 MWe system at European Marine Energy Centre in Orkney and E.On hopes to build a 5 MWe Pelamis array off the north coast of Cornwall (to be connected to the Wave Hub, a “socket in the sea” being developed by the South West of England Regional Development Agency for facilitating marine energy demonstration projects).

E.On has also just announced that it isplanning to develop, with Lunar Energy, a tidal stream project with a capacity of up to 8 MWe off the west coast of Britain, using Rotech’sducted tidal turbine technology.

So the marine renewables indeed now appear to entering a new phase: multi-MW-scale demonstration projects. And this will inevitably lead to some much needed Darwinian evolution as it is determined what really works at large scale and what doesn’t.

Certainly the number of devices needs to be whittled down to manageable proportions, sothat efforts can be prioritised and focused on the technologies most likely to deliver. This is of course where government funded research and development has a crucial role to play. In fact,as the SEI/IEA report referred to above notes, government funding for ocean energy RD&D has been growing in a cluster of IEA countries,notably the UK. But this is from a relatively low base. As the report notes “ocean energy research has been significantly under funded since thedecline in support for renewable energies after the last oil crisis of the late 1970s.”

The priority now would appear to be to get as many machines into the sea as soon as possible to see whether they sink or swim.

Answering the critics

Climate change denial has been getting some air time recently in the UK, notably in the form of a 90 minute programme on Channel 4 by Martin Durkin, called The great global warming swindle. Richard Lindzen, professor of meteorology at MIT, who appears in the programme, has also been getting some coverage. The rather striking headline, “Global warming is the religion of our age: self-righteous, intolerant of dissent and based on superstition”, gives the flavour of a recent article by him in the UK newspaper the Daily Mail.

While such views may be a bit extreme, healthy scepticism about anything that may be described as a “consensus among leading scientists” is to be welcomed and substantive points raised by “deniers” must be addressed.

Prof John Mitchell, director of climatescience at the UK Met Office, has taken the time to do just that and in a response posted on the Met Office website (www.metoffice.gov.uk) refutes some of the main points raised inthe Channel 4 programme, for example thecontention that it is temperature that drives changes in carbon dioxide rather than the other way round, that solar activity is the main driver of climate change not human activity and that there is less warming in the upperatmosphere than at the earth’s surface(which would tend to disprove the existence of human-induced warming).

As the key scientific body in this fieldthe Intergovernmental Panel on ClimateChange must also be prepared to patiently and openly address inconvenient criticisms of itsassessments of the extent of anthropogenicclimate change, whenever and wherever they arise, even if it is deliberately polemical TV shows recycling what many climate scientists regard asmisunderstandings and myths.