Blowing hot and cold on British windmills
Last year the Department of Energy and the Science Research Council together spent less than £1 million in research into wind energy, although £100 million each year goes into nuclear research and development. In sharp contrast the USA has been spending some 60 million dollars each year on wind energy and now plans a 1,000 million dollar demonstration and "commercialisation" programme.
In Germany, Denmark, and Sweden large programmes are under way and a number of megawatt size windmills have been or are being built. In the USA, competitive electricity prices are already envisaged when the present models of machines can be produced in large numbers (bringing down costs). The British Wind Energy Association brings together scientists, engineers, and entrepreneurs from industry, universities, and various Government bodies. With some 120 members, it now presents a respected view on the subject of wind energy.
But the activity has remained small, and in my view seriously under-funded compared with many of the other developed countries of the world. The UK is still without a single really large windmill (in the megawatt range) and this means that we are failing to build up the practical experience which is essential if any serious progress is to be made.
We in the UK are doing some very nice work on many of the associated problems of wind energy. But none of these "generic studies" can replace real life experience with one or two very big windmills.
It is in the light of this background that we must examine the CEGB decision to press ahead with a rather complete and ambitious programme.
It is my guess that the CEGB might well wish to build its first windmill group or "cluster" in the period 1985-1990. This first cluster might have 10 machines in it. In the long term we are thinking, of course, of clusters of 400-1,000 machines (each of about 4MW). Such a cluster would provide an output similar in magnitude to a modern coal fired or nuclear powered station.
The importance of this CEGB decision is that the United Kingdom is at last moving forward towards the building of its first multi-megawatt windmill station. This is a milestone for those who believe that the so called "renewable" energy sources (wind, wave and sun) have an important part to play in our energy future. Even more important from the point of view of UK industry is the fact that it is the potentially largest UK customer (the CEGB) who is taking the initiative.
Meanwhile, why has the CEGB opted for a lowland windmill? Good lowland sites offer average wind speeds of about six metres per second, whereas hilltop and offshore sites can offer average wind speeds in excess of eight metres/second. This ratio of 1.33 in windspeed actually represents a factor of 1.33 cubed (i.e. about 2.5) in available energy, for a given size of windmill.
Three or four years ago UK interest centred on hilltop and coastal sites. Developments since 1977 have greatly changed the picture. Dr Peter Musgrove pioneered in the UK the idea of putting windmills in the shallow waters of the North Sea. He pointed out that there are vast areas of shallow waters (less than 30 metres deep) off the east coast of the UK. He showed that a number of windmill clusters in these shallow waters could meet up to 30 per cent of UK annual electricity needs.
To their credit the Department of Energy took up these ideas and funded a detailed study. No insuperable technical difficulties were found and the estimated building and running costs would indicate a price for electricity which could become competitive in the near future with nuclear or coal-generated electricity.
The CEGB has given the production costs for electricity for stations currently being built. Nuclear power from Dungeness B is put at 2.62p/kWh: coal at Drax B is 3.59p/kWh: oil at Littlebrook D is 6.63p/kWh.
The Taylor Woodrow led study came up with a number of different figures for the cost of North Sea electricity depending on the assumptions made. Let me pick out the figure of 4.20p/kWh which was based on the windmills having a diameter of 100 metres (which is the largest size presently being built in the world). The figure taken for average wind speed is 9.5m/s.
Thus North Sea-generated electricity looks like being close to competitive on present fuel costs. This figure of 4.2p/kWh could come down dramatically if we find that we are able to build much larger diameter windmills than the present 100 metres. This is because foundation and lower costs were dominating the picture. Larger windmills would mean fewer windmills and hence lower overall foundation and tower expenditure.
The CEGB has chosen, in the meantime, to go for the on-land option for their initial programme. This is an eminently sensible decision. A number of windmill designs have been developed in the USA and elsewhere for machines to operate in moderate wind regions. The 6 metres/second average wind speeds that we get in many lowland areas of the UK are considered to be satisfactory speeds for wind turbine operation in the USA. Given a lower wind speed you simply design a larger diameter wind turbine.
What now remains to be seen is not so much whether you can build large windmills or whether they will be economically viable, but whether they will be environmentally and socially acceptable, placed for example in the windy lowlands of Lincolnshire and East Anglia. The CEGB search for its first site should bring out some interesting attitudes.
I have seen the 200 ft. Mod 1 Windmill which is on a hilltop near the small town of Boone in North Carolina. Even from a distance of only two miles it is far from obtrusive. In fact I found it a most attractive sight - but perhaps I am biased. The locals nonetheless are very proud of it!
Professor N. H. Lipman of the Department of Engineering at Reading University, is a member of the Reading Energy Group.
(From an article by Norman Lipman in The Guardian)