Renewables - The Impossible Dream

Fools often think that they can get something for nothing.  Unfortunately a large number of our politicians seem to agree and have decided to make their fantasy come true with our money.  Easy really, all you have to do is harness the infinite power of wind, water, wave and tide.  A concept so simple you have to wonder why it has not been done before.  But of course it has and many centuries ago at that. The first recognisable windmill was produced two thousand years ago by a Greek known as Heron the Engineer water power is even more ancient and goes back to the sixth millennium BC the first patent for wave power was filed by a father and son team in Paris in 1799 and the history of tidal power goes back to 900AD and beyond.  

First generation wind power is still used successfully to provide modest solutions in pumping water and charging batteries where mains electricity is not an option.  Hydro power produces about 18% of the world’s electricity and 95% of all 'renewable' energy production claimed is actually from hydro. Wave power remains a pipedream despite thousands of patents, hundreds of prototypes and many millions handed out in research grants. Tidal power is most effectively captured by a barrage but the Rance Tidal Power Station can only supply a mere 0.012% of France’s electricity.

Wind Turbines:  The first problem is that these machines are not actually turbines at all, the term has been corrupted.  Turbines traditionally worked with contained flows often at high pressure. Wind ‘turbines’ are actually rotors or variable pitch propellers in open flow. According to Betz' law they are at best only 59% efficient in kinetic terms as almost half of the wind leaks to the periphery. They also only record around 30% productivity due to variable wind-speed giving an overall efficiency of less than 18%.  Massive machines, huge costs but only tiny returns, and yet there is an even bigger problem.  Because the entire structure is under stress their estimated total lifespan is only 20 / 25 years. They are also mechanically complex and expensive to run. So not only are they dependent on ongoing subsidy to survive, if that subsidy is ever withdrawn, as has already happened in a number of other countries, they will not be replaced. Some 14,000 abandoned wind turbines now litter America with Spain and Portugal in hot pursuit.

Hydro Power:  There are two types of fresh water hydro power, total loss and pumped storage. Total loss or single pass systems are a successful, predictable and low cost option but totally dependent on rainfall over an enormous catchment area and the best sites have already been utilised.  Due to the limited supply of water they can only be used for peak lopping rather than base load.  Large schemes also raise environmental issues as they can displace people and flood large areas of land. Pumped storage hydro stations fill a header loch using off-peak electricity and generate power on demand to back up the grid. Some 40% of their power is therefore lost to pumps and friction and they have limited capacity. Cruachan pumped storage power station can supply 440MW but only for 12 hour periods and is a net user of electricity.

Wave power:  If ever there was a flight of fantasy then this is it. Despite increasingly desperate efforts by engineers and politicians alike, a viable machine has yet to emerge.  One day the penny will drop that this is mission impossible but no doubt even more time and money will require to be wasted before the laws of physics and economics prevail.

Tidal power.  Estuary barriers do work although their overall efficiency is low due to the four periods of slack tide each day. The environmental disturbance is significant, the capital costs are high and construction liable to take at least ten years. The idea of a tidal barrage across the Severn Estuary has been around for over two hundred years but is unlikely ever to be progressed.  Tidal flow.  Large water driven propellors are now being installed in areas which experience faster than normal tides such as the Sound of Islay.  However, even although water is a much more powerful medium than air, the enormous sums required to achieve pitifully small and intermittent returns are plainly unsustainable.  

Conclusion:  The current crop of so called renewable energy systems cannot replace or significantly augment conventional generation because of three basic and insurmountable problems.  They are all intermittent and, in the case of wind, unpredictable as well, they all depend on locally weak, dispersed sources of energy using very expensive, complex machinery and finally there is no viable technology to store significant amounts of electricity, despite many years of research.  Although the notion of clean, carbon free power from infinite sources has obvious appeal, in reality it cannot happen without extraordinary amounts of taxpayer and consumer subsidies.  This draws us to the rather obvious conclusion that not only will this episode turn out to be a hugely expensive blind alley, but that many lives will be blighted and businesses ruined in the process.  The metal can be scrapped, the concrete bases and the roads grassed over, however the financial damage will be life-long.