Thursday 6 June 2013

As my friends know one of my other big interests in life other than energy is space exploration and although I don’t read as much as I used to I am still a fan of ‘hard science fiction (‘a category of science fiction characterized by an emphasis on scientific or technical detail, or on scientific accuracy, or on both’ according to Wikipedia). We can learn a lot from science fiction and of course many of the technologies and gadgets we take for granted today actually first appeared in yesterday’s science fiction by Arthur C. Clarke, Robert Heinlein and many others.


On my recent trip to the USA I read’ Power Play’ by Ben Bova. I am a huge fan of Ben Bova whose ‘Grand Tour’ series describes an exciting future where we explore the solar system and find life in surprisingly many places. Anyway, ‘Power Play’ is extremely unusual – probably even unique – a science fiction story about the problems of commercializing a new energy efficiency technology. The technology in question is Magneto-Hydro Dynamics, MHD, which is actually a more efficient way of generating electricity rather than an end-use efficiency technology, but we know there are large efficiency opportunities in the power generation system just as there are in end use applications such as buildings, industry and transport and we need to focus on improving efficiency in all areas.


Anyway. ‘Power Play’ deals with the interaction of the power industry with power politics and paints a dismal, (but probably realistic), view of US (and not just the US) politics, with one character saying, ‘It’s the old game, tell the voters you’re giving them what they want, when in reality you’re giving the special interests what they want’. Needless to say the bad guys try to stop the development of MHD, a technology which can improve the efficiency of generation by 50% and, in what one character admits is an exaggeration, offers the potential to cut electricity prices in half. The plot moves with the usual Bova pace and attention to detail and without giving it away, of course the good guys triumph in the end.


MHD is an intriguing technology that has links to rocket technology and in theory could offer high efficiency with no moving parts. The principle is that a when a high temperature, fast moving, (supersonic) plasma passes through a magnetic field it a generates an induced voltage. This is exactly the same as in a normal mechanical dynamo except the stream of plasma, which results from combustion, replaces the metal rotating conductor.


MHD is not a new idea, it first emerged in the late 1930s, resurfaced in the 1960s and then gained widespread publicity and a lot of government funding in various countries in the late 1970s and 1980s, as a response to the energy crises. It was seen as a way of burning coal, including high-sulphur coals, efficiently and cleanly although it was also considered as a way of generating power from nuclear power. Numerous experimental systems were built and in the 1970s Russian MHD systems actually delivered power to the grid.


Like many other technologies, especially in the energy field, the promise and predictions turned out to be optimistic and today we see nothing about MHD. In practice the technological problems are very tough in a number of areas. Firstly there is the problem of containing a high temperature plasma, akin to that in a rocket engine or found during re-entry from space. Chamber walls and electrodes are prone to extreme erosion due to the high temperature and nature of the plasma.


Secondly there is a need to seed the plasma, typically with potassium, to increase its charge, and the seed material needs to be recovered and re-used or disposed of. For maximum efficiency the magnetic coils should be super-conducting to reduce parasitic loads so as in Tokamak fusion reactor designs you end up with very high temperatures close to a containment vessel close to very cold temperatures – not impossible of course- just difficult from a materials perspective. To achieve the high efficiencies talked about by Ben Bova, probably as high as 60%, the MHD generator needs to be combined with a steam turbine system utilizing the heat of the MHD exhaust, effectively a combined cycle. Without that the maximum achieved efficiency of MHD alone is about 22%. The other problem in a carbon constrained world of course is CO2 emissions. Ben Bova – who has included the effects of climate change in several novels – skips over this with a quick reference to Carbon Capture & Storage.


The other factor that inhibits any development of MHD is that conventional generators are getting much more efficient. The average efficiency of all coal fired power stations in the world is c.33% but modern stations can reach an efficiency of 45%, with a target of 50% in sight in the next decade (,32869,en.html). With these efficiencies the relative advantage of MHD, which is far more complex and risky, is greatly reduced even if it could achieve 60% efficiency. The extra cost and complexity just isn’t worth it.


So, MHD remains a technology that has never been fully developed and one for which both the technology and the economics would seem to be challenging at best. It seems set to remain in the realms of science fiction – but don’t let that put you off ‘Power Play’ and the many other fine Ben Bova stories.


There is 1 comment on “Book review – ‘Power Play’ – a science fiction book about energy efficiency by Ben Bova”:

  • Erik Shank on August 18th, 2018 at 1:17 am said:

    I knew a guy that had patents using MHD. His name was Townsend Brown. Have you ever heard of him? He invented/developed a fan with no moving parts which, with a addition of another element also was a speaker + and a real flying saucer.

    I had correspondence with Ben Bova about Townsend (he didn’t know him) and he mentioned that he’s written a book about MHD, simply title MHD – obviously he changed the name somewhere along the line. I will ask for this book for my upcoming birthday…



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