Friday 28 March 2014

A few days after I published my blog on innovation warning about the dangers of technology hype and a lack of understanding of the realities of the innovation process, particularly in the energy sector, the Independent on Sunday provided a perfect example.  Across the bottom of the front page the headline said (screamed?) Exclusive: Renewable energy from rivers and lakes could replace gas in homes and the article started by saying “millions of homes across the UK could be heated using a carbon-free technology that draws energy from rivers and lakes in a revolutionary system that could reduce household bills by 20 per cent”.  The whole of page 4 was devoted to reporting on this “magic” “new” technology that takes heat out of rivers and lakes and turns it into heat for use in heating buildings.  The Secretary of State Ed Davey was quoted as saying it was “game changing” and it reported that he has asked officials at DECC “to draw up a nationwide map showing where renewable heat can be drawn from water to explore the potential of heat pumps. If you read the piece with no prior knowledge you would have thought that this technology would soon be everywhere providing cheap, low carbon heat.


Here are a few facts to consider:


  • Using heat pumps to take low grade heat out of rivers and turn it into higher grade (higher temperature) heat is not new.  (To be fair the article did acknowledge this). The Royal Festival Hall on London’s South Bank had a heat pump installed to use the heat in the Thames in 1951 (subsequently removed I believe).
  • The main advantage of the Mitsubishi technology referred to in the article seems to be the relatively high output temperature of 45oC.  Higher temperatures are usually better but heat pump efficiency goes down as output temperature goes up.  (See below for the real innovation in the system).
  • A traditional wet heating system using radiators operated with flow temperatures of c.75-80oC but modern systems in well insulated houses can operate at 50-55oC.  Large surface area low temperature heating systems such as under-floor heating operate at c.30-60oC but the majority of houses don’t have this (unless the sample of houses is from Grand Designs!
  • The real innovation in the Mitsubishi system referred to seems to be dynamic control of flow temperature rather than the heat pump itself.
  • The combination of having to build coils in water plus use of low temperature heating systems means this kind of system is likely to be confined to new build and will make it expensive (but not impossible of course) for retrofitting existing buildings.
  • Fouling of river coils can be a long-term issue that affects performance and hence costs.
  • Performance of heat pumps is measured by Coefficient of performance or COP.  COP is defined as the total energy out (heat) divided by the electrical energy input.  Heat pumps always sound neat because COPs are typically three to five, meaning you get three to five times more energy out than you put in.  As output temperature goes up COP goes down.
  • The total system efficiency is lower than the COP as it takes into account the delivered heat (less than total heat generated) and electricity supplied to circulation pumps and any additional electric heating required.  An Energy Savings Trust (EST) report on the Mitsubishi web site reported on measured results in 23 heat pump sites between October 2011 and March 2012.  The average system efficiency reported was 2.91 with a standard deviation of 0.37.


A few critical questions:


  • How much does it cost (capital, Operations & Maintenance and running cost) and how much does it save compared to conventional systems?  There was absolutely no mention of cost in the Independent on Sunday article.  The EST report quoted above found in the 23 sites studied that the estimated annual operating cost savings were 8%.  (These installations may not have been the new system so savings on the new system could be higher).  The Mitsubishi web site claims savings of 20% savings compared to conventional radiator systems but does not mention capital costs – either total or marginal compared to a conventional system.
  • Why is the Secretary of State making such a song and dance about this particular technology and this particular solution provider?  Perhaps the Secretary of State is just desperate to show green credentials in the wake of recent pro-nuclear and pro-shale gas decisions he was forced to take?  Or was it just to push the Renewable Heat Incentive (RHI) which applies to heat pumps even if they use grid electricity which is currently 67% driven by gas and coal (source: Digest of UK Energy Statistics).
  • How many houses and buildings in the UK are close enough to rivers and lakes to benefit from this kind of system? (Hopefully to be answered by the DECC study).


I have always been puzzled by the DECC Chief Scientist’s (and consequently DECC’s) apparent obsession with heat pumps.  Replacing gas boilers with heat pumps theoretically makes sense if you are seeking to minimise carbon and you assume a switch to low carbon electricity.  Based on the belief that heat pumps were a good idea and that millions of households (a target of 4.5 million covering both water and air source heat pumps) would somehow switch to heat pumps from gas boilers, along with equally aggressive assumptions about the rate of adoption of electric vehicles led to an analysis that showed electricity demand growing significantly.  This whole analysis always struck me as a neat theoretical set of calculations without much real engineering, economic or market reality and yet it was a major driver for the Electricity Market Reform (EMR).  As opposed to growth in electricity demand there is increasing evidence that we may well find ourselves in a world where more efficient lights and appliances result in stable or even declining electricity use.


It seems extremely unlikely to me that water source heat pumps will be the solution to the UK energy problems of cost and security that the Independent on Sunday seems to think.  This critique is not aimed at the technology per se or the particular solution provider or project developer – more the lack of analysis and quality of reporting on innovation.  There will be some circumstances where water source and air source heat pumps may make good sense for some new buildings but they are unlikely to solve the massive problems of a grossly inefficient building stock and fuel poverty.


To sum up when looking at articles like this remember:


  • the stages of the hype cycle
  • there isn’t a single technology solution to our energy problems
  • the viability of technologies is usually very site specific
  • adoption of technology is usually driven by real cost saving and/or regulation and not by hope
  • answers promoted by politicians – especially before any serious analysis has been done – should be treated with a large pinch of salt.
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Dr Steven Fawkes

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