Friday, January 21, 2011

Research update

From web stats, I know I have a set of regular visitors to my other website at  Over the years I’ve corresponded with some of these visitors, and the message is they like to hear about my research progress.

So, here goes …

Since attending the Australian Solar Energy Conference in Canberra in early December, I’ve been working mainly on thermal storage.  A key realisation from Canberra was that solar thermal needs storage if it is to be competitive long-term with PV.  We all know that PV prices are coming down and PV efficiencies are going up.  Without storage, however, PV won’t keep the lights on after dark.  On the other hand, thermal storage is relatively cheap and also provides a boost to the capacity factor of solar thermal heat engines.  There will be a big opportunity for utility-scale despatchable solar power that only solar thermal can meet with today’s technology.

What are the storage possibilities for my evaporation engine as powered by passive heat collection under a transparent insulated canopy?  It seems to me the answer is – rather good!  Thermal energy can be stored by passing the air heated under the canopy through a bed of loosely packed rocks.  Provided the bed is large enough, both pressure and thermal losses will be small.  The stored heat can be used to generate power after dark or during cloudy periods, thereby increasing the capacity factor of the piston-in-cylinder evaporation engine.  Such storage would be cheap too!

I’ve estimated the pressure losses in the rock bed and I’ve started to build a simulation model for thermal charge and discharge.  A related issue is to develop a control strategy for the concept.  My ultimate goal is to develop software so I can simulate the annual performance of the canopy/storage/engine system at regular (15-minute?) intervals throughout an entire year.  I’d like to present that work at the next Australian Solar Energy Conference to be held in Sydney at the end of 2011.

Meanwhile, I’m planning to present the Wellington simulation results for a sloping canopy at the 2011 Solar World Congress, to be held in Kassel, Germany (29 August – 1 September).  I have already obtained results for the sloping canopy, and they are clearly better than for the horizontal canopy.  No surprises there!

For the next few weeks, another project (still confidential at this stage) has demanded my attention.  I expect to get back to the storage simulations in mid-late February.

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