Thursday, September 29, 2011

2011 Solar World Congress

I was one of 692 delegates privileged to attend the 2011 Solar World Congress in Kassel, Germany, from 28 August to 2 September 2011. 

To recite a few facts about the Congress, the delegates came from 66 countries with 434 of them from Europe, 101 from Asia, 79 from America, 33 from Africa and 26 from Australia.  (Yes, I know that doesn’t add up to 692, but those were the numbers provided by the Congress Chair at the concluding session.)

The overall Congress message was “rapid transition to a renewable energy world”.  There were six major themes (solar heating and cooling, solar buildings, renewable electricity, rural energy supply, resource assessment, and renewable energies and society), which were further broken down into 31 sub-themes.  These topics were addressed by 267 oral and 278 poster presentations. 

Some big points were made in the opening session.  In the last year, investments in electricity generation capacity, worldwide, came 47% from renewables and 53% from fossil fuels.  For the decade from 2000-2010, investments in wind power increased at an annual rate of 27%, whilst the corresponding growth rates for solar thermal (mainly solar heating) and photovoltaics were 13% and 40% per annum.  Germany is undertaking a dramatic restructuring of its energy system.  By 2050, overall greenhouse gas emissions in Germany are to be reduced by 80% compared to 1990 levels, whilst renewables are to be expanded to represent 80-95% of the total energy mix.  As part of these targets, primary energy use is to be lowered by 50%.  Nuclear energy is to be completely eliminated by 2022.

The concept of the “learning curve” was emphasised frequently during the congress.  By this is meant the reduction in cost of a technology as a function of installed capacity or time.  The most famous example is Moore’s Law for semiconductors, and there is now a well-established learning curve for the cost of photovoltaic cells (Breyer & Gerlach, 2010). 

Over the period 1976-2003, the price of a PV module (in 2010 USD/W) decreased by 22% for each doubling of the installed capacity.  For a while in recent years, it seemed as if a variety of issues (including supply problems with pure silicon production) meant that the learning curve was no longer valid, but the curve has now returned to its historic trend. 

So, with increasing installations and public support, the cost of electricity from PV continues to decrease, at the same time that the cost of electricity from fossil fuel and nuclear increases.  Cost parity will be achieved – it’s just a matter of time, and it won’t be long. 

From a societal perspective, the solar industry is now a major source of employment.  The German Solar Industry Association estimates that German solar employment will increase from 80,000 in 2009 to 180,000 in 2020.  Moreover solar power offers the promise of electrification to the 1.4 billion people on the planet who don’t currently have access to electricity.

Solar thermal power generation also featured in many presentations.  Rapid progress is being made with several competing concepts (trough, tower, Fresnel arrays), with the eventual market winner not yet clear to this observer.  Solar thermal also allows for energy storage that is relatively cheap and easy over a period of around 24 hours, and major research agencies in Europe are active in this field. 

Over a longer term, say weeks or months, chemical storage seems to be the best option as described in presentations from the Fraunhofer Institute for Wind Energy and Energy Systems Technology.  The key idea here is that hydrogen produced from electrolysis of water is then converted via the Sabatier reaction into methane, which is an excellent energy carrier and for which an extensive storage and distribution infrastructure is already in place.

So the storage problem is solvable, at a cost, and will be solved.  But can renewables completely meet the electricity needs of major economies such as the USA?  That topic was addressed in an important paper by David Mills, based for many years at the University of Sydney and the celebrated proponent of Fresnel arrays for solar thermal power.  Mills’ answer is that wind and solar can completely provide the needs of the USA, provided enough spare capacity and storage is included in the system. 

This requires a new way of thinking about the structure of the electricity grid.  It’s instructive to think as wind and solar as providing a fluctuating underlying contribution that is augmented by quick-response storage such as batteries, pumped hydro or thermal.  For the worst cases when the sun doesn’t shine and the wind doesn’t blow for two weeks, chemical storage will meet the need.

From a local perspective, the Australian legacy to the international solar energy community is significant.  Of the ten most recent Presidents of the International Solar Energy Society, two were Australians (David Mills, 1997-9, and Monica Oliphant, 2008-9).  The Society, founded in 1954, was headquartered in Melbourne from 1970 to 1995.  With 26 participants, Australia was the 6th best represented country at the congress (behind Germany, Japan, Spain, Brazil and France).  And there have been major Australian contributions to solar power generation; names that occur in this context are David Mills, Martin Green and Shi Zhengrong.  These are achievements to be honoured.

It is abundantly clear that the solar industry is developing rapidly; for example solarbuzz reports that the PV industry generated global sales of USD 38.5 billion in 2009, with expected annual growth rates of around 30%.  Solar thermal power generation is not as developed as PV, but is poised for growth, as are the solar heating and cooling markets. 

Overall, the 2011 Solar World Congress gave a snapshot of research underlying this rapidly developing industry.  In the words of Berthold Goeke, one of the speakers at the opening ceremony of 2011 SWC, Germany’s single greatest contribution to the world is transformation of its energy network.  The world will move to a post-fossil and non-nuclear basis; Germany is showing us how to do it, and the solar industry will be an indispensable part of the process.


C. Breyer and A. Gerlach (2010), Global Overview on Grid-Parity Event Dynamics, in Proceedings 25th European Photovoltaic Solar Energy Conference, Valencia.

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