Interview with Plataforma Solar's Dr. Eduardo Zarza

Setting up of "hybrid" energy centers, an initiative mainly about hybrid technology combining two renewable resources abundant in a particular area, is gaining momentum.

According to Plataforma Solar's Dr. Eduardo Zarza, recent studies have pointed out that wind energy and solar energy show a good complementarity along time when considered in a trasnational level.

"For instance, a very interested study conducted by the German Aerospace Agency (DLR) has shown that the European energy demand could be fully supplied with wind and solar power plants installed in Europe and North Africa. High voltage DC transmission lines would provide an excellent way to distribute wind and solar electricity all over Europe. The main barrier to take this possibility to a reality is the need for an international consensus to invest and accept this long-term approach. The European Commission and the governments of France and United Kingdom have already shown their support to this initiative," Dr. Zarza told CSPToday.com in an interview.

Dr. Zarza, who atended the recently held 2nd Concentrated Solar Thermal Power Summit in Seville, spoke about other industry-related issues. Excerpts:

CSPToday.com: How do you assess progress made by various CSP technologies be it parabolic troughs, dish-Stirling engine systems or power towers especially in the context of their commercialisation as of today?

Dr. Eduardo Zarza: The technical feasibility of these three technologies has been proven. However, the commercial viability is still to be demosntrated for dish-stirling and solar power systems. Improvements have been developed during the last decade for these two technologies, but experimenbtal results from commercial plants are still missing concerning dish-stirlings and solar towers. I think this is the reason why most of the promotors have chosen parabolic troughs for their plants.

The feed-in tariff and tax incentives implemented in some countries has pushed the commercial development of the various CSP technologies and a huge amount of resources are now being devoted by both public and private entities, thus making significant improvements foreseable in a mid term.

CSPToday.com: It is being said that some CSP technologies can be dispatchable, delivering firm power during peak demand. Trough and tower plants using thermal storage or supplemental fossil-fired components are particularly suited to this purpose.  How do you assess the situation?

Dr. Eduardo Zarza: Thermal storage is a must if we want solar thermal power plants to play a significant role in the future energy market. Though hybridisation with fossil fuels (e.g., natural gas) is already posible and problem-free, cost-effective thermal storage systems must be available in order to achieve full sustainability concerning the environment. Though there are already cost-effective thermal storage systems for parabolic trough plants (i.e., molten-salt systems with two tanks) due to the tax incentives and feed-in tariffs,  thermal storage for dish-stirllings and solar towers still need significant R+D work, which is also required to significantly reduce the cost of molten-salt systems for parabolic trough plants.

To my opinion, development of cheap and reliable thermal storage systems for CSP should by considered a high priority target in R+D programs related to solar thermal power plants.

CSPToday.com: Solar panels are being planned at some height to convert solar energy into electricity. It is being said that such technology reduces the cost drastically and the harnessing of solar power becomes economically viable and is pollution free. How do you assess such developments from technology perspective?

Dr. Eduardo Zarza: I think the solution to current energy-related problems (e.g., environmental pollution, limited fossil fuel resources, etc.) must be based on the use of severa renewable energies (solar, wind, geothermal, etc.). There are and there will be market niches for many renewable energies, so that the energy most suitable for energy niches must be used. We all must do a great effort to develope all available renewable energies in order to reduce their costs as much as possible while increasing their efficiency as much as possible. So, any effort aiming at this target should be supported and welcome.

CSPToday.com: Earlier this year, Hawaii-based Sopogy has introduced the new SopoNova 4, combining features of its MicroCSP Parabolic Trough technology that includes modularity, customised tracking, efficient shipping, storm protection, and automatic operation. How do you emergence of both large CSP solar farms to compete with Coal and Nuclear energy and small MicroCSP to compete with Natural Gas and Diesel fired generation at this juncture?

Dr. Eduardo Zarza: The main advantage of large CSP solar plants and small MicroCSP is the lack of environmental pollution, and this is the matter and the reason why these systems must be considered a better option than the ones based on fossil fuels. The price of fossil fuels will be higher and higher so that the current higher costs of solar plants will be smaller and smaller.

CSPToday.com:  CSP can become price competitive in the near term. The Solar Task Force projects that, with a deployment of 4 GW, total nominal cost of CSP electricity would fall below 10¢/kWh. A Solar Task Force poll of the CSP industry indicated capability to produce over 13 GW by 2015 if the market could absorb that much. What role do you technology will play in CSP becoming price competitive?

Dr. Eduardo Zarza: I do not consider this to be a realistic projection...the price of 10¢/kWh after a commercial deployment of 4 GW. It is true that CSP technologies have possibilities for a significant cost reduction in a long-term.

However, I think rather more than 4 GWe is required to achieve the projected cost of of 10¢/kWh. If enough money is devoted and researchers work in close collaboration with promotors and industries to reduce cost while increasing efficiencies, I have no doubt that a significant cost reduction will be achieved. However, I also foresee the possibility to face cost increases in a short term due to the unbalance between offer  and demand of componentes for CSP. The commercial deployment of these technologies must be accompanied by the development of the industrial basis to support such a growth. If the demand for components increases suddenly, the unbalanced offer will lead to a significant cost increase.

CSPToday.com: It is being projected that the combined average growth rate of CSP capacity over the last five years has been at around 250% and 16,000MW could be installed by 2015. What's your viewpoint regarding the same?

Dr. Eduardo Zarza: The number of solar power plants installed by 2015 will depend on how the tax incentives and feed-in tariff evolve. I think that feed-in tariff in Spain will be reduced in 2011 and the construction of CSP plants will not grow afterwards in the same way it is now. In any case, we should not get tough minded with projected figures; if we all do our best to reduce costs and increase efficiency the market will do the rest.