After about a decade of low development, the concentrated solar thermal power sector (CSP) is now reviving, notably due to a favourable supporting framework in Spain and increasing investments in the USA.
After about a decade of low development, the concentrated solar thermal power sector (CSP) is now reviving, notably due to a favourable supporting framework in Spain and increasing investments in the USA. A CSP plant consists basically, of a solar concentrator system made of a receiver and collector to produce heat and a power block (in most cases a Rankine cycle). Three main CSP technologies are under development: Trough, Tower/Central and Dish. Today CSP technologies are in the stage of a first commercial deployment for power production in Europe.
Technological state of the art and anticipated developments
Due to past developments in the US (~350 MWe in operation since 1980), the most mature large scale technology is the parabolic trough/ heat transfer medium system. In Europe, a parabolic trough power plant with a power capacity of 50 MWe and 7.5 hours of storage (Andasol 1), is under construction in Granada in Spain and is expected to be in operation in 2008. Two more plants of 50 MWe each are scheduled to be built on the same site. Central receiving systems (solar tower) are the second main family of CSP technology. An 11 MWe saturated steam central receiver project, named PS 10, is operating since March 2007 in Andalusia. This is the first commercial scale project operating in Europe. Solar Tres is another project under development in Spain based on a molten salt central receiver system. Construction is expected to start end of 2007. Parabolic Dish engines or turbines (e.g. using a Stirling or a small gas turbine) are promising modular systems of relatively small size (between 5 to 50 kWe), in the development phase, and are primarily designed for decentralised power supply. The solar only average load factor without thermal storage of a CSP plant is about 1 800 to 2 500 full-load hours per year. The level of dispatching from CSP technologies can be augmented and secured with thermal storage or with hybrid or combined cycle schemes with natural gas, an important attribute for connection with the conventional grid. For instance, in the Solar Tres project, 15 hours molten salt storage is included leading to a capacity factor of 64% without fossil fuel power back-up. Several Integrated Solar Combined Cycle projects using solar and natural gas are under development, for instance, in Algeria, Egypt, India, Italy and Morocco.
Current capital investment costs of a 50 MWe CSP plant can be found in the key figures section of the web site and used in the Energy Cost Calculator. The cost of electricity for CSP technologies is strongly influenced by the Direct Normal Irradiance (DNI), but also by the reliance on thermal storage that can extend the capacity factor and increase their dispatch capability. For DNI, as encountered in the Sahara region or in the US, the current cost of electricity production could be decreased by 20% to 30% with respect to similar technologies operating in southern Europe. The important resource base in neighbouring Mediterranean countries of Europe makes it possible to envisage importing CSP energy. For a given DNI, cost reduction of the order of 25% to 35% is achievable due to technological innovations and process scaling up. Facility scaling up to 400 MWe will result in cost reduction of the order of 14%.
Market and industry status and potential
The economic potential of CSP electricity in EU-15 is estimated to be around 1500 TWh/year, mainly in Mediterranean countries (DNI > 2000 kWh/m2/year). It is assumed that no installed capacity of CSP energy is forecast in the baseline scenario. The estimated maximum potential for CSP in the EU-27 is up to 1.8 GW by 2020 and 4.6 GW by 2030. Assuming that a grid infrastructure has been built with Northern Africa Countries, the maximum CSP electricity imports would be up to 55 TWh and 216 TWh between 2020 and 2030 respectively. The maximum penetration of CSP electricity for 2020 and 2030 would generate about 1.6% and 5.5% of the projected EU gross electricity consumption. In these scenarios, no fossil fuel back-up is assumed, with average load factors at about 6 000 full load hours in 2020 and 2030, due to the use of thermal storage.
The European industry currently has a market leadership in CSPtechnologies worldwide. At this stage of development, there is a supplychain industry already able to offer turn-key equipments for powerplants in the range of 10 to 50 MWe. However, an industrialramp-up in all aspects (engineering, procurement and construction,components, manufacturing, maintenance) will be necessary to go fromcurrent market shares to significant ones.
If the maximum potential is realised, CSP energy could potentiallyavoid up to 35 Mt/year CO2 in 2020 and 130 Mt/yearCO2 in 2030, with respect to the baseline. The correspondingmaximum cumulative avoided CO2 emission for the period 2010to 2030 would be up to 1035 MtCO2.
Achieving the maximum potential for CSP could lead to avoiding up to 10 Mtoe of fossil fuel use in 2020 and 40 Mtoe in 2030, with a maximum cumulative fossil fuel avoidance of 315 Mtoe, for the period 2010 to 2030. These figures do not account for the possible needs for fossil-fuel based power back-up to support CSP capacities.
The cost-competitiveness of CSP plants is a key barrier. There is a strong need for developing long term policy frameworks to foster and secure CSP technology developments and investments worldwide. On the technology front, component improvements and scaling-up of first generation technologies are necessary for cost reduction. The demonstration of new technologies at system level and relevant scale is also crucial for CSP cost-competitiveness in the long term. However, these R&D and innovation activities are not covered by industrial and private funds. As a result, there is a current shortage of equity capacity. This situation is also relevant for today’s technology. The necessary work on critical elements for first generation technologies such as adjustment of steam turbine to CSP specification is not performed today. Reaching a critical mass among players is an essential ingredient. Nevertheless, a structuring of the CSP industry as well as an expertise broadening is on-going, but it is still in its infancy. Finally, the development of specific enabling technologies, for example, grid infrastructure for importing CSP energy from neighbouring countries, is an important focus for the sector developments.
The implementation of long term frameworks with support schemes iscritical to accelerate the deployment of CSP technologies. Extendingthe Spanish model to other EU MS and fostering its promotion worldwideis important to build a global market. Joint developments with NorthAfrica would allow the EU to benefit from higher solar resource levels.It is important to open the European market for the import of solarelectricity from North Africa. A critical element of this action is theestablishment of a pan-Mediterranean grid infrastructure. On thetechnology front, increased R&D efforts and strategic alignment ofnational and EU programmes are necessary to realise all the potentialembedded in technology innovation. Demonstrating next generation CSPtechnologies is critical to address medium to long termcompetitiveness, but also to attract investors. Due to the privatefinancing dilemma, innovative funding schemes will have to bedeveloped.
Synergies with other sectors
Hydrogen production is a potential industrial field for synergies with CSP technologies. Although these concepts are at an R&D phase, current developments on the heliostat or other heat transfer components will certainly benefit this field. In the short term, shared developments can be envisaged with concentrated photovoltaics as their concentrators respond to the same kind of usage. Other areas of development besides electricity production are district cooling and water desalinisation.