Concentrated Solar Thermal
| Author | European Union Publications Office, 2006 |
| Pages | 43-49 |
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| Concentrated Solar Thermal | |
| R&D Areas | Central towers, parabolic troughs and dish-Stirling systems for power generation and thermochemical production |
| State of Commercialisation | Pre-commercialisation; (2005: 12-15 ct/kWh; target 2015: 6 ct/kWh)59 |
| Key Nations | US, Spain, Germany, Israel |
| Expected contributions to EU energy policy targets | Adding to Europe’s renewable electricity supply energy policy targets Long-term option for renewable hydrogen production |
| EC policy backing | EU Directives on renewable energy supply and green electricity |
| Key Member States | Spain, Germany, Italy (accounting for |
Concentrated Solar Thermal Power (CSP) systems include three distinct technologies: central towers, parabolic troughs and dish-Stirling systems. The last of these has a power range of 5 to 50 kWe. It is best suited to decentralised generation and especially for stand-alone applications in developing countries. The former two technologies are envisaged for use in the range of several hundred megawatts: they can be linked to conventional power generation technologies and can thus be combined with fossil fuel-fired plants. Research demands focus primarily on raising efficiency through higher receiver temperatures and developing storage options. The latest activities in the field of towers explore thermochemical processes, especially direct solar-powered hydrogen production.
So far there are only a few demonstration plants of each type and one commercial solar trough plant, in the US60. However, recently several commercial or near-commercial demonstration projects have been planned or are under construction. In particular, the new solar power feed-in law in Spain, which explicitly includes concentrated solar power, brings a new dynamic to this technology.
Globally, only a very few countries have substantial knowhow of this technology. Intensive expertise and research activities are to be seen in the US and Israel, as well as in Germany and Spain. Italy has been heavily funding CSP, albeit mainly focusing on molten salt parabolic troughs: it has been more or less on its own in adopting this approach and has not yet achieved a major breakthrough.
While FP4 included some research into dish-Sterling systems, FP5 focused solar thermal power research mainly on central tower and parabolic trough systems. Major issues were:
* Cost and performance improvement of parabolic trough collectors.
* Development of solar receivers for central tower systems (mainly air receivers).
* Cost reduction of other new and innovative components (e.g. mirrors).
Research and demonstration activities were often directly linked to commercial power plant activities, as in the case of the Andasol, PS-10 and Solar Tres projects.
Research funding for CSP under FP6 was focused on hybrid systems and reactors for hydrogen production. This priority setting is horizontal to the above-described lines of CSP technology (dish, trough, tower). Although no technology was explicitly excluded from the work programme, funded research projects include only trough and tower-related technologies.
Another alternative path to enhance serviceability of CSP systems is the development of hybrid systems, which can be fuelled by solar heat and conventional (fossil) sources.
A roadmap project funded by the EC (ECOSTAR) evaluated the various technological approaches within CSP and established technological research targets.
The EUROTROUGH project can be considered a "lighthouse" project in the field of concentrated solar thermal power.
The EUROTROUGH project was initiated in October 2000 and ended two years later with an overall euros 1.9 M funding, of which the EC contribution was euros 0.9 M. Building on the findings of previous work, European industry was able to enhance the efficiency of solar trough systems and at the same time reduce costs, thus enhancing the competitiveness of this technology.
The main objective was the development of parabolic solar collectors offering improved efficiency at lower costs. The major results were:
* Within the EUROTROUGH I and EUROTROUGH II projects a 75m section of a parabolic solar collector, was developed, completed and tested under real sunshine conditions for one year.
* The performance and design improvements yielded a 15% cost reduction when compared to existing technology.
* As a result of these projects, the industrial partners are now EU leaders in low-cost parabolic trough technology and are beginning to tender for new solar thermal power plants.
Research priorities set by the EC and its key Member States are very similar. This is mainly due to close cooperation between these Member States - Germany and Spain - in the area of CSP. The main technological focus currently lies on central towers and parabolic troughs.
Probably the most important testing site on a global level is in Spain61: the Plataforma Solar de Almeria (PSA), which is operated by CIEMAT and run in close collaboration with German research. The main focus of research lies on:
* Guided steam generation through parabolic trough collectors.
* A central receiver system with molten salt.
Key "lighthouse" projects in these areas of research are:
* The ANDASOL demonstration plant (50MW steam generation, parabolic trough collectors).
* The SOLAR TREF demonstration plant (25MW central receiver system with molten salt).
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Both of these aim at commercial power production, were established by international consortiums and have received EC RTD funding.
Germany62 has been engaged in CSP since the early 1980s, achieving technological leadership in some fields. Research activities reflect Spanish priorities, in view of the joint-venture nature of the research in these two countries. High-temperature systems have been the focus of research recently, with hydrogen production as a new but growing topic.
Italy63 has put a heavy focus on CSP since 2001. The vast majority of the budget has been dedicated to one research programme focusing on parabolic trough technology with molten salt as a carrier.
Industry in Europe is closely involved in research activities, with the aim of preparing for potential large-scale projects in the global market: coordination with industry is excellent in the case of Spanish, German and EC-funded research. Industrial products are also clearly targeted in ongoing RTD activities in the Italian initiative.
The United States64 is the country with the strongest commercial experience with CSP. However, activities have been greatly reduced in the recent past. The key focus areas of research are solar dishes and solar troughs. In the areas of thermochemical systems and solar production of hydrogen, efforts in the US are less developed than European initiatives. However, expert opinion suggests that this area will gain in prominence in the coming years as part of US hydrogen strategy.
Israel65 is probably, next to Germany, the country with the highest scientific and industrial knowhow in the field of CSP. Specialised companies are heavily involved in research and technology development. Research ranges from multi-megawatt central tower systems to small-scale systems (
Australia has established a national centre to act as a focus for solar thermal energy research at Newcastle, NSW.
This will comprise a high-concentration tower array of around 800 m2, with a peak generation of over 550 kWth, and a medium-temperature array for temperatures up to around 300°C.
Mexico and South Africa have, among other activities, entered the field of parabolic dish-Stirling technology for the purpose of acquiring practical experience in the current technology and assessing the potential for supplying electricity to rural areas.
Japan is not active in concentrated solar thermal research, due to geographical and climate conditions which are unfavourable for the use of CSP in Japan.
International coordination is mainly handled through the IEA SOLAR PACES platform, which aims at the development and marketing of concentrating solar power systems. Active countries are principally Germany and Israel, as well as Spain, the US, Australia and France.
Within Europe a mixed picture emerges when looking at collaboration on CSP research:
* On the one hand, there has been good collaboration on all those activities now led by Germany and Spain. Due to the very limited number of participants in this field, coordination at the EU level is excellent. Research activities are relatively harmonised, e.g. due to the joint utilisation of the Plataforma Solar in Almeria as a common testing site for German and Spanish researchers. Since 2004 coordination has been intensified through the SOLLAB initiative, an alliance between four European laboratories: CIEMAT (Spain), DLR (Germany), ETH (Swiss) and PROMES-CNRS (France). EU projects are mainly operated by German and Spanish research institutes and industry, with the participation of specialised players in France, Italy, Switzerland and Israel.
* On the other hand, there are the relatively recent activities in Italy focusing on molten salt parabolic trough systems. Although there is considerable national funding, there seems to be virtually no collaboration or coordination with other Member States or the EC.
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Research funding for CSP in FP6 includes only trough and tower-related technologies. The major share of funding (60%) is concentrated on thermochemical systems for the production of hydrogen or reformation of natural gas. Further focus has been on cost-effective storage systems and hybrid systems which can be fuelled by solar heat and conventional (fossil) sources. The latter are addressed in one project accounting for ~15% of the CSP budget66.
Most of the European research projects are closely related to and interlinked with the activities at the Spanish Plataforma Solar de Almeria (PSA). Stemming from an IEA initiative, the PSA was for a long time financed by several countries and jointly operated by Germany and Spain, but is now operated by the Spanish CIEMAT. Research funding in Spain on concentrated solar thermal has been euros 8 M per year with an upward trend since 2001. A new programme, CENIP, is due to be launched with R&D funding expected to increase to around euros 60 M per year.
Large demonstration plants in Spain like the 11 MW solar tower plant PS-10 and the 15 MW solar tower plant Solar Tres have been supported by both European and Spanish research funds. Since these projects aim at commercial power production, the bulk of the funding, estimated at several hundred million euro, has been provided by private industry investors and bank grants.
Germany has had a long tradition of involvement in the Plataforma Solar de Almeria and has maintained continuous research activities over the last 20 years. After very strong funding in the 1980s (>euros 15M per year), support was reduced to approx. euros5M per year during the 1990s, dropping subsequently to less than euros 3M in the period 2000- 2004 (displayed in Graph IV-1). Recently, CSP has again been highlighted within German renewables research priorities and a federal budget of euros5 M per year has been allocated to the topic. The largest share (roughly 60%) has been invested in research of components. About 20% each has been allocated for new concepts and solar thermochemical systems, with a growing share of the budget for the latter. Germany has also provided funding for research activities at the commercial 2x50 MW solar trough power plant Andasol.
Italy is putting more money into CSP than all the other EU countries together (see Graph IV-1). With a budget of euros35M in the years 2002-2004, CSP makes up almost 20% of Italian energy NNE RTD funding. The vast majority of the budget has been dedicated to one research programme which focuses on parabolic trough technology with molten salt as a carrier. In the fields of central towers and dish-Sterling systems Italy employs some smaller demonstration and testing sites.
It is worth pointing out that Italian activities on the parabolic trough system are independent of activities of other Member States. Italy is not (or not yet) perceived as a major player in CSP research by energy experts outside Italy. Participation in EC-funded research projects is minimal and restricted to the fields of solar dish and central tower systems.
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Activities in the US have been greatly reduced over the past years. The funding for CSP was around euros 20 M per year before 2000 and only euros 4.5 M per year in 2005-2005. It is expected that funding will increase again in the near future with a targeted figure for 2006 of euros 9 M. In 2005 more than half the budget was addressed to the screening of selected high-temperature solar hydrogen production technologies. In the future hydrogen production will be funded under the US hydrogen programme [DoE 2005].
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Globally only67 a few countries are active in research on concentrated solar thermal power (CSP). Due to the activities of Germany and Spain, Europe has a leading position worldwide, closely followed by Israel. Italy has started to build up competences in very recent years. The United States has reduced its activities to the bare minimum, just in order not to loose track, but has started to become active in solar hydrogen production. Other countries such as Australia, Mexico and South Africa have made some efforts to strengthen their expertise and practical experience in the field of CSP, but play only a minor role in terms of CSP research.
A general characteristic of CSP is that, although there is a large global potential, applications in Europe are restricted to a few southern regions. It is a peculiarity of CSP research that some of the most active Member States have very limited or even no potential at all for using the technology in their own countries. CSP research is thus very much directed towards building up industrial knowledge and to enhancing competitiveness in export markets.
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The EC's concentrated solar thermal research portfolio is strong on central tower and solar trough projects. It has shifted from material and component-oriented questions towards issues vital to the integration of concentrated solar power in Europe's energy systems (hybrid systems and storage). This could allow a reduction in system costs and bring the technology closer to the market. Solar dish-Sterling systems have shifted beyond the focus of EC-funded activities. Although not explicitly excluded from the current work programme, no projects were funded in this area. The main focus in FP6 is on thermochemical technologies, thus exploring a long-term option for CSP and opening up new fields in respect of hydrogen production for storage or transport fuels.
Activities of the main long-term players, Germany and Spain, are very much in line with the EC portfolio. Italy, however, has taken a different path (molten salt solar trough) and is not integrated in European collaboration efforts. In order to come to a common European research strategy, it would be necessary to integrate the emerging Italian CSP efforts into the well coordinated activities supported by Germany, Spain and the EC.
In the US the DoE is currently supporting the CSP industry in carrying out research projects the industry considers to be important. Due to a tight budget, the focus has been on solar dishes and solar troughs: solar towers are not covered currently. However, solar high-temperature production of hydrogen as part of the US hydrogen strategy is already addressed in a few projects and will gain prominence in the future.
Israel's research priorities are quite similar to those of the EC/Spain and Germany, with Israeli institutes also active in EC research projects. In Israel, research is to a large extent carried out by industry and private research companies: if the country realises its plans to build a larger pilot plant in the desert, this will strongly support the Israeli CSP industry.
The main players (Germany, Spain, Israel and the US) invested heavily in concentrated solar thermal power in the late '70s-'80s in order to build up costly demonstration and testing sites. A great part of today's research is conducted on these sites or on sites which are designed for commercial power production (and consequently receive the major investment from private investors). Italy is a new player who has not been very active in the past but has put strong funding into CSP in the last few years, mainly towards the establishment of test and demonstration sites. It is important to look back forward and not focus only on funding activities in the last five to ten years, as this would give a distorted view of the real investment and activities taking place in CSP.
If one sets aside activities in Italy, EU funding (Member States and the EC) is comparable to that of the US. Taking into account the substantial activities in Switzerland, Europe's overall engagement in CSP is more important than that of the United States, where the budget has been reduced by half over the last five years. In Europe 12.6% of the renewable energy RTD budget is allocated to concentrated solar energy research, whereas the proportion for the US dropped from 6% (before 2003) to 3% (2003-2005). Very recent trends hint at increased funding for CSP in both the United States and Europe (especially Germany).
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With a view to the application of concentrated solar thermal power, this field is quite peculiar in the sense that some technological paths (solar trough systems) are relatively well established, but there is basically only one commercial plant operating worldwide (SEGS, US). A major barrier is that, at least for solar trough and central tower technology, a commercially operating plant would have to be of substantial size (multi megawatt), which therefore precludes the "evolutionary" path that wind and photovoltaics have taken. Currently there are several installations in the 1-100 MW range planned or under construction, most of which are directly linked to EC-funded research. For the future the new feed-in law in Spain and several requests from other countries (e.g. Morocco, Algeria) make demonstration under commercial conditions likely. This will definitely give the technology a major push.
Future research demands exist mainly with a view to enhancing efficiency. Also, for thermochemical solar-powered hydrogen production, higher temperatures would be necessary. Pursuing this path would call for new testing and demonstration sites. In order to come to a common European research strategy, it would be necessary to integrate emerging Italian CSP efforts into the well coordinated activities supported by Germany, Spain and the EC. The key priority for dish-Sterling systems is to enhance their reliability for stand-alone applications in developing countries. If this path is to be pursued the emphasis should be on demonstration and field testing: furthermore, co- and tri-generation options could be explored, as well as hybrid systems.
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[59] - Target according to "Global Market Initiative" for concentrated solar thermal energy
[60] - Actually the "Solar Electric Generating System (SEGS)" consists of nine solar fields at three separate but adjoining sites in the Mojave Desert in California, the most famous of which is Kramer Junction. Operating since 1985, peak power capacity is 350 MW.
[61] - For further details of concentrated solar power research in Spain, please refer to Annex IV
[62] - For further details of concentrated solar power research in Germany, please refer to Annex IV
[63] - For further details of concentrated solar power research in Italy, please refer to Annex IV
[64] - For further details of concentrated solar power research in the US, please refer to Annex IV
[65] - For further details of concentrated solar power research in Israel, please refer to Annex IV
[66] - For further details of EC funding of concentrated solar thermal research, please refer to Annex IV
[67] - Data includes public funding only, which is explicitly allocated to concentrated solar thermal energy. For many countries additional funding for CST comes from regional authorities. In the case of Germany, institutional funding (Helmholz Gemeinschaft) is not included.
