infographic csp today: new directions of energy storage in csp
TRANSCRIPT
OPERATION
Thermal storageWith Without
CONSTRCTIONIN
DEVELOPMENT
251401MW
472006MW
9440.8MW
821.8MW
5385MW
2100MW
112MW 13
785MW
5122.5MW
6810MW
656.5MW
332.5MW
8480MW
685.5MW
5136MW
9452.2MW9
605MW
New directions of energy storage in CSPPast, present and future of thermal storage
B U S I N E S S I N T E L L I G E N C E
59% of capacity currently under development will feature thermal energy storage
One of the first plants to utilise thermal storage was the SEGS I plant in California. This system had a total capacity of three hours of storage at full load. It operated between 1985 and 1999, when it was damaged by fire and never replaced. It was ten years later that we would next see another CSP plant with energy storage – Andasol I, the first parabolic trough plant in Europe. The plant has an indirect two-tank system, operating with 28,500 tons of molten salt that allow the turbine to operate at full load for 7 ½ hours. Recent projects have shown that the trend in the market is moving towards increased hours of thermal energy storage (except in cases where this is a limitation imposed by local regulation), in order to take full advantage of the economic benefi ts of storage systems for large scale projects. Some examples include:
Gemasolar – Torresol’s operational 20MW tower plant with 15 hours of storage
Bokpoort – A 50MW parabolic trough plant developed by a consortium headed by ACWA in South Africa, which will provide more than 9 hours of storage
Cerro Dominador – after the Chilean government put out a tender, Abengoa is developing a plant with 17.5 hours of molten salt thermal storage
Pedro de Valdivia – staying in Chile, Ibereólica Solar are developing a plant with 10.5 hours of storage
The trend toward energy storage in numbers
Solar plants Valle 1 and Valle 2, owned by Torresol Energy © SENER
CSP with energy storage are currently
operational, under construction or in development
Parabolic Trough Solar Tower Other
What’s next for storage?
The three main types of technology currently used for energy storage in CSP could be classifi ed as follows. The decision to use a specifi c technology is highly conditional on the heat transfer fl uid used in the plant.
As CSP developers seek to increase operational effi ciency by increasing temperatures, synthetic oils will have severe diffi culties in maintaining stability and market share. Molten salt can operate at higher temperatures than oils, but is currently limited to a maximum of around 650°C. Doping with nanoparticles may prolong the working life of molten salt by boosting this fi gure, and variations of the basic mixtures used may enjoy a second life as PCMs.
Using solid materials for TES seems to be a logical choice given their cheapness, their modularity and scalability, and the relative simplicity of the technology involved. Add to this the use of air as a heat transfer medium and you appear to have a winning combination. But these solutions are also limited by their thermal stability, which is not substantially higher than that of molten salt. The question also has to be asked: if solid material TES has so many advantages, what is preventing its adoption?
Graphite seems to have proved its feasibility as a TES medium, albeit one to be used as part of a hybrid system, for superheating steam, rather than in a standalone CSP power plant. Whether graphite could be used for power generation only remains to be seen, however. Meanwhile, the current interest that the US DoE has in thermochemical processes may be an indication of one direction energy storage may be headed in, although it is too early to be certain.
Furthermore, if CSP starts operating at extremely high temperatures, then exotic processes such as thermolytic production of hydrogen may become possible, paving the way for either hydrogen or ammonia as an energy storage product. This is highly speculative at the moment, though, as is the idea that a hydrogen or ammonia economy will gain widespread political and corporate support, with the necessary funds to back it.
What is clear overall, however, is that there has never been so much attention focused on the research and development of TES. And while molten salt can be expected to dominate the market for the foreseeable future, there are signifi cant drivers for the implementation of new, higher-temperature technologies. A widening of the options for TES can only be a good thing for the industry.
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Thermal energy storage
Latent
Salts
Metal alloys
Sensible
Molten salt two tank
Packed bed thermocline
Concrete thermocline
Sand-shifting two tank
Thermochemical
Metal oxide
Sulfur cycles
Ammonia decomposition
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Project portfolio with thermal storage
SpainOperational: 1132.4 MWUnder construction: 50 MWIn development: 0 MW
ItalyOperational: 5 MWUnder construction: 0 MWIn development: 210 MW
ChileOperational: 0 MWUnder construction: 0 MWIn development: 110 MW
South AfricaOperational: 0 MWUnder construction: 200 MWIn development: 200 MW
OthersOperational: 5.56 MWUnder construction: 37 MWIn development: 200 MW
ChinaOperational: 1 MWUnder construction: 50 MWIn development: 260 MWUnited States
Operational: 346 MWUnder construction: 0 MWIn development: 600 MW
Percentage of plants with thermal storage
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Perc
enta
ge
Operation Construction Development
ChileChinaIsraelItalyMoroccoSouth AfricaUnited StatesSpainOthers
• Egypt • Tunisia • Kuwait • India • France • Australia • Germany
= Without plants
Adding value to your CSP plantObjectives of adding thermal storage: Providing energy in a manageable fashion, extending operating hours
beyond sunset Avoiding fl uctuations associated with intermittent solar resource Reducing the amount of excess energy by the most effi cient plant
Hours 195 Hours 36.5 Hours 101.5174 19.5 1.5 31 14.5 48.540 13
Number of plants Capacity in MW
IsraelOperational: 1 MWUnder construction: 0 MWIn development: 137.5 MW
MoroccoOperational: 0 MWUnder construction: 160 MWIn development: 0 MW
Solar plant Gemasolar, owned by Torresol Energy © SENER
Thermal storageWith Without
Thermal storageWith Without
Source: CSP Today Global Tracker. April 2014
Source: CSP Today Global Tracker. April 2014
Source: CSP Today Global Tracker. April 2014