Concentrating Solar Power Towers are one of the main types of Solar Thermal power plants, they are commercial and ready to deliver baseload, intermediate and peaking power now.

Compared to other solar thermal technologies such as Troughs and Compact Linear Fresnel Reflector systems, they produce much higher temperatures, focusing upto 2000 suns onto the receiver.

The receiver is usually a boiler, or a series of pipes for carrying water or a working fluid, in the Lloyd Energy Storage Power tower the receiver is a graphite block the size of a shipping container that is used to store the heat energy. Steam is pumped through it while the sun is shining to drive a turbine or after hours utilising the thermal properties of the graphite.

Power Towers vendors

Southern View to tower of Abengoa Solar Power Tower 15km to the west of Seville Spain, Heliostat mirrors in the foreground.

PS10 a 11MW tower, and PS20 a 20MW tower are both commercial and operational now. Towers can be ordered in 20MW modules and high pressure steam or nitrate salt storage options are available. The PS20 plant covers Utilising Saturated Steam has a working temperature and pressure: 500 degrees Celcius 40 bars Thermal Power: 50 MW Height: 115 metres / 40 stories Length and Width of field y=1005 metres and x=945 metres

More Videos

BBC News item about PS10 http://www.youtube.com/v/cjYVomYuok0

Green Design Solar Tower http://www.youtube.com/watch?v=pCijcsT5yvk

CNN Eco Solutions http://www.youtube.com/watch?v=Q9vkkFNkE44

Below - a crane moves the reciever (focus area) - a large boiler onto the top of the Solucar PS10 structure.

PS10 Storage Tanks -- 30minutes of Solar Storage using pressurised steam.

http://www.youtube.com/watch?v=55gCiB11qqg Abengoa President

Nitrate salt storage is available for multi hour operation after sun down, by oversizing mirror field relative to power block.

Future Directions

Brayton Cycle very high temperature test site -where a 100kw small scale power tower has tested very high temperatures

The project led by DLR includes Abengoa in collaboration with Ciemat-PSA, the prototype scale project is a success demonstrating

for the first time in history solar electricity through a Brayton cycle. (As opposed to a Rankine cycle used in conventional and currently under development solar electric projects).

eSolar's approach is to use a small mass manufactured heliostat mirror, each with a dual-axis tracker eSolarleverages a commercial supplier to offer 1000s of these small heliostat mirrors at a very low cost. These heliostats are designed for pre-assembly at the factory and to fit efficiently into shipping containers saving money on transport and the simple racking system reduces labour costs during the build out phase.

The system also lends itself to rapid deployment, with a repeating modular structure used throughout the plant. With no need for high precision sureying, or delicate installation minimal skilled labour is required.

The heliostats are shipped for deployment in pre-fabricated "heliostat sticks" eSolar's Low wind profile design allows fields of eSolar heliostats to be installed faster than any competitive CSP solutions.

Brightsource energy and its subsidary Luz II are the modern incarnation of the company that built the first Solar Thermal Trough plants in the Mojave desert California.

Headed up by industry pioneer Mr Arnold Goldman (pictured above) who this time is leading the company to build tower technology.

The company has an operational pilot plant in Israel, and has a contract to build 900MW worth for Pacific Gas & Electric in California, which is one of the world's biggest utilities.

Beyond Zero Radio interview with Dr Arnold Goldman Brightsource - Listen to mp3 podcast or Read the Transcript

The image above shows the mirrors which are stowed horizontally so that maintenance can be done on the boiler. In extreme weather the mirrors can be turned out of wind and driving hail or rain.

Torresol Energy a collaboration of Sener, the Spanish Engineering Group, and the Masdar Initiative in Abu Dhabi is building Gemasolar a 17MW power tower solar thermal plant in Fuentes de Andalucia, just to the East of Seville, Spain

Gemasolar will be built so that it can run autonomously for 16 hours without any sunlight, effectively having an annual capacity factor 74% or 3 times that of a conventional power tower with no aftehours storage.

The system will directly heat a mixture of Potassium and Nitrate salts which then go through a heat exchanger to produce steam. This allows steam to be produced from the salt storage anytime day or night.

Gemasolar Solar Tres will consist of 2493 glass-metal heliostats (96m squared) with higher-reflectivity glass than what was used on a prototype in California named Solar Two that it is based on. Because of simplified design 45% reduction in manufacturing costs. It will consist of a thermal energy storage system, storing 6,250 T of molten nitrate salt (16 hours, 600 MWh). Add to this new advanced pump designs that will pump salt directly from the storage tanks, eliminating the need for pump sumps.

It will also consist of a steam generator system that will have a forced-recirculation steam drum. A more efficient, higher-pressure reheat turbine, and a simplified molten-salt flow loop that reduces by 50% compared to Solar Two California the number of valves.

Lloyd Energy Storage is building two solar thermal power stations in Australia that will store thermal energy in purified graphite, allowing dispatchable generation on demand (Baseload, Intermediate and Peaking Power), reducing the very high losses in remote areas on the grid and reducing the need to upgrade transmission system. Lloyd has built their pilot plant near Cooma, Australia.

The system involves a shipping container sized Graphite Block mounted ontop of a fairly low tower 18-20metres. Graphite has high thermal capability-to 3,500C, low emissivity, very high thermal conductivity, as well as being non-toxic and nonexplosive and stable over many temperature cycles, It increases its heat storage capacity as the storage temperature rises. The system allows thermal energy to be stored at the point of collection and held before being converted to electricity during the day or after sun down.

Listen to Beyond Zero Interview with Steve Hollis CEO Lloyd Energy Storage Listen

Above a 3D drawing of what the commercial plant will look like.

A Solar pitch generates 0.5MW Power

CSIRO Australia has a research Power Tower near the city of Newcastle in New South Wales Australia. At this one site they have Troughs a Tower and a Dish.

The tower has it's own unique architecture and is ready to be the basis of a commercial tower when a financial partner is forthcoming.

References

http://www.solarpaces.org/Tasks/Task1/PS10.HTM

http://www.nrel.gov/csp/troughnet/pdfs/2007/osuna_ps10-20_power_towers.pdf

http://www.abengoasolar.com/sites/solar/en/our_projects/solucar/ps10/index.html

http://www.abengoasolar.com/sites/solar/en/technologies/concentrated_solar_power/power_tower/index.html

http://www.abengoasolar.com/sites/solar/en/abengoa_solar_nt/current_projects/tower/index.html

http://www.nrel.gov/csp/troughnet/pdfs/2007/gilon_distributed_power_tower.pdf

http://www.esolar.com/solution.html

http://www.renewableenergyworld.com/rea/news/story?id=54538

http://www.torresolenergy.com/en/index.html

http://www.torresolenergy.com/en/proyecto_gemasolar.html

http://www.solarpaces.org/Tasks/Task1/Solar_Tres.htm

http://www.nrel.gov/csp/troughnet/pdfs/2007/martin_solar_tres.pdf

http://www.nrel.gov/csp/troughnet/pdfs/2007/osuna_ps10-20_power_towers.pdf

http://www.nrel.gov/csp/troughnet/wkshp_power_2007.html

http://www.nrel.gov/csp/troughnet/pdfs/2007/martin_solar_tres.pdf

http://www.nrel.gov/csp/troughnet/pdfs/2007/rogers_molten_salt_power_towers.pdf

http://www.solar-reserve.com/technology/CSP_Process_Diagram.pdf

http://enr.construction.com/news/powerIndus/archives/080813a.asp

http://www.edig.co.il/archive/en/377ecadfc255

http://www.edig.co.il/archive/en/e2b201df3ddd

http://cleantech-israel.blogspot.com/2009/01/arava-power-solar-project-approved-for.html

http://web.israel21c.net/bin/en.jsp?enDispWho=Articles^l1920&enPage=BlankPage&enDisplay=view&enDispWhat=object&enVersion=0&enZone=Technology&

http://cleantech-israel.blogspot.com/2008/01/edig-solar-provides-hybrid-solution-for.html

http://cleantech-israel.blogspot.com/2009/02/aora-raises-5m-for-solar-thermal.html