At CSP Today we have previously covered his research with a very novel storage material - sand.

What is happening with this 100 kW beam-down solar platform now?

When I arrived at Masdar Institute this plant was almost abandoned. Nobody was using it so I suggested we use this demonstration plant, modify it and make it a unique research tool to develop some solar receiver or storage systems and that’s what I am doing right now. We renamed it the Masdar Institute Solar Platform and it is part of the recently launched Masdar Solar Hub.

What are the advantages of this design?

Instead of moving the salts to the top of the tower, we bring the light into the storage tank. Because we use a beam down concentrator, we can bring this concentrated solar energy right down to the tank on the ground.

You have a heliostat field like in a conventional power tower plant. Each heliostat sends the light to the top of a small tower 20 m height - versus 140 m in conventional power plant. And then at the top of the smaller tower there are secondary mirrors that concentrate the light down on the ground.

You don’t pump the molten salts up the tower. You don't need pump, pipes, you don't need electrical tracing to avoid the freezing in the pipes. You reduce a lot parasitic energy consumption by not moving molten salt in pipes. And you have direct absorption between the concentrated light and the salt in the tank.

Instead of two tanks there’s only one tank. There is a moving divider plate inside it separating the upper part which should be hot and the lower part which should be cold. When you charge your system, this plate is moving down and you have only hot salts. And when you discharge, the plate is moving up and you have only cold salts.

Next, we would like to change the salt because, as we don't need to move the salt, we could think about other kinds, like carbonates that can go to higher temperatures.

We could think about 800 C. If you go to higher temperature, increasing the efficiency of your system; you need less quantity of salt also. By changing all these parameters, I think the economy of the plant would be much more cost-effective than the conventional system.

What is the next step for the CSPonD prototype?

We have one PhD student, Radia, in the CSPonD demonstration project. She is working on a water fall molten salt CPC which is a compound parabolic concentrator to concentrate even more light from the beam down and reach higher temperature. Generally what we do is we try to link each PhD or Master’s thesis with a project.

We are really at the stage of upscaling from lab scale to pre-commercial scale. The concept was tested by MIT in their lab and it works. So now I contacted them to do this project and try to make it possible in a larger scale system.

I contacted Professor Alexander Slocum and we started in June 2014. Basically we are preparing the plant to welcome the prototype that they are building at MIT.

MIT does lots of molten salt research for nuclear, so it was easy for them to apply the knowledge to solar. Giving them the opportunity to test this concept with the real solar plant was really attractive for them.

Masdar's beam down facility. Image courtesy of Masdar.  

Does your molten salt research at NREL and at the CIC Energigune Energy Cooperative Research Centre in Spain facilitate this sort of international collaboration?

That is the beauty of the Masdar Institute Solar Platform. We can give the opportunity to industry or academic partners to come here and test with us new storage concepts.

This is the kind of collaboration that I try to develop as a platform. It can be an academic or an industry partner but all together we are testing new concepts in the real Desertic climate conditions.

We have a project with Ibiden, the Japanese company that launched a new mirror at WFES, the World Future Energy Summit this January in Abu Dhabi. Their new mirror is very lightweight - not using glass - with a silicon carbide coating which protects the silver of the mirror.

At Shams 1, if a wind is more than 45 km per hour you have to defocus to save the trough. So wind should be considered all the time. But by having a light weight mirror you need a less complicated and cheaper structure. They are now upscaling this mirror to one meter, and once they have this size we will also test this mirror on heliostats for tracking the sun.
Right now we are testing different cleaning technology: the goal is to be able to wash the mirror without water because of the limited access to it in the desert.

You have repurposed unlikely materials as feedstocks, as we covered previously at CSP Today. What drives your research choices?

We started this innovative approach in France during my Ph.D. and I try to identify all the waste that industry is producing that doesn’t need any supplementary treatment, like the steel industry in the Basque country which is the third producer of steel in Europe, so they have lots of steel slag.

I have a local student called Kholoud. She’s working with EMAL - Emirates Aluminium and Emirates Steel; two big companies in the UAE producing steel and aluminium for construction. And they provide lots of industrial waste like slag from steel industry or aluminium dross from aluminium industry. We are working on characterisation of this waste.

We found that we could use this waste as a high temperature storage system. It is a ceramic in the end: Metal Oxides. So it is really stable at high temperature. We could use it up to 1000 C without any problem of degradation or cracks.

This could be a way to decrease at the same time the cost of the system, because it’s recycled waste - here in the UAE landfilling is forbidden - and having higher efficiency in your system, because you work at a higher temperature.

The beauty of this project is that from the waste that nobody wants, you are going to produce energy that everybody needs.

What is the motivation of the Emirates: domestic or international sales?

Both. They want us to do research relevant for applications that they can apply in the UAE, and in the Middle East - but also all over the world. Here in Abu Dhabi, Masdar possesses a 60% stake in Shams 1 and 50% in Gemasolar, in Spain.

So the idea is to develop technology which could be applied here in Abu Dhabi but also that we can sell in other countries. As we did in Spain, or even in Great Britain; Masdar developed the London Array, a wind farm in the sea. So Masdar is developing renewable energy not only in the UAE but also all over the world.

One of our team’s objectives is if Shams II is built for example; I would like it to have storage from our research. So our activity is directly linked to future CSP projects in UAE.

Despite big plans, the Saudis have been slow to commission projects compared to the UAE. Is there any interest from Saudi Arabia?

That is an interesting question. This week we have a workshop where we will be training some professors from Saudi Arabia on concentrated solar power, so they are coming here.

We are doing some lecture on linear concentration, point focus concentration, some on energy storage, some on power blocs, and they are visiting our solar platform to see what's going on here, so they have lots of interest. These are high level academic people who are coming here to be trained and collaborate with us.