By Heba Hashem

Dish Stirling technology has shown great promise of high conversion efficiencies with no water cooling demand, although without storage potential. But cost reduction efforts have not been enough to compete with PV, since both generate similar daily energy profiles.

This is evident in the recent bankruptcy of Stirling Energy Systems and Infinia. However, a young Swedish start-up, Cleanergy is still active in the market and signed an agreement last January with Al-Futtaim Carillion (AFC) in Dubai, to build the first Stirling Engine CSP plant in the entire MENA region.

Although the pilot project is small scale at 110kW, it is worth exploring the reasons behind the selection of this CSP technology, in a city where PV has so far dominated the renewable energy landscape.

Critical advantages in the GCC

Comprising 10 parabolic dish units as well as a park management supervision system to oversee the project, Cleanergy’s Stirling engine CSP plant is meant to serve as a learning tool for larger-scale deployment of CSP installations in Dubai.

“The pilot project is a complete installation containing the same components of a mega solar park", Merette Elsayed, director at AFC, told CSP Today.

"The plan is to record the data and monitor the performance and use it as a demonstration park for potential clients in the region, to prove that the technology is suitable for the climate and does indeed meet the required performance criteria.”

Cleanergy uses multiple suppliers of solar concentrators globally, although uses its own software to control them and the complete solar park.

The particular concentrator used in the Dubai installation is produced, designed, and patented by Pakistani engineering design company, AEDesign, to Cleanergy specifications.

According to Alexander Vestin, senior vice president of business development at Cleanergy, there are a number of reasons this technology is adapted for Dubai’s weather conditions.

“We don’t use water for cooling or steam production – the Stirling engine converts the heat into mechanical movement and drives the generator directly which also results in the highest solar to electricity conversion rate out of all available technologies,” explains Vestin.

And because it’s a modular system, if something goes wrong, only a small proportion of production is affected. “These are advantages we share with PV”.

“The differences to PV”, says Vestin, “would be that we’re less sensitive to high ambient temperatures – a critical advantage in the GCC region. Another advantage is that due to tracking, we produce energy more aligned with the grid´s peak demand – i.e. high production from morning to evening and not only around mid-day”.

In addition, the dish that concentrates the sun´s energy/heat into the engine is oversized, allowing the system to reach nameplate (peak) power production at lower DNI than 1000 W/sqm, which is the industry standard for measuring production and efficiency.

“We reach nameplate power at DNI=850 W/sqm which is more relevant since 1000 w/sqm is a theoretical measure that could be of interest when comparing two similar technologies, but a DNI seldom occurring in the region,” Vestin told CSP Today.

“We want to demonstrate the advantages mentioned above, not only to DEWA and Dubai but to the different stakeholders in the GCC and greater MENA region".

"We’ve come to learn that the old expression “seeing is believing” is very true even in today´s modern world with cameras, video links and all other technology that should shorten the physical distances”.

For those reasons, Vestin believes that a real demo installation would be of great essence when it comes to driving the commercial discussions in the region.

“The fact that we are able to do this together with reputable partners like DEWA and Al-Futtaim Carillion gives the installation further credibility and Cleanergy as a system provider great recognition”.

Merette comments: “Solar dish Stirling is a promising technology with a lot of potential for growth. We believe the technology is suitable for Dubai’s weather. Similar to other solar technologies it requires cleaning and maintenance, but we believe it is competitive in this aspect”.

A strong partnership

AFC is a joint venture between the UAE-based Al-Futtaim Group – a multi-faced conglomerate established in the 1930s and operating 65 companies – and Carillion PLC, a British multinational facilities management and construction services company.

Commencing activities in the mid-1950s, the JV has constructed iconic projects in the UAE, most recently the first phase of the City Walk in Dubai’s Jumeirah area and the Yas Hotel in Abu Dhabi.

Although the pilot CSP plant would be their first renewable quest, AFC plans to combine its long history of delivering complex engineering projects in the region, with Cleanergy’s CSP technology and know-how.

“AFC is constantly looking for innovative ideas and new potential markets. Cleanergy are offering a unique technology coupled with their growth aspirations, professionalism, and ethics”, notes Merette.

Cleanergy’s first solar Stirling units were delivered to Spain, Korea and China in 2011, and the first tests in the Chinese concentrator proved successful.

A year later, the company built its first commercial demonstration park of 10 units in the Ordos Desert in Inner Mongolia, China, where verification tests have shown that peak electrical power production was achieved at DNI 850 (W/m2).

Although dish Stirling is still seen as more appropriate for modular deployment due to comprising single units, and its levelized cost of electricity is struggling to compete with other CSP options, developers are confident that these challenges can be overcome via mass production and deployments of single installations.

Could the Dubai installation give dish-Stirling technology the push it needs to transition from a demonstrative scale to a commercial one?

To comment on this article, please contact the author, Heba Hashem.