2011 has been a memorable year for Dish Stirling, but not for the right reasons.This year, several Dish Stirling projects were shelved or forced to scale-down operations – including the relatively high profile Tessera Solar project using SES Suncatcher technology. 

The CSP sub-sector took a further hit this month with the news that Sterling Energy Systems, manufacturer of the SES Suncatcher technology, filed for Chapter 7 bankruptcy.

However, there is some evidence that smaller initiatives are faring better. For example, Innova has made inroads into the CSP market in Southern Italy, while Southwest Solar in Arizona has finished proof-of-concept testing with Brayton Energy – and is exploring an innovative CAES storage system.

The question begs as to why Dish Stirling technology is lagging behind other CSP technologies such as parabolic troughs and central receivers. Is it is better suited to micro-CSP applications, and as such, is it ever likely to take its place in the mainstream energy mix?

According to Tony Robey, Executive Chairman at Australia based CSP outfit Wizard Power, all dish-based technologies have lagged behind troughs in particular – largely due to the prohibitive costs of the cost of building the dishes.  However, he says a recent, significant reduction in dish construction costs, combined with the natural efficiency advantages offered by parabolic dishes, will see their adoption for a range of applications.

“These will include various methods of generating electricity, including Stirling engines, direct steam generation for thermal power-cycles and Brayton cycle gas turbines, as well as supplying heat to an extensive range of high temperature industrial processes,” he explains.

Overly ambitious

Wolfgang Schiel, Managing Director at German solar company Schlaich Bergermann and Partners (SBP), concurs that the technology currently trails behind other CSP alternatives, adding that no Dish Stirling design has yet reached a state of mass commercialisation.   In his view, most of the unsuccessful system developments failed because they suffered from a lack of adequate financial support or adopted targets that were too ambitious. 

“This technology is complex and needs enough time, money and technical competence to succeed.  In addition, Dish Stirling developers need to team up with a mass manufacturer to bring the cost down,” he adds.

According to Robey, at present there is little likelihood that Dish Stirling technology will ever become mainstream.  Having said that, his perspective is that there are such a wide range of opportunities for renewable energy generation that technology such as Stirling engines are, at the very least, likely to have a significant niche in which they will be competitive.

For Schiel, the recent throwback with SES-Tessera project is likely to make many people sceptical about the future of the technology.  However, he agrees that there may be a future for the technology – especially if developers are prepared to seek out niche applications. 

“We still see a considerable potential for improvements and for becoming competitive - especially if the automotives industry takes an interest in this technology,” he says.

“Non-Stirling dish systems shouldn't be disregarded, there are developments that could become attractive, such as the dish development effort of HelioFocus,” he adds.

Size matters

In the long-run is Dish Stirling better suited to utility-scale projects or micro-CSP applications?  Schiel’s view is that, at least in the early period of development, utility-scale projects are needed to bring this technology to a ‘bankable stage.  For him, this will provide the advantage of locating several units in one place - meaning that maintenance and system improvements could be handled much more easily and cost effectively. 

“Within a cluster of some hundred to some thousand dish units in one place, system development can be speeded up.  [As] a second step, decentralized market places can [also] be attacked - but for this market you will need an extremely reliable unit,” he argues.

“I don’t have a strong view on this, at least at present, but I note that the current focus of Dish Stirling developers appears to be utility-scale applications,” adds Robey.

At present there are not many large-scale Dish Stirling projects in the pipeline.  In fact, Robey is not aware of any large-scale dish based schemes aside from the project at Whyalla in South Australia, which will use Wizard Power’s own ‘Big Dish’ technology. 

This is a direct steam generation based project, which will generate around 40MW at stage 1, and which is expected to increase to approximately 200MW.  Stage 1 funding, says Robey, is a standard debt equity funding model supplemented by a Au$60m Australian Government grant.

Schiel agrees that no more large-scale projects are likely within the year.  However, he points out that Infinia is still a good candidate to make the breakthrough, “even if they are still in demonstration phase”.

Looking ahead, despite a number of recent setbacks, Dish Stirling technology remains a viable alternative CSP technology.  While it may not become mainstream, at least for some time, significant niche market potential exists – especially given adequate levels of funding and support.

To respond to this article, please write to:

Andrew Williams: awilliams@csptoday.com

Or write to the Editor:

Rikki Stancich: rstancich@csptoday.com

Image Credit: Wizard Power