Ain-Beni-Mathar ISCC

When, Morocco broke ground on Ain Beni Mathar in 2010, it was the world’s first Integrated Solar Combined Cycle (ISCC) power plant. Algeria and Egypt followed suit soon after and by 2011, all three countries had their own running ISCCs.

A quiet period for ISCCs followed this round of projects, which had comprised similar CSP capacities ranging between 20 MW and 25 MW. That was until Saudi Arabia and Kuwait stepped up and invited expressions of interest for ISCC projects in 2013.

Testing phase

What’s evident from these developments is that all five countries chose to begin with ISCC plants as their very first experience with CSP.

“I believe that implementing ISCC power plants before standalone CSP plants is a risk-reducing step toward beginning to build a larger solar thermal energy portfolio”, says Steven Meyers, researcher at the University of Kassel in the Institute of Thermal Energy Engineering, with a special focus on the solar heat integration into industrial processes.

“Some of these newer countries to the CSP market want to obtain experience building larger CSP plants without risking everything on only ‘going solar.” By building an ISCC facility, says Meyers, they can gain planning and construction experience while providing a low-risk power plant into their country’s portfolio.

Unlike the North African ISCCs, Saudi Arabia and Kuwait have opted for larger solar capacities. While the 550 MW Duba 1 will incorporate a 50 MW CSP capacity, Kuwait’s 280 MW Abdaliyah will integrate 60 MW.

“Successful completion of these projects is very important for the growth of the CSP industry, as an underperforming plant in a large market, such as the MENA region, would cast doubt on the technology and fewer countries would be willing to invest,” Meyers tells CSP Today.

It is evident, then, that these projects are experimental in nature. For Saudi Arabia, this would allow the monitoring of CSP performance before proceeding to the commercial-scale tenders planned by K.A.CARE. As for Kuwait, the success of the ISCC plant would demonstrate the feasibility of utility-scale CSP ahead of the development of the 2,000 MW Shagaya Renewable Energy Park, planned for completion by 2030.

Three-fold benefits

The logic behind building ISCC plants, according to Meyers, lies in the increased fuel efficiency, shared facility infrastructure, and decreased risk. “The benefits of combining the two types of plants are well known: shared power block, utility connection, and civil works. When building such a plant, many things can be shared, such as the power block, utility connection, cooling tower, BOS components, which will minimize the cost of the respective CSP field”.

During operation, the CSP field can provide peak energy, allowing for a reduction in fuel, or an increase in power output, which is especially needed in the summertime when high ambient temperatures reduce the efficiency of the Combined Cycle plant.

Specifically, the GCC and countries with more locally or cheaply sourced fossil fuel, or biomass fuel in Egypt’s case, should be more interested in the ISCC concept as it allows for a better integration into their existing thermal power generation infrastructure with minimal retooling of production methodology.

“If you’re going to be building a conventional power plant anyway, and you have extra land around you for CSP panels, mirrors, collecting units and CSP boiler to add the extra steam, you can share the cost of the infrastructure,” Christopher Cantelmi, principal of Infrastructure and Energy, MENA, at the International Finance Corporation, told CSP Today in a previous report.

“So the unit cost of CSP would be reduced because it’s sharing the cost of infrastructure, by sharing that steam turbine generator. When you look at it as a combined project, it could make financing easier,” Cantelmi had pointed out.

Because there are many open-cycle gas turbines in the region, as efficiency wasn’t a priority in the past, these can be converted into closed cycles by adding a recovery steam generator on the back of them to capture the wasted heat. The steam turbine can then be oversized with a CSP unit as a way of cutting down costs.

Ultimately, hybridization through ISCCs would allow for decreased domestic consumption of fuel, allowing more for potential export or value generation diversification by industrial use or refining into higher value products.

Weighing up technology options

A challenge that may arise relates to the siting of the plants. Thermal power plants are typically located on the salt-water coast due to cooling water availability and desalination demands, but CSP plants in such locations would have decreased performance due to higher levels of aerosols, which can scatter direct solar irradiance.

“ISCC plants will typically be located on the coast and demand steam, which is most closely linked to steam turbine input parameters, which will minimize integration costs. Linear Fresnel systems have been shown to directly produce steam at temperatures at or above 450 degrees Celsius, which can be directly integrated with the turbine,” explains Meyers.

Power towers can also generate steam at levels needed for direct steam turbine integration but carry the highest price tag for thermal generation and are subjected to performance degradation due to humidity and dust particulates.

Parabolic troughs, the most tested and bankable technology, are similarly well suited for ISCCs, however, only produce steam below 400 C. Extra design work would also be needed for the Heat Recovery Steam Generator (HRSG), says Meyers, which increases total project cost.

“Linear Fresnel is also affected by this, but less so, and parabolic trough the least,” he notes. “For the easiest thermal integration and the lowest cost for the solar collector field, linear Fresnel should be more heavily investigated and preferred for ISCC and hybridization projects.”

Despite these considerations, all three operational ISCC plants in North Africa chose to use parabolic trough, yet for the upcoming plants, the technology remains undecided.

Various media reports suggest the Abdaliyah ISCC will be using parabolic trough, but up until July 23rd, which was the deadline for EOIs from developers, Partnerships Technical Bureau had not officially announced the preferred technology.

On the other hand, Saudi Electricity Company left the CSP technology ‘open’ in its latest call for EOIs for the Duba 1 EPC contract, the deadline for which ended on July 21st.

Looking to the future, can five ISCC projects in four years possibly signal a trend? Not necessarily, according to Meyers. “It is hard to predict if this will be a growing trend in the region, as the current frequency for these plants being installed is quite low.”

“Nearly every country wants to try one ISCC plant before progressing further. In the MENA region, I believe that ISCC plants will be more common than in other large CSP markets, due to their expertise in building very large thermal power generating facilities.”

What is certain in all cases is that ISCC plants could potentially unlock the door for stand-alone CSP and pave the way for its bankability in the MENA region.