MENA diversity may dictate CSP technology
Often cited as one region, the Middle East and North Africa (MENA) is more geographically diverse th
Despite having distinct similarities, countries of the MENA region also differ in many ways. For example, while the GCC has demonstrated a high abundance of oil and natural gas, Northern Africa shows significantly less resource availability and current production, especially in the Maghreb.
Implications of differences
Being a highly industrialized region with a massive manufacturing sector as well as many mature oilfields, the GCC region can clearly benefit from using CSP in industrial applications.
“In the GCC, whether you’re looking at thermal desalination, enhanced oil recovery, or even district cooling, any kind of industrial steam usage, I think over time CSP will play a major role in such applications. Right now, the challenge is that in many of these countries the cost of fuel is subsidized; thus solar appears more expensive in comparison,” explains Jayesh Goyal, global vice president for sales at AREVA Solar.
When it comes to the space required for CSP plants, it is widely believed that the MENA’s endless deserts should provide plenty of land to build on; yet it is not always that straightforward.
“Land availability is an often discussed topic in both regions, and the common thought is that due to the wide open tracks of desert, project sites should be fairly easy to obtain. However, land ownership structures in both regions are not perfectly clear and often interlaced with governmental affairs, which leads to increased ambiguity and difficulty for acquisition,” Steven Meyers, research associate at the University of Kassel and former solar engineer at Saudi Aramco, tells CSP Today.
Differences can also be observed in the solar resource received by various parts of the region; a fact which could dictate the choice of CSP technology.
“In high DNI regions, such as in Morocco or the Tabuk region of Saudi Arabia, power towers should perform better due to minimal humidity and dust in the atmosphere. Once dropping below this threshold, as commonly seen in both coastal North Africa and the inland GCC, both trough and towers performance is comparable, but due to the tower’s steeper cost reduction curve, it should be the technology of choice,” notes Meyers.
According to him, however, initial plants built in both regions will most likely be troughs – due to their bankability and lower perceived risk. “Building financially feasible CSP with storage projects in the coastal Gulf region of the GCC will be difficult for either technology, as DNI levels of less than 1900 kWh/m2/a are most common”.
Beyond the variations in natural resources and solar irradiation levels, one issue that is common throughout the entire region is the lack of freshwater resources, meaning that water conservation will be important element of any CSP technology.
“In a CSP plant, water gets consumed mainly for the cooling if you’re using wet cooling and for mirror washing. For the cooling, what we recommend for our customers is dry cooling, which uses one tenth as much water as wet cooling,” states Goyal.
Generally speaking, the concentration technology of choice should be determined based on both, the targeted plant type and the local geography.
Meyers highlights: “Integrated Solar Combined Cycle (ISCC) plants will typically be located on the coast and demand steam which is most closely linked to steam turbine input parameters, minimizing integration costs. Linear Frensel systems have been shown to directly produce steam at temperatures at or above 450° C, which can be directly integrated with the turbine.”
Parabolic troughs, the most tested and bankable technology, are also well situated for ISCC plants, he says. However, because they only produce steam below 400°C, extra design work is needed for the Heat Recovery Steam Generator (HRSG), which increases total project cost.
As for power towers, although they can generate steam at levels needed for direct steam turbine integration, they also carry the highest price tag for thermal generation and are subjected to performance degradation due humidity and dust particulates. Linear Fresnel is also affected by this, but less so, and parabolic trough the least.
“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, with fairly equal suitability within North Africa and the GCC,” suggests Meyers.
Where thermal storage matters
When it comes to thermal storage, it is well established that it is a proven technology which can provide on demand power during low solar availability and at night. But for some countries, thermal storage is more than just an option.
Meyers elaborates: “The need for CSP with storage will be greater in areas which do not have significant or inexpensive backup fossil fuel generation, or in remote locations with weak grid infrastructure. Morocco and MASEN are already demonstrating this through its Ouarzazate project, and Saudi Arabia, via KACARE, with its minimum of 4 hours of thermal storage requirement per their CPP document”.
Indeed, the UAE’s 100 MW Shams 1, being located where fossil fuels are abundant, skipped thermal storage and instead relies on a small amount of natural gas to extend electricity production to the night.
“In countries where you have gas availability, you have the ability to optimize the performance of the combined cycle plant, because typically in the afternoon when it gets really hot, the efficiency of such plants drops, and at that time you can inject solar-generated steam,” explains Goyal.
ISCC: three-fold benefits
Meanwhile, hybridization represents a promising integration method that could increase CSP penetration into both the GCC and North Africa. ISCCs can already be found in Morocco, Algeria, and Egypt, with recent interest from Kuwait and Saudi Arabia, as seen with the Al Abdaliyah and Duba projects, respectively.
The reason for interest in this type of plant, according to Meyers, is three fold: increased plant efficiency, shared facility infrastructure, and decreased risk. “The CapEx ($/W) for the solar field components (relative to a full CSP plant) is also smaller, so the incremental cost of “going solar” is comparable to that of current PV prices.”
As for the GCC and countries with more locally or cheaply sourced fossil fuel, or biomass fuel in Egypt’s case, they should be more interested in the ISCC concept as it allows for a better integration into their current thermal power generation infrastructure with minimal retooling of production methodology.
In addition, an ISCC allows for decreased domestic consumption of fuel, making more available for potential export or value generation diversification, by industrial use or refining into higher value products. The siting of such a plant, though, needs to be carefully considered.
Meyers explains: “Countries with higher domestic electricity costs should be interested in solar thermal hybridization, but only for increased efficiency reasons to save on the high cost of fuel. One concern is that the typical location of thermal power plants is on the salt water coast due to cooling water availability and desalination demands. CSP plants located here will have decreased performance due to higher levels of aerosols which will scatter direct solar irradiance”.
In conclusion, all CSP technologies have their advantages and disadvantages, and depending on the location, the size and the application, the technology choice will vary. What will always be factored in, however, are the investment costs and long-term plant reliability.
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