28 January 2019

Concentrated Solar Power (CSP) – from niche to winning technology (2)

Concentrated Solar Power (CSP) plants initially won their place on the market thanks to government subsidies. Current trends reveal, however, that development efforts have meanwhile pushed this technology in combination with photovoltaic (PV) installations to competitive parity with fossil power generation.

CSP – a trailblazing technology turns competitive

The term “sector coupling” can denote the combining of fossil fuels with renewable energy sources, and any number of CSP projects have been erected that combine solar energy with fossil fuels. The power plants Kuraymat in Egypt and Hassi R’Mel in Algeria are two noteworthy examples. At both of these facilities, a solar field is coupled with a combined-cycled power plant that uses the solar energy collected during daylight hours to provide the boiler with “supplementary firing” capacity. 

Besides this coupled configuration to produce power more efficiently at lower prices, the more than 70 CSP generating installations erected between 2005 and 2012 under various subsidizing programs are having diverse, mutually positive and highly promising impacts:

  • Thanks to this large number of CSP projects, the power plant builders (engineering, procurement and construction (EPC) companies) and component suppliers have successfully worked their way through a learning curve, thereby reducing costs for planning, erection and per component (such as mirror fields and solar fields, boilers and turbine-generator sets, etc.).
  • These projects have led to an optimization of systems and installations that takes into account the interplay of components, the design of the water-steam cycle, the size of installations and the electrical output to be fed to the grid.
Global ordered capacity all steam turbine manufactures, Source: Siemens AG

The scaling of CSP plants for electrical generating capacities of up to 200 MW, such as Noor 2 in Morocco, in conjunction with cost-cutting and reasonable financing has had a significant impact on the dramatically falling levelized cost of energy (LCOE) used as a basic approach for planning new projects. While Spain saw estimated costs ranging from 25 to 30 EUR cents per kilowatt-hour (kWh), the current rate for projects today is 7 EUR cents per kWh.

Despite this trend, the view long held in the years from 2012 to 2016 was that competition between photovoltaics (PV) and CSP would ultimately be won by PV due to the enormous rates of PV expansion and the resultant reductions in cost this would bring. This view was also based on the assumption that the problem of energy storage capacity would be solved by batteries. Yet, as previously noted, it’s plainly evident today that these circumstances have not yet come to pass. The debate furthermore failed to consider that PV brings no rotating machinery serving grid stability – an added benefit that the steam turbine-generator sets of CSP plants do indeed contribute.

The P in PV stands for partner

Today, a rather different trend is becoming apparent in current projects: The benefits of both CSP and PV are being combined in hybrid power plants.

Source: Siemens AG

By combining CSP (7 USD cents per kWh with energy storage) and PV (2 USD cents per kWh without energy storage), power is produced at leveled costs of energy on a par with or even less than fossil fuel power plants – and without fossil-fired emissions.

Seen in this light, the growth rates forecast for CSP installations by various energy agencies around the globe appear realistic.

The Chinese CSP program established in 2016 and launched in a first wave of 20 power plants designed to generate 1.3 GW of electric power all told will most certainly help contribute to cutting costs even more while also further improving this technology. Yet, of these 20 new CSP installations, it must be noted that to date roughly half of it have succeeded in reporting significant progress in this regard. The successful approach applied in other countries of incentivizing projects by guaranteeing certain feed-in tariffs has not worked well for every project in China. It can be assumed that follow-up adjustments will have to be made for the next waves of CSP installations there.

Scratch the treshold of 1 GW

Since 2016, there has once again been growing activity in the CSP sector in addition to these projects in China. Current highlights include the Noor Energy 1 project in Dubai, formerly called Rashid al-Maktoum as well as ACWA DEWA IV, which is designed to deliver over 700 MW of electricity. Hence, 2018 had good prospects of once again scratching the threshold of 1 GW of newly installed CSP generating capacity for the first time since 2011.

In contrast to the years from 2005 to 2012, this most recent growth is attributable to the economic competitiveness finally achieved by CSP plants in terms of LCOE erected in combination with PV capacity, and their emissions-free operation, and not to any boom artificially created by term-limited state subsidization.

I therefore expect that further vast potential created by efforts to optimize the additional 150- to 250-MW power plants now in planning will lead to further cost reductions. These advancements will come in the following areas:

  • Optimizing the modes of operation of overall plants
  • Raising the temperature level within the solar power cycle and thus the main steam parameters for turbine-generator sets
  • Optimizing the water-steamcycle in conjunction with the boiler, preheating train, steam turbine-generator set and condenser
  • Advancing the development of energy storage technologies.

All in all, it’s clearly evident that CSP has become firmly established as a component of the energy turnaround in sunny regions of the world, and will remain so in the future.

And that’s a very bright forecast, indeed!


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