In 2017, approximately 11TWh of global electricity came from concentrating solar power, a substantial jump from the estimated 1TWh produced 17 years earlier.
As of 2021, global installed capacity stood at 6.4GW – far less than the figure for photovoltaics (PV) at 843GW, as reported in IRENA’s Renewable Energy Statistics 2022.
Meanwhile, tracking the numbers, the IEA anticipates that CSP technologies will constitute up to 11% of electricity generation by 2050.
Currently, there are four main types of CSP plants: parabolic trough, solar power tower, dish Stirling, and linear Fresnel reflector (LFR).
Each operates in a slightly different way, but all use the same basic principle of concentrating sunlight to produce heat.
The technology requires water for cooling and condensing processes as in other thermal power generation plants. However, CSP water requirements are relatively high: about 3,000 litres per MWh for parabolic trough and LFR plants (similar to a nuclear reactor).
In comparison, coal and combined cycle natural gas plants need about 2,000 and 800 litres per MWh. Tower CSP plants need less water per MWh than trough plants.
Depending on the efficiency of the technology, the surrounding air cools dishes and requires no cooling water. Another challenge is location.
CSP plants require large land areas and high direct normal irradiation (DNI) levels, typically above 1,800kWh/m2 per year (about 5kWh/m2 per day).
While the technology is most effective in areas with high levels of direct sunlight – limiting potential deployment in areas with lower irradiation or significant continuous cloud cover – advancements in technology have allowed CSP plants to operate more efficiently, increasing their possible deployment in areas with less sunshine.
However, unlike PV, CSP’s technical potential of generating electricity is typically several times greater than the demand, resulting in opportunities to export power.
Furthermore, the advantages outweigh initial capital costs as, once built, CSP plants have relatively low operating costs, can provide electricity at a competitive price, and have an enviable built-in storage component.
The combination of generation and storage makes CSP dispatchable: providing grid power when needed, whether during the day, at night or during peak periods.
Typically, the operation and maintenance (O&M) costs include plant operation, fuel expenses in the case of hybridisation or backup, feed and cooling water, and field maintenance costs.
A typical 50MW trough plant requires about 30 employees for plant operation and 10 for field maintenance.
O&M costs have been assessed from $13/MWh to $30/MWh, including fuel costs for backup and as plants become larger, O&M costs will decrease.
Regardless of the CSP system used, compared to other renewable resources (specifically solar PV, which saw prices drop), the high upfront capital costs to build CSP plants persist. In 2022, IRENA reported that the levelised cost of electricity (LCOE) for new utility-scale solar PV fell by 13% year-on-year to $0.048/ kWh.
In comparison, with only one CSP plant commissioned in 2021, the LCOE rose 7% year-on-year to $0.114/kWh. However, John Roome, the World Bank’s South Asia Regional Director for Sustainable Development, challenged the price point during Africa’s Green Economy Summit. According to Roome, in 2013/14, global CSP plants were operating at approximately $0.20/kWh.
Yet, when Morocco developed the Noor CSP plant, the price was far lower at 15 cents.
This lower price came about through a combination of tight bidding and a small amount of concessional financing, stated Roome, adding: “Then ACWA Power brought the technology to the Northern Cape [South Africa] and Dubai, and that drove the price of CSP down to 5 cents per kilowatt hour.
“In the UAE, it’s under 4 cents and coming down, case by case.”
As the technology became more widely used, more R&D expanded its profile from storing energy in the molten salts for up to eight hours to almost 18 hours.
“What was a variable technology has become stable. This is African technology,” he said.
CSP technology has been deployed in several African countries, with Morocco sporting the world’s largest solar complex and South Africa hosting the most CSP plants and technologies in Africa.
At the same time, Egypt is noted for housing one of the world’s largest solar complexes combining CSP with PV.
The Moroccan Solar Energy Programme (NOOR) comprises five solar complexes with a combined solar power capacity of approximately 2GW.
The world’s largest CSP development is located in the complex, the Noor Ouarzazate Solar Complex, consisting of four plants with a combined capacity of 582MW.
In this complex, you will find the 160MW Noor I (operational since 2015), commissioned three years later, the 200MW Noor II and 150MW Noor III.
Other plants in Morocco are the 20MW parabolic trough Ain Beni Mathar commissioned in 2011, and a smaller project, the 3MW Airlight Energy Ait-Baha Pilot Plant, which has five hours of storage.
South Africa has invested heavily in CSP technology, sporting eight large-scale plants generating 700MW.
Notably, all the plants are in the country’s Northern Cape province, known for its high irradiance levels.
Commissioned in 2016 and part of the second REI4P bid window, the 50MW Bokpoort plant uses a parabolic trough system with 9.3 hours of storage. Another parabolic trough plant is the 100MW Ilanga-1 CSP plant at Karoshoek Solar Valley.
The Ilanga plant, which celebrated its first year of operation in 2019, maintains a fivehour storage capacity. Also commissioned in 2019 is the 100MW Kathu Solar Park, which uses molten salt and dry cooling for its parabolic trough system, and five hours of storage capacity. Another parabolic trough plant is KaXu Solar One.
This 100MW plant uses dry cooling and molten salts with 2.5 hours of storage capacity, whereas the 50MW Khi Solar One plant with two hours of storage uses a dish system with saturated steam and dry cooling.
Operational since 2018, the 100MW !Xina Solar One plant uses dry cooling and molten salt with 5.5 hours of storage capacity. Lastly, to be commissioned in Q4 of 2023, the Redstone plant will be a 100MW molten salt system with an impressive 12-hour storage capacity.
In Egypt, the Benban Solar Park is noted for being one of the largest solar parks worldwide, comprised of several CSP plants combined with PV modules. In addition, the country’s 20MW ISCC Kuraymat power plant has been operational since 2011 and uses wet cooling and SST-900 turbines.
With an annual DNI of up to 3,000kWh/m2, CSP technology fits the country’s energy needs well. In 2022, the government concluded a pre-feasibility study to establish CSP plants and identified more than 33,000km2 of available land with a theoretical potential of more than 250GW of CSP.
In addition, NamPower is considering a 150MW CSP plant in Arandis (the preferred site) or Karibib under a build, own, operate, transfer (BOOT) agreement. Since the Karibib site is only suitable for parabolic trough technology, NamPower is investigating other locations in the region so that Molten Salt Tower technology can also be considered. Through a long-term power purchase agreement, the utility envisages itself as the sole offtaker.
CSP technology has the potential to play an essential role in the global energy transition, providing clean and reliable electricity. In addition, concentrating solar facilities can produce hydrogen, which can be blended with natural gas, and offer low-carbon liquid fuels for transport and other end-use sectors.
In particular, North Africa is considered a good CSP market to export surplus power to neighbouring regions, such as Europe, where demand for electricity from renewable sources is increasing.
With technological advancements and decreasing costs, these power plants will likely become an increasingly important part of Africa’s renewable energy mix in the coming years.
However, for CSP to claim its position in the energy transition, developers, governments and financing institutions need speedy action to commission more plants. ESI
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