This group brings together the best thinkers on energy and climate. Join us for smart, insightful posts and conversations about where the energy industry is and where it is going.


Solar Thermal by the Numbers

David Hone's picture
Chief Climate Change Adviser Shell International Ltd.

David Hone serves as the Chief Climate Change Advisor for Royal Dutch Shell. He combines his work with his responsibilities as a board member of the International Emissions Trading Association...

  • Member since 2018
  • 420 items added with 170,809 views
  • Mar 1, 2016 3:06 pm GMT

Your access to Member Features is limited.

Early in February the King of Morocco, HE Mohammed VI, opened the first phase of what will eventually become a major solar energy facility in the centre of the country. On the same day, the King also laid the foundations for Phase 2. The project is a remarkable piece of engineering, with tracking parabolic mirrors reflecting and concentrating sunlight into a heating loop, which then transfers the energy into steam and ultimately electricity from turbines. The system also includes a molten salt energy storage system which provides 3 hours of turbine operation once the sun has set.

Noor Solar

The Noor Ouarzazate Concentrated Solar Complex is being developed 10 kms north-east of the city of Ouarzazate at the edge of Sahara Desert about 190 kms from Marrakesh. Phase One of the project involves the construction of a 160MW concentrated solar power (CSP) plant named Noor I, while Phase Two involves the construction of the 200MW Noor II CSP plant and the 150MW Noor III CSP plant. Phase Three will involve the construction of the Noor IV CSP plant.

The original cost of Noor I was estimated at about $1.1 billion, but various reports show that upwards of $2 billion has been spent, although a proportion of this must be for overall site development, roads, infrastructure etc. which will benefit all of the phases. A description of Phase II can be found on the World Bank website, with an estimated cost of $2.4 billion for construction and $300 million as a cost mitigation mechanism (i.e. to lower the cost of the electricity produced during the initial years of operation).

The initial 160 MW project has a net capacity of 143 MW, producing some 370 GWh of electricity output. This equates to a capacity factor of nearly 30% which is high for solar, but reflects the nature of the location and the energy storage mechanism using molten salt. Nevertheless, in terms of total annual output, this is similar to building a 60 MW gas turbine, although the gas turbine would always be limited to 60 MW, whereas the solar facility can output at higher levels through much of the day when businesses are open and drawing on the grid.

By the end of Phase 2, total capacity of the facility will be over 500 MW, at a capital cost of some $5 billion (although The Guardian puts this at $9 billion). Annual generation will amount to some 1500 GWhrs per annum. The per capita consumption of electricity in Morocco is around 1 MWhr, so this represents electricity for 1.5 million people. In the case of the USA, it would offer power to only 130,000 people. Phases 1 and 2 will occupy a land area of some 1900 hectares (about 4.4 by 4.4 kms)

The justification for the project is interesting and can be found in one of the documents on the World Bank project site. Carbon pricing figures strongly although there are no immediate plans for a robust carbon pricing system to be implemented in Morocco. The report concludes that Concentrated Solar is not economic on the basis of conventional cost-benefit analysis (the economic rate of return is negative over the anticipated 25-year horizon of the project); the economic benefits are taken as the avoided costs of the next best thermal alternative, which is CCGT using imported LNG. To be economic at the (real) opportunity cost of capital to the Moroccan government, the valuation of CO2 would need to be US$92/ton of CO2 (calculated as switching value, i.e. NPV of zero), or US$57/ton of CO2 when calculated as the Marginal Abatement Cost (MAC). The justification for the project is largely on the basis of macro-economic benefits for Morocco (jobs, technology transfer etc.) and global learning curve benefits.

The project is situated near a reservoir and is quite water intensive. Phase 1 is water cooled, but this is not the case for the later phases. However, there is ongoing water use for cleaning of the solar reflectors. For Phase 1 alone, the water use during operation represents 0.41% of the average yearly contribution to the Mansour Ed Dahbi Reservoir in the wet years, and 2.57% of the lowest recorded yearly contribution to the reservoir. The estimated total wastewater flow to be discharged to the evaporation ponds (visible in the foreground of the picture) is 425,000 m3/year.

Finally, there is the important aspect of emissions reduction. The Noor I CSP plant is expected to displace 240,000 tonnes a year of CO2 emissions. Based on the generation of 370 GWhrs per annum, this assumes an alternative energy mix of natural gas, some oil generation and a proportion of coal. For natural gas alone with its lower carbon footprint, the displacement could fall well below 200,000 tonnes. But like all such projects, this is displacement of CO2 which may result in a lower eventual accumulation. It is not direct management of CO2 such as offered by carbon capture and storage.

The Moroccan CSP is a fascinating project, but even more so as the numbers are put down on paper. With COP22 taking place in that country in November we are bound to hear more about it.

David Hone's picture
Thank David for the Post!
Energy Central contributors share their experience and insights for the benefit of other Members (like you). Please show them your appreciation by leaving a comment, 'liking' this post, or following this Member.
More posts from this member
Spell checking: Press the CTRL or COMMAND key then click on the underlined misspelled word.
Bob Meinetz's picture
Bob Meinetz on Mar 1, 2016

David, recently there have been a spate of reports from representatives of natural gas concerns – Royal Dutch Shell, the Spark Library – posting optimistic reports for solar on TEC. None of these concerns, however, appear to be putting their money behind it.

Why not?

Robert Hargraves's picture
Robert Hargraves on Mar 1, 2016

Great article, David, with real numbers people can sink their teeth into. You presented the numbers coolheadedly; I’d have flogged them. I’ll add just one for comparison. Noor2 will cost $10/watt for electricity generated 30% of the time. The expensive Westinghouse AP1000 nuclear power plant being built in Georgia, US, cost $7/watt for electricity generated 90% of the time.

Willem Post's picture
Willem Post on Mar 1, 2016


Noor 4 will be a 70 to 80 MW PV solar plant.

For Noor 1, a CF of 0.30 with 3 hours of storage is low, but apparently the plant configuration was not optimum for a higher CF.

Noor 2 and 3 will have 7 to 8 hour storage, are more optimum, will have CFs of about 0.40.

CSP with 10 hours of storage, i.e., a bigger solar field, the CF would be 0.45 to 0.50. This allows 24/7/365 operation, but at 55 to 60% of rated output In summer, about 35% less in winter.

The optimizing is tricky, requiring many equations and many computer runs, until the sweet point is arrived at.

The projects are heavily subsidized with low cost loans and grants, but the energy is sold at about 15 c/kWh under 25 year PPAs; without those subsidies, it would be over 20 c/kWh.

Mark Heslep's picture
Mark Heslep on Mar 1, 2016

The pending Noor II appears to cost $43/avg Watt (Noor II $2.6B, Worldbank, for 200 MWpk, 60 MWavg, using CF for 3 hour CSP=0.3.) Power output will have a seasonal effect. February in Morroco is a relatively cloudy month, with sunny days falling 30% from the June peak (Figure 3 here)

A one GW nuclear plant might have been built with these funds.  A 500 MW gas plant might have been built, including a  20 year supply of gas, along with  some carbon credits bought from those who can best manage it. Justification of expensive developing world projects using a carbon cost is mirage; not cost of avoided carbon will reach poor Moroccans. 

Morroco is a developing country where the absolute poverty rate (lack of food,shelter for long period) is high,especially in rural regions where it can hit 50%.  The stunted growth rate is 15%.  Childhood illiteracy ranges from 25% nationally up to 40% in regions.  Access to potable water and electricity is “one of the lowest in the region.”  The consequences of power experiments will be real, immediate. Gross misuse, spending five or ten times the amount necessary, has the whiff of something disconnected from the Morrocan most in need of power. 

Bruce McFarling's picture
Bruce McFarling on Mar 1, 2016

In any event, this isn’t the solar they are bullish on … reducing Morocco’s diesel power generation with CSP solar is a lost sale of a LGN gas terminal and natural gas power plant.

What they would be advocating for would be Solar PV.

Nathan Wilson's picture
Nathan Wilson on Mar 2, 2016

I think it was a gamble that Desertec would happen.  The Guardian article says:

If the dreams of its architects are realised, the resulting energy will eventually be exported north to Europe, and eastwards to Mecca, as well as providing a secure source of energy at home.”

The problem is that long distance transmission is cheapest for high capacity factor, and as Willem points out, the Morrocans should be able to manage a near-baseload 50%+ for CSP with storage; however, the European love for local renewables means that the grid won’t be receptive to baseload.  And Morroco is at about the same latitude as Los Angeles (i.e. not equatorial), so daily output will be highest in the summer, when European power demand and wholesale electricity cost are low.

The Morrocans need to finds some fossil fuel if they want a piece of that action.

Robert Hargraves's picture
Robert Hargraves on Mar 2, 2016

The thermal energy storage does not improve the capacity factor, which is the average power generated to peak power generated. Energy storage does allow delivery of electricity to be spread out through the day; perhaps that is the source of the 0.40 number.

Willem Post's picture
Willem Post on Mar 2, 2016


CSP plants with 10-h energy storage have much larger solar fields.

This enables the steam turbines to operate more hours at higher outputs than CSP plants with 3-h energy storage and smaller solar fields. By reducing output at night, there would be enough stored energy to keep the plant going 24/7/365, if the weather continues to be favorable.

NOTE: CSP plants with 3-h storage need to be restarted every day with a fossil fuel boiler plant to increase the temperature of the stored liquid, and to provide steam to the steam turbines.

Such energy is STEADY, not variable, not intermittent, dispatchable, 25/7/365; a vast improvement over wind and PV solar energy.

Wind and PV solar energy are weather-dependent, variable and intermittent, i.e., therefore are not steady, high-quality, dispatchable, 24/7/365 energy sources. In New England and Germany:

– Wind energy is near zero at least 25% of the hours of the year (it takes a wind speed of about 7 mph to start the rotors), minimal most early mornings and most late afternoons. About 70% of annual wind energy is generated during October – April, and about 30% during May – September.

– PV Solar energy is zero about 65% of the hours of the year, minimal early mornings and late afternoons, minimal much of the winter, and near-zero with snow and ice on the panels. CSP with 10 hours of storage provides steady, high-quality, dispatachable, 24/7/365 energy.

– During winter in New England, PV solar energy, on a monthly basis, is as low as 1/4 of what it is during the best month in summer; 1/6 in Germany. On a daily basis, the worst winter day is as low as 1/25 of the best summer day.

– Often both, wind and PV solar, are simultaneously at near-zero levels during many hours of the year. See URL, click on Renewables. In the Fuel Mix Chart you see the instantaneous wind and PV solar %.

– Germany has excellent public records for the past 12 years showing the variability and intermittency of wind and PV solar energy.

That means, in New England, Germany, etc., without adequate and viable energy storage systems, almost ALL other existing generators must be kept in good running order, staffed, fueled, and ready to provide steady, high-quality, dispatachable, 24/7/365 energy. At higher wind energy percentages, a greater capacity of flexible generators would be required to operate at part load, and ramp up and down, which is inefficient (more Btu/kWh, more CO2/kWh*) to provide energy for peaking, filling-in and balancing the variable PV solar and wind energy.

* The CO2 reduction effectiveness of wind energy in Ireland, with an island grid, is about 52.6% at 17% annual wind energy on the grid. Peaking, filling-in and balancing of the wind energy is mostly with gas-fired, combined-cycle, gas turbine generators, as it would be in New England, unless adequate capacity HVDC lines to Canada were built to enable Hydro-Quebec to perform this service with near-CO2-free hydro energy.

The real and reactive power, and frequency and voltage of the energy of wind turbine plants are variable. These very short-term variations are due to a blade passing the mast*, about once per second, and the various wind speed velocities and directions entering the plane swept by the rotor. A plant with multiple wind turbines would have a “fuzzy”, low-quality, unsteady output. These short-term variations are separate from those due to the weather, and usually need to be reduced, such as by reactive power compensation with synchronous-condenser systems, before feeding into a grid, especially “weak” grids, to avoid excessive grid disturbances.

* This passing creates a burst of audible and inaudible sound of various frequencies; the base frequency is about 1 Hz, similar to a person’s heart beat, and the harmonics at 2, 4 and 8 Hz are similar to the natural frequencies of other human organs. Inaudible sound, a.k.a. infrasound (less than 20 Hz), likely causes adverse health impacts on nearby people and animals, including DNA damage to nearby pregnant animals, and their fetuses and newborn offspring. Because infrasound travels long distances, a buffer zone of at least one mile would be required to sufficiently reduce these adverse impacts on people; roaming animals would continue to be exposed. See URL.

Mark Heslep's picture
Mark Heslep on Mar 2, 2016

I can see a well funded export energy play by in a scenario where the country i) already had in place minimal power sufficient to its own needs, ii) an economy in place to feed and cloth, and iii) a competitively priced project. Norway building, say,  some more hydro or Sweden some more nuclear to push across the Baltic would qualify. 

Ouarzazate is none of this.  At over $40/Watt it is solar for solar’s sake, a check mark for the World Bank and other NGOs, disconnected from the needs of desperatly poor in Morroco.  Nuclear power is not to be found in the World Bank justification report.   It follows that Ouarzazate funders have become oblivious to the main point of climate change mitigation, to assist those most likely to feel its effects. 

Get Published - Build a Following

The Energy Central Power Industry Network is based on one core idea - power industry professionals helping each other and advancing the industry by sharing and learning from each other.

If you have an experience or insight to share or have learned something from a conference or seminar, your peers and colleagues on Energy Central want to hear about it. It's also easy to share a link to an article you've liked or an industry resource that you think would be helpful.

                 Learn more about posting on Energy Central »