Solar thermal by the numbers

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.