Egypt is showing the way in the Middle East and North Africa when it comes to solar-thermal power

By CSP Today staff writer

Several nations in the Middle East have increasingly shown signs of embracing solar-thermal power generation, and Egypt is one of them.

The construction of the first parabolic trough solar field in Kuraymat, south of Cairo, began in late 2008. The hybrid power plant, with an output of 150MW, uses both natural gas and solar thermal energy.

Egyptian general contractor Orascom Construction Industries, together with the German technology company Flagsol GmbH, a subsidiary of Solar Millennium AG, is carrying out the design and construction, with the plant due for completion in summer 2010.

“About 25% of the solar field is erected,” said Paul Nava, managing director of Flagsol, who will speak at the CSP, CPV and Thin Film Summit MENA, scheduled to take place in Abu Dhabi in June 2–3) this year.

Financial support, from both local authorities and international financial institutions, is one of the pillars of this project. The global environment facility (GEF) offered $50 million in grant, and Japan Bank for International Cooperation (JBIC) contributed $200 million as soft loan. Total investment is estimated to be over $300 million.

Ideal location on Nile

The location of the hybrid power plant, on the banks of the Nile 95 kilometres from Cairo, with an annual direct-normal irradiation of over 2,400KwH per square metre, is considered ideal for solar-thermal power plants. It comprises high annual direct normal irradiation, flat land, access to natural gas, cooling water and connection to the grid.

“Due to the proximity to an existing combined cycle power plant in Kuraymat, all required infrastructure, like grid connection, gas piping, water and access roads, are available,” said Nava.

The solar field consists of parabolic troughs with a total mirror surface area of 130,000 square metres. The collector rows, six metres wide and 150 metres long, are assembled on site, segment by segment, in a purpose-built facility.

The high-precision optical collectors consist of a steel frame, surmounted by parabolic mirrors and absorber pipes. The key components are produced in Germany by Schott Solar and Flabeg. During the 10-month solar field mounting period, a total of 53,000 mirrors will be required.

The ISCCS approach

Solar energy from a parabolic trough solar field can be integrated with a combined cycle to increase the efficiency ever further and to decrease the already low emissions. This is accomplished in an integrated solar-combined cycle system (ISCCS).

The setting up of hybrid energy centres, i.e. combining two renewable resources abundant in a particular area, is gaining momentum.

All projects in markets like Morocco, Algeria and Egypt are ISCCS, with a limited solar share.

“This limited solar share limits the cost increase and is an excellent way to start the use of CSP,” said Nava.

The ISCCS calls for part of the heat recovery steam generator to be either replaced or parallelled by equipment serviced by solar thermal energy to supplement turbine exhaust gases. This approach increases thermal energy input, which produces more electrical output.

According to Flagsol, the system design may be thermodynamically optimised by having the exhaust gas and/or the solar thermal energy give up its heat at points in the steam cycle where local heat transfer fluid temperatures are compatible with the local steam temperature, i.e. all heat transfer processes take place at reasonably small temperature differences.

Question of integration

In general, the main consideration for achieving optimal results is related to system integration from solar heat into the combined cycle. On the one hand, thermal energy from the solar field can be converted into electricity with higher efficiency compared with a solar only rankine cycle, as the heat from the flue gas allows a higher temperature level for the water steam cycle. The downside is that the steam turbine operates at partial load efficiency when sunlight is not available.

That optimisation is considered to be the most challenging design task.

Costs

New hybrid systems that combine large CSP plants with conventional natural gas combined cycle or coal plants can reduce costs to $1.5 per watt and drive the cost of solar power to below 8 cents per kilowatt hour. With new competitors in the market, Flagsol expects the prices to drop.

Solar radiation

The amount of solar radiation available in Egypt is estimated to be between 1,900KWh per sq metre per year in the north and 2,600KWh per sq metre per year in the south. If the average for the country is taken as 2,300 KWh per sq metre per year, then there are at least 230 billion KWh of solar radiation.

CSP, CPV and Thin Film Summit MENA

Paul Nava, managing director of Flagsol, is scheduled to speak at the CSP, CPV and Thin Film Summit MENA in Abu Dhabi in June (2–3) this year.

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or Contact: Sara Lloyd-Jones by email sara@csptoday.com