Salt is the new key ingredient to harvest concentrated solar power

If the Middle East and North Africa (Mena) region is to supply Europe with a steady supply of reliable electricity, it will need a technology that does not fail on a cloudy day, and can deliver long after the Sun has dipped below the horizon. 

This is where concentrated solar power (CSP) comes into its own. While conventional solar uses light waves and converts them to electricity, CSP uses the Sun’s heat. Hundreds or even thousands of mirrors focus the Sun’s rays on a point. Usually the rays are directed onto a salt storage unit that can get as hot as 500° Celsius. The salt in turn provides heat to generate steam.

The big advantage that CSP has over other renewables technologies is that the salt retains its heat long after the Sun has set. It is also unaffected by the occasional cloud passing overhead. The biggest CSP plants can therefore theoretically provide electricity around the clock, long after the Sun has gone down.

Abu Dhabi’s Shams 1, and other projects such as Morocco’s Noor 1, are among the pioneers of this technology. Around 10 years ago, CSP cost significantly more than regular solar to build, but in recent years the price has fallen. 

“I expect concentrated-solar power, within 18 months, to be head-to-head with combined-cycle gas, if not more competitive,” Acwa Power International chief executive Paddy Padmanathan told Bloomberg in July. “The focus has been on PV and batteries, but there’s a limit on how long they can hold a charge for. We’re proving that CSP can work through the night.”

For now, much of the Mena region depends on oil and gas for energy. Some countries, such as Morocco, spend upwards of US$3 billion a year on fuel and electricity imports. At the same time, Morocco’s power demand is growing at a rate of 6.5 per cent a year. Morocco is working to overhaul its electricity sector. Last year the Noor 1 CSP plant came on line, and more are set to follow.  In time Morocco hopes to become less dependent on imports, while participating in the European market for energy. An undersea power line already connects to Spain, and the country is in talks with Portugal to build another undersea cable linking the two countries.

It is not only the Mena region looking at renewable exports. Australia is now looking at the feasibility of transporting solar power from the Pilbara and Kimberley regions to Java in Indonesia, entailing a 2000-kilometre undersea transmission cable. 

Undersea cables do, however, have a drawback; outages from damage caused by fishing boats or other factors can cause power losses that last for months. The island of Tasmania suffered through a six-month electricity crisis after its electricity interconnector failed in late 2015.  

Australia is exploring another use of solar – using it to cheaply convert sea water into hydrogen. By splitting a water molecule, hydrogen is harvested and this in turn can be converted into electricity via a fuel cell. These cells generate electricity through a chemical reaction with hydrogen, and leave no waste or emissions.

Japan is one of the biggest proponents of this technology, and is heading towards what it calls a “hydrogen economy”. But because splitting hydrogen from water is energy intensive, the process has been slow to catch on. Australia and Japan are now talking of large-scale solar-hydrogen projects that will create large quantities of the gas to be shipped in ocean-going tankers.

For the meantime the lead in developing CSP will be in the Arabian Gulf, the natural home of energy production. In time as the age of oil draws to a close, Middle Eastern countries will continue to power large parts of the world economy, only this time using Sunlight instead.