For years, the idea of generating solar power for Europe in the Sahara was dismissed as pure fantasy. But then all of sudden it was happening, and Desertec was making headlines worldwide.
The Desertec Industrial Initiative (DII), a consortium of 12 large companies, plans to cover thousands of square kilometers of the Sahara Desert with solar thermal energy collectors. According to the plan, solar power from the desert will sate an energy-hungry world, a world in which oil reserves are dwindling and in which the climate is changing as a result of the use of oil, coal and gas reserves.
The amount of energy that the sun provides every day over the Sahara is so huge that solar plants covering 90,000 square kilometers of desert would be enough to provide the whole world with clean, emissions-free energy. Yet that whole area would be little more than just a glittering speck in the vast expanse of desert, which covers some 9 million square kilometers.
Until now, however, the whole thing has been little more than a mathematical exercise. A fossil fuel-based energy industry which has developed over decades is not going to switch to solar energy overnight. Which is why DII's current goals are relatively modest, namely to cover 15 percent of European electricity needs with energy from the desert by 2050.
With Desertec, low-tech will meet high-tech. The idea itself is a simple one. The sun's rays are collected, water is converted into steam, and this is then used to power turbines. No complicated atomic fusion, no silicon solar cells, no CO2 stored underground -- just solid engineering, which was already being used in Egypt almost 100 years ago.
The challenges lie in the details. How does one improve this sort of simple technology so that it becomes a valid competitor to coal-fired and atomic power?
German engineers are currently working on these issues. And they are having some success. Solar thermal power plant efficiency is nearing the 20 percent mark. And German experts believe that, by 2020, the energy coming from the desert will be cheaper than that from conventional power stations in Germany.
Next week, the world will be meeting in Copenhagen to discuss reductions in CO2 emissions, in a bid to keep global warming in check. Desertec is one example of what a clean, climate-friendly power source could look like.
The State of Solar Power Today
There are four ways of collecting the sun's energy: with parabolic troughs, Fresnel reflectors, solar towers or solar dishes.
According to Nikolaus Benz, the head of Schott Solar CSP GmbH, parabolic troughs are the preferred technology to date. "We have the most experience with these," Benz says. "Parabolic-trough power plants have been in operation in California's Mojave Desert for over 25 years." And they just keep running and running -- experts estimate their operational life to be about 40 years.
Parabolic troughs are made of one curved piece of glass which focuses the sun's rays onto an absorber tube, which contains a special oil. The oil is heated to 400 degrees Celsius (742 degrees Fahrenheit) and is then used to convert water into steam. That steam then drives turbines to generate electricity. Over the course of the day, the trough is tilted so that it follows the course of the sun.
Solar power plants made from these can easily be extended -- one simply builds more collectors.
Fresnel reflectors work in a similar way to the parabolic troughs, but they are not made of just one piece of glass. Instead, they are made of lots of smaller, flat pieces of mirror. This makes Fresnel reflectors less expensive, but they are also less effective. Additionally, Benz points out that nobody has as much experience with the Fresnel mirrors. "No one has built a larger solar power plant with these kinds of mirrors yet," he says.
At the moment solar power towers remain at the more experimental end of the spectrum. Mirrors around the tower focus the sun's rays upon a receiver in the collector tower. This has the advantage of generating extremely high temperatures, so that air can be heated directly to drive gas turbines -- no oil or water is needed. That increases the efficiency of the power plant.
German scientists are closely observing progress at the country's first demonstration model based at Jülich, near Cologne.
And finally, solar dishes or reflectors -- which look a lot like satellite receiver dishes -- use a combination of the technology employed by the parabolic dishes and the solar power towers.
What about Sand Storms, Desert Dunes and Lack of Water?
While every day in the desert tends to be sunny, the conditions are not always optimal. And questions about solar energy generated in the desert have arisen. These include: Can the sensitive mirrors withstand sandstorms? How exactly does one build lasting structures on shifting sand dunes? Where will the project get the required water -- which will be turned into steam -- in the middle of the desert? Finally, how will the project make power during the hours of darkness?
Solar thermal power has one big advantage over photovoltaic solar power systems. It produces heat, which can easily be stored -- in fact, much better than electricity. Giant tanks containing thousands of tons of potassium and sodium nitrate molten salt are attached to the solar power plant. The chemicals involved are not at all poisonous; they are the same ingredients as can be found in ordinary fertilizer. Some of the heat produced during the day is then stored in the tanks and, at night, this stored heat can keep the turbines going for another 7.5 hours.
As for sand storms in the desert, there are nine power plants working with parabolic dishes in California's Mojave Desert, and they have been there for over 20 years without any issues. As Lars Schnatbaum-Laumann of the company Solar Millennium AG, which is currently building its third solar power plant in Spain, explains, should a sand storm endanger them, the moveable dishes are turned to a defensive position that affords the biggest dishes protection. After the storm, it is also possible to clean the dishes efficiently. "We now have cleaning robots that automatically clean the dishes of dust and sand, with very low water consumption," Schnatbaum-Laumann notes.
Additionally, the desert floor is not a problem. "When people think of the desert they automatically think of sand dunes," he says. "But, in fact, about 80 percent of the Sahara is stone or scree."
As for water issues, a solar power plant can actually do without it, if it needs to. "Water cooling is the optimal choice," Schnatbaum-Laumann says. "But you can also cool with air if you need to. It costs the plant about 4 percent efficiency. But it's a matter of balancing things up and figuring out whether putting a plant in a place where there is more sunshine and less water is better than putting one somewhere where there is less sunshine and more water."
Can We Make Solar Power Cheaper?
One kilowatt hour of solar thermal energy costs about 20 euro cents and is therefore still more expensive than an hour of conventional power, which costs around six cents. But according to some experts, if a solar power plant is built in a sun-rich area, then the prices could fall to 18 or even 14 cents an hour.
Many experts believe prices will fall, including Nikolaus Benz from Schott Solar CSP. "By the year 2020, a kilowatt hour of solar energy will cost less than 10 cents," he predicts. If you add to that climbing oil prices, as well as the costs of CO2 emissions, solar power starts to look more and more competitive.
The first solar thermal power plants were built in the 1980s in the Mojave Desert, and they are still going. "And we are expecting operating lives of around 40 years," Benz says. "It is astounding that we can reach these kinds of values already with the first generation."
Coal power plants have been around for over 150 years and, when they started, their efficiency was around 5 percent. Which means solar thermal power has more than a few chances to become equally, if not more, efficient.
So what does a solar thermal power plant cost? "A 250-megawatt parabolic dish power pant with a salt storage facility can be built for €1 billion ($1.5 billion)," Benz says. Coal-fired power plants or nuclear plants, which have 45 and 35 percent efficiency respectively, are therefore less expensive. It is possible to build a coal-fired power plant that performs almost four times better for around €1.2 billion. However the latter requires a constant supply of fuel, which obviously incurs costs. Sunlight, on the other hand, is free.
Additionally, in the six cents that it costs to produce that one kilowatt hour of conventional energy, there are a variety of factors unaccounted for. Coal and uranium must be produced, which costs money as well as damaging the environment and creating more CO2 emissions. In addition, spent fuel rods need to be disposed of, and CO2 emissions must be dealt with.
From 2013 onwards, coal-fired power plants will have to pay for every ton of CO2 that they produce. And the underground CO2 storage that is currently being researched will also reduce the efficiency of coal-fired power plants by around 10 percent. On the other hand, a solar thermal power plant runs without emissions, has made back the energy that it took to build it within a few months of operation and will have recouped its construction costs within 20 years, Schnatbaum-Laumann enthuses.
Werner Platzer, a senior scientist at Europe's largest solar energy institute, the Fraunhofer Institute for Solar Energy Systems, points out that there are other critical points that will determine the price of solar energy. These include the fact that parabolic dishes have yet to be mass-produced -- when they are, they will be cheaper -- and the fact that only small solar thermal power plants have been built so far. It stands to reason that the bigger the plant, the cheaper the power coming out of it. Platzer also notes that the more plants that are built, the more experience we will have with solar power and the cheaper (and faster) future planning processes can be. Additionally, the technology going into solar power will only improve.
How Can Solar Power Be Transported to Europe?
Because you can't transport the raw materials that go into solar power in the same way that coal and uranium can be delivered, solar thermal power plants obviously need to be built where it is sunny. Currently we tend to build power plants close to power users. In the future, experts believe, cleanly produced electricity will be transported over long distances to consumers. To do this, only high voltage, direct-current cables will do for transporting the resulting energy back to the user -- alternating current cables would lose too much power when transporting it over such distances.
This transportation technology is proven. The German company ABB has been laying the required high-voltage direct current (HVDC) cables undersea and on land for years. "For the NorNed project, we laid a 580-kilometer-long (360-mile-long) cable between Norway and the Netherlands," says Günther Stark, head of the power grid section at ABB. The whole thing took two weeks and cost €600 million. The 11-centimeter-thick cable now connects the two countries' power grids.
The largest overland cables are currently being laid in India and China. In China, a hydropower plant in Xiangjiaba is being connected with consumers in Shanghai, over 2,000 kilometers away, via HVDC cables. The energy lost during the transport of the power is a mere 7 percent. Another advantage of these cables is, according to Stark, that "parts of a new HVDC network in Europe could also be laid underground."
State of the Solar Power Nations
The Union for the Mediterranean -- a union which groups existing EU states with several non-EU states bordering the Mediterranean Sea -- has already said that it wants to increase capacity for renewable energy to around 20 gigawatts by 2020. Of this, around 10 to 12 gigawatts is expected to come from solar thermal energy. With that, one could replace around half of Germany's nuclear power plants. The estimated cost is €82 billion.
"The Spanish government has set the goal of bringing around three gigawatts of solar thermal energy into the network by 2013," Schnatbaum-Laumann says. Algeria, Morocco, Abu Dhabi and Egypt are currently building solar thermal power plants. South Africa, China and India have also expressed great interest in the technology, Schnatbaum-Laumann adds.
The Desertec Industrial Initiative has set itself the goal of providing 15 percent of all European power needs from the desert by 2050. A good percentage of the power needs of surrounding countries in the Middle East and North Africa could also be catered for. Just to cover the European requirements would require 100 gigawatts' worth of energy producing capacity. The costs would amount to around €400 billion, spread out over the next 40 years -- €350 billion for the power plants and €50 billion for the high voltage grid.
Not Everyone Dreams the Desertec Dream
Still, critics of the Desertec initiative complain that such a project would create a new energy monopoly. Instead, they argue in favor of a more decentralized energy network.
One of the loudest critics is Hermann Scheer, the chairman of EuroSolar, the European Association for Renewable Energy, and an energy expert for Germany's center-left Social Democratic Party. "Desertec is a mirage that has not been considered carefully enough, either politically or economically," he told SPIEGEL ONLINE. "It is hardly possible to calculate the total cost of this project. There are just too many unknowns."
Scheer also fears that Desertec could lead to a delay in other renewable energy projects around Germany. In an interview with the renewable energy publication Solarmagazin, Scheer claimed that "businesses are trying to delay the required changes in energy production for another 30 or 40 years. They are trying to shift the burden of the cost onto the general public, which would be to their advantage. Desertec can really only be implemented by a handful of large companies, and it could also allow them to determine the price of electricity."
Meanwhile, Matthias Ruchser, energy expert and head of public relations at the German Development Institute, warns of the higher costs that Sahara-sourced solar power could bring. "Because solar power is more expensive than conventional energy at the moment, a framework needs to be established in the countries where the operating companies are based -- either through higher feed-in tariffs or through state-set quotas -- that plug the financial gap," he suggests. Only in this way would the billion-euro investments be worth it in the long term for private investors, he explains.
Lars Josefsson, the chief executive of the major central European energy firm Vattenfall, also thinks that the Desertec plan is unrealistic. The billions of euros required for the project are " a hell of a lot of money," Josefsson told the Financial Times Deutschland. "Additionally, the transport costs are very high. I don't think it's realistic," he said. "Europe must source its power from Europe."
In addition, the North African nations in which the solar power project would be built are unstable and Europe will become dependent on them, he says, adding that there is also the danger of terrorist attacks to consider.