It is a spectacular vision: European households will be supplied with clean energy from african deserts. The Club of Rome has been busy thinking about this idea for a long time with its Desertec-Initiative, and now 20 corporations want to get down to business in the fight against climate change. In two to three years, these corporations (Siemens and Münchner Rück amongst them) plan to have a technological and economical concept for solarenergy out of Africa. But the hurdles seem to be unsurmountable still: Building large solar powerplants in Africa plus the very long powerlines through the desert to Europe would cost an estimated 400 billion €. And it would take ten to fifteen years for the first of the electricity to arrive.
Political support for this project is unknown at this point. The ambitious Desertec-Initiative has recieved positive feedback from Germany's secretary of the environment and other prominent green politicians. But the project, which is beeing planned under the guidance of large reinsurance company Münchener Rück, and which is supposed to end in a large private green energy powercorporation, should be a case for the European Union, says Germany's secretary of the environment Sigmar Gabriel. The critical initiatives for developing an energy consortium in the Mediterranean should take place in the EU.
The participating companies are still at the very beginning as well. A small Münchner Rück team of experts, internally dubbed "Corporate Climate Center", has been approaching big german concerns for the last months. They have all been invited for a constitutive conference on July 13th, and the interest is huge. General feedback for solarthermic powerplants in the sahara is very positive. Desertec is viewed as a visionary and exciting project. Invovled are also solarcompanies Schott, Solar Millenium and Q-Cells (largest producer of photovoltaic cells worldwide). Also the German foreign ministry, politicians from Brussels (EU HQ) and representatives of several northafrican nations stated that they wanted to attend this meeting. The focus of the initiative will be on assessing a feasability study. Concrete investments are as unclear as the leadership of the possible consortium. It is rather questionable that the inviting reinsurer Münchner Rück would be coordinating such a project itself. According to a company spokesman, Münchner Rück is willing to participate as an investor - after all, the concern is one of the largest investors worldwide. Additionally. they see a huge businesspotential for new insurance solutions.
Technically, Desertec also looks promising. The german department of environment has had commissioned a study which estimated that 65 000 km² (less than the size of Bavaria) filled with parabolic through powerplants would be sufficient to produce enough electricity to supply the global power requirements. The largest solarcomplex worldwide is currently being built in Hassi R'Mel in Southalgeria. Aside from the unstable political situation in many african countries, a huge obstacle has not yet been overcome: Sunlight may be for free, but converting it into energy and transport isn't.
DC flows over thousands of kilometers
Transporting large quantities of electricity over huge distances is not only technically possible, it has been done for years. In 2003, a 1450km long powerline with a transmission capacity of 2000 megawatt had been built between indian states Orissa and Karnataka. One year later, China had started building a 890 km long powerline with a transmission capacity of 3000 megawatt between provinces Guizhou and Guangdong. The then most efficient powerline for the time being will be opened in a few months, also in the province of Guangdong. It is a 1400km long powerline transporting emissionfree energy from a hydroelectric powerplant with a transmission capacity of 5000 megawatt, supplying the cities of Guangzhou and Shenzhen. All those powerlines use HVDC transmission technology. This technology has been around for a while. The first HVDC powerlines were built more than 50 years ago in Sweden.
The HVDC technology owes its existence to the disadvantage of conventional transmission technologies of alaternating and rotary currents through highvoltage lines. When transporting large quantities of power over large distances, the losses increase despite the converson of current to voltage. Connections that excede 1000km are thus uneconomical. And the losses increase even more with this technology if the powerlines have to be laid undergound or on the seabed in densly populated areas.
HVDC lines have no competition when it comes to transmitting energy over huge distances. The losses are around 2-3% for distances up to 1000km. Another plus is that they need less space because only 2 lines have to be laid instead of 3. The cabletrack only leaves a small aisle in the environment.
A downside of this method lies in expensive technology that is required to convert AC into DC. AC has to be converted into DC in special powerrelay stations and the reverse process has to happen at the end of the line. To achieve this, semiconductor based thyristors are necessary