Answers on technologies and costs
Which renewable technologies is Dii concerned with?
The focus of Dii's activities is generally the production and transportation of clean energy from the desert. Dii objectively analyses all technologies capable of producing and transmitting power. In very general terms, technologies offering the best cost-benefit-risk ratio will prove viable in the long term. Factors such as potential overall cost reductions, financial viability, baseload capacity, storage capacity, controllability, desert compatibility or lack of reliance on coolants, but also a low probability of error and simple operation, likewise play an important part.
The benefits of Concentrated Solar Power (CSP) technology are found in its baseload capacity. CSP plants can basically be operated in a similar way to gas power stations. Using CSP technology, power can be generated from solar energy for up to 24 hours a day by means of thermal storage in molten salt. Power produced from solar thermal energy has an equal baseload to energy from conventional power stations. Photovoltaic (PV) cells generate power only during daylight hours, whereby the production profile in the desert regions of the MENA territory remains relatively stable. Such technology, which is easy to instal and operate, has become economically attractive in recent years due to price developments. Utilisation of North Africa's wind energy potential also plays an important role in the Desertec vision. Wind energy can often be produced locally at market prices, and the intensity of the winds in certain regions of North Africa is very considerable.
How can concentrated solar power (CSP) plants, which rely on water, function in the desert?
A lack of water is a challenge to CSP plants. Many years of experience with solar power plants, such as in the Mojave Desert (USA), have demonstrated, however, that such systems can be cooled equally as well even if water is scarce. The steam turbine is driven by a closed water-vapour circuit, requiring only 10% of the amount of water usually needed to cool CSP plants. New technologies are also being developed which require a minimal amount of water for cleaning. Other methods entail the use of an electrostatic charge for cleaning the mirrors (and modules for PV).
Can sandstorms damage solar power plants?
Solar thermal plants in the Mojave Desert have been withstanding sandstorms for more than 25 years. If the mirrors do break (approximately 0.4% per year), replacements are covered by the operating costs. Excessive wear and tear has not posed a serious problem in the region in the last 25 years. The solar collectors of a CSP plant are adjustable and can be moved into a resting position, permitting them to withstand wind speeds of 120 km/h. The closely positioned rows of collectors also protect one another from the wind. The outer rows are usually afforded extra protection by a wind fence.
How much power can Desertec produce?
Dii itself is not an energy producer. Companies will work with the nations in the MENA territory to develop more and more projects for producing and distributing renewable energies. To show that this is a long-term development concept, Dii has specified the following objective: By 2050, desert power should be able to cover a considerable percentage (up to 100%) of local energy need in the MENA region, and up to 15% of such need in Europe. How the production and transmission volumes are likely to develop over time depends on many factors, primarily the infrastructure which is already in place or need to be expanded, as well as the difference between production costs and market prices. In the first 10-15 years, moreover, support mechanisms will be pivotal in paving the way for such development. In the years thereafter, Dii anticipates that desert power will be marketable in Europe and the MENA region.
When will renewable power from the desert prove competitively viable?
The objective when it comes to renewable energy in Europe, North Africa and the Middle East should be to become independent as soon as possible, i.e. to manage without subsidisation. In many MENA regions, wind energy has almost reached the point of profitability. Solar power is not quite so advanced, despite the excellent solar radiation conditions. The cost for photovoltaic cells and solar thermal plants are still way above the market level. We expect general market prices to rise over time (with a certain degree of volatility), however, and the costs for producing desert power to decline as the industrial learning curve progresses. Studies by the DLR in 2005 found that profitability will be achieved between 2020 and 2030. Provided investment is made in the relevant technologies, Dii predicts that the break-even point for photovoltaics will be reached before 2020 in regions with favourable climates and conditions, with that of CSP coming some years later.
What is the cost of renewable power from the desert?
The costs of producing power from sun and wind in the deserts of North Africa including transmission are roughly between 15 - 25 euro cents per kilowatt hour, depending mainly on technology, on location, solar radiation and other factors. These costs are expected to decline in the next ten years towards the 10 Ct/kWh mark, i.e. they should approach the anticipated market level. Clear cost reductions are anticipated on account of economies of scale and technological advances. Economies of scale can be achieved, for instance, by the (local) mass production of components, development and creation of larger individual projects and an industrial network of suppliers. Research and development also play an important role. At present, research is concentrated on higher process temperatures, heat storage and a general increase in efficiency (enhanced efficiency).
Is the long-distance transportation of energy (MENA -> EU) economical?
High-voltage, direct current (HVDC) transmission lines are an established form of technology which is already used successfully in submarine cables (e.g. North Sea between Norway and the Netherlands or from Italy to Sardinia and through the Adriatic) and power lines (e.g. Congo, China, India and Brazil). Profitability is determined by the structural, long-term differences between market prices and transmission costs. Today, electrical losses in HVDC lines amount to approx. 3% per 1,000 km – the costs of production in the desert are increased by the same amount. The total transmission costs (capital, operational expenses and losses) amount to approximately 1-2 euro ct/kWh for a line extending up to 1,500 km.
