7.27.2014

Can Africa's desert sun power Europe?

Up to 20% of power demand in Europe can be obtained by connecting African deserts to European cities, according to the DESERTEC Foundation. The idea is to build a large number of concentrated solar power (CSP) plants in Middle Eastern and Northern African (MENA) countries, and to transmit electricity to Europe by means of efficient high-voltage direct-current cables.
CSP in deserts, as explained in greater detail below, has the potential to generate renewable electricity, predictably, for up to 16 hours per day, thus overcoming two major problems with photovoltaic and wind power: intermittency and few operation hours.
A prominent technology roadmap of the International Energy Agency published in 2010 had optimistic prospects for CSP, and projected a significant amount of electricity transmission from MENA countries to Europe – up to 15% of total electricity consumption in 2050 (see IEA 2010).
The DESERTEC project has lost traction since Siemens withdrew from the partnership in October 2012, but the idea of building a trans-Mediterranean power grid is still attractive for many proponents of a quick transition towards a zero-emission European power system.
The main questions we address in this column are the following:
  • Is it economically, technologically and politically feasible to cover a large fraction of power demand in Europe from the MENA deserts?
We answer these questions by relying on numerical scenarios generated using the integrated assessment model WITCH to study when, how much and where it is optimal to invest in CSP, and what the potential size of an EU–MENA power market is (Massetti and Ricci 2013). We find that it is premature for Europe to invest now in large CSP projects. There is scope for pilot projects, but large economic benefits from trans-Mediterranean CSP trade emerge only from 2050 onward. However, the threats to European energy security from extensive trade in electricity with MENA countries should not be underestimated.
The need for a carbon-free power generation system
Europe is setting increasingly strict greenhouse gas emission-reduction targets, with the intent to lead the world in the fight against climate change. If Europe truly aims at achieving the heralded +2°C temperature limit, more stringent targets will follow because aggregate emissions must basically drop to zero.
With uncertain prospects in Europe for both nuclear power and fossil-fuel power plants with carbon capture and storage, renewables will likely play a major role in the future technology mixture. The problem with renewables such as wind and photovoltaic is that they are intermittent – winds are erratic and the sun does not shine at night. A power system that relies on wind and photovoltaic for the bulk of its generation capacity must be upgraded with new transmission and distribution grids, with storage capacity and backup capacity. This is expensive and thus penalizes renewable technologies, compared with coal or natural-gas thermoelectric power plants (EPRI 2011 and IEA 2014).
Concentrated solar power
The ideal technology should provide steady, adjustable, predictable power from totally renewable sources. CSP generation is very close to this optimum. The idea is extremely simple and as old as Archimedes’ mirrors during the Siege of Syracuse – reflecting surfaces are used to concentrate direct sunlight in a narrow area to heat a fluid. The fluid is collected and used to transform water into steam, which is then used to rotate a turbine in a thermoelectric plant. Direct sunlight substitutes coal and gas. The temperature reached by the fluids during the day is so high that it is possible to store heat for most of the night and generate an almost continuous stream of power. A natural gas turbine may complement the system to guarantee 24-hour power generation.
The major drawback of CSP is that it needs virtually cloud-free sky (unlike photovoltaic, which works well even under cloudy skies). The best sites for CSP are deserts because the lack of humidity largely reduces average cloud coverage. Deserts also offer large inexpensive areas of land to host large expanses of mirrors. The problem is that deserts are usually not close to where people live and work. The idea is then to use new generation transmission cables that have minimal power losses to connect deserts to cities.
With a few exceptions in Spain and in southern Italy, Europe lacks the best climatic and geographic conditions for CSP. A large-scale development of CSP is not possible in Europe. However, many of the states on the southern Mediterranean shore have an abundance of deserts with ideal climatic conditions – hence the plan to build a network of cables up to central and northern Europe.
Economic, technological and political feasibility
CSP is a proven technology that can work on a large scale. The leading country is Spain, with 2300 MW of installed capacity, followed by the US, where four plants became operational in the past 10 months, reaching 1435 MW of total installed capacity. More plants are to come in 2014 and the following years in the US, China, India, South Africa, and other countries in the Middle East and Northern Africa (Figure 2).
Is CSP economically attractive? At present, CSP power generation is four or five times more expensive than fossil power generation (see IPCC 2011). Of the investment in CSP, 98% so far has needed public support (Stadelmann et al. 2014). But how would investment incentives change if carbon emissions start being penalized and learning-by-doing contributes to reductions the investment and operation costs of CSP? Will a climate-friendly investment environment incentivize large investments in CSP, and will it become attractive for Europe to import CSP from the deserts of Africa and of the Middle East?>>>

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