Last edited 01 Mar 2017

Large scale solar thermal energy

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[edit] Introduction

Solar thermal energy is the conversion of solar radiation to thermal energy in order to heat a working fluid.

Small scale solar thermal collectors are used for heating things such as swimming pools and for building heating systems, both for residential and commercial use. This occurs at a local scale, and systems can often be fitted to existing buildings (Ecoliving, n.d.).

Large scale solar thermal collectors use mirrors or lenses to focus solar radiation; allowing much higher temperatures to be generated using a technology called Concentrated Solar Power (CSP). The temperatures generated can be used to produce electricity at an efficiency often between 30% and 40%. Over 100 MW of power can be produced by a single plant (Solar-Thermal, 2008).

[edit] Drivers for developing the technology

There are a number of drivers that have led to the recent development of large scale solar thermal energy.

  • The European Union previously set targets to reach a 20% share of energy from renewable sources and a 30% reduction (from 1990 measured levels) in greenhouse gas emissions by 2020. This motivated national governments to provide increased subsidies for renewable technologies.
  • New legislation has allowed the import of electricity generated from renewable sources outside of the EU.
  • The population of Europe is almost 740million (Google, 2011) with an average energy consumption of 125 kWh per person per day (MacKay, 2008). This large demand will be difficult to satisfy using the current transmission network.
  • Much of the existing generating capacity is approaching the end of its working life (Werenfels & Westphal, 2010).
  • The Union for the Mediterranean made the Mediterranean Solar Plan (MSP) one of its six declared priorities. This includes the production of 20 GW of renewable generating capacity in the Mediterranean by 2020 (Werenfels & Westphal, 2010).
  • Countries in the Middle East and North Africa (MENA region) are looking for cleaner, more stable means of energy production than traditional oil and gas. This has led to international initiatives looking to take advantage of the residual solar potential as a solution to Europe’s sustainable energy demands (Werenfels & Westphal, 2010; Zickfeld & Wieland, 2012).
  • Organisations such as the DESERTEC Foundation (a global civil society initiative) have been set up to promote the industry and the global transition to renewable energy.

[edit] The Potential of large scale solar thermal energy

The European Commissions Institute for Energy states that just 0.3% of the solar radiation falling on the Sahara and Middle East deserts would provide enough energy to supply the current average European consumption (Figure 2) (Greenpeace International, 2009).

The predicted 2050 electricity mix includes solar contributions of 25% from a concentration of plants in southern Europe and MENA. This mix would result in Europe meeting its 2020 vision of CO2 reductions and renewable energy input (Zickfeld & Wieland, 2012).

Europe has the potential to receive 700 TWh/y from MENA with transmission losses reduced to 10-15% by 2050 (German Aerospace Center (DLR), 2006).

[edit] The Supergrid

The production and distribution of clean renewable energy from southern Europe and the MENA region requires the modernisation and expansion of the existing electricity distribution network. This has been described as the bottleneck standing in the way of massive expansion (Werenfels & Westphal, 2010).

High Voltage Direct Current (HVDC) transmission lines will assist in the transportation of electricity produced in the MENA regions to the rest of Europe. HVDC cables spanning distances of 2,000km already exist in China, and show transmission losses of just 3 to 4 % per thousand kilometres (Werenfels & Westphal, 2010).

The European Commission believe 200 billion Euros will have been devoted to energy transmission networks in the EU by 2020. This is partly due to the 2009 EU Renewable Energy Directive requiring EU countries to “take appropriate steps to develop transmission and distribution grid infrastructure, intelligent networks, storage facilities and the electricity system”. Although this is a large investment, it is justified by the predicted 20% increase in costs of national solutions (EWEA, 2012; Europa, 2010).

The 2011 communication of the European Commission on Smart Grids identified the rollo-ut of smart grid technologies as a European infrastructure priority. Regional policy also states that 986.5 million Euros will be budgeted for the investment in Renewable energy: solar for the period of 2007-2013 (European Parliment, 2012).

[edit] Current Operations

Spain is the world leader in the development of Concentrated Solar Power (CSP) technologies, currently capable of producing enough electricity to meet 4.1% of the nation’s demand over a period of 17 hours (Solar Server, 2012). This was produced by 35 CSP plants generating 1581 MW. This amounts to 72.85% of global CSP production (EVWIND, 2012).

Large scale solar thermal energy table 1.jpg

Figure 4 - Global CSP in operation (EVWIND, 2012)

In 2011 the DESERTEC Foundation evaluated and endorsed the TuNur 2 Gigawatt CSP project in Tunisia. This has received support from the Tunisian Government and should begin electricity export to 700,000 European households by 2016 (DESERTEC, 2012; Yaros, 2012).

Morocco also plans to develop CSP, and plans to build 2,000 MW by 2020 with work on a 160 MW CSP plant commencing this year with a 2015 commission date (MASEN, 2010).

Large scale solar thermal energy table 2.jpg

Figure 5 - Global CSP in construction (EVWIND, 2012)

NB Although it has been suggested that the overall EU network needs improving if it is to meet its objectives, Imperial College London together with DNV KEMA Energy & Sustainability studied the impact of TuNur on the European network and found no significant bottleneck preventing the electricity from being traded with the UK (Nur Energie Ltd., 2012).

In February 2014, the Ivanpah Solar Electric Generating System, the world's largest solar thermal plant opened in California. It generates 392 megawatts of solar power, enough to supply 140,000 homes. The plant covers 5 square miles and contains three 450-foot solar towers.

[edit] CSP in the future

The future for large scale thermal for Europe is uncertain. Whilst the technology is mature and advanced enough to meet the demands required by the EU 2020 vision, the current European transmission network will need to be improved in order to enable Euro-Mediterranean-MENA electricity trading. For the 2020 goals to be achieved the construction of CSP facilities and infrastructure across the Mediterranean and MENA needs to begin immediately.

Political instability and unrest is also a key restraint on the development of CSP.

With the infrastructure and correct political and legal framework put in place, the potential for large scale thermal for Europe can be achieved, creating a greener future for the economies of MENA and the EU.

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