This paper summarizes the findings of a study undertaken by the European Academies Science Advisory Council to evaluate the development challenges of concentrating solar power (CSP) and its consequent potential to contribute to low carbon electricity systems in Europe, the Middle East and North Africa (the MENA region) to 2050. The study reviewed the current status and prospective developments of the four main CSP technology families, and identified prospective technical developments, quantifying anticipated efficiency improvements and cost reductions. Similarly, developments in thermal energy storage were evaluated, and the role and value of CSP storage in electricity systems were examined. A key conclusion was that as the share of intermittent renewables in an electricity system increases, so does the value of thermal energy storage in CSP plants. Looking ahead, the study concludes that CSP should be cost competitive with fossil-fired power generation at some point in the 2020’s provided that commercial deployment continues at an increasing rate, and through support mechanisms that incentivise technology development. Incentive schemes should reflect the real value of electricity to the system, and should ensure sufficient transparency of cost data that learning rates can be monitored. Key factors which will determine CSP’s contribution in Europe and the MENA region over the period to 2050 are generating costs, physical constraints on construction of new plants and transmission, and considerations of security of supply. The study makes recommendations to European and MENA region policy makers on how the associated issues should be addressed.

To improve the energy efficiency of an industrial process thermochemical energy storage (TCES) can be used to store excess or typically wasted thermal energy for utilisation later. Magnesium carbonate (MgCO₃) has a turning temperature of 396 °C, a theoretical potential to store 1387 J/g and is low cost (~GBP 400/1000 kg). Research studies that assess MgCO₃ for use as a medium temperature TCES material are lacking, and, given its theoretical potential, research to address this is required. Decomposition (charging) tests and carbonation (discharging) tests at a range of different temperatures and pressures, with selected different gases used during the decomposition tests, were conducted to gain a better understanding of the real potential of MgCO₃ for medium temperature TCES. The thermal decomposition (charging) of MgCO₃ has been investigated using thermal analysis techniques including simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC), TGA with attached residual gas analyser (RGA) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (up to 650 °C). TGA, DSC and RGA data have been used to quantify the thermal decomposition enthalpy from each MgCO₃.xH₂O thermal decomposition step and separate the enthalpy from CO₂ decomposition and H₂O decomposition. Thermal analysis experiments were conducted at different temperatures and pressures (up to 40 bar) in a CO₂ atmosphere to investigate the carbonation (discharging) and reversibility of the decarbonation–carbonation reactions for MgCO₃. Experimental results have shown that MgCO₃.xH₂O has a three-step thermal decomposition, with a total decomposition enthalpy of ~1050 J/g under a nitrogen atmosphere. After normalisation the decomposition enthalpy due to CO₂ loss equates to 1030–1054 J/g. A CO₂ atmosphere is shown to change the thermal decomposition (charging) of MgCO₃.xH₂O, requiring a higher final temperature of ~630 °C to complete the decarbonation. The charging input power of MgCO₃.xH₂O was shown to vary from 4 to 8136 W/kg with different isothermal temperatures. The carbonation (discharging) of MgO was found to be problematic at pressures up to 40 bar in a pure CO₂ atmosphere. The experimental results presented show MgCO₃ has some characteristics that make it a candidate for thermochemical energy storage (high energy storage potential) and other characteristics that are problematic for its use (slow discharge) under the experimental test conditions. This study provides a comprehensive foundation for future research assessing the feasibility of using MgCO₃ as a medium temperature TCES material. Future research to determine conditions that improve the carbonation (discharging) process of MgO is required.

A considerable effort is devoted to devising retrofit solutions for reducing space-heating energy in the domestic sector. Existing UK solid-wall dwellings, which have both heritage values and historic fabric, are being improved but they tend to have meagre thermal performance, partly, due to the heat-loss through glazings. This paper takes comparative analyses approach to envisage space-heating supply required in order to maintain thermal comfort temperatures and attainable solar energy gains to households with the retrofit of an experimentally achievable thermal performance of the fabricated sample of triple vacuum glazing to a UK solid-wall dwelling. 3D dynamic thermal models (timely regimes of heating, occupancy, ventilation and internal heat gains) of an externally-insulated solid-wall detached dwelling with a range of existing glazing types along with triple vacuum glazings are modelled. A dramatic decrease of space-heating load and moderate increase of solar gains are resulted with the dwelling of newly achievable triple vacuum glazings (having centre-of-pane U-value of 0.33 Wm-2K-1) compared to conventional glazing types. The space-heating annual cost of single glazed dwellings was minimised to 15.31% (≈USD 90.7) with the retrofit of triple-vacuum glazings. An influence of total heat-loss through the fabric of solid-wall dwelling was analysed with steady-state calculations which indicates a fall of 10.23% with triple vacuum glazings compared to single glazings.