Influence of early colour degradation of asphalt pavements on their thermal behaviour

Environmental goals such as the reduction of fossil fuel consumption or greenhouse gas (GHG) emissions through the development of new renewable energy sources have led to the emergence of the so called asphalt solar collectors. Moreover, in recent years, engineers are devoting increased interest to the effect of the thermal loads on the mechanical behaviour of pavements. Several approaches to these topics can be found in the literature. However, a study of the influence of the colour degradation suffered by pavements on their thermal behaviour is still necessary since both the efficient application of the asphalt collectors and the proper study of the effect of the solar radiation on the asphalt pavement behaviour are directly affected by the loss of colour occurring as time goes by. Therefore, the thermal behaviour of two different asphalt mixes was studied before and after being subjected to a colour degradation process. The degradation of five different asphalt mixes was studied and the results were compared to those obtained in the access roads to seven low volume car parks. The final results show that there are large differences between the two asphalt mixes with different gradations and densities. The importance attributed by other authors to conductivity was also confirmed. Furthermore, the results showed that it was possible to simulate the early colour degradation suffered by a low volume road. Finally, a slight reduction in temperature and energy collection capacity was measured after the colour degradation process

A systematic review of enhanced (or engineered) geothermal systems: past, present and future

Enhanced (or engineered) geothermal systems (EGS) have evolved from the hot dry rock concept, implemented for the first time at Fenton Hill in 1977. This paper systematically reviews all of the EGS projects worldwide, based on the information available in the public domain. The projects are classified by country, reservoir type, depth, reservoir temperature, stimulation methods, associated seismicity, plant capacity and current status. Thirty five years on from the first EGS implementation, the geothermal community can benefit from the lessons learnt and take a more objective approach to the pros and cons of ‘conventional’ EGS systems