Spatial assessment of solar energy potential at global scale. A geographical approach

Abstract

Solar energy is a key renewable source for decarbonization and the future sustainable development of human society. However, the success of the worldwide governments in the large-scale implementation of solar technologies largely depends on the in-depth knowledge of global solar radiation distribution and intensity levels, which is a difficult endeavour due to the fact that up-to-date global-scale information is generally limited. This study primarily aims to analyse solar radiation distribution and intensity globally, continentally (all continents, except for Antarctica) and nationally (194 countries), based on the global horizontal irradiation (GHI) and direct normal irradiation (DNI) data, released at the best spatial resolution currently available in reliable international databases. By means of a statistical analysis of seven potential classes, delimited based on established geostatistical methods, the results showed that, globally, there are 6 major GHI hotspots (western South America, northern, eastern and southwestern Africa, the Arabian Peninsula and Australia), with annual values of >2200 kWh/m2, and 6 other well-defined DNI hotspots (southwestern North America, western South America, southwestern Africa, northwestern Arabian Peninsula, Tibetan Plateau and Australia), with values of >2500 kWh/m2. These regions, with the most intense solar radiation values, assigned to the seventh potential class (superb) of the two parameters, comprise most of the total global GHI (∼15 mil km2, 10% of the world's land area) and DNI (∼8 mil km2, 5%) superb class areas. Continentally, Africa holds the most considerable GHI solar resources (almost 10 mil km2 of the superb class, approximately one third of the continental area), while Australia holds the most abundant DNI resources (∼4 mil km2, ∼50%). Nationally, there are 12 epicentre countries for GHI, considering at least 50% superb potential threshold within national limits (9 in Africa – Namibia, 96%, Sudan, 86%, Niger, 84%, Egypt, 77%, Western Sahara, 72%, Chad, 69%, Eritrea, 58%, Libya, 56%, and Djibouti, 52%, and 3 in Asia – Oman, 92%, Yemen, 87%, and Saudi Arabia, 74%), while for DNI only 3 countries reach this percentual threshold of the maximum solar potential (Namibia, 77%, Jordan, 53%, and Australia, 51%). Our results suggest these epicentre countries (as well as others with extensive absolute GHI and DNI superb class areas, such as the US, Mexico, Chile, Peru, Bolivia, Argentina and China) are among the most favourable for the large-scale installation of photovoltaic and concentrating solar power systems, which are currently the most important technologies used in solar energy production.