This book highlights the importance of geothermal energy by studying its potential either alone or in combination with solar energy, focusing on its industrial application. Its starting point is to identify in a thorough and precise manner the barriers that hinder the implementation of geothermal energy in Spain and the European Union and the measures to be taken to achieve its diffusion and regular use. Next, the book looks at how geothermal energy could contribute to this sector and to the desalination industry in particular, analysing a specific case in the south of Spain and extrapolating its results to a set of existing desalination plants in the Spanish Mediterranean with really interesting results in terms of economic amortisation and CO2 emissions avoided to the atmosphere. Beyond the desalination industry, this work demonstrates that almost 85% of the industrial processes of all industry in Spain can be carried out with very low, low and medium temperature geothermal resources and even applies its results to a set of existing solar plants, comparing in economic terms the results already obtained with those that would have been obtained if geothermal energy had been applied.