Harnessing Solar for District Energy: Europe leading the way

Countries around the world are increasingly recognizing the sun’s tremendous potential as a renewable energy source. According to the U.S. Department of Energy, every hour, more energy from sunlight strikes the Earth than is consumed on the planet in a year. In Europe, many large-scale centralized solar heating systems have been taking advantage of this abundant, environmentally friendly energy source for the past 30 years. In Europe today, there are about 20 million sq m (215 million sq ft) of glazed solar collectors used in a variety of applications, corresponding to about 14 gigawatts of thermal power (GWth). Most of those collectors provide heat for or serve small thermosiphon domestic hot water systems with just 2-3 sq m (21.5-32.3 sq ft) of collectors. Perhaps 10 percent of the total number of systems are hot water plus heating, while very few are used for heating only. About 1 percent of the European collector market comprises large-scale centralized heating applications, with heat loads up to several GWth. About 9 percent of the heating loads in Europe is served by large-scale centralized heating systems (i.e., district heating and ‘block heating’ systems). There is thus a need and opportunity to connect solar heating applications to large-scale centralized heating systems. According to the European Solar Thermal Technology Platform (ESTTP), that is indeed feasible if Europe adopts a more progressive solar district heating policy