Most Recent Trends
Visit the Worldwatch Institute Bookstore to download and purchase more of Worldwatch's award-winning research.
Solar Thermal Heating Up Sharply
Solar thermal heating worldwide expanded by 19 gigawatts of thermal equivalent (GWth) with the highest annual growth rate since 1995 to reach 147 GWth2 (210 million square meters (m2)) of capacity in 2007.1 (See Figures 1 and 2 on solar water heating—a subset of solar thermal heating applications.) Water heating for domestic uses accounts for 126 GWth (180 million m2), or 86 percent of all installations, while space heating, swimming pool heating, and industrial processes account for the remaining 21 GWth (30 million m2).2 Preliminary estimates for global solar thermal heating suggest additions of between 18 and 19 GWth in 2008, mostly in China.3
The most mature of solar technologies, solar thermal heating harnesses the sun’s energy for domestic water heating, space heating, swimming pool heating, and drying and other industrial processes. Solar thermal systems can also meet cooling needs by fueling a compressor driven by heat rather than by traditional mechanical energy. It is one of the most widely used renewable heating technologies and the only one to produce energy at levels comparable to renewable power, second only to wind in terms of energy produced annually.4 Solar thermal heating produced enough energy globally in 2007 to meet the equivalent heating needs of 15 percent of U.S. households.5
China, by far the largest market, has two thirds (79.9 GWth, 114.1 million m2) of global capacity and, despite a one-third decrease in new installations to 16 GWth (22.9 million m2) in 2007 compared with 2006, accounted for 80 percent of newly installed systems in 2007.6 (See Figure 3.) Solar water heating in single-family homes accounts for nearly half of all uses and 97 percent of new installations.7 The remaining applications are split between multi-family homes and hotels, where the other 3 percent of new installations took place.8
For full access to the complete trend and its associated charts, log in to Vital Signs or:Subscribe to all vital signs trends
Annual subscribers to Vital Signs Online have full access to all our trends and charts.