SYDNEY — Australian researchers say a simpler and cheaper method to remove salt from seawater using heat could help combat what they call “unprecedented global water shortages.” The desalination of seawater is a process where salt and impurities are removed to produce drinking water. Most of the world’s desalination methods use a process called reverse osmosis. It uses pressure to force seawater through a membrane. The salt is retained on one side, and purified water is passed through on the other. Researchers at the Australian National University (ANU) say that while widespread, the current processes need large amounts of electricity and other expensive materials that need to be serviced and maintained. Scientists at ANU say they developed the world’s first thermal desalination method. It is powered not by electricity, but by moderate heat generated directly from sunlight, or waste heat from machines such as air conditioners or other industrial processes. It uses a …