When most people think of green energy, wind turbines, solar panels or even hydroelectric dams spring to mind. But there are many more bizarre ways that people are trying to power the planet.
Forget toy kites on the end of a string – Makini Power in the US has developed a kite with four turbines, which can use the powerful wind speeds at high altitudes to produce energy. The finished kite will have a wingspan equal to a jumbo jet. And they are not alone: in Italy, Kitegen is developing another kite-based system. Built like a giant merry-go-round with kites attached to the edge, power is generated as the wind power pulls the base around in a circular motion.
Solar panels were invented in the 1950s and have been used increasingly in the last decade, but there are other ways of harnessing the sun’s energy. From discoveries first made in the Dead Sea, solar ponds are the cheapest way of extracting energy from the sun. An egg placed on the surface in the Dead Sea will stay runny, but a few feet below the surface it will become hard boiled. The salt content of the water at different levels traps large amounts of heat from the sun. This heat can be used to warm buildings and even drive steam turbines. A pond a few metres deep with a very high salt concentration works in the same way, even in winter when the surface is frozen over.
Solar updraft towers are another obscure solar energy source. The theory is very simple – position a large hollow chimney in a desert with a tent around the base. Heat gathers in the tent, rises up the chimney turning a fan that generates the energy. Unfortunately the prototype fell over after only a few years, but since then plans have been made to build more towers in several places around the world, including one in the Europe, which if built will be the tallest structure in Europe.
A wide variety of structures now use wave energy to generate electricity. Pelamis is probably the best-known system: built like a giant snake, it sits on the surface of the ocean and as the waves pass beneath its structure it bends, producing power.