Childhood games are more meaningful than one would think. I well remember the fun I used to have with a magnifying glass focusing sunlight on a piece of paper and watching it eventually burst into flame. Looking back this was an indication of the power of the sun and a good example of a potential alternative energy source as we look ahead toward additional power to run the world in the future.

The most recent National Geographic has a major article on sun power and the technology being used in various places to convert it to every day purposes, "Plugging into the Sun" (Sept 2009). A subhead summarizes the potential, "Sunlight bathes us in far more energy than we could ever need - if we could just catch enough".

The article emphasizes two major directions being examined. Much has been written about photo-voltaics, the direct use of solar panels to provide heat and electricity locally. The second idea is redirection of the sun's rays using mirrors to concentrate energy, creating steam for operation of turbines hence generation of electricity.

A friend living on Manitoulin Island added a solarium adjacent to the kitchen on the south side of their house. Solar panels added heat below ground warming up the stone floor.

On a bright sunny winter day windows in the kitchen were opened providing heat through most of the house, and the solarium was kept from freezing year round facilitating an early start to vegetable seedlings for planting into the garden. I have written before about Rizhad a Chinese city of 3 million people which is largely self contained for electrically heated water using photovoltaics (State of the World, 2007). Use of solar panels on roof tops has a great potential for hot water heating anywhere in the world, minimizing the use of electricity in offices and other urban and rural buildings. One picture in the National Geographic shows workers installing 14 acres of warehouse roof with lightweight photovoltaics providing a power source for 1300 homes.

A major project in southern Spain has established mirrors to "catch some of the 120 quadrillion watts of sunlight that constantly fall on Earth". Mirrors are programmed to rotate reflecting the sun's rays during the day so as to focus on oil-filled pipes which heat water creating steam to turn turbines and provide electricity. An American project has 182,000 curved mirrors on 250 acres of the Mojave Desert programmed to follow the sun and focus light beams on a solar tower providing electricity for the national grid, enough to supply the needs of 14,000 homes. There have been thoughts of utilizing the Sahara desert, an area larger than the U.S., for solar panels with electricity transported below the Mediterranean to Europe.

The major problem with any source of alternative energy is continuous supply. Solar energy obviously operates during daylight hours. Supply is a technical concern but storage of electricity for supply during hours of darkness is a more serious problem. The National Geographic article describes some efforts for storing heat in molten salt. Storage in batteries is cumbersome hence limiting for long range vehicle travel.

Considerable research is going into hydrogen for the next generation of vehicles which emit no carbon dioxide. When they are finally successful in producing cars running on liquid hydrogen much excess electricity will be utilized separating water into hydrogen and oxygen. Hydrogen can be liquidized, stored and distributed to supply our energy needs.

Solar energy is apparently one of the most promising directions for us to take as the supply of fossil fuels diminishes. Wind power, energy from tides, heat from geothermal sources are others while global effort is going into natural energy production such as ethanol, biomass, cellulosic biodiesel and oil from Jatropha seeds.

As previously noted the future promises to supply unlimited quantities of non-polluting energy such as power from the sun. Technology must concentrate on the task of storing such energy and the even greater development of distribution systems having adequate capacity for use in homes, offices, industries and many millions of vehicles.

The world of the 22nd century will undoubtedly be much different to that to which we are accustomed today.