Not all forms of solar energy are as expensive or inefficient as others. Solar energy takes on many forms. Did you know that burning wood is a form of solar energy? The energy given off by the sun, by the reaction of photosynthesis, draws in carbon dioxide and changes that into oxygen and carbon. The carbon is actually the matter created out of the gas, CO2, by the energy of the sun. That matter, in this case, becomes the cells that make up the wood in the oak tree that you cut down, chop up, and burn in your wood stove to heat your house.
Throw all the leaves from the tree in a contained mulch pit. Feed it some air including some of that oxygen that was released when the tree was growing. Introduce some microbes, if they haven’t already crashed the party, and as these tiny organisms breathe the air and eat this carbon based plant matter, they fart a lot. They also like to feast on garbage. This methane gas can then be burned for energy. Modern landfills are making very efficient cost effective use of this first cousin once removed of solar energy. They are trapping and burning these gazillions of micro-farts, turning water to steam used to power turbines that spin generators to produce electricity. Ten years ago, I installed one of these fart burners at a landfill in Massachusetts for an overall cost of $150,000.00.
Wind is one of the cleanest forms of solar energy. Heat from the sun causes temperature changes all over the surface of the earth. As warm air moves toward cold, you have wind. Prop up a propeller in the midst of all this movement energy and it will spin and turn a generator, producing electricity. Wind also causes waves to swell on the worlds oceans. The Japanese have developed floats that by riding the waves up and down compress air that is then used to power on-shore pneumatic turbines attached to generators that again produce electricity.
Solar energy stores itself in these “batteries” like plant matter, or dirt that makes up the earth’s surface that releases it again causing wind. It seems that the most efficient and least expensive forms of solar energy are the type that draws it out of these “batteries.” The more direct types of solar energy are not as cost effective yet. Photovoltaic cells are an example of direct solar energy to electricity.
Photo voltaic cells are intricate and utilize expensive materials and manufacturing processes in their construction. Hopefully, as is the case with everything from plasma TV’s to semiconductors, these processes and materials will become less expensive as systems improve. Inefficiency is another problem with this direct solar energy to electrical energy system. Photons -part of sunlight, that are absorbed by the cells are what produce the electrical energy. The problem is that photons come down on the panels at all different “energies” and certain types of cells can only use photons at certain energies. About 85% of the photons go to waste.
Another direct form of solar energy that has a high expense to efficiency ratio is found in something called a High-Flux Solar Furnace. Simply described, this is a bunch of specially designed mirrors that gather the sunlight / solar energy and reflects it as it focuses it into a furnace. This focused energy can burn through ¼” thick steel plate! When this energy is used to create steam for instance, that steam will transfer its energy to turn a generator’s turbine. Not only are these mirrors expensive to construct but they also need to be attached to a device that can move it precisely to follow the sun as it redirects the energy to the furnace.
The most efficient, least expensive use of direct solar energy can be taken advantage of in the planning stages of home construction. Although this energy will not produce electricity, it will produce heat –without the wood middle man mentioned in the first example. Windows constructed to have insulating properties, and positioned to receive the most golden rays of sunlight possible can be used in combination with a heat sink. A heat sink is a simple mass of matter, like concrete or even barrels of water that will absorb this energy while it’s available –daytime, and release it when it isn’t –nighttime. Now you are using the energy directly from the sun to heat an entire home without burning any carbon fuels. A home designed to use the sun’s bounty of energy can be considered a completely free mechanism for the collection and utilization of solar power because of multi-purposing. The concrete and glass and labor is all necessary for the purpose of shelter. Strategic planning in the use of these materials can produce the byproduct of heat for this structure with virtually no additional cost.
